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Human brain cells live long but acquire thousands of mutations along the way


From Ruth Williams at The Scientist:

Two studies in Science today (December 7)—one that focuses on prenatal development in humans, the other on infancy to old age—provide insights into the extent of DNA sequence errors that the average human brain cell accumulates over a lifetime. Together, they reveal that mutations become more common as fetuses develop, and over a lifetime a person may rack up more than 2,000 mutations per cell.

Within the now burgeoning field of somatic mutation analyses, the brain is a particular area of interest. That’s because unlike organs such as the skin and gut where cells are replaced daily, the brain’s neurons, once established in the fetus, for the most part stick around for life. Somatic mutations in these cells, then, could affect brain function, behavior, and the propensity for disease long-term. Indeed, it’s thought that such mutations could influence the development of diseases such as schizophrenia, autism, and Tourette’s, which have unclear etiologies, says Yale School of Medicine’s Flora Vaccarino who authored one of the studies. More.

This may seem like an inappropriately philosophical question but is it really the same cell after 2000 mutations? If it were a piece of property, we would say it has the same address, no matter what else happened in the location. But will that work for cells? What makes it the same cell? The location? The membrane? The historical record of mutations?

That matters because we can ask the same about ourselves: Are we really the “same person” as we were when we were four years old?  In what sense? That is where we need concept from information theory, not theories of matter and energy.

See also: New Scientist: Was it a huge dose of dopamine that made us so smart? Naturalist ideology requires something like extra dopamine production to be seen as a cause, not an effect. Of course, what we are really talking about is human consciousness, whose origin no one understands. And whatta feast of just-so science!


Boy can see without primary visual cortex of brain

here's an interesting report on brain: https://consumer.healthday.com/disabilities-information-11/amputation-news-720/boy-s-double-hand-transplant-changed-his-brain-729122.html Dionisio
gpuccio, Yes, but not blueberries that have been genetically modified or exposed to potentially toxic chemicals in fertilizers or pest control. It doesn't seem easy to avoid the oxidative damages mentioned in the referenced paper. :) Dionisio
Dionisio: Maybe he should stick to blueberries! :) gpuccio
“[…] one cause of aging in the brain might have to do with oxidative damage,” he says. “So that has me eating a lot of blueberries and drinking a lot of red wine.” drinking a lot of red wine? What about this? https://www.theguardian.com/society/2016/jul/22/alcohol-direct-cause-seven-forms-of-cancer-study https://health.usnews.com/health-care/patient-advice/articles/2017-08-08/whats-the-link-between-alcohol-and-colon-cancer Complex systems can be difficult to control Dionisio
"[...] one cause of aging in the brain might have to do with oxidative damage,” he says. “So that has me eating a lot of blueberries and drinking a lot of red wine.” Those cells were not designed for the extremely hostile environment they're in. Had we stayed in Eden, none of this would have been an issue. Dionisio
"[...] it makes sense that “protecting the genome at embryonic stages is more imperative than at the later stages of differentiation,” where mutations would affect far fewer cells." How does it go from more protective to less protective with time? Could it be that the changes eventually may also affect even the DNA repair mechanism? Dionisio
polistra: From what I can read in the presentation and in the abstract, I suppose they are mainly errors, due for example to oxidative damage. Of course, they are somatic mutations, and therefore they are not transmitted: they only involve the individual neuronal cell and its direct progeny. The tireless DNA repair machines are probably opposing that kind of mutations all the time, but they are not omnipotent. gpuccio
polistra, the changes are probably mostly adaptations, as errors would usually doom the cells. News
Another question: Are those errors or adaptations? Considering the complexity of a cell's innards, why don't we apply the concept of natural selection to the ecosystem inside the cell wall? Are the tireless DNA repair machines intelligently altering DNA to adjust to changing circumstances? polistra

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