Physiology of Higher Nervous Activity59
There is no doubt that inhibition, when spreading and deepening, calls forth different degrees of a hypnotic state, and when irradiating to the utmost from the cerebral hemispheres down the brain, produces normal sleep. Particularly manifest is the diversity and multiplicity of the stages of hypnosis, which at first hardly differs from the wakeful state. In respect of intensity of inhibition the following stages are worth mentioning: the so-called equalisation, paradoxical and ultraparadoxical phases. The law of reciprocal induction begins to operate when there is a concentration of the inhibitory process, just as it does when there is a concentration of the excitatory process. The permanent operation of the law helps to understand the mechanism of the origin of the numerous separate phenomena (among which are many peculiar, at first sight enigmatic, phenomena) of the higher nervous activity.