Parvalbumin-positive (PV+) and somatostatin-positive (SST+) interneurons are two principal subtypes of cortical GABAergic neurons that differ in morphology, physiological properties and postsynaptic targeting. Although GABAergic inhibition is known to be crucial for shaping orientation tuning in the visual cortex, it is unclear whether PV+ and SST+ interneurons have different roles. Recently, we addressed this issue by optogenetically manipulating each interneuron subtype. We found that PV+ and SST+ interneurons show distinct roles in orientation selectivity, depending on the level and duration of interneuron activation. Our results showed that prolonged activation of PV+ interneurons in the mouse primary visual cortex (V1) sharpens neuronal feature selectivity and improves perceptual discrimination. These results provide the first demonstration that visual coding and perception can be improved by increased spiking of a specific subtype of cortical inhibitory interneurons.