Direction selectivity of inhibitory interneurons in mouse barrel cortex differs between interneuron subtypes

GABAergic interneurons represent-15% to 20% of all cortical neurons, but their diversity grants them unique roles in cortical circuits. In the barrel cortex, responses of excitatory neurons to stimulation of facial whiskers are direction selective, whereby excitation is maximized over a narrow range of angular deflections. Whether GABAergic interneurons are also direction selective is unclear. Here, we use two-photon-guided whole-cell recordings in the barrel cortex of anesthetized mice and control whisker stimulation to measure direction selectivity in defined interneuron subtypes. Selectivity is ubiquitous in interneurons, but tuning sharpness varies across populations. Vasoactive intestinal polypeptide (VIP) interneurons are as selective as pyramidal neurons, but parvalbumin (PV) interneurons are more broadly tuned. Furthermore, a majority (2/3) of somatostatin (SST) interneurons receive direction-selective inhibition, with the rest receiving direction-selective excitation. Sensory evoked activity in the barrel cortex is thus cell-type specific, suggesting that interneuron subtypes make distinct contributions to cortical representations of stimuli.

Automated summary

GABAergic interneurons, which make up 15% to 20% of cortical neurons, have unique roles in cortical circuits due to their diversity. In the barrel cortex, excitatory neurons show direction selectivity in response to facial whisker stimulation, but it is unclear whether GABAergic interneurons also exhibit this property. Through two-photon-guided whole-cell recordings in anesthetized mice, this study found that direction selectivity is present in interneurons, but tuning sharpness varies across different subtypes. The findings suggest that different interneuron subtypes make distinct contributions to cortical representations of stimuli in the barrel cortex.