Exogenous expression of human Acetylcholinesterase (hAChE; Alexa Goat-Anti Rabbit 488, Green, A) resulting from bilateral injection of CMV-AAV2 into the hippocampus (outlined by DAPI, Blue) produced a significant interaction with photoperiod (F(1,58)=11.03 4, p=0.002) with significantly reduced immobility in short active photoperiod (SAP) housed mice compared to controls (GFP, B). Immobility was also increased in hAChE-treated mice housed under a normal active photoperiod (C). Placement of bilateral injections represented in schematic (D). Data presented as individual data points, mean, ±S.E.M., *=p<0.05 as indicated. Statistical effects were queried using ANOVA with sex, photoperiod, and viral treatment as factors. Absent a significant 3-way interaction with sex, data shown is collapsed across this variable.