Role of stimulus locale on strain differences in active avoidance after scopolamine of D-amphetamine treatment.

Three strains of mice were trained in a shuttle avoidance task following treatment with scopolamine (2.0 mg/kg) or d-amphetamine (3.0 mg/kg). When required to run towards light (CS) to avoid shock, A/J mice acquired the response more readily than DBA/2J or C57BL/6J mice. However, when required to run away from the light, the strain differences were eliminated. Under both testing conditions scopolamine and d-amphetamine augmented the performance of A/J mice, but had no effect of even disrupted performance of C57BL/6J. In DBA/2J mice d-amphetamine augmented performance only in the toward condition. Results were interpreted to support the hypothesis that scopolamine and d-amphetamine improve performance by response-disinhibition and response excitation, respectively. The presence of associative difficulties limit the effects of these agents.