Activation of visual cortex in REM sleep measured by 24-channel NIRS imaging

To visualize dreaming brain functions we studied hemodynamic changes in the visual cortex during the transition from non-rapid eye movement (NREM) to rapid eye movement (REM) sleep, using a 24-channel Near-Infrared Spectrosco py (NIRS) imaging method. Results were compared to the activation in visual cortex by visual stimulation during wakefulness, Subjects were four health y males between 25 and 49 years of age. Five all-night polysomnographic and NIRS recordings were made. Increases in the oxygenated hemoglobin concentr ation in visual cortex were observed from nine of 14 REM periods. The activ ated areas were broader during REM sleep than during visual stimulation, Th ese findings suggest that activation of visual cortex in REM sleep might re present dream-related brain activity.