Motor Cortex Activity During Rem Sleep: What's Happening?

The motor cortex is activated during REM sleep. This activation is similar to the activation observed during the performance of a voluntary movement during wakefulness. This activation is present during phasic REM sleep but not during tonic REM sleep, the latter resembling relaxed wakefulness.

The motor cortex is more active during REM sleep than during NREM sleep

The motor cortex is more active during REM sleep than during non-rapid eye movement (NREM) sleep. During REM sleep, the brain is highly active and exhibits a wake-like electroencephalogram (EEG), with increased activity in the cerebral cortex. This includes the motor cortex, which is most active during REM sleep, followed by wake and NREM sleep. The activation of the motor cortex during REM sleep is similar to the pattern observed during the performance of a voluntary movement during wakefulness.

The motor cortex is activated during phasic REM sleep, which is characterised by bursts of rapid eye movements (REMs) and increased activity in the hippocampus. Phasic REM sleep is associated with increased theta oscillations in the EEG and an increased eye movement density. The activation of the motor cortex during phasic REM sleep may be related to the occurrence of dream-enacted behaviours, as these are more frequently reported after awakening from phasic REM sleep.

Optogenetic activation of the motor cortex during NREM sleep in mice has been shown to induce a transition to REM sleep, with an increase in theta and gamma oscillations in the EEG and a reduction in delta oscillations. This suggests that the motor cortex plays a role in regulating REM sleep and its phasic activity.

Calcium imaging studies in mice have revealed that a subpopulation of neurons in the motor cortex is maximally activated during REM sleep and is recruited during phasic theta oscillations. These neurons project to the lateral hypothalamus and may be involved in the regulation of REM sleep and phasic events.

The motor cortex is activated during phasic REM sleep but not during tonic REM sleep

REM sleep is associated with an intense neuronal activation, similar to wakefulness. However, the spatial distribution of brain activity during REM sleep and wakefulness differ considerably. The motor cortex is most active during phasic REM sleep, which is reflected in a decrease of power in a large frequency band up to 25Hz, with a slight increase of power above 25Hz.

REM sleep can be divided into two distinct patterns: tonic and phasic. Tonic REM is persistent throughout the sleep stage, while phasic REM is superimposed and characterised by bursts of sympathetic activity, REMs, and brief irregular muscle twitches superimposed on muscle atonia.

The REM sleep-facilitating effect of motor cortex activation is reflected in an increase in the theta and gamma range, with a concomitant reduction in the delta power. The activation of the motor cortex during phasic REM sleep may be the electrophysiological correlate of the higher frequency of REM sleep-associated behaviours during phasic REM sleep.

The motor cortex is also most active during REM sleep, followed by wake and NREM sleep. The activity of the motor cortex starts increasing before the transition to REM sleep and remains elevated throughout.

The motor cortex is activated during REM sleep in a similar way to when a voluntary movement is performed during wakefulness

The motor cortex is most active during REM sleep, followed by wakefulness and non-rapid eye movement (NREM) sleep. Its activity starts increasing before the transition to REM sleep and remains elevated throughout.

The REM sleep-facilitating effect of motor cortex activation is primarily the result of an increase in non-REM to REM transitions, while wakefulness is hardly affected. The activation of the motor cortex during REM sleep is also associated with an increase in the frequency of phasic theta events, which are characterised by rapid eye movements and intensified hippocampal theta oscillations.

The motor cortex is activated during REM sleep in patients with REM sleep behaviour disorder

The motor cortex is activated during REM sleep, particularly during phasic REM sleep, which is characterised by bursts of rapid eye movements. This activation is similar to the pattern observed during the performance of a voluntary movement during wakefulness.

The motor cortex is more active during wakefulness and suppressed during REM sleep, with the exception of the visual cortex and retrosplenial cortex, which show opposing patterns of activity.

REM sleep is associated with a unique pattern of brain activity, with more activation in the somatic sensorimotor network during wakefulness, and more activity in the medial cortical network during REM sleep.

The motor cortex is activated during REM sleep in mice

Using bidirectional optogenetic manipulation and in vivo calcium imaging in mice, it was found that the medial prefrontal cortex (mPFC) strongly promotes REM sleep. Optogenetic activation of mPFC pyramidal neurons induces REM sleep, while activation of mPFC inhibitory neurons suppresses REM sleep. Calcium imaging reveals that the majority of LH-projecting mPFC neurons are maximally activated during REM sleep and a subpopulation is recruited during phasic theta accelerations.

The results delineate a cortico-hypothalamic circuit for the top-down control of REM sleep and identify a critical role of the mPFC in regulating phasic events during REM sleep.

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