Multi-tasking and Memory, One More Time

I have talked about the problems of multi-tasking before. But this trend among youg people is so pernicious and damaging, I just have to bring it up again.

A whole new generation of multi-taskers is upon us. These young people know how to use cell phones, text messages, the Web, video games, IPods, and assorted other electronic gizmos, often at the same time. Sometimes, driving a car is thrown in for good measure (until an accident occurs).

I work with secondary school teachers, and most of them are in awe of these kids. I have seen teachers brag about how talented their own kids must be because they are such impressive multi-taskers. Increasingly, however, teachers come to realize that multi-tasking intereferes with learning. Some teachers are particularly upset with cell phones, which they try to ban, with little success. Talk about trying to take candy from a baby! In the old days, we kids tried to hide reading of comic books during class. Today, the game is to hide text messaging on cell phones. Ah, such is progress.

Multi-tasking is certainly a talent, but one that exacts a high price on learning. Formal brain research has shown that the brain can only do one thing at a time. Multi-tasking is accomplished much in the manner of "multiplexing," an engineering term denoting doing one thing for an instant, then another, and another, and finally returning to the next step of the first task. All this switching is distracting and interferes with memory formation and what memory reseasrchers call "consolidation" into lasting memory.

Memory consolidation is often prevented when one event follows too soon after an initial learning event. There is a whole theory about this, called the Interference Theory of Learning. Memory of initial learning events can be blocked if you try to learn two things at once. In fact, learning may be disrupted for both things.

In a recent test of this phenomenon, a group of 29 people (17 to 30 years of age) was trained to discriminate two sound pips that differed in length by a fraction of a second. In one group of subjects, the training occurred consecutively, which ordinarily produces some inefficiency with learning because the second task interferes with remembering the first. Moreover, results from another group of subjects revealed that when practice on the two tasks was interleaved in multi-task fashion, there was no learning on either condition.

Another recent study should get your attention: a group of study participants, divided into those that were heavy multi-taskers and those that multi-tasked only infrequently. All participants were probably at the higher end of general mental capabilities, given that they were Stanford college students. Each participant was tested in a series of thinking tests to check for any difference in the way the two types of people processed information and disciplined their attentiveness. Heavy multi-taskers were less able to sustain focus in the presence of distractions. The heavy multi-taskers performed worse even though their experience and presumed skill at multi-tasking should have made them more effective at these tasks. The heavy multi-taskers believed they were good at multi-tasking, when in fact they were bad at it.

Nor is intelligent thought likely to benefit from multi-tasking. Multi-tasking bombards working memory with scrambled and unfocused information and probably keeps the brain from learning how to optimize focus and orderly sequence thoughts. Several studies show that intelligence correlates with working memory capacity, which under the best of circumstances is limited. Working memory is the platform on which you think.Over-loading this small-capacity thinking platform just makes it harder to think straight.

So, now tell me again why multi-tasking is a good ability. While you are at it, try to convince me that it has no deleterious effect on ability to focus, sustain attention, and think.

Sources:

Banai, K. et al. 2010. Learning two things at once: differential constraints on the acquisition and consolidation of perceptual learning. Neuroscience. 165: 436-444.

Ophir, E., Nass, C. and Wagner, A. D. 2009. Cognitive control in media multitaskers. Proceedings of the National Academy of Science. Aug. 24. doi: 10.1073/pnas0903620106

Magnesium: a mineral you need and may lack

The only time I ever thought about magnesium,  before I became a scientist, was the summer I swept magnesium shavings off the floor at the Kaiser helicopter-engine factory. When I went to college, I learned that magnesium was an essential mineral in human and animal bodies. As a veterinary medical student, I learned that a magnesium deficiency caused "grass tetany" in cattle that ate lush, heavily fertilized grass growing especially in soils high in potassium or aluminum; these conditions reduce availability of magnesium.

Recently, a MIT scientist, Inna Slutsky reported a five year study showing that magnesium improved learning abilities, working memory and both short- and long-term memory in rats. The improvements were produced in both young and old rats. They fed rats a synthetic magnesium supplement, magnesium-L-threonate (MgT), which improved the ability of magnesium to get across the blood-brain barrier and into nerve cells.

How magnesium benefits brain function is probably related to the fact that magnesium is a cofactor for enzymes that convert adenosine triphosphate (ATP) to adenosine pyrophosphoric acid (ADP), with the subsequent release of energy. The brain is a real energy hog.

How much MgT would humans need to take is not known, but presumably somebody is working on that. The recommended daily amount of magnesium is 400 milligrams for men and 310 milligrams for women. It is estimated that only 32% of Americans get this amount in their diet. Primary food sources are green veggies, fruits, and certain nuts.  Traditional nutritional supplements are not a solution. The researchers found that the magnesium in common dietary supplements does not readily enter the brain.

A commercial product, when it becomes available, may not have been tested for safety (nutritional supplements are not government regulated), On the other hand, healthy kidneys are pretty good at getting rid of excess blood magnesium. The possibility of excess magnesium in the brain from use of MgT has not been investigated.

Source:
Slutsky, I. et al. 2009. Enhancement of learning and  memory by elevating brain magnesium. Neuron. 65 (2): 165-177.

Copyright, 2010, W.  R. Klemm

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 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 kness 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.