Dynamic role of adult-born dentate granule cells in memory processing

•New immature neurons are incorporated to pre-existing networks of the dentate gyrus.•They are hyper-plastic, excitable, uncoupled from inhibition and input unspecific.•They are crucial for tasks involving the discrimination of very similar situations.•While immature they could detect novel input features in a high dimensional space.•Only in their mature stage they would engage in input discrimination.

Throughout the adult life of all mammals including humans, new neurons are incorporated to the dentate gyrus of the hippocampus. During a critical window that lasts about two weeks, adult-born immature neurons are more excitable and plastic than mature ones, and they respond to a wider range of inputs. In apparent contradiction, new neurons have been shown to be crucial to solve behavioral tasks that involve the discrimination of very similar situations, which would instead require high input specificity. We propose that immature neurons are initially unspecific because their task is to identify novel elements inside a high dimensional input space. With maturation, they would specialize to represent details of these novel inputs, favoring discrimination.