Search

The medial right frontal cortex is implicated in fast stopping of an initiated motor action in the stop-signal task (SST). To assess whether this region is also involved in the slower behavioural inhibition induced by goal conflict, we tested for effects of goal conflict (when stop and go tendencies are balanced) on low-frequency rhythms in the SST. Stop trials were divided, according to the delays at which the stop signal occurred, into short-, intermediate-, and long-delay trials. Consistent with goal-conflict processing, intermediate-delay trials were associated with greater 7-8 Hz EEG power than short- or long-delay trials at medial right frontal sites (Fz, F4, and F8). At F8, 7-8 Hz power was linked to high trait anxiety and neuroticism. A separate 4-7 Hz power increase was also seen in stop, relative to go, trials, but this was independent of delay, was maximal at the central midline site Cz, and predicted faster stopping. Together with previous data on the SST, these results suggest that the right frontal region could be involved in multiple inhibition mechanisms. We propose a hierarchical model of the control of stopping that integrates the literature on the neural control of fast motor stopping with that on slower, motive-directed behavioural inhibition. [ABSTRACT FROM AUTHOR]

Approach-avoidance conflict is thought to generate negative affective bias, mediated by theta rhythms. This process is distinct from, and adds to, the effects of simple aversive input. We assessed this distinction by holding gain constant and increasing loss value so that conflict and simple aversion peaked in the conflict (gain equals loss) and loss (net loss) conditions, respectively. Right frontal areas showed increases in both conflict- and loss-induced theta power. However, loss, but not conflict, power was correlated with avoidance and neuroticism, showing a Gender x Hemisphere interaction. We concluded that multiple aversive processes converge in lateral frontal networks and that individual differences in theta response in these networks may reflect differences in behavioural and emotional reactivity to aversive events. [ABSTRACT FROM AUTHOR]