Altered functional brain networks in isolated REM sleep behavior disorder during phasic REM sleep

Area of Science:

• Neuroscience
• Sleep Medicine
• Neurology

Background:

• Isolated REM sleep behavior disorder (iRBD) is characterized by vivid, aggressive dreams.
• The neural basis of these dream characteristics in iRBD remains unclear.
• Understanding iRBD's neurophysiology is crucial for diagnosis and treatment.

Purpose of the Study:

• To investigate functional brain network alterations during REM sleep in iRBD patients.
• To correlate these network changes with dream characteristics and REM atonia.
• To elucidate the neurophysiological underpinnings of iRBD-related dreaming.

Main Methods:

• Analyzed electroencephalogram (EEG) data from 13 drug-naïve iRBD patients and 10 healthy controls.
• Computed source-level functional connectivity during phasic and tonic REM sleep.
• Applied graph theory metrics to assess network topology in 14 cortical regions.

Main Results:

• iRBD patients displayed significantly increased gamma-band functional connectivity during phasic REM sleep (p=0.003).
• This hyperconnectivity correlated with reduced REM atonia (R=-0.725, p=0.007) and trended with symptom severity.
• Key network hubs included the posterior cingulate cortex and right inferior parietal lobule, linked to salience-motor circuits.

Conclusions:

• Gamma-band hyperconnectivity in REM sleep reflects altered dream-related network dynamics in iRBD.
• These network alterations may contribute to the intensity and emotional valence of dreams.
• Functional network changes during REM sleep offer new insights into iRBD's neurophysiological basis.