Fig. 6. Optogenetic stimulation of DAergic VTA neurons increases aggression.

DAT^IRESCre:ai32 double mutant mice expressing ChR2-eYFP in VTA neurons as visualized by immunohistochemistry against eYFP (a) and autofluorescence (b). A fiberoptic cable track demarks the position of an implant with its tip just dorsal of the VTA (indicated by a star, b). Tip locations were assessed histologically after behavioral experiments were concluded (c). DAT^IRESCre:ai32 double transgenic mice and single mutant controls were co-housed in mixed pairs and isolation induced aggressive behavior was assessed by scoring the time spent mounting, tail rattling, or biting during a 10 minute encounter (d). Only one mouse in a pair was stimulated (blue). Aggressive behavior was increased in pairs when DAT^IRESCre:ai32 double mutant mice were stimulated when compared to pairs where the single mutant controls were stimulated (d). (n = 11-18 per group) (*p < 0.05).