Electrical activity of the toad telencephalon during tonic immobility (animal hypnosis).

During tonic immobility obtained in toads by restraining maneuvers there was an increased incidence of waves in the 8-12 c/s range grouped in spindles, in addition to an overall power increase detected by frequency analysis. There was also abolition of phasic movements, increased firing of anti-gravity muscles, and myosis. The electrographic recordings were characteristic of a state of behavioral alert in this species, supporting the hypothesis that a certain level of information processing may occur during tonic immobility, permitting the animal to detect the moment most appropriate for flight. These changes also occurred in animals with sectioned olfactory nerves, showing that they did not depend solely on ventilatory modifications.