CONICET | Buscador de Institutos y Recursos Humanos

Neural progenitor cells of the adult hippocampus develop, mature and integrate as dentate granule cells that are fully capable of information processing. Those steps are modulated by physiological and environmental factors, in particular, the activity of the surrounding circuits. Why does the adult hippocampus produce new neurons? Are newborn neurons unique in their functional properties? Our laboratory has been interested in elucidating how adult-born neurons contribute to hippocampal function, and what intrinsic and extrinsic factors control the timing and quality of the recruitment into the existing network. Over the past few years we have focused on the electrical properties and connectivity of newborn granule cells in the dentate gyrus network. We have used retroviral expression of GFP to label new neurons and study how they establish their inputs and outputs within a fully established circuit, how they process afferent signals and how they convey information onto target cells. Notably, developing neurons of the adult hippocampus are capable of information processing before reaching maturation, at which time they are highly excitable. Our findings support a recent hypothesis whereby a key role of adult neurogenesis relies in the continuous generation of young neurons with distinctive capabilities for information processing. In addition, we have recently found that the timing of high excitability is not uniform along the septotemporal axis of the hippocampus, since septal neurons mature at a faster rate than temporal neurons. We now propose that the septotemporal gradient in the rate of neuronal maturation may result in a graded window for time coding by newborn neurons in the adult dentate gyrus.