[Mechanism and function of dreams].
Man has been fascinated by his dreams for ages. The discovery of rapid eye movement (REM) sleep revived the interest in dream research. The objective study of dream content allowed the characterization of the main features of human dreams: its perceptual content, its pervasive emotional background, its oddity. The particular pattern of cerebral activity observed during REM by functional neuroimaging seems to match these features. Firstly, the perceptual aspects of dreams would be related to the activation of posterior (occipital and temporal) cortices. Accordingly, patients with occipito-temporal lesions may report a cessation of visual dreams imagery. Secondly, emotional features in dreams would be related to the activation of amygdalar complexes, orbito-frontal cortex and anterior cingulate cortex. Thirdly, the activation of mesio-temporal areas would account for the memory content commonly found in dreams. Fourthly, the relative hypoactivation of the prefrontal cortex would explain the alteration in logical reasoning, working memory, episodic memory and executive functions that manifest themselves in dream reports from REM sleep awakenings. Despite these recent results, the precise neural correlates of dreaming remain elusive. Likewise, the functions of dreams are unknown, although usually related to the functions of sleep itself.
Maquet
P
P
Centre de Recherches du Cyclotron, ULg.
D001930:Brain Injuries / Q000503:physiopathology; D004325:Dreams / Q000502:physiology* / Q000523:psychology; D004644:Emotions; D006801:Humans; D012895:Sleep, REM