Training-dependent decay in performance produced by the neuroleptic cis(Z)-flupentixol on spatial navigation by rats in a swimming pool

Rats were trained on place or cue spatial navigation tasks in a swimming pool and then given the neuroleptic, alpha-flupentixol. Initial experiments showed that regardless of testing schedule, including blocks of trials given concurrently or separated by 7 or 30 days, drugged rats showed a trial-by-trial decay in latency and accuracy of responding although they continued to swim. The rate of decay increased with increases in drug dosage. Further experiments showed that: 1) Performance decay was specifically related to conditioned components of the test environment. Animals required to swim in a different test, or to struggle, showed less decay than rats exposed to the test platform only or required to perform all aspects of the task. 2) Decay was not due to nonspecific effects of neuroleptic treatment because rats injected and replaced in their home cage, and then subsequently reinjected and tested performed like rats treated and tested for the first time. 3) A trial-dependent decay of performance was also obtained in hippocampectomized and decorticate rats, suggesting that at least part of the major action of the drug is on subcortical systems. The results are discussed with respect to hypotheses of neuroleptic action and with respect to their possible relevance to experience-dependent changes in animal analogues of Parkinson's disease. Finally, it is suggested that behavior may be organized in subsystems, which when active, become selectively sensitive to neuroleptics.