HIPPOCAMPAL SOMATOSTATIN NEURONS GATE CONTEXT GENERALIZATION DURING FEAR MEMORY UPDATING

Freezing is widely used as a readout of fear memory in rodents, but it remains unclear how distinct freezing features reflect discrimination and generalization of threatening and neutral contexts. Using pose-tracking and unsupervised analysis in mice undergoing contextual fear conditioning, we show that generalized fear is expressed through fragmented freezing patterns that resist experience-dependent updating, in contrast with more sustained, uninterrupted, and adaptable discriminative freezing. Neuronal recordings revealed that recalling generalized fear is associated with increased activity of dentate gyrus somatostatin inhibitory neurons (SST INs). Chemogenetic suppression of SST INs during fear memory updating selectively facilitated generalized freezing adaptation while activation prevented generalization of contextual information by restricting long-term fear reduction in contexts that differed from the updating context. These findings identify DG SST INs as key modulators of context-specific updating of fear memories and suggest that freezing dynamics can serve as a behavioral signature of generalization.