Different inhibitory interneuron cell classes make distinct contributions to visual contrast perception

Abstract

While recent work has revealed how different inhibitory interneurons influence responses of cortical neurons to sensory stimuli, little is known about their distinct contributions to sensory perception. Here, we optogenetically activated different genetically defined interneurons (parvalbumin (PV), somatostatin (SST), vasoactive intestinal peptide (VIP)) in visual cortex (V1) of mice working at threshold in a contrast increment detection task. The visual stimulus was paired with optogenetic stimulation to assess how enhancing V1 inhibitory neuron activity during visual processing altered task performance. PV or SST activation impaired, while VIP stimulation improved, contrast increment detection. The impairment produced by PV or SST activation persisted over several weeks of testing. In contrast, mice learned to reliably detect VIP activation in the absence of any natural visual stimulus. Thus, different inhibitory signals make distinct contributions to visual contrast perception.

Significance Statement Inhibitory interneurons are diverse and influence sensory responses through multiple mechanisms. Currently there is little consensus on how different inhibitory signals affect sensory perception. Here, we investigated how genetically defined interneuron subclasses (parvalbumin (PV), somatostatin (SST), and vasoactive intestinal peptide (VIP)) influence visual contrast perception. Mice were trained to work at threshold in a visual contrast detection task and interneuron activity was enhanced using ChannelRhodopsin-2 on a subset of trials. Different interneuron classes influenced perception in distinct ways. PV and SST stimulation impaired, whereas VIP stimulation improved visual contrast perception. With training, mice learned to perceive VIP activation in the absence of natural visual stimulation. These data highlight how different inhibitory signals affect the transformation of sensory-evoked responses into percepts.