`Sociability depends on brain cell growth during adolescence`

Washington: Scientists have discovered that the growth of brain cells during adolescence holds the key to a person`s sociability, a finding they say could help boost understanding of schizophrenia and other brain disorders.

In experiments on mice, researchers at Yale University in the US found that the animals become profoundly anti-social when they blocked the growth of their brain cells (or neurons) during adolescence.

When the same process is interrupted in adults, no such behavioural changes were noted, found the researchers who detailed their findings in the journal Neuroscience.

"This has important implications in understanding social development at the molecular level," said study author Arie Kaffman, assistant professor of psychiatry.

Scientists have long known that neurons are continually generated in specific brain regions after birth. This process, called neurogenesis, occurs at a significantly greater rate during childhood and adolescence than in adulthood, yet most research has focused upon the function of these neurons in older brains.

The Yale team decided to explore the function of these new brain cells in mice of different ages.

Normal adult mice tend to spend a lot of time exploring and interacting with unfamiliar mice. However, adult mice that had neurogenesis blocked during adolescence showed no interest in exploring other adult mice and even evaded attempts made by other mice to engage in social behaviour.

"These mice acted like they did not recognise other mice as mice," Kaffman said.

Blocking neurogenesis had no effect on social behaviour in adult mice, suggesting that the brain cells generated during adolescence make a very different contribution to brain function and behaviour in adulthood, the scientists noted.

Intriguingly, schizophrenics have a deficit in generating new neurons in the hippocampus, one of the brain areas where new neurons are created.

Given that symptoms of schizophrenia first emerge in adolescence, it is possible that deficits in generating new neurons during adolescence or in childhood holds new insights into the development of some of the social and cognitive deficits seen in this illness, Kaffman said.