Roles for somatostatin and parvalbumin interneurons in learning and arousal during trace conditioning.

Neural circuits must integrate sensory cues and their outcomes to guide learning, yet how distinct inhibitory interneurons contribute to this process remains a central question. This study investigates the specific roles of somatostatin (SST) and parvalbumin (PV) interneurons in the primary somatosensory cortex during trace eyeblink conditioning. We found that SST interneuron activity dynamically tracked the development of learned, anticipatory blinks, declining as learning progressed. Conversely, PV interneuron activity was coupled to locomotion, a proxy for arousal, following the aversive stimulus but was absent during the predictive cue window. Nicotinic cholinergic signaling selectively modulated SST responses. These results demonstrate a functional dissociation: SST interneurons refine predictive motor responses, while PV interneurons process affective arousal. This reveals a fundamental division of labor within cortical microcircuits for segregating and integrating distinct dimensions of learning.