What Makes The Human Brain Different? Study Reveals Clues
What makes people brain distinct from that of all other animals– including also our closest primate relatives? In an analysis of cell kinds in the prefrontal cortex of 4 primate species, Yale researchers identified species-specific– particularly human-specific– features, they report on Aug. 25th in the journal Science.
And they discovered that what makes us human might also makes us susceptible to neuropsychiatric diseases.
For the study, the scientist researchers looked specifically at the dorsolateral prefrontal cortex (dlPFC), a brain area that is unique to primates and essential for higher-order cognition. Utilizing a single cell RNA-sequencing technique, they profiled expression levels of genes in numerous thousands of cells gathered from the dlPFC of adult humans, chimpanzees, macaques, and also marmoset monkeys.
” Today, we see the dorsolateral prefrontal cortex as the core component of human identity, however still, we do not know what makes this unique in humans and distinguishes us from other primate species,” stated Nenad Sestan, the Harvey and Kate Cushing Professor of Neuroscience at Yale, professor of comparative medicine, of genetics. And of psychiatry, and the senior lead author of the paper. “Currently, we have more clues.”
To respond to this, the researchers first asked whether there are there any cell kinds that uniquely exist in humans or other analyzed non-human primate species. After grouping cells with similar expression profiles, they showed 109 shared primate cell kinds and five that were not common to all species. These included one type of microglia or brain-specific immune cell that was present just in humans and a second sort shared by only humans and also chimpanzees.
The human-specific microglia kind exists throughout development and adulthood, the researchers found, suggesting the cells play a role in the maintenance of the brain upkeep rather than combatting the disease.
” We humans live in an extremely different environment with a unique lifestyle compared to other primate species; and glia cells, including microglia, are susceptible to these differences,” Sestan stated. “The type of microglia discovered in the human brain might represent an immune reaction to the environment.”
An evaluation of gene expression in the microglia show another human-specific surprise– the presence of the gene FOXP2. This discovery raised high interest because variants of FOXP2 have been connected to verbal dyspraxia, one condition in which patients have a problem producing language or speech. Other studies have also revealed that FOXP2 is associated with other neuropsychiatric diseases, like autism, schizophrenia, also epilepsy.
Sestan and also colleagues found that this gene exhibits primate-specific expression in a subset of excitatory neurons and human-specific expression in microglia.
” FOXP2 has interested many scientists for years, but still, we had no idea of what makes it unique in humans versus other primate species,” stated Shaojie Ma, a postdoctoral associate in Sestan’s lab and co-lead author. We are incredibly excited about the FOXP2 findings because they open new directions in studying language and diseases.
The study research was funded by the National Institutes of Health and the National Institute of Mental Health.
Other writers include co-lead author Mario Skarica, associate research scientist in neuroscience at Yale School of Medicine; co-senior writer Andre Sousa, assistant professor of neuroscience at the College of Wisconsin-Madison; and also co-senior writer Stephen M. Strittmatter, the Vincent Coates Professor of Neurology and also a professor of neuroscience at Yale, chair of the Division of Neuroscience, and also director of the Kavli Institute for Neuroscience.
More information: Shaojie Ma et al, Molecular and cellular evolution of the primate dorsolateral prefrontal cortex, Science (2022).
DOI: 10.1126/science.abo7257. www.science.org/doi/10.1126/science.abo7257
Read the original article on Medical Xpress.
