The 'scanning hypothesis' of rapid eye movements during REM sleep: a review of the evidence.
Archives italiennes de biologie December 1, 2011 I Arnulf
During REM sleep, rapid eye movements (REMs) may scan dream images, but evidence has been mixed. In a study of 56 patients with REM sleep behavior disorder (RBD), who enact dreams due to absent muscle paralysis, REMs were found to be directed toward the patient's goal-oriented actions (e.g., reaching, greeting) 90% of the time, though REMs were absent in 38% of such behaviors. This directional coherence between eye, head, and limb movements suggests that when REMs occur, they imitate scanning of the dream scene. Because REM characteristics were similar in RBD patients and controls, the finding likely extends to normal REM sleep, supporting a brainstem generator that coordinates images, sounds, limb movements, and REMs in parallel, like a virtual reality.