Differences in unity: The gonogo and stop signal tasks rely on different mechanisms Abstract   Response inhibition refers to the suppression of prepared or initiated actions. Typically, the gonogo task (GNGT) or the stop signal task (SST) are used interchangeably to capture individual differences in response inhibition. On the one hand, factor analytic and conjunction neuroimaging studies support the association of both tasks with a single inhibition construct. On the other hand, studies that directly compare the two tasks indicate distinct mechanisms, corresponding to action restraint and cancellation in the GNGT and SST, respectively. We addressed these contradictory findings with the aim to identify the core differences in the temporal dynamics of the functional networks that are recruited in both tasks. We extracted the timecourses of sensory, motor, attentional, and cognitive control networks by group independent component (GICA) analysis of electroencephalography (EEG) data from both tasks. Additionally, electromyography (EMG) from the responding effector muscles was recorded to detect the timing of response inhibition. The results indicated that inhibitory performance in the GNGT may be comparable to response selection mechanisms, reaching peripheral muscles at around 316xe2x80xafms. In contrast, inhibitory performance in the SST is achieved via biasing of the sensorymotor system in preparation for stopping, followed by fast sensory, motor and frontal integration during outright stopping. Inhibition can be detected at the peripheral level at 140xe2x80xafms after stop stimulus presentation. The GNGT and the SST therefore seem to recruit widely different neural dynamics, implying that the interchangeable use of superficially similar inhibition tasks in both basic and clinical research is unwarranted.

Early attentional processes distinguish selective from global motor inhibitory control: an electrical neuroimaging study The rapid stopping of specific parts of movements is frequently required in daily life. Yet, whether selective inhibitory control of movements is mediated by a specific neural pathway or by the combination between a global stopping of all ongoing motor activity followed by the reinitiation of taskrelevant movements remains unclear. To address this question, we analyzed electrical neuroimaging responses to global vs selective inhibition stimuli presented during a GoNoGo task. Participants had to respond as fast as possible with their two hands to Go stimuli and to withhold the response from the two hands (global inhibition conditions, GNG) or from only one hand (selective inhibition, SNG) when specific NoGo stimuli were presented. Behaviorally, we replicated previous evidence for slower response times in the SNG than in the Go condition. Electrophysiologically, there were two distinct phases of eventrelated potentials modulations between the GNG and the SNG conditions. At 110150ms poststimulus onset, there was a difference in the strength of the electric field without concomitant topographic modulation, indicating the differential engagement of statistically indistinguishable configurations of neural generators for selective and global inhibitory control. At 150200ms, there was a change in the electric field topography, indicating the engagement of distinct configurations of neural generators. Source estimations localized these effects within bilateral temporooccipital and posterior parietal regions and within a parietocentral network, respectively. Our results suggest that while both types of motor inhibitory control depend on global stopping mechanisms, selective and global inhibition still differ quantitatively at early attentionrelated processing phases.