THE H1-RECEPTOR ANTAGONIST CHLORPHENIRAMINE DECREASES THE ENDING PHASE OF THE MISMATCH NEGATIVITY OF THE HUMAN AUDITORY EVENT-RELATED POTENTIALS

Auditory event-related potentials (ERPs) were recorded in 20 healthy m ale humans, who received either a single 4 mg dose of d-chlorphenirami ne or a placebo, according to a double-blind design. Subjects were ins tructed to read a book and to ignore random sequences of 90% standard (1000 Hz) and 10% deviant (1100 Hz) tones, presented with stimulus-ons et asynchrony (SOA) of 480 ms. Deviant tones elicited the mismatch neg ativity (MMN) response, which was smaller at its ending phase in the c hlorpheniramine group. The auditory exogenous components (NI and P2) w ere similar in both groups. Results demonstrate that the antihistamine chlorpheniramine selectively affects the automatic stimulus-change de tector associated with MMN, and suggest an involvement of the histamin e Hi-receptor in the genesis of the MMN.