Somatostatin Neurons Govern Theta Oscillations Induced by Salient Visual Signals.

Salient visual stimuli enhance theta oscillations and spike-phase locking in the theta band in the primary visual cortex (V1) of mice; however, the detailed mechanisms remain unknown. GABAergic neurons play a vital role in regulating these oscillations. Here, we use optogenetic recordings to tag cell-type-specific neurons in V1 of head-fixed mice and demonstrate that salient visual stimuli facilitate somatostatin (SOM)-expressing neuron responses and firing with theta band oscillations but suppress activities of parvalbumin (PV)-expressing neurons. Furthermore, inactivation of SOM neurons attenuates the enhancement of theta oscillations induced by salient visual stimuli and rhythmic activation of SOM neurons enhances theta oscillations. These results reveal a potential cortical theta oscillation mechanism governed by SOM neurons.