It is one of the defining qualities of being human: when compared to our closest primate relatives, we have an excessive brain.
Now scientists have shed light on the causes of the difference by collecting cells from humans, chimps and gorillas and turning them into brain lumps in the laboratory.
Tests on tiny “brain organoids” reveal the hitherto unknown molecular switch that controls brain growth and makes human organs three times larger than the brain in great moves.
With the switch and the human brain the tinker loses its developmental advantage, while the great clown brain can be developed more like a human.
The evolving biologist from the Medical Research Council’s Molecular Biology Laboratory in Cambridge, Dr. “What we see is a huge difference in cellular behavior, which can cause the human brain to grow very early,” said M. Dalin Lancaster. “We are responsible for almost all size differences.”
A healthy human brain is usually about 1,500 cm.3 In adulthood, it is about three times the size of 500 cm3 Gorilla brain or 400 cm.3 Chimp brain. But find out why there is so much trouble, at least because the development of human and great clown brain cannot be easily studied.
In an effort to understand the process, Lan Lancaster and his colleagues collected cells, often leaving them for medical tests or ch operation, humans, gorillas and chimps, reprogramming them into stem cells. They then grew these cells in such a way as to encourage them to turn into brain organoids – a few lumps of brain tissue a few millimeters wide.
A few weeks later, the human brain organoids were by far the largest, and a closer examination revealed the reason why. In the human brain tissue, the so-called neural progenitor cells – which make up all the cells in the brain – divide more than the great ape brain tissue.
Lancaster, whose study is published in Cell, added: “You have an increase in the number of those cells, so once it starts building different brain cells, including neurons, you have to start more, so you get an increase. The entire population of brain cells throughout the cortex. “
The mathematical model of the process, Delling, showed that the difference in cell proliferation occurs so early in brain development that it eventually leads to almost doubling the number of neurons in the adult human cerebral cortex compared to the great tricks.
Researchers began to identify the genes that are crucial to the process. Known as Zeb 2, it later turns into human tissue, allowing cells to further divide before maturation. Tests have shown that delays in the effects of Zeb 2 cause gorilla brain tissue to enlarge, while it is turned on earlier in human brain organoids, so that they will develop more like apes.
John Mason, a professor of molecular neural development at the University of Edinburgh who was not involved in the research, said it highlighted the power of organoids to study brain development.
He said, “It is important to understand how the brain develops normally, partly because it helps us understand what makes a human being unique and partly because it gives us an important understanding of how neurodegenerative disorders can occur. Can give. “
“Brain size can be affected in some neurodevelopmental disorders, for example macrocephaly is a symptom of some autism spectrum disorders, so understanding these basic processes of fetal brain development can lead to a better understanding of such disorders.”
