Supplementary Figure 5: Verification of the fidelity of spiking in mPFC neurons expressing Chronos and optical fEPSP/PS in DMS slices.

(a-e) AAV-Chronos-GFP was infused into the mPFC and coronal sections containing the mPFC or DMS were prepared eight weeks after infusion. (a) Schematic illustration of whole-cell recording in Chronos-expressing mPFC neurons and field recording in the DMS area containing the Chronos-expressing fibers in separated experiments. (b) Whole-cell recording showing that Chronos-expressing mPFC neurons can fire spikes in response to a train of light pulses (2 ms) at 50 Hz. Scale bars: 20 ms, 10 mV. (c) 405-nm light-driven spike probability over a range of frequencies. F_(3,12) = 17.51, *P < 0.05, ***P < 0.001; n = 6 neurons, 2 rats. (d) Field recording demonstrating that Chronos-expressing mPFC fibers in the DMS can exert fEPSP/PS in response to 50-Hz train stimulation of light. Scale bars: 20 ms, 10 µV. (e) An example recording of a light-evoked fEPSP/PS, which was blocked by a mixture of AMPAR and NMDAR antagonists CNQX+CPP. Note that the remaining response in the presence of CNQX and CPP was partially blocked by TTX and completely by reducing light intensity to 2% of the original light intensity. Scale bars: 5 ms, 0.2 mV. One-way RM ANOVA for c. Data are presented as mean ± s.e.m.