Figure 2.

Optogenetic inactivation of L6 corticogeniculate cells. A, Expression of Arch-GFP carried by an AAV 2/9 vector in Ntsr1-Cre mice injected directly into V1. Expression shown is 4 weeks after injection. Shown is a paraformaldehyde-fixed, sagittal section. Scale bar, 0.5 mm. B, Reduction of spontaneous firing of cells in L6. Optical fiber is placed directly in V1; array of tetrodes lowered to approximate L6 depth (example shown: 712 μm). Spontaneous firing of a cell (left) is eliminated by activation of Arch; spontaneous activity of another cell recorded on the same tetrode (right) is unaffected by Arch. C, Reduction of drifting grating evoked firing of a L6 cell. Two cycles of a drifting grating evoke a modulation response (left); enveloping activation of Arch eliminated the activity evoked by the same stimulus (right). D, Distribution of the effect of activating Arch on visual stimulus evoked firing for single and multiclusters recorded in L6.