Figure 2.

Representative example of electrophysiology results and population summary from the eNpHR2.0-expressing site. (a) Raster plots and PSTHs from a light-responsive single unit. The neuron responded with a rapid reduction in firing rate to a train of green laser pulses (20 Hz, 5 ms pulses). The firing rate decreased markedly 2–3 ms after the light pulse (inset). The same neuron showed a complete shutdown of spiking activity during 70–150 Hz pulse trains as well as during continuous illumination with green light (instantaneous power density 27 mW mm⁻², energy density 135 μJ mm⁻² per pulse, average power density 9.6 mW mm⁻² for 1 s complete shutdown caused by 5 ms pulses delivered at 70 Hz; all values refer to the site of electrical recordings; see Online Methods for calculation details). (b) Scatter plot of firing rates of all single units and multi-units recorded at the hThy-1-eNpHr2.0-expressing area during continuous stimulation versus baseline activity. Empty circles mark non-significant responses to light, filled circles show significant responses. The dashed gray line is the unity-slope line, where baseline firing rate and stimulation firing rate are equal.