Dissociating performance and learning deficits on spatial navigation tasks in rats subjected to cholinergic muscarinic blockade.

The spatial navigation abilities of rats, subject to muscarinic blockade with atropine sulfate (50 mg/kg), were examined with the object of dissociating putative performance and learning deficits. A number of aspects of performance were not disrupted by the drug treatments, including development of position responses, cue responses, nonspatial discriminations, and the retention of place responses. Acquisition of place navigation was disrupted in a variety of tasks including: dry-land tasks in which rats searched for a hole from which to escape or searched for buried food and swimming pool tasks in which rats searched for a hidden platform on which to escape from the water. Task acquisition as well as motor performance was changed by the drug treatments in each task. Priming animals with experience on a subset of task variables did not significantly improve subsequent place performance. Priming animals with all motoric and spatial demands of a task, except the use of a specific set of distal cues aided performance, whereas priming animals with the use of a specific set distal cues but not motor experience produced little improvement in performance. The results indicate that impairments in the use of motoric skills contribute significantly to the deficits produced by cholinergic muscarinic blockade in spatial navigation tasks.