Monosynaptic inputs to new neuronsin the dentate gyrus

摘要

Adult hippocampal neurogenesis is considered important for cognition. The integration ofnewborn dentate gyrus granule cells into the existing network is regulated by afferent neuronalactivity of unspecified origin. Here we combine rabies virus-mediated retrograde tracing withretroviral labelling of new granule cells (21, 30, 60, 90 days after injection) to selectivelyidentify and quantify their monosynaptic inputs in vivo. our results show that newborn granulecells receive afferents from intra-hippocampal cells (interneurons, mossy cells, area CA3 andtransiently, mature granule cells) and septal cholinergic cells. Input from distal cortex (perirhinal(PRH) and lateral entorhinal cortex (LEC)) is sparse 21 days after injection and increases overtime. Patch-clamp recordings support innervation by the LEC rather than from the medialentorhinal cortex. mice with excitotoxic PRH/LEC lesions exhibit deficits in pattern separationbut not in water maze learning. Thus, PRH/LEC input is an important functional component ofnew dentate gyrus neuron circuitry.