Memory Research That Has Practical Applications

Don't Forget. To REALLY Improve Your Memory,
Get Dr. Bill Klemm's Book on How To Improve Memory

Well, everybody has at least a casual interest in memory. My interest was a little more than casual, and it all began in high school. Like most kids, I had a lot of interests besides school (girls, sports, clubs, activities, etc.). Yet, I wanted to make good grades, mainly because by then my parents had instilled in me a desire to do well in whatever I was obliged to do. So, to do well in school – while still having time and energy to do all the other things I wanted to do – I had to learn to study EFFICIENTLY. That meant learning how to memorize things efficiently, preferably during class so I would not have to study outside of class. After I learned a few memory tricks, I was able to remember most things from class each day and what I did not get, I memorized on the school bus on the way home. My days were filled with sports (I was never any good. In football, for example, I was the lead blocking dummy), with raising my farm animals, with numerous clubs (I was President of about 4 of them and school President for two years). My evenings were filled with dating, "dragging Main Street," and listening to St. Louis Cardinal baseball games. Yet I graduated with the highest four-year average in all of the schools in Memphis, Tennessee and surrounding Shelby County. A biology teacher (that never had me in class) who knew my IQ was an unimpressive 113, spread the word that I would have trouble in college, because my success was just due to being an "overachiever" – as if that were a dirty word! My point? If you have a good memory, you can look smarter than you really are.

The next motivation came from learning about memory tricks from the Dale Carnegie leadership course. My dad was a recruiter for the course managers. He got me into the course, and I learned the memory tricks that were a part of the course. I was pretty good at it, and they decided to make me a showpiece for their memory training at the meetings where they were recruiting enrollees. At the start of the meeting, they would tell the audience: "Here is the latest issue of Life magazine. Billy Klemm is a 16-year-old who has taken the course and he will demonstrate to you the powerful memory techniques that are a part of this course. Thirty minutes from now, Billy will memorize this magazine. He has never seen it. Yet he will be able to tell you what every page is about, in any order. Or, you can tell him what is on a given page, and he will tell you the page number." Sure enough, after 30 minutes, I had memorized the magazine (and I had NOT seem it before). The audience was astonished that I could tell them what was on each page or could tell them the page number of any page that they described to me. That's heady stuff for a 16-year-old. It certainly motivated me to care about memory.

Abut this same time, I developed an interest in becoming a veterinarian. Back then, getting into veterinary school was very competitive. There were only 19 schools in the whole country and they all had smaller classes than they do now. The only veterinary college I could go to without paying out-of-state tuition was Auburn, which had a contract to take only 10 students from each of the states surrounding Alabama. So to get into veterinary school, I had to be in the top 10 from my home state of Tennessee. I relied on my memory skills to be the top one applicant. As an example of how memory skills helped me, I was stumbling in calculus, going into the final exam with an F. My problem was that I was trying to understand calculus. Finally, I gave up on understanding and just decided to memorize all the formulas and the situations to which they applied. Come final exam time, I made 100. The prof said, "Billy, I know you did not cheat. I watched you like a hawk, because I knew you were desperate to salvage that F grade. How in the world did you do it?"

Later, as a veterinary student, I discovered just how difficult that curriculum is. There is SO much to memorize. Veterinary students take all the standard medical courses (anatomy, physiology, pharmacology, microbiology, pathology, public health, etc.) and in addition take surgery and medicine courses in both large and small animal species. They have to learn about multiple species, each of which has unique biology, diseases and treatments. Well, my memory skills paid off, allowing me to graduate 5th in my class while at the same time being a weekly columnist for our national award-winning university newspaper and being active in campus politics – and enjoying courting my wife-to-be, Doris.

A few years later, I found myself working as a professor, first at Iowa State University's College of Veterinary Medicine, and then at Texas A&M University, first as a professor in the College of Science and then in the College of Veterinary Medicine. I had ample opportunity to observe student performance, good and bad. Not many years had to pass before I realized that the biggest problem that most students had was with poor memory skills. Time and again, students would complain about how hard they worked, without seeing corresponding good results on tests. They taught me many lessons about what NOT to do in studying. At least half of my time as a professor was spent in research, and my area was brain research. Inevitably, some of my research involved memory functions of the brain, ranging from consolidation of short-term memories to what happens to brain electrical activity during memory recall.

The upshot of these experiences motivated me to write a book on what scientific research reveals about how to improve everyday memory. There are over 150 ideas explained in that book that I know can help anyone. See http://thankyoubrain.com

Ever wonder why some people can learn like sponges, soaking up information in great gobs, while others struggle to learn? It is akin to the rich getting richer, while the poor get poorer.

Well, scientists have discovered that good learners have learned how to learn. This is especially evident for specific areas of expertise, where an existing expertise makes it easier to become even more expert. This principle was recently rediscovered (actually it was discovered at least twice before, dating back to 1932). The idea is being framed in terms of “schema,” or pre-existing knowledge that makes it easier to make associations with new information. The experiments actually focused on how having a schema speeds up the consolidation process.

In the study, rats learned to associate six locations in a testing arena with six different flavored foods. Learning was produced by letting the rats taste a given flavor in a start box and then it could get more if it went to the correct matching location. They learned this task gradually, taking about six weeks to learn where in the arena each flavored food was placed. The role of consolidation processes was demonstrated by lesioning the hippocampus in some of the rats, which were unable to learn the task.

So where does evidence of a schema come in? These same rats were able to learn new flavor/place associations within one trial and could remember for at least two weeks. Moreover, it the hippocampus were destroyed as early after two days after the new learning, memory was not impaired. Normally, this would prevent consolidation. Thus, there was a clear indication that having a schema speeded up consolidation, so that it was completed within two days. (Hippocampal lesions do not impair already consolidated memories, only those in the process of consolidation).

So what is the take-home message for people? Just this: learn, learn, learn. The more you learn, the more schemas you are developing, making it easier to learn even more. My guess is that this principle is especially useful for learning such things as a foreign language, music, or an academic discipline. This richness really will become richer.

Source: Tse, D. et al. 2007. Schemas and memory consolidation. Science. 316: 76-82.

I explained in my book on memory that the hippocampus is the brain structure that promotes consolidation of (declarative) short-term memories into long-term memories. I have also reviewed studies showing that the hippocampus is the one structure in the brain that clearly receives newborn nerve cells, even in the adult. New cells can enhance the ability of the hippocampus to create lasting memories. What has not been emphasized is the importance of survival of new neurons. To be of lasting benefit, new neurons must survive beyond just being born.

Insight into the requirements for neuron survival has come in a recent study by J. R. Epp and colleagues at the University of British Columbia. They injected rats with a chemical marker for DNA that shows up in any new DNA, that is in any newly born cells. If that marker shows up in a cell, it means that that this is a new cell that has incorporated the marker along with its new DNA.

Immediately after injection of the marker, the experimenters trained the rats in a large pool of water that had a safe platform located 2 cm under the water surface where rats could learn its location from seeing cues outside of the pool (such as windows, doors, pictures on the wall, etc.). Other studies had established that learning this task is accomplished by the hippocampus. Rats were divided into groups and trained on days 1-5, 6-10, or 11-15 after injection of the DNA marker. The new DNA marker showed up only in rats trained on days 6-10 after marker injection. This indicated that there must have been new neurons in the hippocampus of these rats that did not survive in the two groups where marker was not seen. Put another way, for new neurons to survive there is a critical period where they have to be stimulated by learning experiences. Without that stimulus, they die.

Earlier studies had shown that new neurons in rat hippocampus have a development cycle wherein 6-10 days after birth is a middle stage of development in which new neurons are rapidly sending out membrane processes in search of contacts with other neurons, When neurons make contact with targets they can survive. The stimulus of learning thus provides a stimulus for forming new synapses with other neurons, thus enabling new neurons to survive.

The data were originally pooled across all rats in each test group. However, when the data were segregated by how well rats learned (the top and bottom 50 %), it became clear that it was only the poor learners that were showing an effect on new-neuron survival by maze learning. Poor learners probably got more stimulation from the learning because their brains had to work harder at it. It wasn’t that much of a mental challenge for good learners.

We know that humans are continually producing new neurons in the hippocampus. The issue is the need to experience enough demanding learning to help these new neurons survive. The critical period for learning to influence new-neuron survival in humans is not known.
So, the practical take-home message is that we need to be learning constantly, every day, so that no matter what the critical period is, we will be helping our new neurons to survive. Survival of new neurons means a greater biological capacity for learning, at least in people who are not good learners. In other words, here is a clear case where the “poor get richer.”

Source: Epp, J. D., Spritzer, M. D., and Gales, L. A. M. 2007. Hippocampus-dependent learning promotes survival of new neurons in the dentate gyrus at a specific time during cell maturation. Behavioural Neuroscience. 149: 273-285.

Some things are easier to unlearn than others. In a simple Pavlov conditioned learning situation, for example, it is relatively easy to unlearn something that has been conditioned by separating the paired cue and the learned object. Now a study of humans shows that a conditioned fear response to faces from a social group different from one's own social group is more resistant to extinction than is a similarly conditioned fear response to faces from one's own social group. This bias appears to be less in people who have had greater experience with the social out-group.

In the study, white participants had more trouble unlearning conditioned fears in responses to pictures of black faces than to pictures of white faces when the faces were paired with an aversive stimulus (mild electric shock). Similarly, black participants had more trouble unlearning conditioned fears in responses to pictures of white faces than to pictures of black faces. Unlearning these biases was promoted by inter-racial dating. The implications for racial or ethnic prejudice seem inescapable and may be biologically based.

Social behavior may be a product of evolution. Cohesion within a like-group is promoted by built-in tendencies for suspicion toward strangers and a readiness to develop persistent fear of them. At the same time, however, such social behavior promotes inter-group prejudice and conflict.

The more general point is that our biological nature makes some things easier to learn and harder to unlearn than others.

Source: Olsson, A. et al. 2005. the role of social groups in the persistence of learned fear. Science. 309: 785-787.

An important principle of learning is called "State-dependent Learning," which I describe in the chapter on association and in several other places in my recent book. Basically, the principle holds that memory recall is affected by the mental state you are in. A drunk, for example, remembers events that occurred during drinking better when he is drinking again than he can when sober. Another example is that a student will usually perform better on an exam if it is given in the same room as was used for the original instruction.

Now comes an interesting study in rats that elaborates this principle from collaborating scientists in Norway and at the University of Arizona. They recorded electrical firing from neurons in different parts of the hippocampus, a brain structure that is crucial for formation of explicit memories. Some of these neurons are "place" neurons that are sensitive to location; these neurons help the brain form a spatial map of where you are. Rats were constrained inside a chamber that they could see through, and testing occurred under two conditions: 1) cues in the chamber were varied, but the chamber stayed in the same room, and 2) cues in the chamber stayed the same, but the chamber was tested in two different rooms, each with different cues.

What the researchers observed was that firing rate, and which hippocampal neurons fired, faithfully reflected the environmental condition and that these response patterns were independent of each other. That is, both the chamber cues and the room cues were independently and reliably mapped.

So how does this apply to practical memory? First, it suggests that multiple cues associated with what we are trying to learn are important. The cues can reinforce each other and enhance memory, because all the cues are being faithfully registered (I point out in my book that information is distributed, but linked, throughout the brain). It also says that what we learn can be affected by where we are and the cues present where we are. This is particularly true if where we are stirs up emotions that are not conducive to learning, such as cues that trigger negative emotions (my book has a whole chapter on the role of emotions in memory). And these findings may also help explain certain aspects of state-dependent learning. Synergistic effects on memory can be produced if the where-we-are-information is paired with what-we-are-supposed-to-learn information, both during learning and during the need to recall. Because both kinds of information can get faithfully and independently encoded, they can reinforce each other or interfere with each other during recall, depending on whether a mis-match occurs between the learning and the recall situations.

Source: Leutgeb, S. et al. 2005. Independent codes for spatial and episodic memory in hippocampal neuronal ensembles. Science 309, p. 619-623.

Cells in one area of the hippocampus, the dentate gyrus, are needed to convert short-term, scratch pad, memory into permanent form. This is the part of the brain that is best known for turnover of nerve cells (elsewhere, nerve cells do not die except with aging and they typically are not replaced). Animal experiments have shown that the production of new nerve cells in the hippocampus is stimulated by enriched environments and by learning experiences. But do these new cells function normally? Do they support learning? And do these new neurons survive? Some animal observations indicate that new neurons in the hippocampus only live about one month.

An answer has come from some recent animal experiments that examined the role of new neurons in adults in learning of a water maze and the effect of the maze learning on survival of these new cells. The water maze involved training rats to find a submerged safe platform in a tub of water made opaque so that the platform could not be seen. Training was performed under one of two conditions: 1) location of the platform was cued by an overhead black and white striped rod, or 2) location was indicated by the spatial relationship of the platform to objects outside the tub, such as objects on the room walls, that could be seen by the rat.

The existing population of dentate cells was killed by low-level irradiation. Rats could not form long-term memories for the safe location in the spatially cued task. However, if they were trained after new neurons were born, then they learned the task. This effect was specific to spatial cues, because new cells were not needed to learn the task when the platform was indicated by the vertical rod pointer. By irradiating certain groups of rats at different times before and after training, the researchers found that new neurons 4-28 days old at the time of training were important for the spatial learning. Thus, these new neurons were functional. They knew what to do and how to do it.

Also demonstrated in other studies is the fact that the learning experience prolonged the survival of new neurons.

So, it would seem that new neurons not only can be born in adult hippocampus, but that they perform the learning job that was done by their predecessors, at least as regarding learning that involves spatial relationships. A learning-rich environment helps these new neurons live longer.

Source: Snyder, J. S. et al. 2005. A role for adult neurogenesis in spatial long-term memory. Neuroscience. 130: 843-852.

Many studies have demonstrated that new neurons are continuously being born in the hippocampus, the part of the brain that forms new memories. In rodents, the number of new neurons in the hippocampus is on the order of thousands per day. These new neurons may not survive and become useful in memory formation if they are not needed. Need seems to be established by ongoing requirements to form more memories. Learning increases the survival of neurons born up to a week before the learning. In other words, use them or lose them. A recent study of aged rodent learning of spatial relationships in a water maze has revealed that rats which were naturally good at learning mazes, learning increases the survival of new cells born before the learning. An earlier study had shown that in young rats, increased survival of new neurons occurred in all rats, irrespective of their previous memory abilities.

A critical window of time determines whether or not the new neurons survive. In an experimental test of this time window, mice were housed for one week in an environmentally rich environment, or for controls in regular cages, beginning one week after injection with a new-neuron DNA-synthesis marker. Results showed that lasting increase was restricted to new neurons that appeared between one and three weeks before living in an enriched environment. This corresponds to the time when new neurons are extending their neurons in search of targets and their dendrites are developing synaptic contacts to the neurotransmitters normally used in the hippocampus. The new neurons that developed during this time window survived up to the four months of monitoring, even when removed the enriched environment. It would seem that the learning experiences encountered in a rich environment provide the stimulus needed to help new neurons get established into memory-forming circuits, but there is a limited critical time when this effect occurs.

Sources: Drapeau, E. et al. 2007. Learning-induced survival of new neurons depends on the cognitive status of aged rats. J. Neuroscience. 27 (22): 6037-6044.

Tashiro, A., Makino, H., and Gage, F. H. 2007. Experience-specific functional modification of the dentate gyrus through adult neurogenesis: A critical period during an immature stage. J. Neurosci. 27: 3252-3259.

Remembering Names and Faces

The conventional wisdom about remembering names and faces goes like this: find some special facial feature (like big nose, moles in certain places, hairline, etc.) and use that to make an association with the name. For example, someone named Bill who has a long nose can be visualized like a bird with a long beak (bill). Someone named Barbara with a mole on her check can be visualized as being shaved by a barber (a.k.a. Barbara) to remove the mole.

Research, however, suggests that this approach may be counter-productive. Experiments show that using verbal descriptions of facial details can actually impair subsequent recognition of the face. In one experiment, subjects were shown a video of a bank robbery. Half the group was required to write down a verbal description before being asked to pick out the "robber" in a lineup.
These people made significantly more identification errors than the control group that had not been asked to provide a description before the lineup.

It seems that the brain registers images best when it can process them as a whole, rather than as a sum of its parts. Images are remembered best with a global processing orientation during learning, without verbalization. Actually, it is not words themselves that are the problem but the attention to detailed features of an image rather than the "big picture."

So how do we deal with that for practical purposes of remembering names and faces? No particular strategy has been tested, but let me suggest this: when you meet a new person think first of the whole face. Ignore facial details that might be distracting. See the forests, not the trees. Rehearse in you mind's eye what the whole face looks like.

Now, how do you pin the name to that image? This gets even trickier, for now you have to try to make an association of the name with a whole face. Maybe the conventional approach would still work, if you first have cemented in your mind the whole-face image. In some cases, you can make an association with the whole face. The image of Bill, for example, can have a baseball cap (and its bill) placed on top of the whole face image.

Maybe shortcuts can work. In some social environments, you don't need to remember the face, it's the name that is important. In other situations, you need only the first name, or the last name. In a few situations, it is only the face that has to be remembered. The point is, limit the memory work load whenever you can. If only the first name needs remembering, don't bother with anything else.

Source: Macrae, C. N., and Lewis, H. L. 2002. Do I know you? Processing orientation and face recognition. Psychological Science. 13 (2): 194-196.

Few people would argue against using drugs like Aricept to help Alzheimer's patients. Few would complain about using propranolol to assist in treatment of post-traumatic stress syndrome. But what about using memory-enhancing drugs for normal people?

For now, the question is moot, because there are no drugs that have been proven to help normal people. But such drugs are on the horizon. Several drug companies are working on such drugs. One drug was recently discovered in animals to have a positive side effect of improving memory. The drug, Fasudil, increases blood flow in the brain of rats and has potential for treating stroke in humans. This drug has now been found by Matthew Huentelman, an investigator at the non-profit Translational Genomics Research Institute in Phoenix, Arizona. to affect a gene that promotes memory, and when tested in 18-month old (middle-aged) rats, enabled the rats to perform better in water-maze learning and memory tests. The older rats performed as well as young rats. I don't know if this work is published yet (it is widely reported in the lay press), and it certainly has not been replicated.

But for the sake of argument, let us assume that it is correct. Are there ethical issues for normal people taking it to improve their memory, to get better performance at work, or for students to get better grades? Some students already take Ritalin or amphetamines to improve their performance. Is this like doping in sports? Or will we come to accept use of such drugs as preventive medicine, forestalling or preventing dementia, Alzheimers's or even normal mental decline with age?

Do Schools Teach "Cognitive Tools?"

In this age of high-stakes testing, schools focus on telling students WHAT to learn. How well do they teach students HOW to learn? ... not very well in my experience both as a middle-school curriculum developer and as a university science professor. I ran across a review of a new book entitled "The Future of Education. Re-imagining Our Schools from the Ground Up." The book apparently focuses on three goals of education: 1) socialization, 2) mastery of information, and 3) promotion of mental development. The book's author emphasizes a need to re-orient these goals around teaching "cognitive tools." Neuroscience is expected to reveal what those tools are, and it is the job of the school to teach those cognitive tools. Have schools even identified a set of cognitive tools? I know they don't explicitly appear in the national science standards. Communication between neuroscientists and school teachers is limited--they live in two different worlds. Moreover, the educational culture is not amenable to major change, especially one that requires teachers to re-orient their basic approach to teaching.

An example that I have mentioned before is the need to teach students how to memorize more effectively, using for example, the principles in my book. Few teachers teach memorization skills, and many have a prejudice against doing so. Also, it is increasingly clear that teaching students to increase the span of their working memory will raise student IQ and problem-solving skills. Yet I know of no school system or teacher that does that. Memorization skills are not tested on standardized tests and therefore are not taught. Real reform is a long way off. Many politicians and teachers think the solution for school reform is more money. Wrong!

Source: Egan, K. 2008. The Future of Education. Reimagining Our Schools from the Ground Up. Yale University Press. New Have, Ct. 203 p.

Even when I was a kid, people said that being physically active could help you perform better in school. But this was mostly anecdotal, with very little research evidence. Now there is some evidence.

Charles Hillman and colleagues at the University of Illinois recently reported a study on the effects of exercise on cognitive function of 20 preadolescent children aged 9 to 10. They administered some stimulus discrimination tests and academic tests for reading, spelling and math. On one day, students were tested following a 20-minute resting period; on another day, students walked on a treadmill before testing. The exercise consisted of 20 min of treadmill exercise at 60% of estimated maximum heart rate. Mental function was then tested once heart rate returned to within 10% of pre-exercise levels. Results indicated improved performance on the tests following aerobic exercise relative to the resting session. Recordings of brain responses to stimuli suggested that the difference was attributable to improved attentiveness after exercise.

Note that this is just from a single aerobic exercise experience. How can that be beneficial? The most obvious explanation is that exercise generates more blood supply to the brain, but I don't know that this has been documented with MRI studies, for example. Actually, what is known is that exercise diverts blood to the muscles. The generally accepted view is that the body tightly regulates blood flow to the brain and that the brain always gets what it needs. Another possibility is that exercise relieves anxiety and stress, which are known to disrupt attentiveness and learning. Maybe the repetitive discipline of exercises like treadmill walking help entrain the brain into a more attentive mode. We need a study that compares tradmill walking with a different kind of exercise regimen (like a vigorous and competitive basketball game, for example).

As for what goes on in a typical school recess, I doubt that such activities as shooting marbles, gossiping, or whatever else goes on these days with kids at recess, really helps school work. Gym class might be another matter, but unfortunately many schools do not provide a meaningful gym class. Some of the authors' suggestions don't seem to be supported by this particular research. For example, they advocate:

• scheduling outdoor recess as a part of each school day (recess does not typically provide aerobic levels of exercise)

• offering formal physical education 150 minutes per week at the elementary level, 225 minutes at the secondary level (again, the beneficial effects likely come from aerobic levels of exercise, not just any exercise)

• encouraging classroom teachers to integrate physical activity into learning (this almost certainly will not be at aerobic levels of exercise.)

There is the also the issue of a continuing aerobic exercise program, which presumably could produce long-lasting beneficial effects in young children. My own prejudice is that schools and parents ought to get serious about requiring an aerobic exercise program for kids. It should not only improve the quality of school work but also help combat the epidemic of obesity and diabetes. One caveat: running to achieve aerobic levels of exercise may not be advisable in children. My own experience with jogging, for example, might have been great for my heart and brain, but I now have two artificial knees to show for it.

If exercise is so good for academic performance, why do varsity athletes generally make poorer grades than their classmates? Well, there are many other factors, of course. One prevailing attitude among athletes is that academics are less important to them than their sport. Their peers idolize athletic stars. Students who make all As are not considered heroes; they are considered nerds or otherwise abnormal. Athletes devote their time and energy to their sport, not school work.

Reference:

Hillman, C. H., et al. 2009. The effect of acute treadmill walking on cognitive control and academic achievement in preadolescent children. Neuroscience. 31;159(3):1044-54.

Can Exercise Help Kids Do Better in School?

Even when I was a kid, people said that being physically active could help you perform better in school. But this was mostly anecdotal, with very little research evidence. Now there is some evidence.

Charles Hillman and colleagues at the University of Illinois recently reported a study on the effects of exercise on cognitive function of 20 preadolescent children aged 9 to 10. They administered some stimulus discrimination tests and academic tests for reading, spelling and math. On one day, students were tested following a 20-minute resting period; on another day, students walked on a treadmill before testing. The exercise consisted of 20 min of treadmill exercise at 60% of estimated maximum heart rate. Mental function was then tested once heart rate returned to within 10% of pre-exercise levels. Results indicated improved performance on the tests following aerobic exercise relative to the resting session. Recordings of brain responses to stimuli suggested that the difference was attributable to improved attentiveness after exercise.

Note that this is just from a single aerobic exercise experience. How can that be beneficial? The most obvious explanation is that exercise generates more blood supply to the brain, but I don't know that this has been documented with MRI studies, for example. Actually, what is known is that exercise diverts blood to the muscles. The generally accepted view is that the body tightly regulates blood flow to the brain and that the brain always gets what it needs. Another possibility is that exercise relieves anxiety and stress, which are known to disrupt attentiveness and learning. Maybe the repetitive discipline of exercises like treadmill walking help entrain the brain into a more attentive mode. We need a study that compares treadmill walking with a different kind of exercise regimen (like a vigorous and competitive basketball game, for example).

As for what goes on in a typical school recess, I doubt that such activities as shooting marbles, gossiping, or whatever else goes on these days with kids at recess, really helps school work. Gym class might be another matter, but unfortunately many schools do not provide a meaningful gym class. Some of the authors' suggestions don't seem to be supported by this particular research. For example, they advocate:

• scheduling outdoor recess as a part of each school day (recess does not typically provide aerobic levels of exercise)

• offering formal physical education 150 minutes per week at the elementary level, 225 minutes at the secondary level (again, the beneficial effects likely come from aerobic levels of exercise, not just any exercise)

• encouraging classroom teachers to integrate physical activity into learning (this almost certainly will not be at aerobic levels of exercise.)

There is the also the issue of a continuing aerobic exercise program, which presumably could produce long-lasting beneficial effects in young children. My own prejudice is that schools and parents ought to get serious about requiring an aerobic exercise program for kids. It should not only improve the quality of school work but also help combat the epidemic of obesity and diabetes. One caveat: running to achieve aerobic levels of exercise may not be advisable in children. My own experience with jogging, for example, might have been great for my heart and brain, but I now have two artificial knees to show for it.

If exercise is so good for academic performance, why do varsity athletes generally make poorer grades than their classmates? Well, there are many other factors, of course. One prevailing attitude among athletes is that academics are less important to them than their sport. Their peers idolize athletic stars. Students who make all As are not considered heroes; they are considered nerds or otherwise abnormal. Athletes devote their time and energy to their sport, not school work.

Reference:

Hillman, C. H., et al. 2009. The effect of acute treadmill walking on cognitive control and academic achievement in preadolescent children. Neuroscience. 31;159(3):1044-54.

Rehearsal of the “same old stuff:” can get boring. There is some research evidence to suggest that interposing some novel stimuli into the rehearsal session can help memory formation. In a study on the neurochemical effects of novel stimuli during learning, a group at University College of London found that the brain’s reward-system neurons respond better to novel stimuli than to ordinary stimuli. That is, novel stimuli can have rewarding properties, and thus make us pay more attention to them. In the purely behavioral aspects of their study, subjects viewing a succession of visual images were able to remember more of them if an occasional new image was presented.

I suspect that another reason novelty may help is that it breaks the routine and helps you pay attention better (see my book about attention and other posts on this Web page on attention). For those who want to use novelty to assist their studies or memory in general, I suggest that you have to be careful to make sure that novel stimuli are not distracting. Remember, memory consolidation is very vulnerable to interference from distracting stimuli. The best bet is to use novel stimuli that are relevant and can be used in construction associational cues for the items you are really trying to remember.

What is a practical way to do that? One thing that comes to mind is in studying flash cards. I suggest creating some “extraneous” flash cards. In a given stack of such cards, you can randomly slip in a couple of the novel ones. In fact, the novel cards can have legitimate memory items on them, but you don’t review these particular cards every time you go through the deck. A variant of this idea is to separate cards into stacks based on how well you have learned them. When rehearsing a stack that you know fairly well, insert a few of the cards from the stack that you have not memorized.

Source: Bunzeck, N. And Düzel, E. 2006.l Absolute coding of stimulus novelty in the human substantia nigra. Neuron. 51: 369-379.

Multi-tasking Is the Wrong Way To Learn

Today's kids are in to multi-tasking. This is the generation hooked on iPods, IM'ing, video games - not to mention TV!
According to a Kaiser Family Foundation study last year, school kids in all grades beyond the second grade committed, on average, more than six hours per day to TV or videos, music, video games, and computers. Almost one-third reported that "most of the time" they did their homework while chatting on the phone, surfing the Web, sending instant messages, watching TV, or listening to music.

Kids think that this entertainment while studying helps their learning. It probably does make learning less tedious, but it clearly makes learning less efficient and less effective. Multi-tasking violates everything we know about how memory works. Now we have objective scientific evidence that multi-tasking impairs learning. A recent National Academy of Sciences study with college-age students did an experiment where the subjects were to learn a task under two conditions, one with no distractions and the other while listening to high- and low-tone beeps, attending to the high ones. The total amount of learning was the superficially the same in both conditions, but with distractions, the learned was stereotyped and learners had difficulty in applying what they learned to other contexts and situations. The study also used functional MRI (fMRI) to assess brain activity under test conditions and the data indicated that the memory task and the distraction stimuli engage different parts of the brain and that these regions may be in competition with each other.

The study did not address the issue of passive distraction, such as listening to music while studying. I think that music can also be a major distraction, except for certain kinds of music played under muted conditions (see my book, pages 47, 165, and 197).

Source:
Foerde, K., Knowlton, Barbara J., and Poldrack, Russell A. 2006. Modulation of competing memory systems by distraction. Proc. Nat. Acad. Sci. 103: 11778-11783.

Are you impressed with the multi-tasking abilities of young people? Don't be. Our brain works hard to fool us into thinking it can do more than one thing at a time. It can't. Recent MRI studies at Vanderbilt prove that the brain is not built for good multi-tasking. When trying to do two things at once, the brain temporarily shuts down one task while trying to do the other. In their study, even doing something as simple as pressing a button when an image is flashed causes a delay in brain operation. Their MRI images showed a central bottleneck occurs when subjects were trying to do two things at once, such as pressing the appropriate computer key in response to hearing one of eight possible sounds and uttering an appropriate verbal response when seeing images. Activity in the brain that was associated with each task was prioritized, showing up first in one area and then in the other ― not in both areas simultaneously. In other words, the brain only worked on one task at a time, postponing the second task and deceiving the subjects into thinking they were working on both tasks simultaneously. The delay between switching functions can be as long as a second. It is highly likely, though not yet studied, that the delays and confusing magnify with increases in the number of different things one tries to do simultaneously.

Source:
Dux, P. E., Ivanoff, J., Asplund, C. LO., and Marois, R. 2007. Isolation of a Central Bottleneck of Information Processing with Time-Resolved fMRI. Neuron. 52 (6): 1109-1120

Students Who E-communicate Have Lower Grades

A new study of 517 California high-school students found that grades were lower in those who socially interacted over the Internet using MySpace, instant messaging (IM) accounts, or who used cell phones, had lower grades than those who did not. In the study, students answered a questionnaire on what social networking devices they used and when they used them. The answers were paired with the grades (from the previous year and the most recent report card).

In this study, 72% of the students had a My Space account, 76% had a cell phone, and 68% had an IM address. Those who had a MySpace account had significantly lower grades than those without an account. The same was true for those that used IM, compared with thos who did not. Cell phone use was also associate4d with lower grades and the effect was magnified if text messaging was used on cell phones. Not surprisingly, if these devices were used during homework, the grades were even lower than for students who used these technologies outside of homework. Almost half reported text messaging during class time, and their grades were lower than the students who only used IM outside of class.

These are correlational data and do not prove that using these devices causes lower grades. But it is a good bet. Multi-tasking, as when using the communication devices while trying to do homework or learn in class, is well-known to interfere with memory . Poor memory yields lower grades. See my other posts on multi-tasking.

Source:

Pierce, Tamyra, and Vaca, Roberto. 2007. Distracted: academic performance differences between teen users of MySpace and other communication technologies. Proceedings EISTA. Orlando, FL. July. http://www.cyber-inf.org/imsci2007/Program/html/program-5.htm

One of the things that sets professionals apart from amateurs is their ability to focus on their area of expertise. I mean that literally. For example, recent brain imaging studies of 20 non-musicians and 20 musical conductors showed that the brains of both groups diverted activity from visual areas of brain during listening tasks. Activity rose in auditory areas of brain as it fell in visual areas. But during the harder tasks, brain activity changes were less marked in the conductors. The conventional interpretation is that when the brain focuses, it becomes more active in the areas that are processing the subject of the focus. In well-trained subjects, such as conductors in this case, their brain doesn't have to work so hard to pay attention to music, so there is less need for the brain to be more active in the auditory areas.So what this suggests is that ability to focus is a learned capability that derives from an actual lasting change in brain.

In the experiment, subjects during the scan were asked to listen to two different musical tones played a few thousandths of a second apart and identify which was played first. The task was made harder for the conductors, to allow for the differences from non-musicians. During the task, brain activity increased in the auditory areas, while it decreased in visual areas. In other words, the brain seems to allocate processing resources to the part of the brain that needs it the most. As the task was made harder, non-musicians diverted more and more activity to the auditory region as they struggled to concentrate.

The leader of the study, Jonathan Burdette, said "This is like closing your eyes when you listen to music." That is, you can pay attention to the music better when you brain is not being distracted by visual stimuli. He went on to make this analogy: "Imagine the difference between listening to someone talk in a quiet room and that same discussion in a noisy room - you don't see as much of what's going on in the noisy room."

Three conclusions for improving everyday memory come to my mind:

1. The more knowledgeable you become in a certain area, the easier it is to pay attention to salient information. This is a different twist on the old saying, "The rich get richer and the poor get poorer."

2. Focus, and the attendant remembering that focus enables, is affected by distracting stimuli. If you are trying to learn visual information (graphics or text), a noisy background of music will make remembering worse because your brain can't focus its resources where it belongs.

3. The more you know, the more you can know.

Source: Wake Forest University Baptist Medical Center (2007, November 6). Listen Up, Tune Out: Training And Experience Can Affect Brain

A new brain imaging study showed that going online stimulated larger parts of the brain than the relatively passive activity of reading a novel or non-fiction book.The science writer, Richard Alleyenne, of the lay article claims that this proves that Internet browsing is better for brain development than reading books. The scientists involved in the research seem to agree. Here are quotes from the article:

It was so stimulating that the authors of the study believe it could actually help people maintain healthier brains into their old age. The study results are encouraging, that emerging computerized technologies may have physiological effects and potential benefits for middle-aged and older adults," said principal investigator Dr Gary Small, a professor at the Semel Institute for Neuroscience and Human Behavior at University of California. Internet searching engages complicated brain activity, which may help exercise and improve brain function." The study, the first of its kind to assess the impact of internet searching on brain performance, is published in the American Journal of Geriatric Psychiatry.

Well, before you tell schools to throw away the textbooks and let the kids browse away, you should know this: when a brain lights up in many places, it means the brain does not know how to deal with all the stimuli. It has not mobilized or focused its neural circuitry to deal with the stimuli efficiently and effectively. In most imaging studies I have read, when a brain knows how to cope with a task, FEWER areas light up. In other words, a brain works best when it can focus its resources. If you want your kids to grow up scatterbrained, put them on the Web. If you want them to develop longer attention spans and improve critical thinking skills, have them read good books. Their brain will thank you.

Visual memory has astounding capacity. My book on memory improvement presents much anecdotal evidence that people with outstanding memories use mental images of what they are trying to remember. Now, a formal scientific study validates the conclusion that ordinary humans have astounding memory capacity for visual (but not auditory) memories.

In this study, young adults (20-35 yrs) were shown a succession of object images, one every three seconds. They were told to remember as much as they could. After about each block of about 300 images, they were given a 5-minute rest break. After 10 such blocks (total images seen = 2,500; total time about 5.5 hours), they were tested with probe images and asked for each one if it had been seen before. Probe object images were paired in three ways: objects that were in a different category, the same category, or the same object but in a different state or pose. Performance accuracy was remarkably high for all conditions, respectively 92%, 88%, and 87% accuracy. Remembering 2,500 images with this level of recognition accuracy is truly astounding.

As comparison, a related study by another research group showed that auditory memory was markedly inferior. When subjects listened to sound clips (conversation, animal sounds, music, etc.) and then asked to distinguish new from old clips, under all conditions performance was systematically inferior to visual-memory performance.

Apparently, everyone has a degree of photographic memory. Certainly, the odds of recognizing that you have seen something are very high, at least under conditions where the image is a simple object. The storage capacity is huge. Does this apply to complex images that contain multiple details? Who knows for sure? The details can serve as useful cues or could even become confusing distractors. It is also not clear, if the visual-image capacity is limited to recognition or whether it applies to generating a recall without an image probe.

Even so, it is a good bet that memory performance will be optimized if memory items are converted to mental images.

Sources:
Brady, T. F. 2009. Visual long-term memory has a massive storage capacity for object details. Proc. Natl. Acad. Sci. USA. 106: 6008-6010.

Cohen, M. A. et al. 2009. Auditory recognition memory is inferior to visual recognition memory. Proc. Natl. Acad. Sci. USA. 106 (14): 6008-6010.

Conscious thought involves moving a succession of items through scratch-pad or working memory. Think of it like streaming audio/video, where “thought bites” move on to the scratch pad where they are used in the thought process and then moved off the scratch pad to make room for the next thought bite.

We think with what is in working or "scratch pad" memory. What we know, stored in memory, is brought onto the scratch pad in successive stages, each involving subjecting the knowledge to analysis, integration into the current context, and creative re-organization via our thinking processes ("thought engine"). The animated version of this graphic shows item 1 moving on to the scratch pad and then sent on to the "thought engine." This is followed by item 2, then 3, etc.

Conscious thinking thus requires the ability to hold information “on line” long enough to use it in thinking. What is on the scratch pad has to be remembered long enough to generate the associated thought. Conscious thought thus seems to be a serially ordered process of moving thought bites on to and off of the scratch pad.

What about unconscious thought ... the kind that occurs when you are not paying attention? We know that the subconscious mind is processing information (i.e. “thinking”) all the time, even while we sleep. In fact, I have several blog postings on the role of sleep on memory formation. Subconscious thinking and its related memories may not involve a scratch pad of working memory. Subconscious thinking could occur as multiple parallel processes and may be more non-linear than conscious thought.

A recent paper, not explicitly concerning memory, sheds some important light both on how we think and on the role of working memory in thought. In this study, the researchers examined how people make the right choice. They compared the quality of choice that resulted from conscious thinking with that resulting from unconscious thinking. They found that best choice does not necessarily come from conscious deliberation, although that is what most people would expect. An alternative way of making choices is to “mull it over,” or “sleep on it,” letting the subconscious mind work on the problem while you pay attention to other things.

Here is how they studied this issue. In one study, subjects were given information about the attributes of four hypothetical cars, and they were to decide which was the best car based on the attributes assigned to each car. Analysis conditions were either simple (based on only four attributes) or complex (based on 12 attributes). After reading about the attributes, subjects were assigned to one of two groups: conscious analysis or to an unconscious thought condition. In the conscious condition, they thought about the attributes for 4 minutes before making a choice. In the unconscious condition, subjects were told they would have to make a choice in 4 minutes, but they were distracted during that time by solving anagrams.

Not surprisingly, when only 4 attributes were involved, subjects in the conscious-thought condition made the best choice of car. But when the complex condition of 12 attributes was involved, results reversed. The best car was chosen most reliably in the unconscious-thought condition.

In a second study, one change was made. Instead of choosing the best car, subjects were asked about their attitudes toward the four cards. Again, conscious thinkers made the clearest distinctions among the cars when only four attributes were considered, but the opposite occurred when 12 attributes had to be considered.

In another experiment, two stores were selected, one that sold complicated items like furniture and the other a department store that sold simple products. As people left the store, people were asked questions about what they bought, why they bought it, how costly was it, and how much they thought about making the choice. The buyers were categorized as either “thinkers” (those who spent a lot of time consciously making a decision) and “impulse buyers” (who did not spend much time consciously thinking about the choice). Several weeks later, these same people were called to check on how satisfied they were with the purchase. As expected, more post-choice satisfaction was found in the conscious thinker group, but only for the simple items in the department store. For the complex choices in the furniture store, the unconscious thinkers expressed the most satisfaction with their purchases.

What all this says is that simple decisions are best made by careful conscious thought. But for complicated decisions, the best choices may result from “deliberation without paying attention,” that is letting the thinking be done by the unconscious mind.

I interpret these results to reflect the dependence of conscious thought on scratch-pad memory and the relative independence of subconscious thought on scratch-pad memory. Conscious thought is very effective as long as it can work on information that it can hold on-line in working memory. But working memory has limited capacity. Therefore it cannot be very effective when the amount of information needed for high-quality thought exceeds the carrying capacity of working memory.

The corollary of this new evidence about working memory and thinking processes is that if we had a bigger working memory, we might think better. I alluded to this point in an earlier blog based on the work of Japanese scientists who showed that in children, working memory capacity correlated with IQ and that training aimed at expanding working memory capacity actually increased IQ.

Sources

1. Repovs, G and Bresjanac, M. 2006. Cognitive neuroscience of working memory: a prologue. Neuroscience. 139: 1-3.

2. Dijksterhuis, A. et al. 2006. On making the right choice: the deliberation-without-attention effect. Science. 311: 1005-1007.

Studies have shown that it is possible to train ADHD children to have better working memories. This led researchers in Japan to try to develop a simple working memory training method and to test whether this method can increase the working memory capacity and whether this has any effect on a child's IQ. Children ages 6-8 were trained 10 minutes a day each day for two months. The training task to expand working memory capacity consisted of presenting a digit or a word item for a second, with one-second intervals between items. For example, a sequence might be 5, 8, 4, 7, with one-second intervals between each digit. Test for recall could take the form of "Where in the sequence was the 4?" or "What was the 3rd item?" Thus students had to practice holding the item sequence in working memory. With practice, the trainers increased the number of items from 3 to 8.

After training, researchers tested the children on another working memory task. Scores on this test indicated in all children that working memory correlated with IQ test scores. That is, children with better working memory ability also had higher IQs. When comparing children who got working memory training with those who did not, investigators found that children who got the working memory training performed better than controls on the working memory test. When first graders were tested for intelligence, the data showed that intelligence scores increased during the year by 6% in controls, but increased by 9% in the group that had been given the memory training. The memory training effect was even more evident in the second graders, with a 12% gain in intelligence score in the memory trained group, compared with a 6% gain in controls. As might be expected, the lower IQ children showed the greatest gain from memory training.

So in conclusion, it seems that working memory capacity can be increased by training and that such training may even raise IQ, at least in young children.

Source: Wajima, Kayo, and Sawaguchi, T. 2005. The effect of working memory training on general intelligence in children. Society for Neuroscience Abstracts. Abstract 772.11.

Increase Working Memory and Increase IQ

A key research report on working memory was summarized in a recent guest column in the New York Times by Sam Wang and Sandra Aamodt. Below is an excerpt of what they said in the article:

J. R. Flynn first noted that standardized intelligence quotient (I.Q.) scores were rising by three points per decade in many countries, and even faster in some countries like the Netherlands and Israel. For instance, in verbal and performance I.Q., an average Dutch 14-year-old in 1982 scored 20 points higher than the average person of the same age in his parents’ generation in 1952. These I.Q. increases over a single generation suggest that the environmental conditions for developing brains have become more favorable in some way.

What might be changing? One strong candidate is working memory, defined as the ability to hold information in mind while manipulating it to achieve a cognitive goal. Examples include remembering a clause while figuring out how it relates the rest of a sentence, or keeping track of the solutions you’ve already tried while solving a puzzle. Flynn has pointed out that modern times have increasingly rewarded complex and abstract reasoning. Differences in working memory capacity account for 50 to 70 percent of individual differences in fluid intelligence (abstract reasoning ability) in various meta-analyses, suggesting that it is one of the major building blocks of I.Q. (2-4). This idea is intriguing because working memory can be improved by training.

A common way to measure working memory is called the "n-back" task. Presented with a sequential series of items, the person taking the test has to report when the current item is identical to the item that was presented a certain number (n) of items ago in the series. For example, the test taker might see a sequence of letters like

L K L R K H H N T T N X

presented one at a time. If the test is an easy 1-back task, she should press a button when she sees the second H and the second T. For a 3-back task, the right answers are K and N, since they are identical to items three places before them in the list. Most people find the 3-back condition to be challenging.

A recent paper reported (5) that training on a particularly fiendish version of the n-back task improves I.Q. scores. Instead of seeing a single series of items like the one above, test-takers saw two different sequences, one of single letters and one of spatial locations. They had to report n-back repetitions of both letters and locations, a task that required them to simultaneously keep track of both sequences. As the trainees got better, n was increased to make the task harder. If their performance dropped, the task was made easier until they recovered.

Each day, test-takers trained for 25 minutes. On the first day, the average participant could handle the 3-back condition. By the 19th day, average performance reached the 5-back level, and participants showed a four-point gain in their I.Q. scores.

The I.Q. improvement was larger in people who’d had more days of practice, suggesting that the effect was a direct result of training. People benefited across the board, regardless of their starting levels of working memory or I.Q. scores (though the results hint that those with lower I.Q.s may have shown larger gains). Simply practicing an I.Q. test can lead to some improvement on the test (6), but control subjects who took the same two I.Q. tests without training improved only slightly.
Since the gains accumulated over a period of weeks, training is likely to have drawn upon brain mechanisms for learning that can potentially outlast the training. But this is not certain. If continual practice is necessary to maintain I.Q. gains, then this finding looks like a laboratory curiosity. But if the gains last for months (or longer), working memory training may become as popular as and more effective than games like sudoku among people who worry about maintaining their cognitive abilities.

Now, some caveats. The results, though tantalizing, are not perfect. It would have been better to give the control group some other training not related to working memory, to show that the hard work of training did not simply motivate the experimental group to try harder on the second I.Q. test. The researchers did not test whether working memory training improved problem-solving tasks of the type that might occur in real life. Finally, they did not explore how much improvement would be seen with further training.

Sources:

1. Flynn, J. R. 1987. Massive IQ gaijns in 14 nations: What IQ tests really measure. Psych. Bull. 101 (2) 171-191.

2. P.L. Ackerman (1987) Individual differences in skill learning: An integration of psychometric and information processing perspectives. Psychological Bulletin 102:3–27.

3. M.J. Kane, D.Z. Hambrick, and A.R.A. Conway (2005) Working memory capacity and fluid intelligence are strongly related constructs: comment on Ackerman, Beier, and Boyle (2005). Psychological Bulletin 131:66–71.

4. H.-M. Süss, K. Oberauer, W.W. Wittmann, O. Wilhelm, and R. Schulze (2002) Working-memory capacity explains reasoning ability—and a little bit more. Intelligence 30:261–288.

5. S.M. Jaeggi, M. Buschkuehl, J. Jonides, and W.J. Perrig (2008) Improving fluid intelligence with training on working memory. Proceedings of the National Academy of Sciences USA 105:6829-6833.

6. D.A. Bors, F. Vigneau (2003) The effect of practice on Raven’s Advanced Progressive Matrices. Learning and Individual Differences 13:291–312.

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Working Memory Training Raises IQ of Adults

I have pointed out in an earlier post how training young children to increase their working memory capacity will increase their IQ. This same phenomenon has now been demonstrated in young adults (mean age = 25.6 years).

Subjects were pre-tested on an IQ test involving visual analogy problems of increasing difficulty. Each problem presented a matrix of patterns in which one pattern was missing. The test was to identify the missing pattern from a set of alternatives. After training or a control without training, the test was repeated and scores compared.

The working memory task consisted of presenting at the same time two short series of stimuli, one visual and one auditory. The visual stimuli consisted of a small white square positioned at one of eight locations on a black screen and presented sequentially every three seconds. After seeing the series, the subject was tested with a test screen and asked to say if it matched the screen that was presented some n-number of screens earlier. This is a standard n-back paradigm often used to test working memory capacity. The n was adjusted to performance level and increased as subjects became proficient at remembering 2, then 3, etc. prior screens. A similar protocol was used for the auditory task, which involved hearing a recording of the sounds of a sequence of alphabet letters, with subjects asked to tell if a target test sound was the same as one they had heard 2, 3, or more sounds earlier.

Both working memory capacity and IQ improvements were seen in as little as 8 daily training sessions, and subjects steadily improved as training was extended to 19 days of training.

Paying attention is pre-requisite to learning. The ability to pay attention seems to be affected by how much information (load) is being carried in working (scratch-pad) memory. These principles have been elucidated in human experiments that tested the assumption that attending to relevant details in a learning situation requires that the details be held in working memory. Having other, non-relevant, information in working memory at the same time serves as a distraction, lowering attention, and interfering with memory formation.

In this experiment, participants performed an attention task that required them to ignore pictures of distracter faces while holding in working memory a string of digits that were in the same order (low memory load) or different order (high memory order) on every trial. The test thus was one of multi-tasking, one task being holding the digits in working memory and the other task being identifying whether a name flashed on the screen was that of a famous politician or a pop star, while a contradictory face was projected. For example, the name Mick Jagger would have the face of Bill Clinton superimposed, and the task was to know that Mick Jagger is a pop star, not a politician.

The attention performance degraded severely with high working memory load. That is, the distracting faces created confusion when subjects were also required to hold mixed-order digits in working memory at the same time.

The point is simple. It is hard to do two complicated things at once. The growing trend, especially among young people, to multi-task may seem wonderful. But actually, multi-tasking is most likely to interfere with focused attention and, in turn, degrade memory formation and recall.

Source: de Fockert, J. W. et al. 2001. The role of working memory in visual selective attention. Science. 291: 1803-1806.

In an earlier post, I summarized some Japanese research showing that working memory capacity can be increased in young children and that such increase even improves IQ. Accumulating evidence seems to indicate that working memory, with proper training, can be improved in anyone, even adults. Improved working memory results in improved attention (recall my other posts about how the main memory problem in aging is usually not memory per se but poor attentiveness), better reasoning ability, and better self control.

I recently found a paper in which lasting increases in brain function were produced in healthy adults by only 5 weeks of practice on three working-memory tasks that involved the location of objects in space. Subjects performed 90 trials per day on a training regimen (CogMed) and MRI scans showed increased activity in the cortical areas that were involved in processing the visual stimuli. Brain activity increases in these areas appeared within the first week and grew over time.

Similar results have been reported by other investigators. In a few cases, where different kinds of stimuli were used, memory training induced a decrease of brain activity in certain areas, which is interpreted to indicate that the trained brain did not have to work as hard.

While we clearly don’t understand things very well, it seems clear that working memory training not only improves memory capability but also causes lasting changes in the brain.

Olesen, P. J., Westerberg, H., and Kingberg, T. 2004. Increased prefrontal and parietal activity after training of working memory. Nature Neuroscience. 7: 75-79.

I just read a fascinating book on increasing teacher awareness of the importance of working-memory capacity for teaching and learning strategies. Many youngsters have working memory limitations, and they usually do not grow out of them. This is a major and serious cause of low grades, poor learning skills, poor confidence, and life-long diminished motivation to learn

Limited working-memory capacity not only makes it difficult to form long-term memories, but it also impairs the ability to think and solve problems. I was told once by a middle-school teacher that her “special needs” students could do the same math as regular students, but they just couldn’t remember all the steps. This clearly reflects a limited working-memory capacity. If the demands made on working memory could be lessened, better thinking can result.

Certain strategies can help to reduce the load on working memory. Learners should encouraged to employ the following devices:

• KISS (Keep It Simple, Stupid!)(example: use short, simple sentences, present much of the instruction as pictures/diagrams).

• Get engaged by asking questions, taking notes, and creating diagrams and concept maps.

• Attach meaning from what you already know. (The more you know, the more you can know).

• Break down tasks into small chunks. Master each chunk sequentially, one at a time.

Source: Gathercole, Susan E., and Alloway, Tracy P. 2008. Working Memory and Learning. Sage Publications, 124 pages.

As a newly forming memory develops (see chapter on memory consolidation in my book), it is susceptible to disruption by mind wandering, other stimuli, distractions, etc. When a new memory is retrieved, a re-consolidation process will be required if updated information needs to be incorporated. Such re-consolidation involves a new round of protein synthesis in brain cells, similar to that which is needed to make the initial learning a lasting memory. Likewise, a re-consolidation process must be protected from disruptive influences if the updated information is to be integrated and consolidated with the original learning.

Source: Rodriguez-Ortiz, C. J. et al. 2005. Spatial memory undergoes post-retrieval consolidation only if updating information is acquired. Soc. Neuroscience Abstract 654.20.

I have mentioned earlier the recent discovery that when a memory is recalled, it is then re-saved ("consolidated," as researchers llke to say). During that reconsolidation time window, which in rats is about 6 hours, the memory becomes vulnerable to new information and interference, and can become distorted or even abolished.

Researchers have discovered that injecting a beta blocker drug during this reconsolidation period can prevent re-consolidation of the memory that was recalled, and this is an effective therapy for some patients. The problem is that this is a prescription drug and is potentially toxic.

Another approach is to use extinction therapy. Most phobias and emotional traumas arise from a conditioned association between a neutral stimulus and the traumatic event, much like the conditioning discovered by Pavlov and his dogs. If one repeats the conditioning cue, without re-presenting the bad event, the patient may develop a new memory in which the cue becomes innocuous because it is no longer associated with the bad event. The problem here is that the effect can wear off over time, because the original fear memory was never erased.

A new approach has been devised by Marie Monfils, Joseph LeDoux, and colleagues at several neuroscience and psychiatric institutions. Their idea capitalizes on the differences between reconsolidation and extinction. They reasoned that if the non-threatening conditioning stimulus were given during the reconsolidation window, a new memory that the situation was safe would be formed. Use of a drug could be avoided.

They tested this idea in rats that were trained to be fearful by pairing a tone cue with electric shock to the feet. This was done three times. The intervention therapy consisted of testing for recall with the tone cue, followed by a series of extinction trials in which the cue was repeatedly delivered without accompanying foot shock. Some rat groups were given the intervention during the window and others outside it, like the next day. The behavioral response of fear was movement freezing. That is, when the tone was sounded, rats indicated their memory of the training by freezing out of fear.

The day after the extinction session, all groups showed a similar abolition of freeze behavior. Extinction worked, but did it last? A month later, the same rats were tested again, and the freeze behavior had returned in all rats except those that had received the neutral cue and extinction training during the reconsolidation window. Multiple other experiments supported the value of this intervention approach.

The investigators are now exploring clinical implications in human psychotherapy. There is a possible negative consequence. Erasing the phobia may be accompanied by the conditioning stimulus acquiring the status of being safe and not just neutral. Studies on humans can also allow experimenters to study not just the behavioral expression of fear but also allow them to examine the thought processes. The fear memory may still be there, with the major change being in the behavioral expression.

Source:
Monfils, M.-H. et al. 2009. Extinction-reconsolidation boundaries: key to persistent attentuation of fear memories. Science. 324: 951-955.

Tests do more than just measure learning. Tests are learning events. That is, testing forces retrieval of incompletely learned material and that very act of retrieval helps to make the learning more permanent. Testing, and not actual studying, is the key factor on whether or not learning is consolidated into longer term memory.

A recent experiment by J. D.Karpicke and H. L. Roediger at Washington University in St. Louis, examined the role that retrieval had on the ability to recall that same material after a delay of a week. In the experiment, college students were to learn a list of 40 foreign language vocabulary word pairs, which were manipulated so that the pairs either remained in the list (were repeatedly studied) or were dropped from the list once they were recalled. It is like studying flash cards: one way is to keep studying all the cards over and over again; the other way is to drop out a card from the stack every time you correctly recalled what was on the other side of the card. In the experiment, after a fixed period of study time, students were tested over either the entire list or a partial list of only the pairs that had not been dropped. Four study and test periods alternated back-to-back. Students were also asked to predict how many pairs they would be able to remember a week later, and their predictions were compared with actual results on a final test a week later.

The initial learning took about 3-4 trials to master the list, and was not significantly affected by the strategy used (rehearsing the entire list or dropping items out as they were recalled). On average, the students predicted that they would be able to remember about half of the list on a test that was to be given a week later. However, actual recall a week later varied considerably depending on learning conditions. On the final test, students remembered about 80% of the word pairs if they had been tested on all the word pairs, no matter whether they had been studied multiple times with all of them in the list or if they dropped correctly recalled words from the list in later study trials. However, recall was only about 30% correct when correctly identified words were dropped from subsequent tests, even though all words were studied repeatedly. In other words, it was the repeated testing, not the studying, that was the key factor in successful longer-term memory.

So, what is the practical application? When using flash cards, for example, you need to follow each study session (whether or not you drop cards from the stack because you know them), with a formal test over all the cards. Then, repeat the process several times, with study and test epochs back-to-back. Can we extend this principle of frequent testing to other kinds of learning strategies? Probably. But there are no formal experiments.

Let us speculate on the case of trying to remember names of people at a party. You might study the name of each person by using it in conversation or associating the name with some feature of the person's anatomy or personality. Then, silently quiz yourself, looking at the person and asking yourself to recall the person's name. Then, repeat the study-and-test process several times. You would have to keep number of people low (say four to six), because you may not have many opportunities to hear the name repeated other than your own repeating it in conversation. In most practical learning situations, you will not be given repeat tests immediately after each study session, so you must simulate that with self-tests.

Why does forced recall, as during testing, promote consolidation? It probably relates to other recent discoveries showing that each time something is recalled the memory is re-consolidated. If the same information is consolidated again and again, the memory is presumably reinforced.

The failure of students to predict how well they would remember is consistent with my 40 years experience as a professor. Students are frequently surprised to discover after an examination that they did not know the material as well as they thought they did. Tests not only reveal what you know and don't know, they serve to increase how much you eventually learn. If I were still teaching, I would give more tests. And I would encourage students to use self-testing as a routine learning strategy, something that one study revealed to be a seldom-used strategy. The repeated self-tests should include all the study material and not drop out the material that the student thinks is already mastered.

Source: Karpicke, Jeffrey D., and Roedinger, Henry L. III. 2008. The critical importance of retrieval for learning. Science. 319: 966-968.

Did you know that you could learn a motor skill just by watching somebody perform the skill? Well you may not learn to pitch like Roger Clemens just by watching him, but there is now scientific evidence that some motor learning can occur just by watching. This is somewhat like the "off-line" learning that I described in an earlier blog posting "Are Motor Skills Learned Better at Night?"

Here, the idea, based originally on studies in monkeys, is that several parts of the brain involved in controlling movement, such as the motor cortex, contain some neurons that discharge both when a motor act is performed AND when it is just observed. These have been called "mirror neurons" because they mirror the neural activity that goes on when the movement is actually performed. Recently, a team of scientists at the National Institutes of Health and in a German university have developed a way to test for this kind of observational learning in humans. The approach is to elicit a reproducible movement, of the thumb for example, by a magnetic stimulator placed on the scalp overlying the motor cortex. Then, the experimental subjects teach themselves to move the thumb in the direction opposite to that which is created by the stimulus. So the stimulus comes on, and you make yourself over-ride it by moving the thumb in the opposite direction. For example, if the stimulus caused the thumb to go up (extend), the learning task is to make the thumb go down (flex) during stimulation. The investigators hypothesized that humans would have mirror neuron systems that would enable learning of this movement task just by watching somebody else do it. Guess what? It works!

All 10 subjects that they trained in this way could learn the task just by watching it performed for 30 minutes. They practiced the movement in their "mind's eye." All subjects showed about a four-fold increase in desired movement after observation practice only. Actual physical practice achieved about a 12-fold increase of correct movement compared to the untrained state. So, although actual practice works better than just watching, there is clear indication that significant "off-line" learning occurs just from watching correct movements.

Practical implications: the authors of the study pointed out that observational learning could be very helpful for rehabilitation of patients who have difficulty in generating movements or who are unable to understand verbal instructions. I would add that observational motor learning could supplement actual practice learning in normal people who want to improve a motor skill for a sport, musical instrument, or work task.

Source: Stefan, K. et al. 2005. Formation of a motor memory by action observation. J. Neuroscience. 25 (4): 9339-9346.

"Motor memory" refers to a mental model (MM) that the brain constructs from past experience. In the example given by researchers Reza Shadmehr and Thomas Brashara-Krug, when a person plans to pick up a brick, a MM of the amount of force required to pick up the brick is used to execute the action. The brain does not estimate the force as if it were a feather nor if it were a sack of cement, rather it uses its memory of what a brick weighs to create a model of how much force will be needed to pick it up.

In the studies they reported, they used a robotic arm that subjects used to manipulate objects. In learning how to use the mechanical arm, subjects had to create a MM of how to make it do what they wanted. Like other kinds of learning, the MM is consolidated with practice into long-term memory. Moreover, motor performance continues to improve, even after actual practice has stopped, indicating that the MM itself may be subconsciously rehearsed, off-line so to speak.

Motor memory processes have great applicability in everything from learning to touch-type to learning to throw a football to a moving target. The study by Shadmehr and Brashara-Krug explored the finding that a recently acquired MM (MM1) can be disrupted if a second MM (MM2) was introduced too soon after MM1.That is, a MM1 has to have enough time to consolidate, just as declarative memories do.

Also, a MM1 can interfere with learning a MM2, if there is not enough time separation between learning the two motor tasks. This was demonstrated in the present study by having 60 subjects learn how to make two conflicting movements using the robotic arm. The MM for both tasks could be learned but only if the training sessions were separated by at least 5 hours. If the interval was shorter, learning of the second MM (MM2) was impaired, as was the likelihood of consolidating the first MM.

The “take home message” of this research is that learning different movement tasks should be separated in time, lest there be interference with forming long-term memory of both tasks. My explanation is the following: Once MM1 gets consolidated (that is, after about 5 hours), the circuits that sustain its short-term representation now become available for learning a second motor memory (MM2. That is, MM1 has proactive interfering after-effects that dissipate with consolidation of the MM1 and thus no longer interfere with learning an MM2.

Athletic coaches might be well advised to ponder the application of this principle.

Shadmehr, R., and Brfashers-Krug, T. 1997. Functional stages in the formation of human long-term motor memory. J. Neuroscience. 17(1): 409-419.

Losing Your Past

Do you remember the names of your elementary-school teachers? How about the name of the bully in middle school? Or names of your friends when you were a kid? These are all things you remembered well at one time and remembered for a long time. But you may well have forgotten by now.

Scientists like to talk about "long-term" memory, but even long-term memory has its limits. A recent study on rats suggests what it takes to sustain longer term memories. Rats in the study learned a "bait shyness" task. Rats were given a drink of saccharin-flavored water, and then shortly afterwards injected with lithium, which made them nauseated. This was a typical conditioned learning situation, as with Pavlov's dogs. In this case, rats typically remember to avoid such water for many weeks. This is the basis for "bait shyness." If rats survive a rat poisoning episode, they will avoid that bait in the future. However, in this experiment, one group of rats received an injection directly into the part of the brain that holds taste memories. This injection contained a drug that blocks a certain enzyme, a protein kinase. These rats lost their learned taste aversion. The bad memory was lost irrespective of when the injection was made during the 25 days after learning occurred. Giving the enzyme blocker before learning had no effect on the ability to learn to avoid the flavored water. The protein kinase thus seems to be necessary for sustaining a long-term memory. It is possible that other long-term memories the rats may have had were also wiped out by the enzyme-blocking drug, but this was not tested.

So what is the practical importance of these findings? I suggest that even "long-term" memories have to get rehearsed once and a while or they may eventually fail to remember (see my earlier post on "reconsolidation" of memories. Or if you do remember, there is a good chance that the memory is corrupted, that is, not totally correct. The consequence is that things that happened long ago may be either forgotten, misremembered, or so buried in memory that it takes a great deal of cuing to retrieve the memory. I have a whole chapter in my book, Thank You Brain for All You Remember on the subject of false memory.

The study showed that a certain enzyme has to be present to preserve a memory. Without the enzyme, the memory disappears. What sustains the enzyme? I suspect it is rehearsal and periodic reactivation of the memory, although this possibility has not been tested yet. Some scientists are excited about the possibility of developing a drug that would eliminate the enzyme or insure its presence. The problem with that, however, is that the drug could abolish old memories that you might not want to forget (like your name) or may cause you to remember too much that is now irrelevant.

Source:

Shema, R., Sacktor, T. C., and Dudai, Y. 2007. Rapid erasure of long-term memory associations in the cortex by an inhibitor of PKM. Science. 317:951-953.

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Overtraining: You Can Learn Too Much

Naps may be helpful for learning tasks other than those involving movement (see earlier note on work by Korman et al.). An early study on the effects of napping had developed a useful texture discrimination task in which a visual display of horizontal bars has superimposed on it a brief display of three diagonal bars, followed by a blank screen, and then by a mask. The interval between the target and the mask is varied and the interval needed to achieve 80% correct responses is used as a measure of perceptual ability and working memory.

After a single training session, performance on this task improves only after subjects have had a normal night's sleep after the day's training. To be effective, a normal amount of dream sleep, which occurs mostly in early morning, is needed.

In a follow up study by another investigator, subject performance unexpectedly deteriorated if they were given 60-minute training sessions four times at regular intervals on the same day. In other words, the more the subjects were trained, the poorer they performed. However, this interference did not occur if subjects were allowed to nap for 30-60 minutes between the second and third sessions.

It is hard to explain why over-training disrupts performance, but one has to suspect that as training trials are repeated the information starts to interfere with memory consolidation, perhaps because of boredom or fatigue in the neural circuits that mediate the learning. Napping must have a restorative function that compensates for the negative effects of overtraining. What all this suggests to me is that memory consolidation would be optimized if learning occurred in short sessions that are repeated but only with intervening naps and on different days with regular night-time sleep. In other words, repeating long study periods in the same day on the same task can be counter-productive. This is yet another reason why students should not cram-study for exams. Learning should be optimized by rehearsing the same learning material on separate days where normal sleep occurred each night.

Sources:

Maquet, P. et al. 2002. Be caught napping: you're doing more than resting your eyes.Nature Neuroscience. 5 (7); 618-619.

Mednick, Sara, et al. 2002. The restorative effect of naps on perceptual deterioration.Nature Neuroscience. 5 (7): 677-681.

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In earlier postings, I told readers about research showing how sleep is necessary to consolidate memories of the day's learning events. Now, there is a new study that reveals that lack of sleep BEFORE learning interferes with the consolidation of memories. Formally, this is called a "proactive interference" effect, because it occurs in advance.

In this study Matthew Walker and colleagues at Harvard conducted an experiment in which students were paid not to sleep one night and then try to learn 30 words the next day. Then they were given two nights' of full sleep to catch up on sleep loss, whereupon they returned to the lab for testing on how many of the 30 words they remembered. Compared to a control group that was not sleep deprived prior to the learning session, sleep-deprived students remembered 40% fewer words. In accordance with what other labs had shown, remembering was affected by emotional associations. Sleep-deprived subjects were only 19% worse than controls for words that had negative connotations, while they were 59% worse with positive-connotation words.

The upshot of it all is that lack of sleep is bad for remembering, whether the sleep loss occurs before or after learning events.

Source: Walker, M. 2006. Annual meeting, Society for Neuroscience.

How Marijuana Impairs Memory Formation

Scientists have know for some time that marijuana impairs the ability to convert short-term or working memories into lasting form. Now they know why. The protein synthesis machinery in the hippocampus is necessary to accomplish lasting memory formation, and a study of mouse hippocampus revealed that marijuana impairs the protein synthesis pathway responsible for memory consolidation.

Source:
Puighermannal, E. et al. 2009. Cannabinoid modulation of hippocampal long-term memory is mediated by mTOR signaling. Nature Neuroscience. On-line edition, Aug. 2; doi:10.1038/nn.2369

There is much evidence to indicate that memory for a day's events is being formed during sleep. I go into all this in my memory book's chapter on sleep. Nobody knows how sleep helps memory, but I have come across a study that may explain why sleep helps to consolidate short-term memories into longer-term memory.

The study was conducted in the brain imaging lab of Thomas Pollmacher at the Max Planck Institute in Munich, Germany. He and his colleagues performed magnetic resonance images in human volunteers. A text stimulus was presented to sleep-deprived subjects prior to and after the onset of sleep, and imaging was performed to compare wakefulness response to the sound stimuli with that during various stages of non-dreaming sleep. The results indicated a suppression of activity in the usual auditory pathways during sleep. Activity in the visual cortex is also greatly suppressed, suggesting that sleep protects the brain from the arousing effects of external stimulation during sleep, not only in the primary targeted sensory cortex but also in other brain regions that are interconnected with visual cortex.

In my book I stress how important it is to avoid distractions and new learning before old-learning processes are completed. Most studies of this issue have led to the conclusion that consolidation processes only take a few hours. But it now seems that consolidation of memory occurs over many hours (at least in sleep-deprived subjects) and that sleep facilitates consolidation by blocking out interference effects.

This is not the whole story, however. The Pollmacher study dealt with non-dream sleep. We know from many other studies that dreaming is also important to memory formation. Just how remains to be discovered.

Source: Czisch M.; Wetter T.C.; Kaufmann C.; Pollmächer T.; Holsboer F.; Auer D.P. 2002. Altered Processing of Acoustic Stimuli during Sleep: Reduced Auditory Activation and Visual Deactivation Detected by a Combined fMRI/EEG Study. Neuroimage. 16(1): 251-258.

Want to learn how to touch type? Or play the piano? Or hit a dime with football passes? Maybe you should do your learning at night. Some intriguing recent research raises the possibility that such motor skills may be learned better with night-time training than with training in the morning. As I point out in my book, Thank You Brain For All You Remember, there is abundant evidence that sleep helps to stabilize and consolidate memories of the day's learning, but this study adds a new dimension.

What this present study did was evaluate the stabilization and consolidation of a learned finger-movement sequence that occurs as time elapses after the initial learning session. Other investigators had shown that memory of motor learning develops "off-line," without practice, after the learning session. This is true whether the non-practice interval is during the day or during sleep at night. In this study, one group of subjects was trained at 8 AM and re-tested 12 hours later. Another group was trained at 8 PM and likewise re-tested 8 hours later. In both groups skill was demonstrably better after the off-line interval. But the investigators wanted to know if memory-disrupting influences would have the same effect in morning or evening training sessions. To test this, they disrupted function of the motor cortex with magnetic stimulation delivered to the scalp overlying the motor cortex for 10 minutes immediately after the learning session. When such subjects were re-tested 12 hours later, they found that the expected off-line learning improvement did occur in the overnight off-line condition but no improvement occurred in the daytime off-line condition. In other words, the memory interference caused by magnetic stimulation could not be compensated for by off-line learning during the daytime but was compensated for by the night-time off-line situation.

Is this analogous to real-world conditions? Though our learning is not normally disrupted by transcranial magnetic stimulation, numerous stimuli, experiences and thoughts after a learning experience can disrupt memory consolidation. During the daytime, the numerous memory-disruptive influences can definitely interfere with off-line consolidation of material that we learn in the morning. But with night-time learning, there are far fewer disruptive sensory and cognitive influences, because we are asleep.

Since our football team is not doing very well these days, I think I'll tell the coach about this study. Maybe the daily practice sessions ought to be held in early evening.

Source: Robertson, E. M., Press, D. Z., and Pascual-Leone, A. 2005. Off-line learning and the primary motor cortex. J. Neuroscience. 25(27):6372-6378.

Daytime naps are said to rejuvenate energy and lower stress. Now there is evidence that naps speed up consolidation of memories. Maria Korman and her group at the University of Haifa evaluated consolidation of a procedural memory task of learning to bring the thumb and finger together in a specific sequence. Half of the subjects were allowed to take an afternoon 90-min nap after training, while the other group stayed awake. The group that napped showed a distinct improvement in task performance when tested that evening. After a night's sleep, both groups showed the same improvement in acquired skill. So, it would appear that the nap just speeded up the consolidation process, rather than improving on the improvement that a regular night's sleep can produce.

The role of napping on interference effects was also tested. We know from numerous studies that consolidation of new learning is easily disrupted by distracting or other new learning experiences. In this experiment, another group of subjects learned a different thumb-to-finger movement sequence two hours after practicing the first task. Learning a second task right after the first was expected to interfere with learning of the first task. This proved to be the case; there was no improvement in performance of the first task either that evening or the next day after a normal night's sleep. However, based on the findings of the first experiment where a nap speeded up consolidation, the experimenters created yet another group of subjects that were allowed a 90-min nap between learning the first movement task and the second movement task. In this case, performance on the first task was improved when they were tested the next day after a normal night's sleep. Thus, the nap actually prevented the otherwise memory disrupting effect of a second learning task, presumably because the nap speeded up memory consolidation of the initial learning so that it was resistant to interference effects.

There are practical implications here, at least for procedural memories. This study indicates that if you need to learn a "how to" kind of task quickly, you should take a nap just afterward. One perhaps trivial illustration might be for football coaches who introduce some new training in the morning of a game to be played later that evening. After the morning workout, they should let the players take a nap that afternoon. Or for "two-a-days" workouts in the summer, maybe players need a nap between sessions, not just to rest but to consolidate the training.

Source: Korman, M. et al. 2007. Daytime sleep condenses the time course of motor memory consolidation. Nature Neuroscience. 10 (9): 1206-1213.

In this study, 28 healthy young adults were divided into two groups. On the first day, one group was kept awake for 35 straight hours. Participants in the other group spent a normal sleep night at home. At 6 PM of the next day, all subjects watched a slide show of 150 slides of landscapes, objects, and people who weren't celebrities. All subjects also got MRI brain scans. The scans showed that brain areas involved in memory, such as the hippocampus, were more active in the subjects who got a normal night's sleep. It is as if these areas were too tired to work well. All subjects then were sent home to have a normal night's sleep.

The next evening all subjects took a pop quiz on the slides, which were randomly mixed with 75 new slides. The test was for subjects to recognize whether they had seen each slide before. Those subjects who had been sleep deprived on the first night scored the lowest, even though they later had a night to catch up on lost sleep. Note that the test conditions involved losing sleep on one night, then learning stuff on the next day, followed by a normal night's sleep, and then being tested the next day. This is a "proactive" effect, where sleep loss before learning impairs learning. I have reviewed other studies that show impairment when sleep loss occurs at the same time as learning, as in cramming for exams.

Source: Yoo, S., Hu, P. T., Gujar, N., Jolesz, F. A., and Walker, M. P. 2007. A deficit in the ability to form new human memories without sleep. Nature Neuroscience. 10: 385-392.

"Mental time travel" is what we do when we retrieve a memory. Our brain has to go back in time to reactivate the neural networks that contain the representation of the original memory and its associated cues. How does the brain do that? That is, how does the brain select among its hundreds of thousands of representational networks the one network that it needs to find at the moment

Is this a random-access process like that used in computer searches? Probably not. Computers can do random-access searches because they operate at time scales of microseconds or nanoseconds. The brain, alas, must lumber along at millisecond speeds.

A leading theory for how the brain does it is that memories are indexed by category, thus reducing the difficulty of a search. The basic idea is that during recall, the brain uses categorical general knowledge as contextual cues for the specific memory being sought. For example, in trying to remember what you saw on a trip to a zoo, you would use your zoo category, that is, your general knowledge of the kinds of animals usually seen at zoos as cues to assist in the recall of animals that you actually did see. As specific details emerge in the recall process, these serve as further cues to refine the search. By the way, in my book, Thank You Brain for All You Remember, I go to great lengths to explain and illustrate the importance of cues in both creating and retrieving memory.

This theory has now been tested in a brain-scan (MRI) study of humans engaged in memory retrieval tasks. Scans were made during recall for three categories of pictures (faces, objects, locations). Specific patterns of cerebral cortex activity were associated with specific picture categories. During recall testing, these cortical activity patterns correlated with correct verbal recalls from the category normally associated with that pattern of cortex activity. Moreover, the cortical activity pattern preceded by several seconds the verbalization of the correct memory response. Correctness of recall could actually be predicted by the pattern of MRI activity that was seen just prior to recall attempt.

So, the brain seems to have circuits that select for specific categories of information. Think of it like a huge filing cabinet, where each drawer (set of cortex circuitry) contains files that all share the same category.

As a practical memory-improvement matter, all of this emphasizes the importance of organizing learning by category and by creating many associative cues for the items in that category. I illustrate this with a practical example of how I go about retrieving the name of someone I used to know. See "tip-of-the-tongue" example in my memory advice column (http://thankyoubrain.com/AnswerArchives.htm).

Source: Polyn, Sean M. et al. 2005. Category-specific cortical activity precedes retrieval during memory search. Science. 310: 1963-1966.

Ever go to the refrigerator to get something and suddenly realize that you don’t remember what you were looking for? Well, you are not alone, and we think we know why this happens. There are two possibilities: 1) something distracted you and put new information “on top of” what was in your working memory, or 2) something that was on your mind before you decided to get something out of the refrigerator impaired your ability to hold the item in your working memory.

Working memory, necessary as it is for thinking (see the post dated just before this one), has several limitations. One is that the capacity is limited. Remember the 7 + rule described in another post? There is also the problem that distractions or new information can over-write and erase what is in working memory.

Now we learning that there is such a thing as “proactive” interference. That is, working memory is impaired by previous material that was in the working memory. One study even indicated that forgetting from working memory would be minimal if it were not for proactive interference. People differ in their susceptibility to such interference, and it is not clear if there are training protocols that could make the brain less susceptible.

Experimentally, these issues are studied by a “recent-probes” task, in which participants are presented a target set of items, such as letters, to remember for several seconds (letters have to be held in working memory). Then participants are given a single probe item (letter, for example) and must decide whether this probe item matches one of the letters in the original set. Some probes match (considered positive probes) and some will not (negative probes). To demonstrate the ability of a previous trial to influence the current one, experimenters can introduce a probe (letter) that was not a member of the current trial’s target set (but was a member of the prior set) just prior to presentation of the current trial’s set. Then, the ability to remember if the next probe letter was in the current set can be tested to see if interference had occurred. They find that letters in a prior trial can interfere with ability to recall the letters in the current trial.

Researchers are now studying with brain imaging how these influences are controlled in the brain. Activity in the left inferior frontal cortex is important in resolving such conflicts and in correctly remembering what was in working memory.

So what is the practical application of such studies? For one thing, the notorious low-capacity of working memory could be due to proactive interference. If we could reduce the interference, we should be able to increase working memory capacity. As I described in an earlier post, just practicing working memory demands for more items may actually increase memory span, and that effect might be due to unintended training to resolve proactive interferences. I think that such studies show why it is so important to pay attention and stay focused when trying to remember. Any non-relevant stimuli carry the potential to cause proactive interference. When faced with serious memory tasks, get in an environment that does not supply irrelevant information. Force yourself to think only of things that are relevant to what you are trying to think about and remember. Concentrate!

Sources:

Jonides, J., and Nee, D. E. 2006. Brain mechanisms of proactive interference in working memory. Neuroscience. 139: 181-193.

Keppel, G.,and Underwood, B. J. 1962. Proactive inhibition in short-term retention of single items. J. Verb. Learn. Verb. Behav. 1: 153-161.

Forgetting Can Be Good - Solving the "Tip-of-the-Tongue" Problem

Ever forget something you know you know ... like a friend's name or some other equally embarrassing piece of information? It is on the tip of your tongue, but you just can't get it out.

New research suggests that the problem is a failure to forget. That is, you remember too many wrong things that interfere with the recall of what you want. Researchers at Stanford University recently clarified this problem by a study in which subjects were required to recall words from among many similar words that they had also seen.They viewed a succession of word pairs. A given cue word was paired with six associated words; example: ATTIC - dust, ATTIC - junk, etc. Participants practiced retrieving only half of the associates of half of the cues, with each practiced associate repeated three times. During practice and recall testing, a word cue was presented along with the first letter of the missing word in the pair. This design forced subjects to recall in the face of competing memories. For example, the might have to recall ATTIC - d (dust), even though their memories were cluttered with the other five ATTIC word pairs (ATTIC - junk, etc.). Subjects were also tested on how well they remembered the word pairs that they had seen before but not practiced.

Recall effectiveness ranged from about 30 to 80%, with better performance correlating with poor recall of those words that they were not supposed to remember. In other words, the better subjects could forget irrelevant information, the better they could recall what they were supposed to remember.

During all of the testing, subjects had their brains scanned by MRI, and these results showed a decrease in brain activity in the brain areas that detect and resolve memory competition as a given word pair was rehearsed. That is, as the learning progressed, there is a decrease in the amount of work the brain has to do. Interestingly, with the irrelevant word pairs, the effectiveness at forgetting was associated with still greater decreases in brain activity. That is, forgetting of competing memories lowered the required workload for remembering the relevant memories.

Clearly, "tip-of-the-tongue" recall problems would benefit from strategies that improve the ability to forget irrelevant memories. I am not aware of any formal studies that tell you how to do this. My own experience shows the importance of two strategies: 1) recognize irrelevant memories and try hard not to thing of them, and 2) try to remember all the cues that were associated with what you are trying to remember. For example, I recently had a need to remember the first name of a graduate student I had some 30 years ago. His last name was Smith. Unfortunately, the only first name for Smith that came to mind was Stan Smith, the famous tennis player (I am a tennis fan). I immediately knew this was not my Smith and I had to force myself not to thing of Stan, because that was blocking retrieval. The next step was to think of all the cues that I did remember about my Smith. I remembered what he looked like (tall, skinny). I remembered the research project we did (hypnotizing rabbits) and the details of the experiments. I recalled the front paper of our publication, where it listed the title of the paper and our names. Voila! I saw his first first name: Greg. The right answer just popped into my brain, no doubt triggered by all the cues.

Source: Kuhl, B. A. et al. 2007. Decreased demands on cognitive control reveal the neural processing benefits of forgetting. Nature Neuroscience. Published online: 3 June; | doi:10.1038/nn1918. http://www.nature.com/neuro/journal/vaop/ncurrent/suppinfo/nn1918_S1.html

Now, evidence from multiple labs shows that each time you recall something you have learned, the memory has to be re-consolidated. This means that during recall, the memory again becomes susceptible to change or even forgetting.

One striking example of this is recently reported from a study of rats that were conditioned to be afraid anytime they were put in the test chamber, because the first time that they were first put in there, they got electric shocks to their feet. Such learned fear in rats leads to freeze behavior — they don’t move much, and a researcher can measure how much time they spend without moving as a metric of fear. In this study, after rats had learned this conditioned fear response (it only takes one time), they were later tested for the time they spent immobile when put back into the chamber. But in one group of rats, a tranquilizing drug was given 5 min after rats were put in the “fear chamber” a second time, after they had learned to fear impending foot shock (even though feet were never shocked again). When retested some 10 days later, the rats that had been given tranquilizer during the earlier recall trial showed little freeze behavior, indicating that they had forgotten what they learned and what they were forced to rehearse when they were put into the fear chamber a second time. The drug treatment and its timing caused them to forget to be afraid. Note that there was a rather surprising finding that the drug had no convincing impairing effect when given during the consolidation period of the initial learning trial. But when given during a re-consolidation period of a second rehearsal trial, profound forgetting effects were noted. The drug interference effect could be seen for up to 60 minutes after re-consolidation, not later. That is, rats would forget if they were given the tranquilizer any time up to 60 minutes after being re-tested in the fear chamber during a recall trial, but injections after that time did not impair the memory (i.e., it had been re-consolidated successfully).

So what is the practical application of such studies? We don’t know for sure yet, because the idea has not been tested yet in humans. But such experiments do suggest strongly that during recall, a memory trace becomes vulnerable once again. The memory may be lost altogether. That could be good, if you are trying to erase bad memories that are having a bad effect on mental health. The memory may also be altered. That can be bad or good. If the memory becomes corrupted, it can lead to a false memory that one firmly believes for a long time, even though it is wrong. On the other hand, the memory can actually become enriched, if re-consolidation involves new information that expands the amount of information stored and the improves the quality of the original information. So, remember, that even though rehearsal promotes retention, it may not always be helpful. Be careful about what happens during the process of recall. Stayed focused during rehearsal of things you are trying to remember. Make certain there are not distractions or extraneous information being inserted into your memorizing process.

Source: Bustos, S. G, H. Maldonado, and Molina, V. A. 2006. Midazolam disrupts fear memory reconsolidation. Neuroscience. 138: 831-842.

If you think you don’t have a good memory, you probably don’t. But it is not just a matter of self-awareness. Beliefs about memory ability seem to cause poor memory. A recent study of memory in the elderly provides strong evidence that stereotypical attitudes about losing memory with age may actually cause poor memory. More importantly, more positive, yet implicit, self-stereotyping can improve memory.

Earlier investigators had noticed that older people do NOT have poor memories if they live in cultures (such as China) where old age is venerated and there is no general bias about mental deterioration with age. Picking up on this theme, a Harvard University researcher studied 90 people, age 60 or older, and found that memory task performance was improved by a single-session intervention that created positive stereotypes. A corresponding decrease in memory performance was produced by interventions that created negative stereotypes. The intervention conditioned belief about memory capability in an implicit way; that is, subjects were not aware that they were being "brainwashed."

In the implicit procedure, subjects viewed a list of about 50 words that either represented senile behaviors (absent-minded, etc.) or represented “wise” behaviors (“sees all sides of issues,” etc.). The lists were presented subliminally on a computer screen, and the subjects were asked to notice whether a flash occurred above or below a bullseye that they were to focus on. Subjects were to signal the location of the flash as soon as they could with a computer key press. The rate of stimulus presentation was slow enough to allow the subliminal messages to be encoded but fast enough to keep them from being registered consciously. Messages were presented in five sets, each containing 20 words.

Before and after the intervention, subjects were given three different kinds of memory tests that are known to assess the kinds of memory decline that occur in old age. Compared with their pre-test memory scores, post-test scores increased in the group that was primed with words signifying wisdom and were lower in the group that was primed with words suggesting senility.

A subset of subjects was exposed to a fake “memory-enhancing light.” They then read a story and were quizzed on its contents, but they were given false positive feedback and attributions of success. When they took the standard battery of tests taken by the implicitly primed group, there was no improvement in memory scores over their pre-test scores. Failure of the explicit conditioning to have an effect is attributed to a failure for the words to penetrate deeply into the subconscious.

In any case, it was clear that implicit priming with positive verbal images of old age was effective, despite the fact that all the priming was done in one training session. The implications for real-world memory performance seem clear. If we believe that we can’t memorize well, we probably can’t. If we truly believe that we can remember well, maybe we can! Believing makes it so.

Source: Levy, Becca. 1996. Improving memory in old age through implicit self-stereotyping. J. Personality and Social Psychology. 71 (6): 1092-1107.

Some experiments have shown that acute (short-term) stress and the adrenal hormones it releases can help memory. But this is not always true, and the discrepancy may have something to do with the kind of stress. One study, for example, showed that the stress hormone, cortisol , impaired immediate recall of stimuli that induced positive or neutral emotions (recall of stimuli that induced negative emotions was not impaired by the hormone). In another study using delayed recall testing, memory of stimuli that evoked negative emotions was impaired by cortisol.

In the study that I describe here, young healthy men were tested for their ability to recall lists of 10 positive, 10 neutral, and 10 negative words. Subjects were given 2 minutes to learn the lists and were then tested immediately. Thirty minutes later they were given a psychosocial stress which included fictitious job interview in front of live interviewers and counting backwards in steps of 17 in front of judges. Control groups did a 5-minute speech and did the same counting, but not in the presence of judges. On the next day, subjects were tested again (delayed recall) 10 minutes after cortisol. Other psychological tests were administered and the amount of cortisol in the saliva was measured at several key points in time.

As expected, the stressed group had elevated cortisol levels after stress. Recall of both negative and positive emotionally arousing words was impaired, but there was no effect with neutral words. These effects could not be attributed to decreased attention or working memory span, which were not affected by the stress. Providing cues for recall eliminated signs of the stress effect on emotionally charged words.

So, this study shows that recall of emotionally charged information can be impaired under stressed conditions. Imagine how great the deleterious effect of stress could be in situations where there is real stress, as in witnessing car accidents, crimes, or dangerous situations in which recalling what happened could be very important. Studies like this are consistent with many real-life observations with eye witness accounts, where what is remembered may well be false. My book, Thank You Brain For All You Remember, has a whole chapter on this subject of "false memory."

Source: Kuhlmann, S., Piel, M., and Wolf, O. T. 2005. Impaired memory retrieval after psychosocial stress in healthy young men. J. Neuroscience. 25 (11): 2977-2982.

Teenage Angst Is Bad for the Brain

Remember being a teenager? ... and all the stress of boy-girl problems, over-bearing parent problems, bullies, worries about school and your future, and frustrated attempts to be popular? Scientists have long known that chronic stress can kill nerve cells. Now it seems that an especially vulnerable time is adolescence. It now seems clear that the brain is being re-built during teenage.

Human imaging studies show that the cerebral cortex shrinks during adolescence. In a recent study of "adolescent" rats, researchers found that the cortex shrinks in both males and females and that there is a loss of neurons in the ventral prefrontal cortex, the part of the brain that humans use to make rational decisions and do higher-level thinking. More loss occurred in females than in males.

Until now, the reason for neuron loss has not been clear, but now we may be able to explain it by looking at the stresses that afflict teenagers. Another study of rats showed that the prefrontal cortex is a special target of stress. Chronic stress reduced learning effects on synaptic strength in the pathways between the hippocampus and the prefrontal cortex, shrunk the prefrontal cortex, and severely disrupted working memory and behavioral flexibility.

A third study, this time of adolescent rats, showed that even a single severe stress (20 min of bullying by an older aggressive rat) was strong enough to kill new nerve cells. Fewer than normal new neurons appeared in the hippocampus and of those, fewer were likely to survive in adolescents that were stressed.

Sources:
Markham, J. A., Morris, J. R., and Juraska, J. M. 2007. Neuron number decreases in the rat ventral, but not dorsal, medial prefrontal cortex between adolescence and adulthood. Neuroscience. 144: 961-968.

Cerqueira, J. J. et al. 2007. The prefrontal cortex as a key target of the maladaptive response to stress. Journal of Neuroscience. 27 (11): 2781-2787.

Thomas, R. M., Hotsenpiller, G., and Peterson, D. A. 2007. Acute psychosocial stress reduces cell survival in adult hippocampal neurogenesis without altering proliferation. Journal of Neuroscience. 27 (11): 2734-2743.

Memory of a distressing event and memory of its extinction can co-exist.
Which memory is retrieved determines whether or not anxiety results.

As this picture shows, memory of a CR and its extinction can co-exist. The practical consequence is that these memories compete for which one is strong enough to be retrieved. Sadly, the CR memory is often stronger. As I explain in my book, cues are extremely important to both forming and retrieving and memory. It seems likely that in typical human situations, there are many more cues in CR than in extinction. Therapy should be aimed at enriching the number and variety of cues associated with extinction learning.

Here is an example applied to humans that this kind of research suggests to me: if you are afraid of heights, it could be because some frightening event happened, perhaps years ago, that involved a high place. You may not even remember what caused the fear, but clearly any high place provides plenty of cues to trigger the memory of that conditioned memory. Now, if you progressively force yourself in small steps to go to high places, under clearly safe conditions, you can learn to extinguish this memory by thinking about how irrational your fear is. For instance, walking up a staircase should not evoke fear if there is no way you can fall off. These new extinction learning experiences need to be consciously attended, rehearsed, protected from interfering stimuli, and otherwise nurtured to promote consolidation. You should strive to construct all sorts of cues that can be associated with your extinction trials. These cues should strengthen the consolidation of your extinction learning and moreover, make the extinction memory more retrievable in the face of other cues that were associated with the original CR. Like any other memory, the extinction cues and environment need to be re-experienced often at periodic intervals so the extinction memory is strengthened at the expense of the original CR that created the anxiety disorder.

There is another aspect to learning called generalization or learning to learn. It is entirely possible (though nobody has been smart enough to study it) that if you have multiple anxieties they generalize and "spread" to facilitate learning new anxieties. The corollary would be that learning how to promote extinction could also generalize. Obviously, for one's brain to learn how to do that, one should begin with the easy tasks.

For example, consider a fear which you might have for about walking down a crowded hallway in church. That should be really easy to extinguish. For example, if you progressively force yourself to walk in such a hall under obviously safe conditions, perhaps only short distances or semi-crowded halls at first, you can learn to extinguish this memory by thinking about how irrational your fear is. These new extinction learning experiences need to be consciously attended, rehearsed, protected from interfering stimuli, and otherwise nurtured to promote consolidation. You should strive to construct all sorts of cues that can be associated with your extinction trials. These cues should strengthen the consolidation of your extinction learning and moreover, make the extinction memory more retrievable in the face of other cues that were associated with the original CR. Like any other memory, the extinction cues and environment need to be re-experienced often at periodic intervals so the extinction memory is strengthened at the expense of the original CR that created the anxiety disorder. As you master extinction of this task, and progress in small steps to other anxieties, you ought to get better at it.

Source:

Quirk, G. J. et al. 2006. Prefrontal mechanisms in extinction of conditioned fear. Biological Psychiatry. 60: 337-343,

Feedback is essential for learning. Not only does the feedback need to ensure that learning was achieved (as in testing), but feedback also needs to reinforce the motivation to learn. The age-old questions arises: do we use the carrot or the stick? Which works best, negative or positive reinforcement? Most people have an opinion, but now we have scientific studies of the question. And the answer is, it depends.

For example, three studies showed that adults correct their behavior better in response to negative feedback rather than positive feedback, whereas 8- to 11-year old children respond just the opposite. A follow-up study by Anna van Duijvenvoorde and colleagues in the Netherlands used MRI scans to examine how the brain changes with age and how that relates to feedback-based learning. The subjects were divided into three age groups, 8-9, 11-13, and 18-25. Each subject performed the same learning task and were given positive and negative feedback to improve their performance. After each trial, subjects were shown on a screen an “X” or a “+” to tell them they were wrong or right.

Regardless of the nature of the feedback, young adults learned bdetter than the children. For all three age groups, learning was more effective with positive feedback. Moreover, the decreased learning from negative feedback was conspicuously greater in the youngest age group, while in the young adults, the effect of feedback type was negligible.

Not surprisingly, there were brain scan indicators of differing response to type of feedback. With age, both types of feedback produced a shift toward recruiting more activity in the dorsolateral prefrontal cortex. This part of the cortex was more active after negative feed back in adults but after positive feedback in the 8-9 year-old children. The prefrontal cortex activity was about the same for negative and positive feedback in the 11-13 year olds, suggesting that this is a transition stage in development of learning style and capability.

Take home message? Positive feedback usually works best in young children (that is, after all, how they train seals). Negative feedback works just about as well as positive feedback in young adults. One more point: with the exception of language acquisition, young children are not the superior learners that many people believe.

Source: van Duijvenvoorde, A. C. K. 2008. Evaluating the negative or valuing the positive? Neural mechanisms supporting feedback-based learning across development. J. Neuroscience. 28 (38) 9495-9503.

Biological reward comes from the release of the neurotransmitter, dopamine. Performing working memory tasks promotes dopamine release. In the study of human subjects by Fiona McNab and colleagues in Stockholm, human males (age 20-28) were trained on working memory tasks with a difficulty level close to their individual capacity limit for 35 minutes per day for 5 weeks. After such training, all subjects showed increased working memory capacity. Functional MRI scans also showed that the memory training increased the cerebral cortex density of dopamine D1 receptors, the receptor subtype that mediates feelings of euphoria and reward.

Students who make good grades feel good about their success. Likewise, people who are "life-long learners" have discovered that learning lots of new things makes them feel good. Though this present study did not rigorously test the idea, it is possible that learning how to improve your working memory capacity can also make you feel good.

Source: McNab, F. et al. 2009. Changes in cortical dopamine D1 receptor binding associated with cognitive training. Science. 323: 800-802.

I have discussed elsewhere a new idea for treating unpleasant memories, such as post-traumatic stress syndrome. The latest treatment being investigated by some researchers is based on using a common blood pressure drug, propranolol, which has a side effect of blocking the re-consolidation of emotions associated with old memories when those memories are recalled.

The original idea was first confirmed in rats. Now a study indicates that the approach can work in humans and might become a clinically valuable treatment. In this human study, subjects were given a mild shock when shown pictures of spiders on the first day of the study. Their fear response was measured as the eyeblink startle reflex to a loud noise. On day 2 of the study, the memory reactivation phase, the study volunteers exhibited the same response to the fearful stimuli (the spider pictures) as on day 1. On day 3, 20 of the subjects were given 40 mg of propranolol, and the remaining 20 were given a placebo. Next, the entire group was exposed to the fearful stimuli. The propranolol group did not exhibit the same startle response as on previous days. The placebo group showed no change in startle response compared to days 1 or 2. In other words, the drug reduced the emotional response, yet did not reduced the memory of the learned event.

Thus, it seems that if propranolol is in the body at the time when one recalls a bad memory, the emotional impact of the memory can diminish without impairing the ability to remember the item. Psychiatric treatment protocols remain to be worked out. Notice that in this situation the learned fear response was recent. Nobody knows if this effect occurs with old, well-entrenched fear memories. Another issue that nobody seems to be asking is the possibility that people on this kind of blood pressure medication might be suffering impairments of emotional memories that they don't want to lose. Does this drug cause a general dulling of emotions?

Source:

Merel Kindt, Marieke Soeter, Bram Vervliet (2009). Beyond extinction: erasing human fear responses and preventing the return of fear Nature Neuroscience DOI: 10.1038/nn.2271

Your chances of getting Alzheimer's Disease are affected by how much education you have had. In a study of 642 elderly people, Denis Evans and his colleagues at the Rush Medical Center in Chicago found that each year of education reduced a person's risk of Alzheimer's Disease by 17%. Scientists think that the explanation relates to the fact that education stimulates the brain to increase the number and strength of connections among neurons. These enhanced connections give the brain a so-called cognitive reserve that supposedly compensates for the ravages of Alzheimer's Disease.

Support for this conclusion comes from a related study by D. A. Bennett and colleagues at Rush Medical Center. This study was based on autopsy of 130 elderly nuns, brothers and priests who had donated their brains to science. The results showed that the more highly educated participants in the study did not develop Alzheimer's disease until they had about five times as many plaques and tangles as the less educated participants.

In yet another study by K. P. Riley and colleagues of a population of nearly 100 nuns, mental skills at a younger age were found to be an even better predictor of whether a person would get Alzheimer's Disease later in life. In this study, the investigators examined the essays that the ladies wrote as they were applying to become nuns. The nuns who had written the poorest essays when they were in their 20s had a very high risk of developing Alzheimer's Disease when they got older. Most of the elderly nuns who developed the disease had essays that ranked in the bottom third of the linguistic ability scale. The most obvious interpretation is that young nuns who wrote the best essays had already developed their mental abilities and presumably kept up the mental stimulation throughout the rest of their lives.

Sources:

Evans, D. A. et al. 1997. Education and other measures of socioeconomic status and risk of incident Alzheimer disease in a defined population of older persons. Arch Neurol. 1997 Nov;54(11):1399-405.

Bennett, D. A. et al. 2003. Education modifies the relation of AD pathology to level of cognitive function in older persons. Neurology. 60: 1909-1915.

Riley KP, Snowdon DA, Desrosiers MF, Markesbery WR: 2005. Early life linguistic ability, late life cognitive function, and neuropathology: findings from the Nun Study. Neurobiology of Aging, 26(3):341-347.

Social Networks Provide "Protective Reserve" for Alzheimer's Disease

In an earlier posting, I reviewed a study that showed that staying mentally active can help some people to protect against development of symptoms of Alzheimer's disease, even when some brain lesions of the disease are present. The usual explanation is that a lifetime of high mental activity creates a kind of protective reserve. Now another study reveals that close contact with friends, relatives and social networks can offer a similar protective-reserve effect.

David Bennett and colleagues at Rush University examined postmortem brains from 89 donors and found the pathological signs of Alzheimer's disease (plaques and tangles) in many people who had not shown any behavioral signs of the disease before they died. When the researchers examined the social and lifestyle history of these people, they found that a strong social network had apparently protected these people from the consequences of their brain lesions. The explanation is that strong social networks (and mental activity of any kind) had caused the brain to develop richer and more extensive synaptic connections, allowing the brain to compensate for the damaging effects of Alzeheimer lesions.

Another possible benefit of good social networks is that they reduce stress, and the cumulative effect of chronic stress hormones (glucocorticoids) actually kills neurons. Such a stress effect would aggravate the consequences of having Alzheimer lesions.

Source: David A Bennett, D.A. et al. 2006. The effect of social networks on the relation between Alzheimer's disease pathology and level of cognitive function in old people: a longitudinal cohort study. The Lancet Neurology, May 2006, pages 406-412.

Most of the time most of us wish we could remember things better. But some of the time all of us have things we wish we could forget. Traumas, emotional upset, grief — all can be more than we can wish to bear.

Now there is some relief in sight, at least for memories that cause so-called post-traumatic stress disorder. Common examples of this syndrome include rape and battlefield stress. Two lines of memory research have converged to produce a treatment, and sometimes even a cure, for the most serious need to forget: post-traumatic stress syndrome. At least two research groups have been discovering that there is a drug that helps us to forget overwhelmingly stressful memories and thus reduces the stress that goes with those memories.

One reason it is possible to forget or at least edit memories is that when even well-formed memories are recalled, they are put back on the scratch pad of working memory where they are accessible to “editing.” This fundamental idea was revealed in research on rats in 2000 by Karim Nader at McGill University in Canada. This is part of the "re-consolidation" idea that is discussed elsewhere on this page. The second idea, discussed at length in my book Thank You Brain For All You Forget, is that memory consolidation is greatly influenced by the impact of the experiential event, and that impact is magnified by strong emotion and the hormones that such emotions releases.

While memories reside on the scratch pad, either for the first time or during recall, they can be changed by drugs. Most drugs, if they do anything for memory, impair it. One drug, propranolol seems particularly adept at disrupting memory of fearful or unpleasant emotional events. The rationale for testing propranolol was explained in the seminal work by Roger Pitman and colleagues. They noted earlier studies showing that adrenalin (epinephrine), either injected or released naturally, strengthens memory formation and fear conditioning. When confronted with stressful or fearful events, epinephrine is normally released, and this helps you to remember the bad event and hopefully you can avoid facing that threat again by being prudent. Adrenaline acts on a class of molecular receptors called beta-adrenergic receptors. Other drugs, among them propranolol, block beta receptors and thus might theoretically disrupt fear-induced memories. Several groups confirmed that propranolol does impair fear-conditioned memory in both animals and humans.

Pitman’s group sought to extend this notion to post traumatic stress disorder (PTSD) in a pilot study of 41 patients. They conducted a double-blind, placebo-controlled study in which a single 40 mg oral dose of propranolol was given as soon as possible (within 6 hours) after a traumatic event experienced by patients who had been rushed to a hospital emergency room. Patients then continued the medication four times a day for 10 days followed by a 9 days when the dose was progressively reduced to zero.

One and three months later, patients returned for psychological testing aimed at measuring PTSD. At one month post trauma, the number of patients with PTSD in the propranolol group was almost half that of placebo controls. Not tested was the possibility that a larger dose, especially at first, might be even more efficacious, since there probably is a narrow window of opportunity for the drug to be beneficial in impairing the consolidation of bad memories.

A similar, though less dramatic result was obtained in a later study by Guillaume Vaiva and colleagues. Their hospital emergency room patients were given propranolol or a placebo 2-20 hours after experiencing an auto accident or physical assault. The patients tested were also selected for having abnormally fast heart rates, because propranolol is a common therapeutic for that condition. Propranolol was given in a dose of 40 mg three times daily for seven days, followed by gradual reduction to zero over 8-12 days.

Together, this studies suggest the need to optimize the treatment regimen. Timing of drug taking, for example, is probably not optimal, given that intense memories can be consolidated in a matter of minutes. The optimal dose is not known, nor for that matter have other beta blockers been tested.

Finally, the obvious treatment approach for PTSD is to have patients recall the traumatic event while under the influence of propranolol. The idea is that during recall, the memory and its association emotion have to be re-consolidated, and this is blocked by the drug. Each time a memory is recalled, it is vulnerable, and recalling multiple times in the presence of the drug that impairs that memory might be especially effective. Indeed, this idea is being hailed as a major breakthrough in treatment of PTSD and, according to a TV special by "60 Minutes" on Nov. 26, 2006, many positive results are being reported by physicians and the Army is considering using this approach for combat-related PTSD. The National Institute of Mental Health is now recruiting patients for a Phase IV Clinical trial.

A side note — millions of people routinely take beta blockers to treat high blood pressure. If a particular blocker crosses the blood-brain barrier in significant amount, it could have the potential of reducing emotionally stressful memories on a continuing day-to-day basis. The blood pressure lowering effect of the drug may arise in part from reduction of psychological stress. Some scientist should probably look into the possibility that beta blockers might impair memory in general.

References

Pitman, R. K. et al. 2002. Pilot study of secondary prevention of posttraumatic stress disorder with propranalol. Biol. Psychiat. 51 (2): 189-192.

Vaiva, G. Et al. 2003. Immediate treatment with propranalol decreases posttraumatic stress disorder two months after trauma. Biol. Psychiat. 54 (9): 947-949.

Addiction to drugs and compulsive behaviors (e.g. gambling, bad habits, etc.) are notoriously persistent, even in the face of great effort to change. All addictions have a strong memory component that includes not only remembering how good it feels to satisfy the craving but also memory of the numerous addictive behavior's associated environmental cues (context, people, places, paraphenalia, etc.). Too much or too powerful a memory of these things can overwhelm efforts to abstain.

The rewarding properties of addictive substances or behavior are mediated by the release of dopamine in the brain. Dopamine release can thus be thought of as the common currency for valuing a variety of positive reinforcers. Memory of past reinforcers uses that same currency. Curing the addiction is promoted not only by finding substitute reinforcers but also by extinguishing the memories of addiction. Therapies for addiction should therefore take both ideas into account.

Substitute positive reinforcers have to be found. For example, to quit cigarette smoking jogging is good, because it releases endorphins, which are positively reinforcing - not to mention the fact that you can't smoke and jog at the same time. Kicking the habit also requires you to extinghish cues that have been learned in association with the addiction. For example, cigarette smokers commonly crave a cigarette most strongly with their morning coffee. Repeatedly having morning coffee without a cigarette at this time will help extinguish the rewarding memory associations (see my book's comments on extinction of conditioned behaviors).

Source: Hyman, S. E. 2005. Addiction: A Disease of Learning and Memory. Am. J. Psychiatry. 162 (8): 1414-1422.

Folic acid, a B vitamin, might slow the cognitive decline seen with aging. In this study, 818 men and women 50-75 years old who took 800 micrograms of folic acid a day over three years scored better in cognitive tests than people in a control group that took a placebo. On memory tests, people in the folic acid group had scores comparable to people 5.5 years younger. The amount used in the study was 800 micrograms, twice the amount official RDA amount.

Folic levels are low in most foods, except foods such as oranges and dark green vegetables.

Source: Durga, J. et al. 2007. Effect of 3-year folic acid supplementation on cognitive function in older adults in the FACIT trial: a randomised, doubled blind controlled trial. The Lancet. 369: 208-216.

Omega-3 Fatty Acid Supplements Improve Memory

Taken your omega 3 tablet today? A new study suggests that you need to get in the habit of taking omega-3 (specifically the omega-3 fatty acid, docosahexaenoic acid). Such supplementation benefited mice that were genetically engineered to produce the two different proteins that create the amyloid plaques and neurofibrillary tangles that characterize the disease in humans.

The study focused on testing the dietary ratio of omega 3 to another fatty acid, omega 6. People typically consume omega-3 from fish, eggs, and organ meats, while omega-6 is prominent in corn, peanut, and sunflower oils. It turns out that it is the ratio of the two fatty acids that is important, and the diet of most people does not have enough omega-3. A typical Western diet produces a ratio ranging from 1:10 to 1:30, where ideally it should be 1:5 to 1:3.

In the experiment, four diets were compared: 1:10 (omega3/omega 6), omega-3 only supplement, and two other diets that need not concern us here. After only three months, the omega 3 diet reduced the accumulation of plaques and tangles in the brain. However, the benefit of omega-3 was diminished when the omega-3 was combined with omega-6. After 9 months, only the omega-3 diet was beneficial.

Previous mouse-model studies in other labs have shown some benefit from a variety of such dietary sources as green tea, fish, blueberries and from exercise and environmental enrichment.

Alzheimer's disease is a growing public-health problem as people live longer. Today, roughly 5% of the population over 65 has Alzheimer's disease, and as many as one half of the 80-year-olds have it. By 2050, predictions are that 20 million people in the U.S. will have Alzheimer's disease (it is 4.5 million now).

Sources:

Green, K. N. et al. 2007. Dietary docosahexaenoic acid and docosapentaenoic acid ameliorate amyloid-beta and tau pathology via a mechanism involving presinilin 1 levels. J. Neuroscience. 27:4385-4395.

Radulescu, A. 2007. Omega-3 fatty acid may help prevent Alzheimer's brain lesions. www.playfuls.com/news, April 18.

Epicatechin - Newly Discovered Memory Chemical

It is found in blueberries, tea, grapes, and cocoa, and it improves memory in laboratory animals. Epicatechin, is one of a family of chemicals known as flavonols. It improves blood flow in the brain and presumably also in the heart. The discovery was made by comparing water maze memory in mice. Mice had to learn and remember where a hidden, "safe" platform was located in the maze. Mice were divided into two groups, one that got epicatechin supplement in their diet and also a group that did not. In addition, half of each group got exercise (two hours per day in a running wheel). Treatment lasted one month, followed by learning the maze task and then tested later for memory of the safe platform location. Results showed that memory lasted longer in the group that got the supplement and also exercised. Memory also improved in the sedentary mice, but was not as pronounced. When the animals were sacrificed and their brains examined, the epicatechin mice were seen to have more blood vessels in the brain and also had neurons with more synaptic junctions.

Source:
van Praag, H. et al. 2007. Plant-derived flavanol (-) epicatechin enhances angiogenesis and retention of spatial memory in mice.
J. Neuroscience. 27 (22) 5869-5878.

I have reported earlier on a study indicating that blueberries are good for memory. Actually, there are several studies indicating that blueberries are good for mental function in general. Blueberries contain polyphenolics, the levels of which are indicated by the amount of two compounds, ferulic acid and caffeic acid. Ferulic acid helps to stabilize cell walls and protects the nervous system. It lowers blood pressure. Caffeic acid also protects neurons and may even prevent neural degeneration. Both compounds are powerful antioxidants.

Blueberries are potent anti-inflammatory agents. One study in rats fed a diet including a non-steroidal anti-inflammatory drug or a 2% blueberry diet showed that within just two weeks the blueberry supplement activated anti-inflammatory genes in the brain much more than did the anti-inflammatory drug.

Now, a recent report indicates that the health benefits of blueberries are blocked by milk. Phenolics have a high affinity for protein, and the binding to milk protein prevents phenolics from accessing body cells. The study that demonstrated this effect involved measuring blood levels of the blueberry phenolics at various times after human volunteers consumed 200 gms of blueberries with 200 ml of either water or milk. Levels of phenolics rose sharply when water was consumed, but there was no increase when milk was consumed.

Heat destroys blueberry phenolics. So even though blueberry pie tastes great, it won't help your health. Only fresh blueberries provide useful levels of phenolics.

So, the recommendation is to consume blueberries without proteins. It should suffice to eat blueberries either one hour before eating other foods or two hours afterwards. For me, I will eat my blueberries alone an hour before my milk and cereal.

Sources:

Serafini, M. et al. 2009. Antioxidant activity of blueberry fruit is impaired by association with milk. Free Radical Biology and Medicine. doi:10.1016/j.freeradbiomed.2008.11.023

Shukitt-Hale, B. et al. 2008. Blueberry polyphenols attenuate kainic acid-induced decrements in cognition and alter inflammatory gene expression in rat hippocampus. Nutr. Neuroscience. 11 (4): 172-182.

It is well established from animal research that exercise increases learning and memory capability, presumably because exercise stimulates the birth of new nerve cells in the hippocampus, the part of the brain that is crucial for forming long-term memory. What was not known was whether this effect could be produced in aged animals. So in this study, the investigators designed an experiment to compare the effects of young mice and elderly mice. Mice were housed with and without running wheels, and they were also injected with a DNA precursor that would indicate how many new brain cells appeared. After one month of the daily opportunity to run in the wheels (mice do this voluntarily), the animals were tested in a maze. Results confirmed that exercised young mice did learn quicker and remember better than comparable mice that did not exercise. In addition, a similar effect occurred in aged mice. New cells appeared in the hippocampus in all groups, but many more new cells appeared in the mice that exercised, both young and old. The effect of running on cell number was greater in young mice than in aged mice. Moreover, the fine structure of the new neurons in both young and aged runners indicated that they were fully mature and functional. It was clear that exercise improved learning and memory even in aged mice, and that they even gave birth to more new neurons than age-matched controls that did not exercise.

There is every reason the believe that these results can be extrapolated to humans, although this kind of study has not been specifically performed in humans (and there is no practical way to test for new neuron formation and development in humans).

Source: van Praag, H., et al. 2005. Exercise enhances learning and hippocampal neurogenesis in aged mice. J. Neuroscience. 25 (38): 8680-8685.

Moderate physical exercise, dietary restriction, and enriched environment stimulation are all known to be good for the brain in general and memory in particular. However, few studies have directly compared these three factors all in the same study, as has been done in the lab of Alois Strasser in the University of Veterinary Medicine in Austria. Moreover, Strasser examined also a brain chemical that is likely to cause some of the brain improvement, the so-called brain-derived neurotrophic factor (BNDF), which sustains neuron life and promotes growth of neuronal processes and synapse formation. AS brain ages, the levels of BNDF typically decline. Several studies have demonstrated that BNDF is important for memory function.

Research prior to that of Strasser’s lab showed that exercise “up-regulates” BNDF; that is, exercise stimulates its production. And there had been some indication that environmental enrichment (stimulation, social interactions, etc.) had a similar effect. Therefore, Strasser and colleagues examined the tissue concentrations of BDNF in the cerebral cortex of old rats. Rats were divided randomly into six groups, living from 5 months up to 23 months. In each age group, rats were divided into those that were given free access to running wheels (RW), forced running on treadmills, food restriction, and sedentary controls with no food restriction. Rats were either either housed individually or in groups of 4 to provide social enrichment. At the end of experiments, BDNF concentrations were determined.

They found higher BNDF concentrations in the 5-month-old animals than in the 23-month-old-animals, suggesting that decline in BNDF accompanies old age and probably accounts for some of the mental decline. Within the older group of rats, sedentary rats that were housed in groups had significantly higher BNDF concentration ns compared to the old individually caged groups. Their BNDF concentrations were even higher than those of the young baseline group. The results suggest that housing and social interactions have more influence on BDNF concentrations in the cerebral cortex of aging rats than do physical exercise and food restriction.

There was some benefit of the exercise, but only from forced running on the treadmill, not voluntary activity. However, other studies had established that even voluntary exercise by old animals increased BNDF in other parts of brain, including the area so crucial to memory formation, the hippocampus.

The lack of beneficial effect of caloric restriction in sedentary rats to weight levels matching those of the voluntary exercise group was somewhat unexpected. Prior studies in other labs had shown that such restriction does promote synaptic plasticity and even birth of new neurons. Thus, there are no doubt multiple influences that can be beneficial to brain that are not mediated by BNDF.

So, to the extent that these results can be extrapolated to aging humans, it would seem like a good idea to:

Strasser, A. et al. 2006. The impact of environment in comparison with moderate physical exercise and dietary restriction on BNDF in the cerebral parietotemporal cortex of aged Sprague-Dawley rats. Gerontology. 52: 377-381.

As you get older, you will probably at some point start to worry about staying on top of your mental game. Will you get senile? Will you get Alzheimer's? These frightening questions may have a hopeful answer if you live a healthy lifestyle and get plenty of aerobic exercise.

A recent study by Arthur Kramer and colleagues at the University of Illinois used MRI brain scans to evaluate the effects of exercise in aged humans on parts of the brain that are most involved in age-related decline. The study 59 healthy but sedentary volunteers, aged 60-79, during a 6-month exercise period. Half of the subjects participated in aerobic exercise, and the other half did toning and stretching exercises. Twenty young adults who did no exercise served as a control group. A before-and-after comparison of MRI images revealed that the aerobic group developed more brain volume, both in white- and grey-matter areas. These improvements did not occur in the young subjects nor in the older ones who did only muscle-toning exercise.

While memory as such was not tested, it is highly likely that increased brain volume could only help memory function.

Source: Colcombe, S. J. et al. 2006. Aerobic exercise training increases brain volume in aging humans. The Journals of Gerontology, Series A: Biological Sciences and medical Sciences. 61: 1166-1170.

Chronic stress induces a progressive loss of memory ability that is especially pronounced in older humans (see my book chapters on emotions and on aging). One recent study monitored blood levels of the stress hormone, cortisol, in 57 aged, healthy volunteers once each year for 5-6 years.

Subjects varied considerably in the extent of their stress, as indicated by cortisol blood levels and also by psychological test measures of stress. Some subjects had high cortisol levels that progressively increased each year. These people had nearly half the memory performance capability of the elderly subjects that had only moderate levels of cortisol that decreased each successive year. The memory task involved recall of line drawings one day after they were presented. Stressed subjects also showed impaired memory, though lesser in degree, in a spatial memory maze task, similar to a scaled up version of the kind of mazes used to test rats.

Subgroups of subjects were also examined with MRI brain scans, with specific analysis of the volume of the hippocampus, which is the brain structure that mediates the formation of declarative memories (see book explanation of declarative vs. procedural memory). The high-stress group showed a 14% reduction in hippocampal volume, compared to the moderately stressed group. This effect should be of special concern because other studies have shown that the hippocampus is also involved in the regulation of cortisol levels. Damage to the hippocampus by cortisol serves to trigger more release of cortisol. Thus, stress induces an unfortunate chain of events in which cortisol damages the hippocampus, which in turn can lead to even more cortisol release and added hippocampal damage.

As a Senior citizen, I am increasingly aware that aging has its own set of stressors. I know too that stress of earlier years can linger, even magnify, and accumulate as the years go by. These cumulative and new stressors may be the main cause of the memory decline that most elderly people experience. Clearly, learning how to reduce stress can reduce the loss of memory capability, not to mention making life more enjoyable.

Yoga, anyone?

Source: Lupien, S. J. et al. 1998. Cortisol levels during human aging predict hippocampal atrophy and memory deficits. Nature Neuroscience. 1 (1): 69-73.

We all know that early-life stress can cause long-lasting emotional problems. A much less recognized problem is the effect of early-life stress on mental performance in old age. Why do some old-timers seem sharp as a tack and others become senile? No doubt there are many causes, but one cause may be early-life stress. There is some anecdotal evidence supporting this possibility.

In order to systematically study such a possibility, a team at the University of California at Irvine created an early life stress environment for baby rats. The stress seemed innocuous enough: the only difference from controls was that beginning on postnatal day 2, for one week, the stressed rats had only one paper towel in their cage for the mother to make a nest. This was not enough paper to make a good nest, and the mother consequently spent less than the usual amount of time grooming and nursing the pups.

Of those rats that were sacrificed immediately after the early stress period, clear bodily signs of stress were evident in the stressed group: enlarged adrenal glands, increased stress hormone levels, and mild weight loss.

Control and test rats were tested for memory performance at 4-5 months of age and at 12 months of age. When rats were tested in a water maze task where they had to swim and learn how to find a submerged safe platform, there was no difference in performance in either group when testing occurred at 4-5 months. But when tested at 12 months, the early-stressed rats could not learn the task. Sure, they could find the platform by trial and error, but repeated testing indicated that they were not learning anything about the location of the safe platform from the cues in the room that housed the water tank.

Some rats in both groups were sacrificed at the middle- and old-age periods and their hippocampus was tested for the ability to develop so-called long-term post-tetanic potentiation. This is a cell-level indicator of learning in the part of the brain that is most crucial for formation of memories. This test involves high-intensity stimulation of input to the hippocampus and monitoring how it later responds to single pulses. Normally, the response is much greater if it has been preceded by the "learning experience" of high rate stimulation. In this study, early-stress experience had no effect on the learned hippocampus response at 4-5 months of age, but significant impairment was evident at 12-months.

Finally, some rats were sacrificed to examine the histology of the neurons in the hippocampus. The neuronal dendrites, which are cell-surface processes that reflect synapse formation, were much less developed in the early-stressed, old-age group.

Why these deficiencies are delayed, showing up only in old-age is not known. One possibility is that the early-stress makes the rats hyper-responsive to the ravages of stress that occur over a lifetime. In my book, I have a whole chapter describing how long-term stress impairs memory in humans. Now it appears that if early-life stress occurs it can predispose to old-age mental decline. Mommas: nurture your babies early. A few months of extra love and care at birth might make a lifetime of difference.

Reference: Brunson, K. et al. 2005. Mechanisms of late-onset cognitive decline after early-life stress. J. Neuroscience. 25 (41): 9328-9338.

Prolonged exposure to stress and its accompanying release of the adrenal stress hormone, cortisol, damages brain. It actually kills neurons in the hippocampus, a key brain area for consolidating memories. In my memory book, I explain that things are not hopeless and that there are things you can do to prevent and even reverse some of this stress damage.

The study summarized here followed up prior studies in rodents that showed stress effects on the hippocampus and on memory function. In this study of humans, control and experimental groups were distinguished by their persistent levels of cortisol in saliva and by their self reports of stress in their lives. Aged humans with a history of chronic stress had shrunken hippocampi, as measured by MRI imaging. In addition, they performed worse than controls on delayed-recall memory tests of line-drawings and a spatial memory maze test.

We can therefore expect that how much memory deficit will occur as one ages depends on how much life stress has been endured. Reducing stress should not only make for better living but also better memory.

Reference: Lupien, S. J. et al. 1998. Cortisol levels during human aging predict hippocampal atrophy and memory deficits. Nature Neuroscience. 1 (1): 69-73.

Many studies have now indicated that the main cause of memory deficits in aging is related to attention problems. More specifically, older people tend to have difficulty in ignoring distractions and irrelevant stimuli. Here is yet another study that makes this point. In this study, normal young adults were compared with older adults (60-77 yrs) in a memory task that required the subjects to ignore a previous stimulus that was still in working memory. For example, subjects were presented a series of pictures of alternating faces and scenes and instructed to remember the one kind of picture but ignore the other. A typical group of trials involved presenting a picture of a face for about a second, a picture of a scene for about a second, then a picture of another face for about a second, and then another picture of a different scene for about a second. Then after a nine-second delay a picture was presented and the subject was instructed to press a button to indicate whether the stimulus matched one of the previously presented stimuli. In this kind of task the subject must recognize whether an image was relevant to the assigned task or was not relevant. Or in other words, the subject had to suppress the memory of irrelevant stimuli.

In this study the investigators went beyond behavioral assessment of the responses, because that kind of thing had been done before. What they wanted to know was what was happening in the brain during this suppression of irrelevant task. They used functional magnetic resonance imaging over a region of brain that was responsive to the visual images. What was being measured was the amount of brain activity under conditions when the instructions were to remember a type of image or ignore it. What they found was that brain activity in all of the young subjects increased when they were viewing scenes they were asked to remember and decreased when presented with an image that they were supposed to have ignored. Many older participants, however, were unable to suppress brain activity when presented with stimuli that they had been asked to ignore — that is, irrelevant stimuli. All responses were compared to a control state of passive viewing of images where no memory task was involved.

So what these data suggest is that older individuals can focus on pertinent information but have difficulty in ignoring irrelevant or distracting information that is contained in working memory. Although the study notes the fact that nearly half of the older adults performed as well as the younger adults in suppressing responses to irrelevant stimuli, what is emphasized is the deficiency of working memory. So let us not come away with the conclusion that memory deficits in the elderly are inevitable, when in fact in this study nearly half of the elderly showed no deficit.

Few studies have attempted to explain why some older adults have impaired working memory while others do not. however it is obvious that disease, such as impaired circulation to the brain, could by itself account for impaired memory. It is likewise unclear to what extent an older person can improve working memory capabilities through drills or special training.

Source: Gazzaley, A. et al. 2005. Top-down suppression deficit underlies working memory impairment in normal aging. Nature Neuroscience. 8: 1298-1300.

Filtering out irrelevant stimuli is done more easily when you are young than when you are old. This has profound implications for changes in memory ability. A study at the University of Toronto used MRI imaging of people while they performed a variety of memory tasks, both during encoding and recognition. The found an age-related increase in activity in brain areas that normally decrease during task performance. This is interpreted to indicate that these areas normally do not respond during a memory task because the brain is paying attention to the task and assigning the memory work only to the parts of brain that need to process the memory. However, another interpretation is that as you get older, your brain has to recruit more help from other parts of the brain. A related finding of the research was an age-related decrease of activity in brain areas that normally become activated during the memory task. The researchers thought that this finding indicated an age-related decline in ability to distinguish task-related demands from those that were irrelevant. It could also be that as you age, the circuits that are normally needed to handle memory work are less capable. However, you look at it, the findings document an age-related decline in the brain's ability to focus its neural resources on memory tasks. What may be most troublesome to contemplate is that the brain activity-pattern changes showed signs of decline around age 40.

So, what do we do about it? One possibility is that by keeping our brain working hard as we age, we might reduce this tendency to lose ability to handle memory workload. Think of it like exercise for the brain, which strengthens the neural circuits in the parts of the brain that have to distinguish irrelevant from relevant information in memory tasks and those parts of the brain that have to do the memory work. Another general strategy is to reduce the distractions in our life, at least distractions that are present when we are trying to remember something. Multi-tasking is hard enough to do when you are young. That ability probably declines markedly as you get older. On those occasions when I forget what I opened the refrigerator door for, it is always because I let myself get distracted between the time I decided what I wanted and the time when I opened the door. Focus, focus, focus.

Source: Grady, C. L. et al. 2006. Age-related changes in brain activity across the adult lifespan. J. Cognitive Neuroscience. 18:227-241.

Many, not all, older people suffer from diminished memory capability. Scientists are now trying to unravel just where the problem lies. Is it reduced ability to pay attention? Yes, that is part of the problem, which I explained in an earlier blog. Now, a study has examined this issue in more detail. Two possibilities come to mind, that older people: 1) can’t hold information very long in short-term memory (i.e. the memory decays too quickly), or 2) are less able to inhibit distractions (i.e. filter out distractions).

In a study at the University of Illinois, researchers recorded brain electrical responses in young adults and old subjects (65-78) who were passively listening to bursts of sound that contained a base frequency of 500 cycles per second, with superimposed higher frequencies at lower amplitude. Sound volume was adjusted to the hearing threshold for each subject. Sound was presented while subjects were instructed to concentrate on reading a book and to ignore the sound bursts. Four bursts were delivered with variable silent intervals. The brain registered the memory of each burst in the size of the evoked electrical response. The repetition of sound burst was expected to induce suppression of the sound-evoked electrical response to later bursts in the train, while the silent interval was expected to allow for recovery as the memory of a preceding burst decays. By varying the interval, researchers could evaluate the decay process.

Results revealed that the electrical responses persisted longer in older people, but the effects of delay interval were the same irrespective of age. Since age did not seem to affect memory decay, one is left to conclude that the brains of older subjects were less able to inhibit the sound burst distractions. The good news for the elderly is that age does not make you forget any faster. It does, apparently, make you more distractible.

Such studies should probably also be done in children, who I would suspect are more like older people in being less able to inhibit distractions.

What is the memory solution? Obviously, older people (and children) need to work at paying attention, training the brain to concentrate. Second, since they are so distractible, information should be absorbed in smaller chunks, which are more manageable. By lowering the memory demand, the brain’s limited resources can deal with it more effectively.

Source: Fabiani, M. et al. 2006. Reduced suppression or labile memory? Mechanisms of inefficient filtering of irrelevant information in older adults. J. Cognitive Neuroscience. 18 (4): 637-650.

Source: Gazzaley, A. et al. 2005. Top-down suppression deficit underlies working memory impairment in normal aging. Nature Neuroscience. 8: 1298-1300.

CATEGORY	TOPIC
GENERAL	How I Got Interested in Improving Memory Capability Learning to Learn Learning to Learn II―Learning Can Increase Biological Capacity to Learn Unlearning Built-in Bias Where You Are Affects What You Learn What Do New Neurons Do To Help Memory? New Neurons. Use Them or Lose Them Remembering Names and Faces The Ethics of Drug Enhancers of Memory Do Schools Teach "Cognitive Tools?" There's A Reason for School Recess Can Exercise Help Kids Do Better in School?
ATTENTION	Novel Stimuli Can Help Learning Multi-tasking Is The Wrong Way To Learn How The Brain Fools You Into Thinking You Are Multi-tasking Students Who E-communicate Have Lower Grades Learning to Pay Attention What Teaches You to Concentrate: the Internet or Books?
ASSOCIATIONS	Think of Memory Like a Fish Net Images Are Easier to Remember
WORKING MEMORY	How Well People Think Depends On Working Memory Training Working Memory and IQ Increase Working Memory and Increase IQ Working Memory Training Raises IQ of Adults Working Memory Load Affects Paying Attention Benefits of Increasing Working Memory Help Your Working-Memory Capacity
CONSOLIDATION	Updating Existing Memories Also Requires Consolidation A Possible New Therapy for Phobias and Psychological Traumas Testing Promotes Learning Motor Learning: Watch It! Learn One Movement Skill at a Time Losing Your Past Overtraining: You Can Learn Too Much How Marijuana Impairs Memory Consolidation
CONSOLIDATION & SLEEP	Why Sleep Helps You Remember Are Motor Skills Learned Better at Night? Need to Learn Something Quickly? Try a Nap Sleep Loss Has Proactive Memory Impairing Effects More Confirmation on Sleep Loss Impairment of Memory
RECALL	The Brain's File Cabinet The Sudden Loss of Memory Phenomenon Forgetting Can Be Good - Solving the "Tip-of-the-Tongue" Problem Each Time You Recollect, Something New Can Happen
EMOTIONS	Belief About Memory Ability Becomes a Self-fulfilling Prophecy Social Stress Impairs Memory in Healthy Young Men Teenage Angst Damages Brain Role of Memory in PTSD and Other Anxiety Disorders Make Them Learn. Carrot or Stick? Training Working Memory May Be Rewarding Erasing Fear Memories
MEDICAL ISSUES	Education Protects Against Alzheimer's Disease Social Networks Provide "Protective Reserve" for Alzheimer's Disease Blood Pressure Medicine Can Treat Post-traumatic Stress Disorder Addiction: A Disease of Learning and Memory Folic Acid Supplements Improve Memory Omega-3 Fatty Acid Supplements Improve Memory Epicatechin - Newly Discovered Memory Chemical Eat Your Blueberries—But Not With Cereal.
AGING	Exercise Enhances Learning and Memory - Even in Old Age Three Ways to Slow Brain Aging It Is Aerobic Exercise That Counts As You Age, Remember To Get the Stress Out of Your Life Early-life Stress Magnifies Mental Decline in Old Age Stress Magnifies the Memory Defects of Aging Working Memory Impairment With Age Is Caused by a Suppression Deficit Distractibility Increases with Age Distractibility: the Cause of Memory Decline with Aging (2 papers)