Fig. 7.

Only activation of VP glutamate but not GABA projections to LHb recapitulates behavioral responses. a Whole-cell recordings in the LHb reveal that single-pulse (5-ms, blue dash) photostimulation of VGAT⁺ VP terminals triggered PTx-sensitive IPSCs (n = 7, paired t-test, t₍₆₎ = 2.19, p = 0.07). Pie chart shows the fraction of responding neurons, bar graphs show peak IPSC amplitude, insets show individual cells pre- and post-PTx and representative trace; numbers inside bars represent sample size. b Cell-attached recordings in the LHb show that photostimulation of GABA terminals from the VP consistently reduced action potential firing frequency in the LHb (n = 12, Wilcoxon matched-pairs signed-rank test, p = 0.0005). The bar graph shows mean change in firing rate 5-s before, during, and after 40-Hz photostimulation, gray axis and plots show individual neuron responses, inset (right) shows a representative trace. c VGAT-Cre mice did not show a preference for the compartment paired with photostimulation of VP terminals in the LHb on the RTPP assay (n = 12) and did not self-stimulate LHb terminals stimulation in the two-nosepoke ICSS task. d Whole-cell recordings, as described in a, show that photostimulation of VGLUT2⁺ VP terminals in the LHb triggered DNQX-sensitive EPSCs (n = 6, paired t-test, t₍₅₎ = 4.73, p = 0.005) as well as PTx-sensitive IPSCs (n = 4, paired t-test, t₍₃₎ = 3.77, p = 0.033); e and cell-attached recordings, as described in b, show that train of photostimulation increased (n = 7) or decreased (n = 6) action potential firing frequency in the LHb. f VGLUT2-Cre mice showed avoidance for the compartment paired with photostimulation of VP terminals in the LHb on the RTPP assay (n = 6). Example images of ChR2:YFP and optic fiber (OF) tracks in the LHb of c VGAT-Cre or f VGLUT-Cre mice; DAPI (blue), scale = 200 µm. Scales for a are 250 pA, 50 ms. Scales for d are 200 pA, 50 ms (PTx) and 500 pA, 10 ms (DNQX). Scales for b and e are 1 s; *p < 0.05, **p < 0.01, ***p < 0.001. See also Supplementary Figure 7 and Supplementary Table 3