Changes in socio-emotional behavior under imipramine treatment in normal and amygdalo-hypothalamic dogs

The effects of imipramine on learned social responses were examined in ten dogs with dorsomedial amygdalar lesions and/or lateral hypothalamic lesions. Six of the ten dogs were also tested preoperatively. The social responses were instrumentally conditioned using social interaction with the experimenter as reinforcement (petting and verbal reassurance). In the non-lesioned dogs imipramine treatment produced a dose-dependent deterioration of performance during drug administration followed by a long-term amelioration of performance. In the lesioned dogs imipramine produced various changes in performance depending on the pretreatment level of responding. When the pretreatment level of performance was high drug administration resulted in a long-term deterioration, and when performance was poor imipramine produced a continuous and long-term increase. It is suggested that imipramine facilitates the recovery of performance, but suppresses well-performed responses.