Impact of chemogenetic excitation of distinct PL projections on behavior. A, Projection-specific chemogenetic approach involving a Cre-dependent Vector 1 (AAV8-hSyn-DIO-hM3Dq(mCherry) or AAV8-hSyn-DIO-mCherry) infused into the PL, and AAV2retro-hSyn-Cre(GFP) was infused into the BLA, NAc, or VTA. B, Cre-dependent mCherry expression in the PL of a C57BL/6J mouse treated with intra-PL AAV8-hSyn-DIO-mCherry and intra-BLA AAV2retro-hSyn-Cre(GFP). Scale bar, 325 μm. C, Trace fear conditioning in male C57BL/6J mice treated with intra-PL DIO-hM3Dq(mCherry) or control vector, and intra-BLA AAV2retro-Cre(GFP). Percent freezing observed during the cue recall test, conducted 2 d after trace fear conditioning in the presence of CNO (2 mg/kg, i.p.) (unpaired Student's t test; N = 8-11 mice/group). D, Saline- and acute cocaine-induced (15 mg/kg, i.p.) motor activity in male C57BL/6J mice treated with intra-PL DIO-hM3Dq(mCherry) or control vector, and intra-BLA AAV2retro-Cre(GFP), measured 30 min after CNO administration (2 mg/kg, i.p.). ****p < 0.0001 (two-way repeated-measures ANOVA with Bonferroni's post hoc test). N = 8-11 mice/group. E, Cre-dependent mCherry expression in the PL of a C57BL/6J mouse treated with intra-PL AAV8-hSyn-DIO-mCherry and intra-NAc AAV2retro-hSyn-Cre(GFP). Scale bar, 325 μm. F, Trace fear conditioning in male C57BL/6J mice treated with intra-PL DIO-hM3Dq(mCherry) or control vector, and intra-NAc AAV2retro-Cre(GFP). Percent freezing observed during the cue recall test, conducted 2 d after trace fear conditioning in the presence of CNO (2 mg/kg, i.p.) (unpaired Student's t test; N = 9-11 mice/group). G, Saline- and acute cocaine-induced (15 mg/kg, i.p.) motor activity in male C57BL/6J mice treated with intra-PL DIO-hM3Dq(mCherry) or control vector, and intra-NAc AAV2retro-Cre(GFP), measured 30 min after CNO administration (2 mg/kg, i.p.) (two-way repeated-measures ANOVA; N = 9-11 mice/group). H, Cre-dependent mCherry expression in the PL of a C57BL/6J mouse treated with intra-PL AAV8-hSyn-DIO-mCherry and intra-VTA AAV2retro-hSyn-Cre(GFP). Scale bar, 325 μm. I, Trace fear conditioning in male C57BL/6J mice treated with intra-PL DIO-hM3Dq(mCherry) or control vector, and intra-VTA AAV2retro-Cre(GFP). Percent freezing observed during the cue recall test, conducted 2 d after trace fear conditioning in the presence of CNO (2 mg/kg, i.p.). *p < 0.05 (unpaired Student's t test). N = 10 or 11 mice/group. J, Saline- and acute cocaine-induced (15 mg/kg, i.p.) motor activity in male C57BL/6J mice treated with intra-PL DIO-hM3Dq(mCherry) or control vector, and intra-VTA AAV2retro-Cre(GFP), measured 30 min after systemic CNO administration (2 mg/kg, i.p.). ###p < 0.001 (main effect of viral treatment). N = 10 or 11 mice/group.