The MMN amplitude increases in hypnosis: a case study

THE neural mechanisms associated with hypnosis were investigated in a singl e highly hypnotizable subject by measuring the mismatch negativity (MMN) co mponent of auditory ERP, reflecting the preattentive discrimination of chan ge in stimulus flow, in normal baseline state and under hypnosis. It has be en proposed that the frontal inhibition associated with hypnosis can be mea sured as a decrease in MMN. ERPs were elicited using the passive oddball pa radigm with standard and deviant sine tone stimuli of 500 and 553 Hz, respe ctively. The measurement was repeated in five separate sessions. In hypnosi s the MMN was significantly larger compared to baseline. The results indica te that hypnosis can give rise to altered information processing in the bra in even at a relatively early, i.e. preattentive level and that the larger MMN measured under hypnosis does not support frontal inhibition theory.; (C ) 1999 Lippincott Williams & Wilkins.