“…The DLS, a brain region comprised of a heterogeneous population of inhibitory neurons, by virtue of receiving direct hippocampal synaptic inputs, is ideally positioned to relay DG-CA3 computations resolving overlapping contextual information to the hypothalamus and the supramammilary nucleus (SUM) (McGlinchey and Aston-Jones, 2018; Pan and McNaughton, 2004;Risold and Swanson, 1996, 1997a, 1997bSheehan et al, 2004;Yang, 2015, 2016), a potent modulator of defensive behavior (Blanchard et al, 1998) (exploration, freezing), arousal, and stress responses (Campeau and Watson, 2000;Pan and McNaughton, 2004). We recently found that within the DLS, somatostatin (SST)-expressing neurons receive monosynaptic inputs from hippocampal CA3, CA1, and subiculum and these neurons gate mobility in aversive contexts (Besnard et al, 2019). Together, these observations suggest that contextual information may be relayed out of CA3 by CA1 or the DLS to cortical and subcortical circuits to calibrate fear responses.…”