FIGURE 2. Combining NpHR with ChR2 for noninvasive optical control.

a, Hippocampal neurons co-expressing NpHR–EYFP under control of the EF1 promoter and ChR2–mCherry under control of the synapsin I promoter. b, Cell-attached and whole-cell recording of neurons co-expressing NpHR–EYFP and ChR2–mCherry. Action potentials are evoked by brief pulses of blue light (473 nm, 15 ms per pulse; length of blue bars is not to scale for ease of visualization). Simultaneous illumination with yellow light inhibited spike firing. c, Voltage-clamp recording from a single neuron co-expressing NpHR–EYFP and ChR2–mCherry, showing independently addressable outward and inward photocurrents in response to yellow and blue light, respectively.