The brain has more than 3,000 different types of neurons and glial cells, a landmark scientific project involving hundreds of neuroscientists from the United States and Europe has revealed since 2017. The results provide the most detailed atlas of the human brain yet so far, which lays the groundwork for advancing research into neurological and psychiatric diseases and better understanding how the brain works.
Researchers have applied the latest cell analysis techniques to study the nervous system at the scale of individual cells, something that had been technically impossible until now. This has allowed them to map the different regions of the brain, assess the differences between the brains of different people, study how the brain evolves from the prenatal stage to adulthood and compare the human brain with that of other species.
"It is the beginning of a new era in brain science," said Joseph Ecker, from the Salk Institute in California, one of the three institutions that coordinated the project, in a statement. The aforementioned project, called BICCN (for the Brain Initiative Cell Census Network), is mainly funded by the US Government through its National Institutes of Health (NIH). It is part of the BRAIN initiative, launched in 2013 by the NIH to "revolutionize our understanding of the human brain".
The results of the BICCN project are presented today in 21 scientific papers that are published simultaneously, most of them in the journal Science.
A team from the Allen Institute, in collaboration with the Karolinska Institute in Stockholm, has sequenced the RNA of individual cells in one hundred different brain regions of three people. RNA tells which genes are active and which proteins are made in each neuron and each glial cell, which are cells of the nervous system that complement neurons.
In the hundred regions analyzed, more than 2,400 types of neurons and more than 600 different types of glial cells have been identified. The greatest diversity has been found in regions such as the hypothalamus, brainstem and cerebellum, which is consistent with the diversity of functions of these regions.
