Archive for July, 2010

Neurogenesis

July 27, 2010

This blog post was inspired by the book, The Scientific American Brave New Brain.1 When I was a graduate student I learned that neurogenesis, the creation of neurons, might occur after birth in other species, but not in humans. Moreover, this was dogma. There was no question about it. Recent research has invalidated this dogma. Neurogenesis has been found in at least two sections of the human brain: the olfactory bulbs and the dentate gyrus of the hippocampus. The hippocampus is critically involved in learning and memory. It is difficult to underestimate the significance of this finding. Well into old-age new brain cells continue to develop. It is likely that neurogenesis occurs in other parts of the brain, but that remains to be documented.

This turns out to be sort of a good news/bad news story. Neurogenesis does occur, but these new brain cells disappear if they are not used. Moreover, it appears that simple use is not sufficient. They need to be challenged and exercised hard if they are to survive.

A reasonable question is whether we can do anything to generate new brain cells. Most of the research in this area has used animals for subjects. Rats and mice that exercise on a running wheel produce twice as many new cells than sedentary rats do. Eating anti-oxidant-rich blueberries seems to generate new neurons in the rat hippocampus as do changes in their cages or new toys.

One experiment injected rats with a drug, BrdU (bromodeoxyuridine), that marks only new cells. A week later half of the treated rats were assigned to a training program whereas the other group stayed in their home cages. Rats that successfully completed the training course retained many more newborn neurons than did the stay at home group or rats who failed to complete the training course.

So although we do not yet have proof that mental activity will either produce neurogenisis or maintain more of the cells normally produced through neurogenesis, it should not be surprising when such evidence appears. Indeed, it is reasonable to engage in these activities now. Two activities are recommended by the Healthymemory Blog to further brain health. One is the use of mnemonic techniques, which not only enhance memory performance, but also make demands on both hemispheres of the brain. Note that there is a whole category of blog posts devoted to this to topic. The other recommendation is to use technology, the internet being a prime example, to provide challenges to the brain. Blog posts on this topic can be found in the category Transactive Memory.

The conjecture offered in Brave New Brain is that in the future new cells will be generated at will, where and when you need them. How this will be done remains to be. Perhaps we shall learn how different types of cognitive activity produce neurogenesis in specific parts of the brain. Or perhaps it will be learned how brain stimulation can produce neurogenesis. The benefits of meditation are also mentioned. It is noted that exercise was not very popular in the 1950s, but has become commonplace today. Perhaps meditation will become just as popular in the future. Healthymemory Blog posts on meditation and similar restorative activities include “Restoring Attentional Resources,” More on Restoring Attentional Resources,” and “The Relaxation Response.”

1Horstman, J. (2010). San Francisco” Jossey-Bass.

© Douglas Griffith and healthymemory.wordpress.com, 2010. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and healthymemory.wordpress.com with appropriate and specific direction to the original content. 

The Brain: Past, Present, Future

July 23, 2010

There is a recently published book that I would recommend to anyone interested in the brain, cognition, neuroscience, or in how to keep their memory healthy. In other words this is a book that should interest anyone who reads the Healthymemory Blog. This is a publication from Scientific American, more specifically Scientific American Mind, titled, Brave New Brain,by Judith Horstman. The following is taken from the cover, “How Neuroscience, Brain-Machine Interfaces, Neuroimaging, Psychopharmacology, The Internet, and our Own Minds are Stimulating and Enhancing the Future of Mental Power.” This book consists of 176 pages and is an easy read.

For anyone who wants to learn where the study of the brain was, where it is now, and where it might takes us in the future, this is definitely the book. The book contains color plates of pictures of the brain, showing where the important parts are and how they look. There are also pictorial representation of neuronal and epigenetic activity. Two pages contain a chart titled “The Way We Were” contain eleven ideas ranging from stroke to consciousness with brief synopses of what was once thought, what is now thought, and what tomorrow might bring. In just these two pages one can become informed and enlightened.

This book is more than informative; it is fun, particularly the conjectures about what the future might bring. However, I would encourage readers to bring a good deal of skepticism to their consideration. I am at the leading edge (born in 1946) of the baby boomers. I have distinct memories of what we were told our future lives would be like. For example, there would be no energy problem. We would be using nuclear energy and the pesky problem of what to do with nuclear waste would have been solved. We would be flying helicopters as personal vehicles. The work week would be much shorter, and we would have many more hours of leisure and free time. I find this last prediction particularly ironic. At that time, working mothers were the exception and not the norm. Now both partners typically work and usually full time. What happened to all those leisure hours that were predicted?

Now there was one item that permeates our lives that was not predicted. That one is personal computers. If there is anything I envy most about the younger generations is their access to personal computers. I wish that my formal education had included them.

Subsequent Healthmemory Blog postings will delve somewhat deeper into the research and ideas presented in Brave New Brain. There is much there worthy of future consideration

© Douglas Griffith and healthymemory.wordpress.com, 2010. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and healthymemory.wordpress.com with appropriate and specific direction to the original content.

Remembering is Good For You

July 20, 2010

A recent article, “Yearning for Yesterday,” in Scientific American Mind,1 extols the virtues of nostalgia. This is ironic since it derives from the Greek words nostos (“return”) and algos (“pain”). So the literal meaning of nostalgia is suffering that results from a desire to return to a place, a time, a way of life. According to the article, the Swiss physician Johannes Hofer coined the term to describe the behavior of Swiss mercenaries in the service of foreign monarchs. So these soldiers were suffering from what we would call today, “homesickness.” However, recent research has concluded that in many cases nostalgia can be good for you.

According to the article nostalgia is a sentimental yearning for the past that consists of particularly intense, complex and vivid memories. At one time nostalgia was regarded as an unhealthy preoccupation. However, new research indicates that it improves people’s moods and is a sign of emotional well-being. Nostalgia can also promote a sense of social integration in people who are sad or alone.

Now standard disclaimers do apply. Obviously if you spend a large portion of your time living in the past, this is not healthy. It is also important that you find your nostalgia to be pleasant. Some people do dredge up unpleasant times and their nostalgia is a disturbing not a restoring experience. Moreover, people suffering from depression do not easily identify with the happier self of their past. So a distinction need be made between healthy nostlgia, which is pleasant and restorative, from unhealthy nostalgia, which is unpleasant and debilitative.

The Healthymemory Blog has previously recommended that trying to recall events of the past in and of itself can be beneficial. This causes the retracing and perhaps reactivation of old memory circuits (See the immediately preceding blog post, “Human Memory: A Machine for Time Travel”). Moreover, this retracing and reactivation can go on long after you are even aware that you are trying to retrieve the memory. Although you might have unconsciously abandoned the effort, your unconscious mind has kept plugging away. Sometimes this apparently lost memory will pop into your mind hours, or even days later,

1Gebauer, J. & Sedikes, C. (2010). Yearning for Yesterday. Scientific American Mind, July/August 2010. pp 30-35.

© Douglas Griffith and healthymemory.wordpress.com, 2010. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and healthymemory.wordpress.com with appropriate and specific direction to the original content. 

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July 15, 2010

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Transactive Memory: An Aid to Short and Long Term Memory and to Stroke Recovery

July 11, 2010

Readers of this blog should be familiar with the concept of transactive memory. Transactive memory refers to those memories that are not stored in one’s own biological memory, but are found in the memories of fellow humans and in technology. Technology ranges from modern digital storage, to older, conventional storage such as books and paper. Transactive memory vastly increases the capacity of our personal long term memories. Just imagine how constrained our memories would be without books and paper. Modern technology has vastly increased the capacity of transactive memory. A distinction can be made between three types of transactive memory: accessible transactive memory, available transactive memory, and potential transactive memory. Accessible transactive memory refers to information that cannot be directly recalled, but can be easily looked up or accessed on the internet. Available transactive memory refers to information that you know exists, but need to search for or look up. Potential transactive memory refers to the enormous amount of information that you cannot recall, that you not only cannot easily access, but are uncertain if it even exists. This is the repository of new knowledge, some of which you can potentially know, or know how to acquire or create.

Transactive memory also supports short term memory. Imagine the difficulty of multiplying two three digit numbers together without a calculator or some medium on which to write. Mathematics would be virtually impossible without transactive memory. Indeed, any intellectual enterprise would not get far without support from transactive memory. Writing about a topic is a matter or interactions between your own internal memory and what you have recorded externally on transactive memory. These interactions not only provide the basis, for making communication with others clearer, but they also provide the basis for new insights.

Transactive memory can also aid recovering from the harmful effects of stroke. Oliver Sacks relates an interesting case history in an article, “A Man of Letters.”1 Stone relates the story of a professional author of detective novels, Howard Engel, who reached to pick up his morning paper and found that he could not read it. It appeared to be written in a foreign language. He reasoned that “Since this isn’t somebody’s idea of a joke, I have suffered a stroke.” He was correct. What was most curious was that although he could not read, he could still write. The medical term for this condition is “alexia sine agraphia.” So he could write, but he could not read what he has written. So he could not use transactive memory.

Very slowly, bit by bit, as he started to recover from his stroke, his ability to read returned. His therapist suggested that he keep a “memory book” (a transactive memory book” of appointments and to record his thoughts. He pursued this quite vigorously and found that it was quite beneficial in getting him back to his former self. He returned home and started using his computer. Although he remained alexic he found clever ways of circumventing this disability through transactive memory and some other techniques (tracing outlines of words with his hands and using his tongue to trace the shapes of letters on his teeth and the roof of his mouth). These techniques have proved so successful that he has managed to author and publish two books, Memory Book, and The Man Who Forgot How to Read.

1The New Yorker, June 28, 2010, pp. 22-28 

© Douglas Griffith and healthymemory.wordpress.com, 2010. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and healthymemory.wordpress.com with appropriate and specific direction to the original content.

The Dangers of Multi-Tasking

July 5, 2010

 A recent article in the AARP Magazine (“May I Have Your Attention Please,” July/August 2010, pp 28-31) stressed the dangers of multitasking. You might be surprised that such an article would appear in the AARP Magazine as multi-tasking presents dangers to all humans. The reason is that information overload is even more serious for those over 50. Katy Read, the author of the article, begins by recounting a day in which she had 49 browser tabs open on her computer. Now admittedly this is a tad extreme, but it does illustrate how bad things can get.

The article states that the average American hears, sees, or reads 34 gigabytes of information a day from the internet, radio, newspapers, and other sources. This number strikes me as being rather high. Moreover, it states that this is about 100,000 words. Now the complete works of Shakespeare total about five megabytes, which is but a small fraction of a gigabyte. Moreover, a two-hour film, when compressed, is about one to two gigabytes (See the Healthymemory Blog Post, “Cyberspace: How Much Data is Out There”, to get a feel for the quantity of data that is available). So, I find the 100,000 words estimate more plausible. The article also states that this figure has grown more than 5 percent annually since 1980, a figure I can well believe.

Our attention is limited, and we should use it wisely. Here are some tips offered in the article.

Study you habits –Ask yourself every day whether you are focusing on the right things.

Limit Your Inputs – Stick to favorite websites and TV programs and resist aimless Web and Channel surfing. Although I would agree that in general this is a good goal, it is still a good idea to give a certain amount of time and attention to new things.

Exercise Your Concentration Muscles – Focused activities such as reading an absorbing book or meditating will sharpen attention and relieve stress. (See the Healthymemory Blog Post, “The Relaxation Response” to learn more about meditating.)

Leave a Trail – When you are engaged in an activity and think of something to do or something to read that is not directly relevant to your current task, make a note to return to it later. Then continue with your task.

Get Some Air – When you take a break, unplug completely. Take a walk, meet a friend, or play with your dog. This will refresh your attention and provide better focus.

Regarding this final point, there seem to be special benefits in going to nature to restore your attentional resources (See the Healthymemory Blog Posts, “More on Restoring Attentional Resources”, and “Restoring Attentional Resources.”)