Human Regional Cerebral Blood Flow during Rapid-Eye-Movement Sleep

TLDR

Regional cerebral blood flow reflects neuronal activity across brain regions. The study measured regional cerebral blood flow during REM sleep using SPECT and the tracer 99mTc‑dl‑hexamethylpropyleneamine. Eleven healthy volunteers (aged 22–27 y) had CBF measured on separate nights during REM sleep and EEG‑verified wakefulness. All subjects reported visual dreams upon awakening, and REM sleep was associated with a 4 % CBF increase in the associative visual area and a 9 % decrease in the inferior frontal cortex, linking visual processing activation to dream content and frontal hypo‑activation to poor temporal organization.

Abstract

Owing to the coupling between CBF and neuronal activity, regional CBF is a reflection of neural activity in different brain regions. In this study we measured regional CBF during polysomnographically well-defined rapid-eye-movement (REM) sleep by the use of single photon emission computerized tomography and the new tracer 99mTc-dl-hexamethylpropyleneamine. Eleven healthy volunteers aged between 22 and 27 years were studied. CBF was measured on separate nights during REM sleep and during EEG-verified wakefulness. On awakening from REM sleep, all subjects reported visual dreams. During REM sleep CBF increased by 4% (p less than 0.01) in the associative visual area, while it decreased by 9% (p less than 0.01) in the inferior frontal cortex. The CBF increase in the associative visual area suggests that activation of cerebral structures processing complex visual material is correlated to visual dream experiences. On the other hand, the reduced involvement of the inferior frontal cortex observed during REM sleep might explain the poor temporal organization and bizarreness often experienced in dreams.