Scientists seek explanations about what makes the brain different from all other animals, including even the closest primates. Research conducted by experts at Yale University, in the United States, suggests some clues to this scientific mystery.
In an analysis of the cell types present in the prefrontal cortex of four primate species, the researchers identified species-specific characteristics – particularly human ones. The study also points out that what makes us human may also be the mechanism that makes us susceptible to neuropsychiatric diseases.
The research was funded by the National Institutes of Health (NIH) and the National Institute of Mental Health. The findings were published in Science magazine.
The primate brain is made up of a region essential for advanced cognition, called the dorsolateral prefrontal cortex. Using a genetic sequencing technique, the researchers traced gene expression levels in hundreds of thousands of cells collected from the cortex of adult humans, chimpanzees, monkeys and marmosets.
“Today, we see the dorsolateral prefrontal cortex as the central component of human identity, but we still don’t know what makes it unique in humans and distinguishes us from other primate species.” Nenad Sestan, a professor of neuroscience at Yale and lead author of the paper, said in a statement. “Now we have more clues”, he adds.
To better understand these differences, the researchers hypothesized that there are cell types that are uniquely present in humans or other non-human primate species.
The scientists pooled cells with similar expression profiles and identified at least 109 shared primate cell types, in addition to five that were not common to all species. The narrowest group included one type of microglia, or brain-specific immune cell, that was present only in humans, and a second type shared only by humans and chimpanzees.
The study reveals that the type of microglia specific to humans is present throughout development and into adulthood, which suggests that the cells play a role in maintaining the brain, rather than fighting disease – like others in the immune system.
“We humans live in a very different environment with a unique lifestyle compared to other primate species and glial cells, including microglia, are very sensitive to these differences,” said Sestan. “The type of microglia found in the human brain may represent an immune response to the environment.”
The genetic evaluation of microglia revealed another specific human characteristic: the presence of a gene called FOXP2.
The researchers point out that variants of FOXP2 have been linked to verbal dyspraxia, a condition in which patients have difficulty producing language or speech. Other studies have revealed the gene is linked to other neuropsychiatric disorders such as autism spectrum disorder, schizophrenia and epilepsy.
“FOXP2 has intrigued many scientists for decades, but we still had no idea what makes it unique in humans. versus other primate species,” said Shaojie Ma, a postdoctoral associate in Sestan’s lab and co-lead author. “We are extremely excited about the findings because they open up new directions in the study of language and disease,” he says.
Source: CNN Brasil
