The role of body turn-brightness associations in the effect of scopolamine on response-to-change in the rat.

We explored further the different effects of anticholinergics on response-to-change in the passive and active tests. We hypothesized that body turn-brightness associations are formed in the active but not in the passive test, where the turns were prevented by transparent partitions blocking maze arm entrance. This difference might account for the resistance of the active test performance to anticholinergic drugs. To examine this idea, the passive test conditions were modified so that body turns were possible. However, scopolamine (1.0 mg/kg) interfered with response-to-change performance to the same extent as observed previously in the typical passive test procedure. Thus, body turn-brightness associations are not the source of resistance of active test performance to cholinergic receptor blockade.