Phase-amplitude coupling (PAC) between slow waves (0.5-0.6 Hz) and gamma activities occurs not only during light sleep and slow-wave sleep but also during wakefulness and rapid eye movement (REM) sleep, as shown by electrocorticography in 11 patients with epilepsy. During slow-wave sleep, PAC is high over a large region, whereas during REM sleep it is stronger in the posterior cortical region around the temporoparietal junction than in the frontal region. PAC also tends to be higher posteriorly during wakefulness. The findings suggest the posterior cortical region has a functional role in REM sleep and may contribute to maintaining the dreaming experience.
An 18-year-old man experienced visual symptoms—a diagonal line shifting his upper visual field right and lower left, rippled distortion, and moving black spots—followed by an out-of-body experience (OBE) where he felt he saw his own body from behind his left shoulder, then headache attacks. Brain MRI showed suspected bilateral occipital atrophy; EEG revealed intermittent irregular delta in the bilateral occipital area without epileptiform discharges. He was diagnosed with migraine with multiple visual auras and OBE. A small dose of valproic acid was well tolerated and effective. OBE rarely occurs in migraine and should be distinguished from epilepsy.