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WASHINGTON — By examining the human brain in greater detail than ever before at the cellular level, scientists have identified more than 3,300 vast cell types in our most complex organ and uncovered the cellular basis of neurological diseases. We have created an atlas to help pinpoint and promote new treatments.
The ambitious study published Thursday also examined the similarities and differences between the brains of humans and other primates (chimpanzees, gorillas, rhesus monkeys, marmosets) that separate us from our evolutionary cousins and differentiate us from our Several factors have been identified that make us truly human.
The research was published in 21 other studies in Science and two other journals, and was supported by the U.S. government’s National Institutes of Health BRAIN Initiative Cell Census Network Consortium.
The human brain is complex in its ability to feel, move, read, write, speak, and think, as well as in its cellular diversity.
Neurons (or nerve cells) are the basic units of the brain, receiving sensory input, transmitting commands to muscles, and electrical signals along the way. The brain is made up of approximately 100 billion neurons and many more non-neuronal cells. All of this is organized in hundreds of different brain structures that control different functions.
The study identified 3,313 cell types, about 10 times more than previously known, the complete set of genes used by each cell type, and mapped their regional distribution in the brain.
“The entire brain cell atlas provides the cellular basis for everything we can do as humans,” said one of the researchers, Ed Lane, a neuroscientist at the Seattle-based Allen Institute for Brain Science. said.
Different types of cells have different properties and are likely to be affected differently during disease, Lane said.
One surprise is that cellular diversity is found in evolutionarily older parts of the brain, the midbrain and hindbrain, rather than in the neocortex, which is responsible for higher cognitive functions such as learning, decision-making, sensory perception, memory, and language. That was what I was concentrating on.
Brain-related diseases such as Alzheimer’s disease, Parkinson’s disease, and amyotrophic lateral sclerosis are among the most intractable diseases.
“Most brain diseases still do not have a cure or even a cure. This atlas should serve as a baseline to understand the detailed cellular basis of the disease and accelerate progress in targeting the next generation of treatments.” ,” Professor Lane said.
Researchers mapped genetic switches and brain cell types associated with Alzheimer’s disease, the most common type of dementia, and a variety of neuropsychiatric disorders, including schizophrenia, bipolar disorder, and major depression. .
They confirmed a link between microglial cells, a type of immune cell in the brain, and Alzheimer’s disease, and schizophrenia, a severe mental illness characterized by a disconnection between certain types of brain neurons and reality. clarified the relationship.
The researchers also compared the temporal cortex (an area of the neocortex associated with language comprehension, among other higher cognitive functions) with its closest evolutionary relatives, chimpanzees and gorillas. By doing this, they searched for characteristics unique to humans.
Although the cell organization was similar, certain genes, including those involved in neuron connections, were found to be used differently in humans than in the other two species.
“This means that the specialization of human cortical neurons is accelerating, leading to differences in cortical circuit function and our unique cognitive abilities,” said Trygve Bakken, a neuroscientist at the Allen Institute. It may be contributing to this.”
Lane said that these molecular modifications that occur in specific cell types in humans compared to chimpanzees and gorillas are likely to affect how they “bond together, or the plasticity of that bonding,” which could potentially affect humans. “It may be an important part of what makes the brain unique.”
Scientists expect a long road ahead for brain research.
“We are just at the beginning of uncovering the complexity of the human brain,” said another researcher, Bing Ren, director of the Center for Epigenomics at the University of California, San Diego. “Much more research is needed to fully understand the diversity, variability, and function of brain structure and function.”
