Maturation of the brain takes longer than expected
Last reviewed: 23.04.2024
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Reduction of the number of synapses in the cerebral cortex at the late stages of its development continues almost to thirty years.
In the formation of the human brain, a significant role is played by a decrease in the number of synapses, however paradoxical it may sound. This fact has long been known to scientists: with intrauterine development and all childhood in the brain, more and more synapses are formed, and then their number begins to rapidly decline. It is due to this reduction that a person is considered to have the opportunity to learn and master new skills.
Overproduction of synaptic contacts in childhood is necessary for the brain to choose from, but then the excess of electrochemical connections between the neurons can quite confuse and slow down the work of gray matter. Maintaining synaptic contact requires some expenditure, so the brain gets rid of unnecessary to send more resources to important neural circuits; in other words, less is better, but better. Maturation of the brain can be compared with garden and park craft - when trees and bushes cut off excess branches for greater splendor of the crown.
It was assumed that the brain reaches the desired "synaptic balance" by the age of 20. But it turned out that this age is greatly understated. A group of neurophysiologists from the universities of Zagreb (Croatia) and Yale (USA) studied the structure of the prefrontal cortex in 32 people, whose age was from one week to 91 years. The scientists were interested in the density of the so-called dendritic spines of the neurons of the cortex-a variety of membrane protrusions on the surface of the neuronal processes. Spines, roughly speaking, represent a connector for connection with another neuron; synapses are formed with the help of such membrane protrusions.
As expected, the density of dendritic spines on the neurons of the cortex increased to 9 years, after which the membrane protrusions began to retract, but this retraction did not end with the exit from adolescence, but lasted almost to 30 years. The scientists presented their results in the journal PNAS.
It turns out that the brain improves its architecture much longer than expected. Therefore, on the one hand, you can learn a lot after the twenty years, but with caution that the brain is already tuned to other things and will save before something new. On the other hand, according to researchers, the results allow a new assessment of the causes and development of certain mental illnesses. So, about schizophrenia, there are different opinions, whether it arises as a result of developmental problems or due to some degenerative processes occurring in the already formed brain. Probably, at least some of the cases of schizophrenia can be attributed to the first option ...
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