Figure 8.
Optogenetic effects on V1 spiking and detection performance scale with the optogenetic stimulus power. A, Population PSTH (n = 83 units) combined for both contrast change types (±48%, each neuron contributes two responses to each trace while the color scheme follows the increment convention used in the manuscript). Spikes were convolved with a Gaussian with σ = 25 ms. Black line indicates the population response without optogenetic activation of PV interneurons. Line transparency corresponds to the different PV stimulation powers. Inset, Bar plot represents the evoked change in spiking for the different stimulus conditions. The strength of PV-mediated suppression significantly depends on LED power (p < 10−34, Friedman's test). B, Summary of behavioral performance for 1 PV mouse tested with different optogenetic stimulus powers. Bar plot represents the cumulative percent correct (±95% CI) for decreases (left, aqua) or increases in contrast (right, gold) presented without (black) or with optogenetic stimulation (colored) of PV neurons. Powers used = 0.05 mW, 7 sessions; 0.12 mW, 7 sessions; 0.20 mW, 8 sessions. The reduction in detection performance scales with power in the PV mouse (contrast decreases, increases both p < 10−16, logistic regression). C, Equivalent experiments in 1 Emx mouse revealed that optogenetic improvements in detection performance similarly scale with power (minimum 7 sessions per condition; contrast decreases, increases both p < 10−7, logistic regression).