But if those cells can't migrate to the right place and morph into the right kinds of neural links, our cognitive and psychological functions fail.
Researchers at the University of Illinois at Chicago have found that a protein called reelin, whose function in the adult brain has long been a mystery, is responsible for directing the migration of neural stem cells to the appropriate location in the brain as it adapts to new information. The results of the study are published in the March 19 issue of the Proceedings of the National Academy of Sciences.
"Neural stem cells are the precursors to the variety of cell types found in the brain," said Kiminobu Sugaya, assistant professor of psychiatry and the study's principal investigator. "Triggered by unknown environmental cues or factors, they migrate to specific areas to become a glial cell or a neuron, forming a link in the adult brain's complex neural network."
In the study, human neural stem cells were transplanted into an empty space of the brain, called the ventricle, in normal mice and in mice incapable of producing reelin (called "reeler" mice because of their peculiar gait, a result of their genetic defect).
"In the reeler mice, the stem cells got lost," Sugaya said. "They failed to migrate."
In the normal mice, however, the cells migrated into the hippocampus, the central processing unit of the brain; the olfactory lobes, controlling the sense of smell; and the cerebral cortex, responsible for higher mental activities like learning, memory, perception and problem solving. Once located in those regions, the cells turned into mature cells capable of functioning in the new environs.