engleski

Neurophysiological Mechanisms of Sleep Disturbances

It is now believed that specific neuronal groups within the hypothalamus, pons, and medulla oblongata are responsible for the regulation of behavioral states of sleep and wakefulness. Sleep generating GABAergic neurons are thought to be located in the hypothalamic ventrolateral preoptic nucleus (VLPO). These neurons can be characterized as ‘ sleep-on neurons’ as they are specifically active during sleep, showing a significantly higher firing rate than during wakefulness. Other groups of neurons, noradrenergic neurons located in the locus coeruleus (LC), serotonergic neurons in the dorsal and median raphe nuclei (RN) or histaminergic neurons in the tuberomammillary nucleus (TMN) are part of the ascending arousal system that provides diffuse cortical excitation. During wake, TMN, RN and LC neurons are active and their widespread projections to the cortex maintain a tonic drive, allowing it to maintain the wake state. Due to the inhibition of VLPO sleep promoting neurons by noradrenaline and serotonin, these neurons are silent during wake. There is solid evidence showing that the neural network involved in state control are tightly connected to respiratory-related areas and/or to respiratory neurons, and the changes affecting these networks during the sleep/wake cycle may also affect the control of breathing. A specific depression of minute ventilation occurs during sleep in normal subjects. This sleep-related ventilatory depression is partially related to mechanical events and upper airway atonia but some data also indicate that it is likely to be centrally mediated. The sleep-related ventilatory depression depends upon the enhanced GABAergic activity together with a loss of suprapontine influence depending on the cessation of activity of the reticular formation.

NREM sleep ; REM sleep ; neurotransmitters ; GABA ; serotonin ; norepinephrine ; acethylcholine ; sleep disturbance ; control of breathing

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