Sleep
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This study examined the effects of elevated ambient temperature (Ta) on body temperature (Tb) and rapid eye movement (REM) sleep in depressed and control rats. Previous studies have shown that elevations of Ta to the rat's thermoneutral zone of 29 degrees C produced an increase of REM sleep in control rats. In this study, 15 male Sprague-Dawley rats, seven saline control rats (SAL) and eight rats that were classified as depressed according to the chlorimipramine model of depression (CLI rats), were implanted for continuous Tb and polysomnographic recording and were exposed to two Ta's, 22 degrees C and 29 degrees C. ⋯ At 22 degrees C, CLI rats had significantly more REM sleep during the light period and a higher Tb in the light and dark periods than SAL control rats. At 29 degrees C, there were no significant differences in REM sleep or in Tb between CLI and SAL rats. Because human endogenous depression is associated with abnormal REM sleep and an elevated nocturnal Tb, these results give further support for the validity of the CLI model of depression and provide insight into the relationships among Tb, Ta, REM sleep and depression.
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The present paper has three major objectives: first, to document the reliability of a published criteria set for sleep/wake scoring in the rat; second, to develop a computer algorithm implementation of the criteria set; and third, to document the reliability and functional validity of the computer algorithm for sleep/wake scoring. The reliability of the visual criteria was assessed by letting two raters separately score 8 hours of polygraph records from the light period from five rats (14,040 10-second scoring epochs). Scored stages were waking, slow-wave sleep-1, slow-wave sleep-2, transition type sleep and rapid eye movement (REM) sleep. ⋯ The computer scoring algorithm was applied to data from a third independent group of rats (n = 6) from an acoustical stimulus arousal threshold experiment, to assess the functional validity of the scoring directly with respect to arousal threshold. The computer algorithm scoring performed as well as the original visual sleep/wake stage scoring. This indicated that the lower intrarater reliability did not have a significant negative influence on the functional validity of the sleep/wake score.
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Electrodermal activity (EDA) was recorded as skin potential responses (SPRs), on the hindpaws of cats during waking and sleep. SPRs recorded on both paws showed an overall parallelism during all stages of vigilance. SPRs on both paws significantly decreased in amplitude and in frequency from wakefulness to sleep. ⋯ Bilateral differences between evoked SPR amplitudes did not show significant variations as a function of the stages of vigilance. Moreover, the bilateral asymmetry of the evoked SPRs was significantly lower than that of the spontaneous SPRs. These results are discussed in relation to the variations in bilateral EDA recorded in humans during waking and sleep; the influence of central and peripheral factors on EDA laterality is also discussed.