In studies of normal persons deprived of sleep, and colleagues at the Walter Reed Army Institute of Research, the Maryland Psychiatric Research Center, and the Division of Nuclear Medicine of Johns Hopkins, examined the effect of 24, 48, and 72 h of sleep deprivation on the regional cerebral metabolic rate for glucose (CMRglu), young, normal, healthy male volunteers who were performing complex cognitive tasks. They carried out PET studies with 18F-FDG.
Brain glucose utilization decreases when alertness and cognitive performance are impaired by sleep deprivation, especially in the prefrontal cortex, a region involved in alertness, attention, and higher order cognitive processes and in the thalamus, a subcortical structure involved in alertness and attention.
Absolute and relative regional glucose use decreased after 48 and 72 h of sleep deprivation in the same areas that showed decreases after 24 h of sleep deprivation. The decrease in glucose use in the prefrontal-thalamic network by prolonged sleep deprivation was proportional to the decline in alertness and cognitive performance, whereas the increases in visual and motor areas may reflect the subjects attempt to remain awake and perform assigned tasks. As the subjects tried to fight sleeplessness, characterized by decreased neuronal activity in the prefrontal cortex and thalamus, other regions of the brain increased neuronal activity.
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