Experience-dependent inhibitory plasticity is mediated by CCK+ basket cells in the developing dentate gyrus

Abstract

Early postnatal experience shapes both inhibitory and excitatory networks in the hippocampus. However, the underlying circuit plasticity is unclear. Using an enriched environment (EE) paradigm, we assessed the circuit plasticity of inhibitory cell-types in the hippocampus. We found that cholecystokinin (CCK)-expressing basket cells strongly increased somatic inhibition on the excitatory granular cells (GC) following EE while another pivotal inhibitory cell-type, parvalbumin (PV)-expressing cells did not show changes. By inhibiting activity of the entorhinal cortex (EC) using a chemogenetic approach, we demonstrate that the projections from the EC is responsible for the developmental plasticity of CCK+ basket cells. Our measurement of the input decorrelation by DG circuit suggests that EE has little effect on pattern separation despite of the altered CCK+ basket cell circuit. Altogether, our study places the activity-dependent remodeling of CCK+ basket cell innervation as a central process to adjust inhibition in the DG, while maintaining the computation in the circuit.