Brain complexity: DNA plasticity and personality (Introduction)

by David Turell , Wednesday, July 25, 2018, 20:34 (2313 days ago) @ David Turell

Studies in mice and how they are nurtured dictates what changes may occur in neuronal DNA to alter their potential personalities:

https://www.scientificamerican.com/article/early-life-experience-its-in-your-dna/?utm_s...

"What most people do not realize, however, is that the brain has remarkable genetic diversity, with some studies suggesting there may be hundreds of mutations in each nerve cell. In the developing brain, mutations and other genetic changes that occur while brain cells divide are passed down to a cluster of daughter cells. As a result, the adult brain is composed of a mosaic of genetically distinct cell clusters.

"We know that the activity and organization of the brain changes in response to experience. Memories and learning are reflected in the number and strength of connections between nerve cells. We also know that the brain is genetically mosaic, but a new study makes a remarkable connection between experience and the genetic diversity of the brain. It suggests that experience can change the DNA sequence of the genome contained in brain cells.

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"...experience has an equally powerful capacity to change the genome, but only in cells of the brain. The care that a newborn receives in early life can have profound effects on psychological and intellectual growth. Attentive nurturing, feeding and grooming can reduce stress and anxiety and enhance psychological wellbeing. On the other hand, indifference can lead to increased anxiety and impaired psychological adjustment. This study reveals that one way the quality of early care could cause lifelong changes in behavior is by changing the brain’s genetic nature.

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"Many of the differences in the genomes of nerve cells are due to the presence of mobile genetic elements called retrotransposons. These are stretches of DNA that can be copied and, as the name suggests transposed or incorporated into other areas of the genome. This study measured the accumulation of these mobile genetic elements in the brain as a consequence of maternal care. Mobile genetic elements accumulated in specific regions of the brains of mouse pups if the pups had poor maternal care. If a pup was born to a mother animal that provided low maternal care, but raised by a mother animal that provided high maternal care that accumulation of mobile genetic elements was eliminated. This supported the idea that the accumulation of genetic elements was due to the care provided by the mothers rather than some inherited difference. Most of the excess was found in the hippocampus, a region of the brain involved in memory, but not in other regions of the brain, nor in a completely different organ like the heart, suggesting a very specific impact on brain mosaicism.

"The authors also report that the changes in levels of mobile genetic elements might in turn be mediated by a modification to the genomic DNA known as methylation. Methylation is not itself a change in the DNA sequence, but it can alter when and how DNA sequences are read and utilized by the cell. Pups raised with poor maternal care had decreased methylation of key regulatory sequences in the mobile genetic elements which in turn led to increased numbers of these elements and increases in their activity.

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"Linking early experience to the genomic variability of nerves suggests that early experience leaves an irreversible genomic imprint in the brain. This is an intriguing new twist on a debate that has been raging for centuries concerning the importance of nature versus nurture in behavior. This study implies that nature and nurture are not as independent as may have been been imagined, and that nature is not as immutable as once thought. As with all iconoclastic studies, there are caveats to this research, most importantly the fact that the number of mobile genetic elements is much higher in the neurons of the rodents studied here than it is in humans. Furthermore, we don’t yet understand how these genetic changes alter the brain activities that give rise to behavior. Nevertheless, this is a provocative study that links early experience with the genetic structure of neurons, and that highlights the remarkable plasticity and adaptability of the brain.

Comment: I know this is the material side of how the brain works in regard to experience and how it changes to reflect what has happened in an animal's life. Note the caveats stated above as to how this may apply to humans and their personality, which would be directly reflected in their souls.