LOCALIZED AND LATERALIZED CEREBRAL GLUCOSE-METABOLISM ASSOCIATED WITHEYE-MOVEMENTS DURING REM-SLEEP AND WAKEFULNESS - A POSITRON EMISSION TOMOGRAPHY (PET) STUDY

In order to study the neural substrate for eye movements during rapid eye movement (REM) sleep, we analyzed the positron emission tomography ((18)Fluorodeoxyglucose positron emission tomography) scan data obtai ned from normal subjects. Eye movement data were available on nine sub jects studied during nighttime REM sleep and six control subjects stud ied during waking as they periodically moved their eyes. The number of eye movements during REM sleep was positively correlated with glucose metabolic rate in the areas corresponding to (a) the saccadic eye mov ement system (frontal eye field and dorsolateral prefrontal cortex, st atistically significant only on the right side), (b) the midline atten tional system (cingulate and medial frontal cortex, precuneus) and (c) the parietal visual spatial attentional system (bilateral superior pa rietal lobules, right inferior parietal lobule); and negatively correl ated with relative metabolic rate in the left inferior parietal lobule . Positive correlations between waking eye movements and metabolic rat e were observed in the same areas except inferior parietal lobule. Our results show that the same cortical areas are involved in eye movemen ts in both REM sleep and wakefulness and suggest that REM sleep eye mo vements are saccadic scans of targets in the dream scene. Our data als o suggest right hemispheric specialization in saccadic eye movement co ntrol and reciprocal inhibition in the contralateral homologous area d uring higher cortical functioning.