Abstract
It is known that animal hypnosis is induced by either inversion, giving a pressure on body parts or monotonous repetitive stimulation. The characteristics of animal hypnosis were investigated by frequency analysed EEG. To creat animal hypnosis, rabbits were inverted in a wooden chute or either a pressure to the base of the ear or peripheral low frequency stimulation was given. EEG of various subcortical regions under animal hypnosis by inversion showed a reduction of B and a activities in 252 of 374 trials (67.4%) in 39 rabbits or a reduction of θ (21.9%) or α (6.4%) alone. In the later of inversion, the delayed augementation of a was accompanied in 249 of 374 trials (66.7%) Similar changes were induced by other procedures to creat animal hypnosis. Arousal stimuli at inversion abolished the augemented σ, however the reduction of θ activity did not change.
θ activity induced by inversion always showed a fixed value in various background EEG. This was shown under application of chlorpromazine which reduced θ and augemented α.
These dataes indicated that 1) the characteristic of frequency analysed EEG of animal hypnosis is the reduction of θ and α activities, 2) animal hypnosis is induced by the sites other than those to cause sedative or sleep state.
