In remarkable research being conducted by Christopher Walsh from Boston Children’s Hospital is found further confirmation of how incredibly plastic the brain is even at the tissue level.
Walsh has been building up to this since the early 1990s, when he charted the migration of neurons in rat brains, and found that closely related cells would often end up in very different places. Now, using powerful techniques that can sequence the DNA from individual cells, he can trace these lineages with much more precision, and in human brains.
His postdoc Michael Lodato sequenced the genomes of 36 single neurons, extracted from the preserved brains of three healthy people who had died in accidents. He found that each neuron contains around 1,500 unique mutations, making them more variable than the team had anticipated. Contra Pahlaniuk, each neuron really is a beautiful and unique snowflake.
These mutations are different than those that typically exist in, say, skin cells or cancer cells. Those arise when cells divide and make mistakes when duplicating their DNA, or when that DNA is bombarded by damaging stimuli like ultraviolet radiation or tobacco chemicals. By contrast, neurons pick up most of their mutations through the simple act of switching on their genes. “When DNA isn’t being used, it is packed up and put away,” explains Walsh. “When a cell wants to use a gene, it unwinds the DNA and opens it up, and that unwinding is a little dangerous. It makes the DNA more vulnerable and can induce damage.”
Psychotherapists should find this interesting as not only is it confirm just how important the early environment is as it literally shapes the brain tissue by triggering genomes.