Les Potentiels Cerebraux Lents en Psychiatrie

Abstract

Classical electroencephalography has brought no major contribution to psychiatric diagnosis over the last 40 years. However, new hopes have recently arisen with the introduction of new methods — the use of long-time constants together with averagers and/or computers. Cerebral electrogenesis is explored during a more or less complex task, for instance pushing a button following a visual or auditory stimulus. The amplitude and duration of potentials preceding and following the decision and the motor activity are recorded. Many of the workers have attempted to establish psychological correlations of phenomena such as the CNV (contingent negative variation or expectancy wave) (8) and RP (readiness potential, pre-motor potential) (5). The cerebral events immediately following the decision and motor action PINV, (post imperative negative variations) are studied. These are considered to be of special interest in psychiatric patients. A minority of normal subjects (16 percent) show what is described as abnormalities of these potentials, whereas the majority of psychotics (75 percent) show these abnormalities. Neurotic patients show an intermediary percentage of abnormalities (37 percent). In early schizophrenia, abnormal PINV are present in 94 percent of the cases, which makes the test of practical significance in doubtful cases. Studies of event-related slow potentials in more complex situations, with discriminative decisions requested from the subjests, are underway.