INFLUENCE OF DIAZEPAM ON CONTINGENT NEGATIVE-VARIATION

Contingent Negative Variation (CNV) is an event-related potential that develops during a simple experimental situation associating a warning and an imperative stimuli. A neurochemical model of CNV has been rece ntly proposed where CNV amplitude and duration are mediated by choline rgic neurons, themselves stimulated by catecholaminergic neurons and i nhibited by GABAergic mechanisms. To test this inhibitory influence of GABAergic mechanisms on CNV amplitude, we recorded CNV and spectral a nalysis in 10 depressed patients before and after 4 weeks of treatment with diazepam (30-45 mg/day) which potentiates GABAergic transmission . The results showed a significant decrease of CNV amplitude after dia zepam (from -12.4 mu V+/-8.0 to -4.5 mu V+/-9.8, t = -3.4, p<0.01). Th is modification did not depend on changes in depressive symptomatology as assessed by the Hamilton depression scale or on changes in the lev el of arousal, as evaluated by spectral analysis. Therefore, these res ults support our hypothesis of a specific GABA inhibitory tone in the genesis of CNV. (C) 1997 by John Wiley & Sons, Ltd.