[Neurophysiological bases of hypnosis].

A neurophysiological hypothesis for hypnosis is suggested. Frequently, a hypnotic state is considered close to sleep. Experiments show that it closer to wakefulness, that attention is present and, at times, increased. Physiological changes under hypnosis, changes in suggestibility, conditionability, memory, visceral and endocrine changes, are outlined. Four large neuronal groups with diverse functions are described: wakefulness system, sleep system, that of conscious experience and the executive system; these last two, localized in the midbrain, pons and medulla, are considered the structural basis for the hypnotic state which arises from their increased or decreased functions. In the hypnotic state, through functional variations in these groups, modifications are seen in the spinal chord, in afferent fibers such as the optic ribbon and in complicated cortical functions such as memory.