Functional relevance of pre-supplementary motor areas for the choice to stop during Stop signal task

There exists an ongoing debate about the functional relevance of the pre-supplementary motor area (pre-SMA) and right ventrolateral prefrontal cortex (VLPFC) for response inhibition during Stop signal task, because of difficulties in segregating cognitive elements involved in stopping, such as response inhibition, attentional control and error monitoring.To further understand the precise brain representation of response inhibition, we developed a new “Double-press signal task” that requires subjects to decide pressing the button once or twice as quickly as possible according to the cue and conducted an event-related functional MRI study of the conventional Stop signal and Double-press signal tasks for 13 healthy subjects. The advantage of our experimental design is that the latter task does not contain any response inhibition and that its difficulty measured by error rate is not significantly different from that of Stop signal task.Activations of the right VLPFC and pre-SMA were observed only for Stop signal task. Moreover, voxel-by-voxel analysis comparing these two tasks showed the significantly larger activation in the pre-SMA for Stop signal task, supporting the hypothesis that the pre-SMA is functionally essential for response inhibition.

► We developed a new task which requires behavior change without response inhibition.
► Activations in the pre-SMA and right VLPFC were seen for response inhibition task.
► ROI and voxel-based analyses suggested the pre-SMA's relevance during inhibition.