Waking and sleeping最新文献

The experiment was performed in order to investigate whether the suprachiasmatic nucleus is a potent circadian pacemaker also in mice. Cortical EEG activity and neck muscle EMG were continuously recorded in 19 albino mice under 12 h light-12 h dark cycles. Computer analysis revealed that after bilateral suprachiasmatic nucleus (SCN) lesions, the diurnal rhythm in slow wave sleep (SWS) and paradoxical sleep (PS) stages was completely eliminated although ultradian rhythms with 2-4 h periodicity persisted. However, the daily amount of either slow wave sleep or paradoxical sleep did not show any significant change after small hypothalamic lesions with a complete destruction of SCN.

Rapid or paradoxical sleep in the rat is usually preceded and often followed by a stage of short duration characterized by large spindles in the frontal cortex and theta rhythm in the hippocampus. The midbrain transection induces for hours the same electrophysiological patterns suggesting the existence in the rat of a short physiologically isolated, forebrain stage during sleep.

A number of studies dealing with electrographically defined wakefulness, NREM sleep, REM sleep and locomotor activity patterns in M. musculus are reviewed. The effects of genetic and environmental factors on postnatal maturation of the EEG and on sleep patterns of adult mice are considered. The effects of short light-dark cycles and of constant light on sleep and activity rhythms of different strains of mice suggest that there are different pacemaker mechanisms which regulate circadian sleep and activity rhythms and that the expansion of these mechanisms is regulated by the genetic factors.

In rats, the presynaptic alpha-receptor blocking drug yohimbine given at low doses increases paradoxical sleep (PS) while much higher doses are necessary to depress it. These results are in line with the postulated preferential affinity of this drug for presynaptic noradrenergic (NA) receptors, resulting in an increased activity in NA synapses. The depression of PS under high doses of yohimbine may be related to a post-synaptic blockade of NA receptors, thus cancelling the presynaptic effect. This type of study illustrates the necessity of investigating the temporal evolution of PS instead of simply counting its total amount in a given period of time.

Two successive main steps are usually performed in automatic sleep classification: a) a periodic quantification of the EEG signal by a set of indices featuring each polygraphic epoch by a point in a multidimensional space, b) a stage decision to determine the cluster that includes the representative point for a given epoch (discriminant analysis). As solid state logic comparators simulate linear discriminant functions, this article describes an improved classifier for automatic sleep scoring in laboratory rodents. Four indices were found to be discriminant on both rats and mice: F(the energy in the EEG theta band relative to that in the delta band), Z(number of EEG zero-crossings), D(variability of the EEG amplitude) and M(integrated EMG). They are measured by analog techniques for 30 sec epochs from an EEG and an EMG lead per animal. At the end of each epoch, the logic results of their respective comparators serves as an input to a hardwired modifiable truthtable where a sleep stage decision is elaborated. The outputs of 4 multiplexed classifiers are controlled by microprocessor and may be used for chart or digital recordings on various peripherals. The overall agreement with visual scoring is more than 95% for both rats and mice.

The sleep-waking activities of intact and of capsaicin-desensitized rats (animals with damaged peripheral and central warm receptors) were studied at room temperature and at the warm ambient temperatures of 32 and 34 degrees C. At 32 degrees C, the time spent in sleep increased significantly in the desensitized animals, while a decrease in the amount of deep slow wave sleep was found in the controls. At 34 degrees C, the amount of the sleep-waking stages returned to the levels observed at room temperature in the desensitized rats. A further decrease in sleep and a significantly increased wakefulness was found in the controls. At both warm ambient temperatures, the body temperature of the desensitized rats was significantly higher than that of the controls. We suggest that warm environments exert a dual effect on the sleep-waking activity. The activating effect abolished by desensitization seems to be in connection with capsaicin-sensitive thermoreceptors, while the deactivation brought about by heat is not influenced by capsaicin.

This article presents the characteristics of ECoGs of arousal, slow wave sleep and paradoxical sleep in the rat, in terms of analysis of data. In a first part, we have applied four different methods of analysis to the three tracings: the instantaneous amplitude histograms computation, the integrative method of Drohocki, the spectral analysis and the normalized slope descriptor method of Hjorth. Each method provides, after data reduction, characteristic parameters of the tracings. A graph which displays peak spectral frequency versus mean integrated value is enough to discriminate between the 3 quantified tracings. Multivariate discriminant analysis reveals that 3 coefficients altogether allow a good discrimination. In the second part we ask the question: which kind of signal is the paradoxical sleep tracing? After the impossibility to choose between a narrow-band Gaussian process or a sinusoidal wave burried in noise, we propose a third kind of signal found after modulation analysis. This signal is modulated both in amplitude and frequency around a carrier frequency beeing the dominant theta rhythm.