Extended Data Fig. 5: Analysis of light-evoked synaptic responses with ChR2–eYFP expressed in dCA2 pyramidal neurons.

a, Schematic of hippocampal or septal slice recordings from Amigo2-Cre mouse injected into dCA2 with rAAV5-EF1a-DIO-hChR2(E123T/T159C)-eYFP (5 cells from 3 mice). b, CA2 pyramidal neuron voltage response under current-clamp to a 20-Hz train of 1-ms light pulses. Scale bars, 20 mV and 200 ms. c, dCA2 pyramidal neuron current responses under voltage-clamp with increasing light stimulation intensity (onset at blue spot). Negative (excitatory) currents plotted upwards. Responses to different light intensities coloured as in d. Note action currents reflecting escaped action potentials with two highest light intensities. Scale bars, 1 nA and 5 ms. d, Input–output curve for light-induced current in ChR2-expressing dCA2 pyramidal neurons. e, Schematic of dLS synaptic voltage recordings in septal slice from Amigo2-Cre mouse injected with the same virus as in a. f, g, Maximal dLS PSP amplitude (f) and latency (g) following light stimulation (65 cells from 32 mice; mean ± s.e.m.). h, Quantification of effect of GABA_A and GABA_B receptor antagonist application (1 µM SR 95531 and 2 µM CGP 55845, respectively) on light-induced PSP amplitude in dLS showing individual cells (black, 6 cells from 4 mice) and mean ± s.e.m. (red). Two-sided Wilcoxon test, *P = 0.03. Scale bars, 2 mV and 100 ms. i, Light-induced PSP amplitude in dLS before and after application of NMDA and AMPA receptor antagonists 25 µM AP5 and 20 µM CNQX, respectively (6 cells from 3 mice). Two-sided Wilcoxon test compared to baseline, P = 0.03. Scale bars, 5 mV and 100 ms. j, vLS recording under same conditions as in a and e. k, Amplitude of light-induced IPSCs in vLS before and after application of 25 µM AP5 and 20 µM CNQX (6 cells from 3 mice). Two-sided Wilcoxon test, P = 0.03. Scale bars, 200 pA and 100 ms.