A team of scientists from the University of California, San Diego School of Medicine conducted a study that provides new insights into how the human forebrain develops.

Research, Ph.D. Changuk Chung and Ph.D. It was conducted by Xiaoxu Yang in the laboratory of Joseph G. Gleason, MD, of the Department of Neuroscience in the School of Medicine and the Council of the Children’s Genomic Medicine Institute. provides a better understanding of how the human brain develops at the cellular level.

The study also provides evidence for a different source of inhibitory neurons (dInN) in the human brain than in other species, such as mice, a common laboratory animal used in brain research. The group summarized their findings in a paper recently published in the journal. Nature.

Functional functions and values ​​of the forebrain

The forebrain, or cerebral cortex, is the largest part of the brain and is important for many functions, from cognitive thinking to vision to attention and memory. Neurons are cells that function as separate circuits in the brain. Inhibitory neurons often function as a type of neural “off” switch, as opposed to the “on” switch of excitatory neurons.

“Humans have a very large and convoluted cortex that likely supports higher cognitive functions compared to other species such as rodents,” Gleason explained.

Inhibitory neurons in mice originate deep within the developing brain, he said. The current study tests this model by assessing cellular origin. They discovered the existence of dInNs, which were not found in mice. Finding evidence of this specific type of neurons in humans would open the door to a better understanding of why the human brain is special, he said.

“We expect DinNs to support new, more accurate models of the human brain,” Gleason said. “This updated model of the brain could help explain the origins of some diseases, such as epilepsy, schizophrenia or autism.”

Cell lineage and structure of the brain

The group was particularly interested in tracing the lineages of mosaic variants of brain cells. “If two cells share the same parent cell, we say they share the same lineage,” Chang said.

“If two individual cells have the same mosaic variant, they arose from a common parent cell that passed it on to all of its children,” Young said. he explained. “So the mosaic variants in the cells function like surnames in humans.”

The researchers gained direct access to the brains of two neurotypical donors who died of natural causes. They used mosaic variants to track where these cells came from, identify sister cells born in the same brain region, and determine how far each “ancestral name” had spread in the brain.

They found that some inhibitory and excitatory neurons actually have the same name; This means that the two types of neurons share a common lineage, Chang says. These two types probably branched out late in embryonic brain development, he noted, and this cellular connection is not found in other types.

“We hope our paper will help other researchers create better models of neurological disease and determine what types of brain diseases may result from developmental disorders,” Gleason said.