EN
Somatostatin-expressing interneurons (SST INT) are one of the types of GABAergic neurons in the brain. Inhibition through SST INT is a powerful potential mechanism for gain control in cortical networks, and it has been extensively investigated in studies on learning and memory mechanisms. Learning‑related intrinsic excitability changes of SST interneurons have been recognized in the hippocampus. The aim of the study was to analyze how associative learning influences on SST INT‑mediated inhibition in the somatosensory cortex of mice. Using a transgenic mouse line with channelrhodopsin expressed in SST cells, we studied SST INT-mediated inhibition onto excitatory neurons, whereas using a transgenic line with fluorescently labeled SST INT, we analyzed intrinsic excitability of SST neurons. The associative learning protocol consisted of whisker stimulation paired with a tail shock (classical conditioning). As control groups, we used naïve mice and mice subjected to stimulation of vibrissae and a tail shock given at random relative to whisker stroking (pseudoconditioning). After learning protocols, we prepared acute brain slices and performed whole-cell patch-clamp recordings in excitatory neurons or SST INT of layer IV in the cortical representation of the whiskers stimulated during learning. Our experiments show that the charge transfer of inhibitory postsynaptic currents evoked in excitatory cells in response to the optical stimulation of SST INT is larger in the conditioned group of mice in comparison to controls. Also, intrinsic excitability of layer IV SST interneurons increases after the conditioning paradigm. Presented data indicate that associative learning increases SST INT-mediated inhibition of excitatory neurons in the somatosensory cortex. The enhancement of this inhibition might rely on the increment of intrinsic excitability of SST cells. FINANCIAL SUPPORT: National Science Centre UMO‑2015/18/E/NZ4/00721 to J.U.C.`