Posts Tagged ‘myleinogenesis’

REST, Epigenesis, Neuroplasticity, Cognitive Reserve, & Alzheimer’s

April 8, 2014

The March 19 Washington Post published an article written by Angela Zimm, “Fetal brain protein reactivates in old age, may fight dementia.” The research was conducted by scientists at Harvard University and published in the journal Nature. It reported that a protein called REST is depleted in the brains of people with Alzheimer’s. It was found at a level three times as high in people who did not experience dementia even when their brains had indications of the disease. According to Yanker, a professor of genetics at Harvard Medical School in Boston, “There’s a long-standing puzzle in neurology why a large percentage of the aging population when they die have enough abnormalities in the brain to classify as Alzheimer’s, though they don’t develop the dementia.”
This is a rarely publicized fact about Alzheimer’s, that there are many people who do not exhibit the symptoms of dementia even though their brains at autopsy are found to have the so-called tell tale neurofibrillary tangles and amyloid plaques. These are the only signs that allow a conclusive diagnosis of Alzheimer’s . So it appears that these tangles and plaques might be a necessary, but not a sufficient condition for Alzheimer’s disease. Most research on Alzheimer’s has been on attacking the tangles and plaques.
The only explanation that has been offered is that the people with the tangles and plaques, but not Alzheimer’s have built up a cognitive reserve to fend off this disease. Indeed, this is one of the exhortations of the healthymemory blog, to build up a cognitive reserve/. However, what has been lacking to this point is an explanation as to how this cognitive reserve is built up. The process of epigenesis is one possible mechanism for the release and maintenance of the REST protein. Possible mechanisms for building a cognitive reserve can be found in the healthymemory blog, “What is Neuroplasticity and How Does it Work”, and include, in addition to epigenesis, synaptogenesis, myleinogenesis, and neurogenesis. The healthymemory blog post, “Supporting Neuroplasticity” lists some specific practices that could aid in building a cognitive reserve.

© Douglas Griffith and healthymemory.wordpress.com, 2014. 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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What is Neuroplasticity and How Does It Work?

March 15, 2014

Neuroplasticity is the ability of the brain to change its structure in response to experience.”1

What follows is a brief synopsis as to how this change is accomplished. We have an average of ten thousand connections linking an average neuron to other neurons. Given that there a hundred billion neurons, there are hundreds of trillions of synaptic linkages. Moreover there are trillions of glial cells supporting the effort. One type of glial cell is the oligodendrocyte. When we develop skills after many hours of practice the oligodendrocytes produce myelin. Mylein is a fatty sheath that coils around the neuron’s axon that sends signals to other neurons. When myelin is present, the speed of the action potential down the axon is 100 times faster. Myelin also decreases the time for recovery before the next firing, the refractory period. This refractory period is 30 times shorter. So the enhanced functoning of a myleinated circuit is 3,000 (30 times 100) faster than a non-myleinated circuit. This provides the basis for the phenomena performances we sometimes see.

Synaptogenesis is the process by which synapses are created or strengthened. Myleinogenesis the process by which these circuits become much faster. In addition to these two ways in which the brain changes as the result of experience there is neurogenesis. Neurogenesis occurs throughout the entire life span and involves the differentiation of neuro stem cells into fully mature neurons in the brain. This process may take from two to three months in contrast to the more rapid synaptogenesis that occurs within minutes to hours and becomes consolidated over days or weeks. Studies have identified this more slowly occurring neurogenesis in the hippocampal region, but it is expected that this will be found in other areas in the future. Of course, the hippocampus is important for its central role in memory. Research has also shown that physical exercise benefits hippocampal growth (see the healthymemory blog post, “To Improve Your Memory, Build Your Hippocakmpus.”)

Epigenesis is the process by which experience alters the regulation of gene expression by way of changing the various molecules (histones and methyl) on the chromosome. Understand that genes themselves are not changed. Rather the way that information is read out from the genes is changed. This is how experience and genetics interact.

SNAG is the acronym to explain how these processes result in neuroplasticity. SNAG stands for stimulating neural activation and growth. Add to this the expression that neurons that fire together , wire together. That’s how we learn, but this is also the basis for remembering. Neurons that have not fired together for a long time, can result in that memory circuit being difficult to find. The memory is likely still available, but not currently accessible. That’s why healthy memory recommends revisiting old memory circuits. When you can’t remember something, sometimes it is good not to look it up, but to keep trying to remember. Even if this attempt fails, your nonconscious mind is apt to keep looking for it, and it might suddently pop into memory hours or even days later.

Remember to use your mind to control, exercise, and grow neural circuits. This is the fundamental means of keeping a memory healthy.

1Siegel, D. J. (2012). Pocket Guide to Interpersonal Neurobiology. New York: Norton & Company. This blog post is based primarily on this reference.

© Douglas Griffith and healthymemory.wordpress.com, 2014. 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.