Effects of Amygdala lesions on social behavior in rats

Despite its importance mechanisms of prosociality are still not well known. In the literature, helping behaviour of rats to a restrained rat is becoming a tool for assesing this topic. Helping behavior is closely associated with sensitivity to another one's distress, and amygdala plays an important role in this sensitivity. The present study investigated whether bilateral amygdala lesion would affect rats' decision making to help when their cage-mate was restrained. Adult Wistar rats were subjected to a role reversal acquisition where they acquired the behavior of opening the door of the restrainer in which one of their cagemates was captive. Then, they were divided in three groups; naive, sham operated (Sham) and basolateral amygdala lessioned (Lesion). The rats were tested in an open field with three restrainers (empty, with a Sham or Lesion, with a Naive). The door opening and side preferences of rats were measured. In the control test there was a naive in the formerly empty restrainer, and the other two restrainers were empty which they formerly were not. No significant differences were found among the groups with respect to door opening and side preferences in both the main and the control tests. Door opening and to be close to the empty restrainer preferences were lowest in the main test and highest in the control test. The lower interest in the restrainer with a cagemate during the control test indicates that, the dominant door opening behaviour drive was not helping but was probably habit formation.