A switch from integrative to orthogonal input processing by adult-born neurons

MA. BELEN PARDI; LUCAS MONGIAT; ALEJANDRO F. SCHINDER; ANTONIA MARIN BURGIN

Huerta Grande

Congreso; Sociedad Argentina de Neurociencias; 2011

Sociedad Argentina de Neurociencias

Immature granule cells (GC) born in the adult hippocampus present higher excitability than mature GC, and require weaker inputs to be recruited in response to the activation of afferent inputs. These properties suggest that while mature GC are presumably more selective in their responses, immature GC could be recruited by several inputs, allowing integrations to occur. To study this hypothesis, we worked on hippocampal slices from adult mice injected with a retrovirus to express RFP in newborn GC. We monitored GC activity by loading them with the calcium dye OGB-1 AM. Two electrodes were placed to stimulate independent medial perforant path inputs at different intensities. Under these conditions, the majority of mature GC responded to only one of the two stimuli, but most immature GC were equally recruited by both. Blocking GABAergic inhibition increased mature GC input integration but did not modify immature GC values. Our results suggest immature GC integrate different sources of information whereas mature neurons process incoming information in an orthogonal manner. These functions could imply a specific role of both GC populations in learning and memory, such as temporal associations and dissociations of spatial and object information.