Sleep rebound in animals deprived of paradoxical sleep by the modified multiple platform method

The objective of the present study was to assess the sleep rebound of anima ls exposed to the modified multiple platform method (MMPM), in which cage-m ate rats were placed onto narrow platforms (NP=6.5 cm in diameter), onto wi de platforms (WP=14 cm in diameter) or onto a grid (GR). The last two group s were included as environmental controls for the deprivation method. Anima ls were implanted with bipolar electrodes in the cortex, hippocampus and ne ck muscle. Baseline sleep was recorded for 6 h, after which the animals wer e placed in one of the above-mentioned settings for 90 h and their sleep wa s again recorded. Comparison between baseline and post-GR recordings reveal ed no sleep differences in these animals. Placement of animals onto WP resu lted in augmented sleep time (16%), time spent in PS (+99%), duration of PS episodes (+77%), sleep efficiency (+16%), and in reduced latency to PS (-8 4.8%). Finally, NP animals exhibited a dramatic increase in Sleep time (+34 .3%), time spent in PS (+184.7%), duration of PS episodes (+106%), and in s leep efficiency (+34.4%). Moreover, sleep latency (-52.2%) and time spent i n SWS (-12.2%) were reduced. Based on the results of sleep rebound, the dat a indicated that placement of animals onto narrow platforms in the MMPM was an effective PS deprivation method and the grid should be considered as an adequate environmental control. (C) 2000 Elsevier Science B.V. All rights reserved.