Researchers at the University of Illinois have found that adolescence is a time of remodeling in the prefrontal cortex, a brain structure dedicated to higher functions such as planning and social behaviors.
The study of rats found that both males and females lose neurons in the ventral prefrontal cortex between adolescence and adulthood, with females losing about 13 percent more neurons in this brain region than males.
This is the first study to demonstrate that the number of neurons in the prefrontal cortex decreases during adolescence. It is also the first to document sex differences in the number of neurons in the PFC. The study appears in the Feb. 9 issue of the journal Neuroscience.
Earlier studies in humans have found gradual reductions in the volume of the prefrontal cortex from adolescence to adulthood, said psychology professor and principal investigator Janice M. Juraska. "But the finding that neurons are actually dying is completely new. This indicates that the brain reorganizes in a very fundamental way in adolescence."
Juraska, graduate student Julie Markham and undergraduate student John Morris found that the number of neurons decreased in the ventral, but not dorsal, prefrontal cortex during adolescence. The number of glial cells, which surround and support the neurons, remained stable in the ventral PFC and increased in the dorsal PFC.
These findings challenge current models of brain development by showing that some parts of the brain are still being organized well after puberty.
This could have implications for understanding human psychopathologies, such as schizophrenia, which often arise in late adolescence, Juraska said.
Other psychological conditions, such as depression, often first occur in adolescence. And alcohol and nicotine addictions that start in adolescence are harder to overcome than those that begin in adulthood, Juraska said.