Cold exposure impairs dark-pulse capacity to induce REM sleep in the albino rat. (57/156)

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The microstructure of active and quiet sleep as cortical delta activity emerges in infant rats. (58/156)

STUDY OBJECTIVES: Previous investigators have suggested that quiet sleep (QS) in rats develops rapidly upon the emergence of cortical delta activity around postnatal day (P)11 and that the presence of "half-activated" active sleep (AS) suggests that infant sleep is initially disorganized. To address these issues, we examined the temporal organization of sleep states during the second postnatal week in rats as delta activity emerges. DESIGN: Subjects were P9, P11, and P13 Sprague-Dawley rats. Electroencephalogram and nuchal electromyogram electrodes were implanted, and data were recorded at thermoneutrality for 2 hours. RESULTS: At all ages, using electromyogram and behavioral criteria, QS (defined as nuchal atonia and behavioral quiescence) dominated the first third of each sleep period, whereas AS (defined as nuchal atonia accompanied by myoclonic twitching) dominated the last third. When delta activity, which was first detected at P11, could be added to the definition of QS, gross assessments of sleep-state organization were not altered, although it was now possible to identify brief periods of QS interposed between periods of AS. No evidence of "half-activated" AS was found. Finally, "slow activity transients" were detected and were primarily associated with QS; their rate of occurrence declined as delta activity emerged. CONCLUSIONS: When delta activity emerges at P11, it integrates smoothly with periods of QS, as defined using electromyogram and behavioral criteria alone. Delta activity helps to refine estimates of QS duration but does not reflect a significant alteration of sleep-state organization. Rather, this organization is expressed much earlier in ontogeny as fluctuations in muscle tone and associated phasic motor activity.  (+info)

Neuronal synchrony during anesthesia: a thalamocortical model. (59/156)

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Is the pain in chronic pancreatitis of neuropathic origin? Support from EEG studies during experimental pain. (60/156)

AIM: To prove the hypothesis that patients with chronic pancreatitis would show increased theta activity during painful visceral stimulation. METHODS: Eight patients and 12 healthy controls underwent an experiment where the esophagus was electrically stimulated at the pain threshold using a nasal endoscope. The electroencephalogram (EEG) was recorded from 64 surface electrodes and "topographic matching pursuit" was used to extract the EEG information in the early brain activation after stimulation. RESULTS: A major difference between controls and patients were seen in delta and theta bands, whereas there were only minor differences in other frequency bands. In the theta band, the patients showed higher activity than controls persisting throughout the 450 ms of analysis with synchronous brain activation between the channels. The main theta components oscillated with 4.4 Hz in the patients and 5.5 Hz in the controls. The energy in the delta (0.5-3.5 Hz) band was higher in the controls, whereas the patients only showed scattered activity in this band. CONCLUSION: The differences in the theta band indicate that neuropathic pain mechanisms are involved in chronic pancreatitis. This has important implications for the understanding and treatment of pain in these patients, which should be directed against drugs with effects on neuropathic pain disorders.  (+info)

Association of single nucleotide polymorphisms in a glutamate receptor gene (GRM8) with theta power of event-related oscillations and alcohol dependence. (61/156)

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Cortical modulation by nucleus basalis magnocellularis corticopetal cholinergic neurons during anxiety-like states is reflected by decreases in delta. (62/156)

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The dependence of P300 amplitude on gamma synchrony breaks down in schizophrenia. (63/156)

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Sex steroid hormone profiles are related to sleep measures from polysomnography and the Pittsburgh Sleep Quality Index. (64/156)

STUDY OBJECTIVES: To relate reproductive hormones (and the preceding 7-year rates of their change) to objectively and subjectively assessed sleep measures, independent of age, vasomotor symptom frequency, depressive symptoms, and body size. DESIGN: A cross-sectional sleep substudy nested in the Study of Women's Health Across the Nation (SWAN), a longitudinal study of the menopausal transition. SETTING: Community-based. PARTICIPANTS: 365 Caucasian, African American, and Chinese women. MEASUREMENTS AND RESULTS: Sleep duration, continuity, and architecture were measured during two nights of in-home polysomnography (PSG) studies. Participants completed the Pittsburgh Sleep Quality Index (PSQI) for sleep quality, sleep diaries for medication, vasomotor symptoms, lifestyle information and questionnaires for depressive symptoms. Blood collected annually in the years prior to sleep study was assayed for follicle stimulating hormone (FSH), estradiol (E2), and total testosterone (T). More rapid rate of FSH change was significantly associated with higher delta sleep percent, longer total sleep time (TST), but less favorable self-reported sleep quality (PSQI). Baseline E2 was modestly and negatively associated with sleep quality. Women in the lowest total testosterone quartile at baseline had more wake time after sleep onset (WASO) than women in the highest quartile. Lower E2/T ratio, an index reflecting the increasing androgenic environment with the menopause transition, was associated with less WASO. CONCLUSIONS: More rapid rate of FSH change was associated with longer sleep duration but poor sleep quality. Women with higher T or who were closer to the completion of the transition process (as indexed by a lower E2/T) had less sleep discontinuity (less WASO).  (+info)