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.
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