Activation of Parvalbumin-Positive Neurons in Both Retina and Primary Visual Cortex Improves the Feature-Selectivity of Primary Visual Cortex Neurons.

Several recent studies using either viral or transgenic mouse models have shown different results on whether the activation of parvalbumin-positive (PV+) neurons expressing channelrhodopsin-2 (ChR2) in the primary visual cortex (V1) improves the orientation- and direction-selectivity of V1 neurons. Although this discrepancy was thoroughly discussed in a follow-up communication, the issue of using different models to express ChR2 in V1 was not mentioned. We found that ChR2 was expressed in retinal ganglion cells (RGCs) and V1 neurons in ChR2fl/+; PV-Cre mice. Our results showed that the activation of PV+ RGCs using white drifting gratings alone significantly decreased the firing rates of V1 neurons and improved their direction- and orientation-selectivity. Long-duration activation of PV+ interneurons in V1 further enhanced the feature-selectivity of V1 neurons in anesthetized mice, confirming the conclusions from previous findings. These results suggest that the activation of both PV+ RGCs and V1 neurons improves feature-selectivity in mice.