(A) Illustration of adeno-associated virus (AAV) injections into the VTA of ErbB4 Cyt-1fl/fl mice used to generate controls (AAV9-hSynI-GFP) and acute Cyt-1 KOs (AAV9-hSynI-Cre & AAV9-hSynI-DIO-GFP). (B-E) Controls (n=8) and acute Cyt-1 KOs (n=11) were tested in different behavioral paradigms. (B) Acute Cyt-1 KOs spend less time in closed arms of the elevated plus maze (two-way ANOVA, F(1,17)=4.421, p=0.0507, Sidak’s multiple comparison test ctrl vs. Cre, closed arms p=0.0234*, open arms p=0.4123). (C) No differences were found between cohorts in the Y-maze (unpaired two-tailed t-test, p=0.5380). (D) Acute Cyt-1 KOs exhibit an enhanced startle response relative to controls, (mixed-effects analysis, F(11,181)=1.874, p=0.0454*, ctrl vs. Cre p=0.0490*; 6 outlier values from a total of 209 values in 5 mice); however, (E) PPI does not differ between cohorts, (two-way ANOVA, F(3,51)=0.09446, p=0.9628, ctrl vs. Cre p=0.0601).