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

M. BELÉN PARDI; LUCAS A. MONGIAT; ALEJANDRO F. SCHINDER; ANTONIA MARÍN-BURGIN

Huerta Grande - Cordoba

Congreso; XXVI Congreso Anual de la Sociedad Argentina de Investigación en Neurociencia; 2011

Sociedad Argentina de Investigación en Neurociencia

Immature granule cells (GCs) born in the adult hippocampus present higher excitability than mature GCs, and require weaker inputs to be recruited. These properties suggest that while mature GCs are presumably more selective in their responses, immature GCs could be recruited by different inputs, allowing integrations to occur. To test this hypothesis, we worked on hippocampal slices from adult mice injected with a retrovirus to express RFP in newborn GCs. We monitored GCs activity by loading them with the calcium-sensitive 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 GCs responded to only one of the two stimuli, but most immature GCs were recruited by both. Blocking GABAergic inhibition increased mature GCs input integration but did not modify immature GCs. Our results suggest that immature GCs integrate different sources of information whereas mature neurons process incoming information in an orthogonal manner. These functions could imply a specific role of both GCs populations in learning and memory, such as temporal associations and dissociations of space and object information.