Interaction among scopolamine, conditioned stimulus modality, genotype, and either-way avoidance behavior of rats.

Effects of scopolamine were investigated on either-way avoidance in three genetic lines under auditory and visual conditioned stimuli (CS). In the either-way task, the animal has the option to respond in either of the two directions available. In the genetic line selected for high-avoidance the effects of scopolamine were similar with both auditory and visual CS modes. In the genetic line selected for low-avoidance, and in the genetically heterogeneous line, the effects of the drug were different between the auditory and visual CS. It is suggested that scopolamine is more likely to disrupt responsiveness to visual stimuli, which have become less effective in the low-avoidance line during the course of genetic selection.