Supplementary Figure 4: Impact of PV neuron suppression on cortical dynamics.

a) Example image of a V1 brain section from a PV-Cre;Rosa-LSL-tdtomato mouse injected with a Cre-dependent AAV virus driving eNpHR3.0-YFP. Scale bar is 130μm. b) Scatter plots of gamma power in control conditions (black) and during optogenetic suppression of PV cells. From left to right: relative power (n = 18 mice, p = 0.06), peak/trough power (n = 18 mice, p = 0.95), absolute power when the illumination light turned on after the visual stimulus (n = 18 mice, p < 0.001), absolute power when the light turned on before the visual stimulus (n = 8 mice, p = 0.008), and absolute power in the high gamma band ~60Hz (n = 13 mice, p = 0.008). All tests: Wilcoxon signed rank test. c) Average pairwise phase consistency spectrum for RS units in PV-Cre mice in the absence (black) and presence (red) of light, n=105, thickness of line denotes mean ± standard error. d) Example PSTH of a putative eNpHR3.0-expressing FS/PV unit during visual stimulation in the absence (black) and presence (red) of light. e) Population average change of the power spectrum in PV-Cre mice during optogenetic suppression. Upper and lower edge of filled area denote mean ± standard error (n = 18 mice). f) Histogram of the optogenetic modulation index (OMI) for isolated regular spiking, putative excitatory units in SOM-Cre;eNpHR3.0 mice. g) Dose response curve for the change in absolute visually induced gamma power in four different conditions as a function of light intensity. Yellow: SOM-Cre;eNpHR3.0 mice; Light green: PV-Cre;eNpHR3.0 mice; Dark green: PV-Cre:eArCH3.0 mice; black: control mice not expressing any opsin. Error bars are s.e.m. h) As in g) but for induced gamma power. i) Example power spectra of the visual responses to a large grating with (red) and without (black) light in a SOM-Cre mouse not expressing eNpHR3.0. Thickness of line denotes mean ± standard error. j) Left: Example power spectra form a PV-CRE:eArCH3.0 mouse under control (black) and illumination (red). Right: Example LFP traces during visual stimulation with a large grating under control (black) and during illumination (red). Thickness of line denotes mean ± standard error. k) As in j), but in another mouse.