Fig. S7.

Activation of ChR2 by varying intensities of LED light. (A) Whole-cell current clamp recordings from a ChR2-expressing CA1 pyramidal neuron, stimulated by a blue LED at 10%, 20%, and 40% light intensity. The stimulation consisted of a burst of five flashes (indicated by blue bars below traces), each lasting 20 ms, delivered at 20 Hz. Bursts were delivered every 5 s. Lower traces depict magnification of the boxed areas. (B) Number of APs elicited in response to a burst of blue LED light as described in A, at varying light intensities. Thin lines represent responses from individual neurons, thick black line represents mean ± SEM. The light intensity used throughout the experiments was set to 40%, where APs were evoked reliably to each flash of light.