Figure 5.
Comparative analysis of ChR kinetic variants in distinct cell types. Measurement of the kinetics of channel closure (Tauoff) following a brief 2-ms light stimulation was performed using whole-cell voltage clamp (−70 mV) as a sensitive assay for screening novel ChR kinetic variants.(A) Experiment #1: comparison of Tauoff measured in cortical pyramidal neurons with transgenic expression of ChR2R or VChR1. Scale bars: 200 pA, 100 ms. Experiment #2: comparison of Tauoff measured in cortical pyramidal neurons expressing the novel variants ChETAARC or oChIEFAC. Scale bars: 50 pA, 100 ms.(B) Combined data for pyramidal neurons.(C) Comparison of Tauoff measured in cortical fast spiking interneurons with transgenic expression of ChR2R (VGAT-ChR2R-EYFP line 8) or ChETATR (R26-2XChETATR/Pvalb-IRES-Cre). Scale bars: 200pA, 10 ms.(D) Summary data comparing Tauoff measured from either cortical fast-spiking interneurons or cortical pyramidal neurons both expressing ChR2R. Intrinsic cell type differences influence measured kinetic properties and thus preclude comparative analysis across cell-types.