Fig. 3.

Brief light flashes caused prolonged effects on neuronal excitability in melanopsin-expressing cortical pyramidal neurons. A₁: under current-clamp conditions, a brief flash of light (10 ms, blue bar) elicits a sustained depolarization [illustrated by the dots between the traces] and an increase in the spiking induced by constant depolarizing current injection (70 pA, 700 ms). A₂: plot illustrating the time course of the increase in current-induced spiking of the cell shown in A₁. Gray-filled circles correspond to the traces depicted in A₁. B: summary plot illustrating the light-induced increase in spiking in the 11 pyramidal cells tested (paired t-test, P = 6.18E-6). C: traces from a cell receiving 5-ms light stimulation 50 ms prior to the current injection (250 pA, 1.5 s).