Brain complexity: methylation of DNA type cells (Introduction)

by David Turell @, Thursday, August 10, 2017, 22:32 (222 days ago) @ David Turell

In epipgenetic alterations methylation modifies DNA and specific genes. This is now studied in human and animal brains, demonstrating, in part, the plasticity of the brain, by modifying neurons in addition to adding neurons and new circuits:

"Salk Institute and University of California San Diego scientists have, for the first time, profiled chemical modifications of DNA molecules in individual neurons, giving the most detailed information yet on what makes one brain cell different from its neighbor. This is a critical step in beginning to identify how many types of neurons exist, which has eluded neuroscientists but could lead to a dramatically better understanding about brain development and dysfunction. Each cell's methylome—the pattern of chemical markers made up of methyl groups that stud its DNA—gave a distinct readout that helped the Salk team sort neurons into subtypes.


"'Our research shows that we can clearly define neuronal types based on their methylomes," says Margarita Behrens, a Salk senior staff-scientist and co-senior author of the new paper. "This opens up the possibility of understanding what makes two neurons—that sit in the same brain region and otherwise look similar—behave differently."

"The team began their work on both mouse and human brains by focusing on the frontal cortex, the area of the brain responsible for complex thinking, personality, social behaviors and decision making, among other things. They isolated 3,377 neurons from the frontal cortex of mice and 2,784 neurons from the frontal cortex of a deceased 25-year-old human.


"Neurons from the mouse frontal cortex, they found, clustered into 16 subtypes based on methylation patterns, while neurons from the human frontal cortex were more diverse and formed 21 subtypes. Inhibitory neurons—those that provide stop signals for messages in the brain—showed more conserved methylation patterns between mice and humans compared to excitatory neurons. The study also identified unique human neuron subtypes that had never been defined before. These results open the door to a deeper understanding of what sets human brains apart from those of other animals. (my bold)

"'This study opens a new window into the incredible diversity of brain cells," says Eran Mukamel of the UC San Diego Department of Cognitive Science, a co-senior author of the work.

"Next, the researchers plan to expand their methylome study to look at more parts of the brain, and more brains.

"'There are hundreds, if not thousands, of types of brain cells that have different functions and behaviors and it's important to know what all these types are to understand how the brain works,'"

Comment: Note the bold. The human brain is more plastic than a mouse brain, based on those findings. Not surprising. Considering the functional capacities of our brain, as we develop new conceptual ways of using our brain, the plasticity ability is of prime importance. Compare us to Heidelbergus: they had shelter clothing, and stone tools, not much more. The Neanderthals added art, ceremonies, but nothing like sapiens accomplishments even 50-70,000 years ago. Size first, use second.

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