THE NEUROPSYCHOLOGY OF REM-SLEEP DREAMING

RECENT PET imaging and brain lesion studies in humans are integrated w ith new basic research findings at the cellular level in animals to ex plain how the formal cognitive features of dreaming may be the combine d product of a shift in neuromodulatory balance of the brain and a rel ated redistribution of regional blood flow. The human PET data indicat e a preferential activation in REM of the pontine brain stem and of li mbic and paralimbic cortical structures involved in mediating emotion and a corresponding deactivation of dorsolateral prefrontal cortical s tructures involved in the executive and mnemonic aspects of cognition. The pontine brainstem mechanisms controlling the neuromodulatory bala nce of the brain in rats and cats include noradrenergic and serotonerg ic influences which enhance making and impede REM via anticholinergic mechanisms and cholinergic mechanisms which are essential to REM sleep and only come into full play when the serotonergic and noradrenergic systems are inhibited. In REM, the brain thus becomes activated but pr ocesses its internally generated data in a manner quite different from that of waking.