EFFECT OF THE DOPAMINE D-2 ANTAGONIST SULPIRIDE ON EVENT-RELATED POTENTIALS AND ITS RELATION TO THE LAW OF INITIAL-VALUE

Effects of the dopamine antagonist sulpiride on event-related potentia ls (ERPs) were investigated during an auditory odd ball task in 18 hea lthy volunteers. Sulpiride (150 or 300 mg) or an inactive placebo was administered according to a completely randomized double-blind cross-o ver design. ERPs were recorded 1 h after medication was given. Sulpiri de shortened the P200 latency for frequent stimuli, but tended to incr ease the N200 and P300 latencies for rare stimuli. Although on the who le sulpiride had no effect on the amplitudes of the ERP components in the subjects, it increased the P300 amplitudes in the low P300 amplitu de subjects and decreased them in the high P300 amplitude subjects. Th is tendency for a bidirectional response was also found for the N100 a nd N200 amplitudes. A single administration of 150 or 300 mg sulpiride is considered to affect the ERP latencies and amplitudes in healthy s ubjects, the bidirectional response that takes place being dependent o n the difference in the initial values. The results of this study are discussed in relation to the 'Law of initial value'.