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Arousal Thresholds (arousal + threshold)

Distribution by Scientific Domains

Medical Sciences	80%

Selected Abstracts

Experience-dependent plasticity in hypocretin/orexin neurones: re-setting arousal threshold

ACTA PHYSIOLOGICA, Issue 3 2010
X.-B. Gao
Abstract The neuropeptide hypocretin is synthesized exclusively in the lateral hypothalamus and participates in many brain functions critical for animal survival, particularly in the promotion and maintenance of arousal in animals , a core process in animal behaviours. Consistent with its arousal-promoting role in animals, the neurones synthesizing hypocretin receive extensive innervations encoding physiological, psychological and environmental cues and send final outputs to key arousal-promoting brain areas. The activity in hypocretin neurones fluctuates and correlates with the behavioural state of animals and intensive activity has been detected in hypocretin neurones during wakefulness, foraging for food and craving for addictive drugs. Therefore, it is likely that hypocretin neurones undergo experience-dependent changes resulting from intensive activations by stimuli encoding changes in the internal and external environments. This review summarizes the most recent evidence supporting experience-dependent plasticity in hypocretin neurones. Current data suggest that nutritional and behavioural factors lead to synaptic plasticity and re-organization of synaptic architecture in hypocretin neurones. This may be the substrate of enhanced levels of arousal resulting from behavioural changes in animals and may help to explain the mechanisms underlying the changes in arousal levels induced by physiological, psychological and environmental factors. [source]

How does the pitch and pattern of a signal affect auditory arousal thresholds?

JOURNAL OF SLEEP RESEARCH, Issue 2 2009
DOROTHY BRUCK
Summary How arousal thresholds vary with different sounds is a critical issue for emergency awakenings, especially as sleepers are dying in fires despite having a working smoke alarm. Previous research shows that the current high-pitched (3000+ Hz) smoke alarm signal is significantly less effective than an alternative signal, the 520 Hz square wave, in all populations tested. However, as the number of sounds tested has been small further research is needed. Here we measured auditory arousal thresholds (AATs) across signals with a range of characteristics to determine the most effective waking signal. Thirty-nine young adults participated over three nights. In Part A, nine signals were presented in stage 4 sleep with ascending decibel levels. Signals were short beeps in the low- to mid-frequency range with different spectral complexities: square waves, pure tones, whoops and white noise. Part B manipulated temporal patterns, inserting silences of 0, 10 and 21 s after each 12 s of beeps. It was found that the low-frequency (400 and 520 Hz) square waves yielded significantly lower AATs than the alternatives. A trend was found across the three temporal manipulations, with a 10 s intervening silence showing some advantage. These findings support earlier research indicating that the best sound for awakening from deep sleep is a low-frequency square wave. It is argued that the signal with the lowest response threshold when awake may be the same as the most arousing signal when asleep, especially where the sleeper processes the signal as meaningful. [source]

The role of sleep and arousal in nocturnal enuresis

ACTA PAEDIATRICA, Issue 10 2003
T Nevéus
Aim: To review what is known about the role of sleep and arousal mechanisms in the pathogenesis of nocturnal enuresis. Methods: A review of the literature was carried out. Results: The sleep of enuretic children, although polysomnographically quite normal, is exceedingly "deep"; that is enuretic children have high arousal thresholds. Apart from some overlap between enuresis and the (other) classic parasomnias, the sleep of enuretic children is no more problematic than that of the general population. Recently, the exciting possibility has arisen that the low arousability of enuretic children may be linked to the autonomous nervous system and to disturbances in the upper pons. Conclusions: Enuresis is not just a nocturnal problem but a disorder of sleep. The high arousal threshold is one of three major pathogenetic factors in enuresis,nocturnal polyuria and detrusor hyperactivity being the other two. [source]