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Abstract

An important aspect of volition is the internal decision whether to act or to withhold an action. We used EEG frequency analysis of sensorimotor rhythms to investigate brain activity when people prepare and then cancel a voluntary action. Participants used a rotating clock-hand to report when they experienced the intention to press a key with their right hand, even on trials where they freely decided to inhibit movement at the last moment. On action trials, we observed the classical pattern of reduced beta-band spectral power prior to movement, followed by beta rebound after movement. On inhibition trials where participants prepared but then cancelled a movement, we found a left frontal increase in spectral power (event-related synchronisation: ERS) peaking 12 ms before the perceived intention to move. This neural correlate of intentional inhibition was significantly different from the activity at the corresponding moment in action trials. The results are discussed in the context of a recent model of voluntary action (WWW model; Brass & Haggard, 2008). Planned actions can be subjected to a final predictive check which either commits actions for execution or suspends and withholds them. The neural mechanism of intentional inhibition may play an important role in self-control. Crown Copyright © 2009.