Researchers find ‘human-specific’ functions in the prefrontal cortex the brain. However, what “makes us human” can also make us susceptible to mental and neurological illnesses.
Researching primate brains
In particular, the researchers looked at the dorsolateral prefrontal cortex (dlPFC) of four different types of primates. It is a specific area of the brain that is essential for higher cognition. Using single-cell RNA sequencing technology, the researchers produced a gene expression profile in hundreds of thousands of cells taken from adult human, chimpanzee, macaque and marmoset dlPFCs.
When grouping cells with similar expression profiles, they revealed 109 common primate cell types, but also five that were not common to all types. This included a type of microglia or brain-specific immune cell that was only present in humans, and a second type that was common only to humans and chimpanzees. Scientists have found that a type of human microglia is present throughout development and puberty.
This type of cell is only found in the human brain
“We humans live in a completely different environment with a unique lifestyle compared to other primate species; glial cells, including microglia, are very sensitive to these differences,” said Nenad Sestan, professor of neurobiology at Harvey University and Kate Cushing at Yale University.
According to him, the type of microglia present in the human brain may represent an immune response to the environment. Gene expression analysis in microglia revealed another human-specific surprise -; Presence of the FOXP2 gene.
This finding attracted a lot of attention as FOXP2 variants have been linked to verbal dyslexia – a condition in which patients have difficulty with tongue or speaking. Other studies have also shown that FOXP2 is associated with other neuropsychiatric diseases such as AutismAnd the Schizophrenia And the epilepsy.
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