Opto-mGluR6 flips the polarity of light responses in RGCs.

<p>(A) Example spike trains recorded from an ON-Alpha RGC in an isolated <i>Pde6b</i>⁺_Opto-mGluR6 retina in response to a series of light steps (yellow underlay, 5.4 x 10¹⁶ photons cm^-2 s^-1, 100% contrast, yellow highlights), before (top trace) and after (bottom trace) the photoreceptor cells were bleached. (B) The same experiment from panel A performed on an OFF-Alpha cell. After recording, cells were labeled with neurobiotin (red). Panels (C,D) show flat views of the cells recorded from in A and B, respectively. (E,F) show transverse views of the marked areas in C and D, respectively. Colabeling with ChAT (green) confirms the identity of the ON- and OFF-Alpha cells on the basis of their dendritic stratification depth. Scale bars, 50 μm. (G) Spike-time histograms comparing the response kinetics of OFF-Alpha cells from C57BL/6 retinas (black) with that of ON-Alpha cells from bleached <i>Pde6b</i>⁺_Opto-mGluR6 retinas (red). Each trace shows the average of eight traces recorded from four cells from four retinas, bin width 20 ms.