Figure 6.

Optically evoked plasticity is normal with transgenic ChR2 expression. A, Left, Whole-cell current clamp recordings from CA3 hippocampal pyramidal cells in Thy1-ChR2 mice. Cells were stimulated optically with light focused either over the cell soma (open circle) or 500 μm away over the stratum radiatum (closed circle). Right, The probability of optically evoking a spike in CA3 pyramidal cells for either somatic or axonal illumination (soma, n = 25; axon, n = 10). B, Representative spike train elicited by flashes delivered at 50 Hz. C, Top, Representative EPSCs evoked by 10 and 50 Hz stimulation of Schaffer collateral axons; both stimulation methods were recorded from the same CA1 pyramidal neuron. Bottom, Averaged normalized EPSC amplitudes during trains evoked electrically (n = 6) and optically (n = 9) at 10 and 50 Hz. D, Left, Representative EPSCs evoked optically and electrically by pairs of stimuli at 10–200 ms ISI recorded from the same neuron. Right, Averaged paired-pulse ratios evoked electrically (n = 6) and optically (n = 9). Vertical scale bars, 100 pA. Data are expressed as average ± SEM.