Figure 5. AmgC/M neurons provide direct inhibition onto PAG-USV neurons.
(A) Viral strategy (left) and schematic (right) for whole-cell patch clamp recordings from fluorescently identified CANE-tagged PAG-USV neurons while optogenetically activating AmgC/M-PAG axons. (B) Example image of overlap of neurobiotin and mCherry-labeled PAG-USV cells with ChR2-expressing AmgC/M-PAG axon terminals in the PAG. (C) Example of light-evoked IPSCs at different voltages from one PAG-USV cell recorded in TTX/4AP while stimulating AmgC/M-PAG axons (left). Inhibitory postsynaptic currents (IPSCs) were abolished by bath gabazine application (right). (D) The peak magnitude of light-evoked currents at different membrane voltages for the same cell as (C) shows that the current reverses around the reversal potential of chloride and is abolished by gabazine. Currents were identified as IPSCs in this manner based on their reversal behavior and, for a subset of cells, by disappearance in gabazine. (E,F) Light-evoked IPSCs recorded in TTX/4AP (observed in n = 16 of 29 CANE-tagged cells from nine mice) were abolished by application of gabazine (n = 10 cells also recorded in gabazine, N = 10 cells, p<0.001, paired t-test). IPSC amplitude refers to the peak of the light-evoked current at 0 mV holding potential. Error bars represent S.E.M. See also Figure 5—source data 1.