Neurological approaches to the dream problem

Data derived from electrophysiological studies, from performances in right-hemisphere - mediated tasks after REM awakenings, and from brain-lesioned patients, though not always homogeneous, suggest prevalent involvement of the right hemisphere in elaborating mental activity during sleep. This conforms with the hypothesis that the characteristics of dream content holistic and visuospatial, with many bizarre aspects - express a prevalent right-hemisphere (RH) activity (Bakan, 1976; Broughton, 1975; Jouvet, 1973) or that the RH is more involved only in the visuospatial aspects of dreaming (Kerr & Foulkes, 1981). The first electrophysiological data were supplied by Goldstein, Stoltzfus, and Gardocki (1972), who observed an EEG asymmetry, with an amplitude reduction on the left during NREM, which shifted to the right during REM. On the basis of the assumption that mental activity is reflected in an EEG power decrease, we can hypothesize that right- or left-side asymmetries reflect the involvement of different hemispheres in cognitive functions elaboration.