The brain adds new cells during puberty to help navigate the complex social world of adulthood, a new study has found.
The new cells added during adolescence survive into adulthood and mature to become part of the brain circuitry that underlies adult behaviour, Michigan State University neuroscientists found.
Scientists for long believed that growth of new brain cells in adults was limited to two brain regions associated with memory and smell.
However, MSU researchers studying hamsters found that mammalian brains also add cells during puberty in the amygdala and interconnected regions where it was thought no new growth occurred.
The amygdala plays an important role in helping the brain make sense of social cues. For hamsters, it picks up signals transmitted by smell through pheromones; in humans, the amygdala evaluates facial expressions and body language.
"These regions are important for social behaviours, particularly mating behaviour. So, we thought maybe cells that are added to those parts of the brain during puberty could be important for adult reproductive function," said lead author Maggie Mohr.
To test that idea, Mohr and Cheryl Sisk, MSU professor of psychology, injected male hamsters with a chemical marker to show cell birth during puberty. When the hamsters matured into adults, the researchers allowed them to interact and mate with females.
Examining the brains immediately after that rendezvous, the researchers found new cells born during puberty had been added to the amygdala and associated regions.
Some of the new cells contained a protein that indicates cell activation, which told researchers those cells had become part of the neural networks involved in social and sexual behaviour.
"Before this study it was unclear if cells born during puberty even survived into adulthood. We've shown that they can mature to become part of the brain circuitry that underlies adult behaviour," Mohr said in a statement.
The study was published in journal Proceedings of the National Academy of Sciences.
