Modulating dream experience: Noninvasive brain stimulation over the sensorimotor cortex reduces dream movement

Area of Science:

• Neuroscience
• Sleep Research
• Cognitive Neuroscience

Background:

• Cortical activation during dreaming often mirrors wakeful activity.
• However, the causal mechanisms for specific dream content, like movement, are not fully understood.

Purpose of the Study:

• To investigate the causal role of the sensorimotor cortex in generating movement and bodily sensations during REM sleep dreaming.
• To explore how stimulating the sensorimotor cortex impacts dream content.

Main Methods:

• Bihemispheric transcranial direct current stimulation (tDCS) or sham stimulation targeting the primary motor cortex.
• Participants were awakened from REM sleep for questionnaires on dream sensations.
• Electromyography (EMG) and electroencephalography (EEG) monitored physiological changes.

Main Results:

• tDCS significantly reduced self-reported dream movement, particularly repetitive actions, compared to sham stimulation.
• Other bodily sensations (tactile, vestibular) were unaffected, indicating specificity.
• tDCS altered EEG interhemispheric coherence and EMG correlations between arms.

Conclusions:

• Stimulating the sensorimotor cortex causally influences movement experiences during REM sleep dreaming.
• Findings link motor network activity and peripheral processes to the subjective experience of movement in dreams.
• This research deepens the understanding of the neural basis of self-experience during sleep.