POSTTRAINING PARADOXICAL SLEEP IN RATS IS INCREASED AFTER SPATIAL-LEARNING IN THE MORRIS WATER MAZE

The role of posttraining paradoxical sleep (PS) in spatial or nonspati al learning in the Morris water maze was evaluated. Sprague-Dawley rat s were given a 12-trial training session in either the hidden or the v isible platform versions of the task. Subgroups then underwent paradox ical sleep deprivation (PSD) beginning at different times after traini ng. Rats with PSD imposed from 1-4 hr after spatial training had poore r retest scores than any other group. Other rats, implanted with elect rodes to permit continuous recording of sleep electroencephalography, were found to undergo a prolonged period of elevated PS after spatial training. By contrast, rats trained in the nonspatial version of the w ater maze task did not show retention deficits after PSD or elevated P S after training. These results support a role for PS in spatial, but not nonspatial, learning in the Morris water maze.