(ORDO NEWS) — Only in humans, in the cerebral cortex, immune cells are found in which the FOXP2 gene, which is key for the vocal apparatus and speech, works.
Scientists from the American Yale University compared the activity of genes in the cells of the cerebral cortex in humans and other primate species.
This made it possible to discover a lot in common between them – and several important differences that may be key for the formation and functioning of the human brain. Among these differences are microglial cells, which use the FOXP2 gene, which is important for speech.
Biologists studied the structures of the dorsolateral anterior cortex ( dlPFC ), an area closely associated with speech and emotions, short-term memory, decision making, and other higher cognitive functions of the brain. We used dlPFC tissues from four primate species: humans, chimpanzees, macaques, and marmosets.
For each of them, scientists have identified a transcriptome – a complete set of RNAs that are synthesized from active genes, showing which ones work in each particular cell. Thus, the authors obtained more than 600 thousand transcriptomes for different types of primates, after which they compared them with each other.
The comparison made it possible to identify more than a hundred types of cells common to both humans and other animals, and five types of cells that are not found in all. Four of them are found only in humans, and one is found in humans and chimpanzees.
These cells belong to microglia, the immune system of the brain, which is important not so much for fighting infections as for the formation and maintenance of nervous tissue.
Genetic analysis of these microglial cells showed that the FOXP2 gene works in humans , while it remains inactive in other primates. This gene acts as a regulator of many other genes, participating in the development of not only the brain, but also other internal organs.
It is known that FOXP2 malfunctions in the nervous system lead to speech disorders and the overall functioning of the vocal apparatus. Now scientists have found that FOXP2 functions in some neurons in all primates, but in microglia only in humans.
Thus, we have become even a little closer to understanding how exactly the brains of primates and specifically humans differ.
“Today, the dorsolateral prefrontal cortex is considered a key part of human identity,” adds Nenad Sestan. “But we still don’t know what exactly makes it unique in humans, distinguishing it from other primate species. Now we have new evidence of this.”
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