Cortical potentials related to decision-making: Comparison of two types ofgo/no-go decision

THE S1-S2 go/no-go reaction time task has been frequently used to assess vo litional inhibition. In this study our aim was to compare the ERPs elicited by S1 and S2 by using a modified S1-S2 paradigm which involved a two-stage go/no-go decision. The go and the no-go S1 ERPs did not differ substantial ly, and both displayed a prominent negativity with peaks at 260 ms ((S1)N26 0) and at 330 ms ((S1)N330) post-S1. The (S1)N260 was similar to the N2 fro m no-go S2 trials. Since after all three types of stimuli, movement is not required and is inappropriate, this negativity may represent the correlate of the voluntary decision to suppress movement. Later, the S1 ERPs were dom inated by frontal negativity ((S1)N330), probably reflecting further proces ses related to response preparation, while the S2 ERPs displayed a large ce ntral and parietal positivity (P3), probably reflecting the processes of ev aluation of response accuracy. (C) 1999 Lippincott Williams & Wilkins.