SCOPOLAMINE - EFFECTS ON FEAR OR DEFENSE RESPONSES IN RAT

In previous studies, scopolamine reduced fear or defense responses of rats to cat, and removal of the rats'' olfactory bulbs had the same effect. This suggested that scopolamine might have affected defense responses by blocking olfactory perception of the stimulus cat. The present experiments studied this possibility and further explored the effects of scopolamine on defense responses of the hooded rat. In Experiment 1 rats treated with scopolamine were responsive to olfactory cues from a cat. When cat smell, but not a cat, was present in the apparatus, scopolamine-treated rats showed a large and significant suppression of food consumption. In Experiment 2 the effects of scopolamine on defense responses were generalizable to an inanimate stimulus, mechanical robot. Scopolamine caused significantly less freezing and avoidance and significantly shorter latencies to drink in the presence of the robot. Scopolamine reduced the defensive response of freezing in a variety of stimulus situations.