April 29, 2024

Small but Significant: Differences Between Brains of Primates Revealed – Humans, Apes and Monkeys

A new study investigated the differences and similarities of cells in the prefrontal cortex– the frontmost area of the brain, a location that plays a central role in greater cognitive functions– in between humans and non-human primates such as chimpanzees, Rhesus macaques, and marmosets.
A new study reveals that the brains of humans and non-human primates may be extremely comparable, in spite of the extremely unique physical differences between them. And yet, the smallest changes may make huge distinctions in developmental and psychiatric conditions.
Comprehending the molecular distinctions that make the human brain distinct can assist scientists examine disruptions in its development. A new research study investigates the differences and similarities of cells in the prefrontal cortex– the frontmost area of the brain, an area that plays a main role in greater cognitive functions– between humans and non-human primates such as chimpanzees, Rhesus macaques, and marmosets. Released just recently in the journal Science, the research study was carried out by a group of scientists including University of Wisconsin– Madison neuroscience teacher Andre Sousa.
The cellular distinctions between these species might light up steps in their advancement and how those differences can be linked in disorders, such as autism and intellectual disabilities, seen in people. Sousa, who studies the developmental biology of the brain at UW– Madisons Waisman Center, chose to begin by studying and categorizing the cells in the prefrontal cortex in collaboration with the Yale University lab where he worked as a postdoctoral scientist.

Understanding the molecular differences that make the human brain distinct can help scientists investigate disturbances in its development. A new study investigates the differences and similarities of cells in the prefrontal cortex– the frontmost area of the brain, an area that plays a central role in greater cognitive functions– in between people and non-human primates such as chimpanzees, Rhesus macaques, and marmosets. If these genes are appropriate for brain advancement, for example, how numerous of a specific cell is produced, or how cells are linking to other cells, how is it impacting the neuronal circuitry and their physiological properties? We want to comprehend how these differences lead to distinctions in the brain and then lead to differences we can observe in grownups.”
The scientists next step is to study samples from establishing brains and extend their location of examination past the prefrontal cortex to possibly find where and when these distinctions come from.

Researchers examined genetic material from cells in the prefrontal cortex (the location shaded in each brain) from 4 closely-related primates to identify subtle distinctions in cell type and genes. University of Wisconsin-Madison
” We are profiling the dorsolateral prefrontal cortex due to the fact that it is particularly fascinating. This cortical area just exists in primates. It doesnt exist in other types,” Sousa says. “It has actually been related to numerous relevant functions in terms of high cognition, like working memory. It has also been linked in a number of neuropsychiatric disorders. We decided to do this study to comprehend what is special about people in this brain area.”
Sousa and his lab gathered hereditary information from more than 600,000 prefrontal cortex cells from tissue samples from humans, chimpanzees, marmosets and macaques. They examined that data to categorize the cells into types and determine the distinctions in similar cells across types. Unsurprisingly, the vast bulk of the cells were relatively similar.
” Most of the cells are in fact very comparable due to the fact that these species are relatively close evolutionarily,” Sousa states.
Andre Sousa. Credit: Photo by Andy Manis
They also discovered differences in the abundances of particular cell types as well as variety amongst similar cell populations throughout types. When comparing a chimpanzee to a human the distinctions seem huge– from their physical looks down to the capabilities of their brains.
” Our laboratory really needs to know what is distinct about the human brain. Obviously from this study and our previous work, the majority of it is actually the same, at least among primates,” Sousa says.
The small distinctions the scientists found may be the beginning of identifying a few of those special factors, which details could cause discoveries about advancement and developmental conditions at a molecular level.
” We want to know what happened after the evolutionary split between humans and other primates,” Sousa states. “The idea is you have an anomaly in a gene or in a number of genes and those genes now have somewhat different functions. If these genes are appropriate for brain development, for example, how numerous of a certain cell is produced, or how cells are linking to other cells, how is it affecting the neuronal circuitry and their physiological homes? We wish to comprehend how these differences lead to differences in the brain and after that result in differences we can observe in adults.”
The studys observations were made in the brains of adults, after much of the development is complete. This indicates that the differences might be occurring throughout the brains advancement. The researchers next step is to study samples from developing brains and extend their location of examination past the prefrontal cortex to potentially find where and when these differences stem. The hope is that this information will result in a more robust structure to lay developmental condition research on top of.
“If we have these unique capabilities, it has to be something in the brain? There is something in the brain that enables us to do all of that and we are truly interested in knowing what it is.”
For more on this research, see New Clues to What Makes the Human Brain Different.
Referral: “Molecular and cellular advancement of the primate dorsolateral prefrontal cortex” by Shaojie Ma, Mario Skarica, Qian Li, Chuan Xu, Ryan D. Risgaard, Andrew T. N. Tebbenkamp, Xoel Mato-Blanco, Rothem Kovner, Željka Krsnik, Xabier de Martin, Victor Luria, Xavier Martí-Pérez, Dan Liang, Amir Karger, Danielle K. Schmidt, Zachary Gomez-Sanchez, Cai Qi, Kevin T. Gobeske, Sirisha Pochareddy, Ashwin Debnath, Cade J. Hottman, Joshua Spurrier, Leon Teo, Anthony G. Boghdadi, Jihane Homman-Ludiye, John J. Ely, Etienne W. Daadi, Da Mi, Marcel Daadi, Oscar Marín, Patrick R. Hof, Mladen-Roko Rasin, James Bourne, Chet C. Sherwood, Gabriel Santpere, Matthew J. Girgenti, Stephen M. Strittmatter, André M. M. Sousa and Nenad Sestan, 25 August 2022, Science.DOI: 10.1126/ science.abo7257.