| Abstract: | 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 recently proposed where CNV amplitude and duration are mediated by cholinergic neurons, themselves stimulated by catecholaminergic neurons and inhibited by GABAergic mechanisms. To test this inhibitory influence of GABAergic mechanisms on CNV amplitude, we recorded CNV and spectral analysis 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 diazepam (from −12·4 μV±8·0 to −4·5 μV±9·8, t=−3·4, p<0·01). This modification did not depend on changes in depressive symptomatology as assessed by the Hamilton depression scale or on changes in the level of arousal, as evaluated by spectral analysis. Therefore, these results support our hypothesis of a specific GABA inhibitory tone in the genesis of CNV. © 1997 by John Wiley & Sons, Ltd. |
