Synaptic organization and associative learning-related activity of basolateral amygdala interneurons.

Basolateral amygdala (BLA) GABAergic interneurons (INs) are critical for associative learning; however, the comparative synaptic organization and learning-related activity of BLA IN types have not been systematically evaluated. Here, we show somatostatin (SOM) INs provide inhibition onto, and are excited by, local pyramidal cells (PCs), whereas vasoactive intestinal peptide (VIP) INs are driven by extrinsic afferents. Parvalbumin (PV) INs inhibit PCs and are activated by local and extrinsic inputs. Thus, SOM and VIP INs exhibit complementary roles in feedback and feedforward inhibition, respectively, while PV INs contribute to both microcircuit motifs. Functionally, each IN subtype exhibits unique activity patterns across fear and extinction learning, with SOM and VIP INs showing most divergent characteristics, and PV INs display an intermediate phenotype. Finally, SOM and PV INs dynamically track behavioral-state transitions across learning. These data provide insight into the synaptic microcircuit organization and activity of distinct BLA IN classes across aversive associative learning.