The Pause-then-Cancel model of human action-stopping: Theoretical considerations and empirical evidence

Abstract

The study of human action stopping has been dominated by two controversial debates.First, the contributions (and neural signatures) of attentional orienting and motor inhibition to the stopping process are near-impossible to disentangle. Second, the timing of purportedly inhibitory brain activity after to stop-signals has called into question which neural signatures actually contribute to stopping. Here, we propose that a two-stage model of stopping in rodents -proposed by Schmidt and Berke (2017) -may resolve these controversies. In translating this model to humans, we first argue that attentional orienting and motor inhibition are inseparable because orienting (to stop-signals and other salient events) automatically invokes broad motor inhibition, reflecting a fast-acting, ubiquitous Pause process. We then argue that inhibitory signatures after stop-signals differ in latency because they map onto different phases of this two-stage model: the global Pause and a slower Cancel process, which is specific to stop-signals. We formulate the model, discuss recent supporting evidence in humans, and interpret existing data within its context.

Cortico-subcortical β burst dynamics underlying movement cancellation in humans

“…While we had no hypothesis about such a finding a priori (as the Mosher et al, 2020 report of these late-latency β bursts was published after our investigation concluded), we surmise that these later peaks in β bursting may relate to the slower activation of the basal ganglia indirect pathway during movement cancellation ( Jahfari et al, 2011 ; Sano et al, 2013 ; Schmidt et al, 2013 ; Mallet et al, 2016 ). Indeed, one recent framework of movement cancellation, supported by a body of neurophysiological work in rodents, contains the proposition that stopping is a two-step and not a unitary process ( Schmidt et al, 2013 ; Schmidt and Berke, 2017 ; Diesburg and Wessel, 2021 ). This two-step model, termed the ‘Pause then Cancel’ model, consists of two phases.…”

Two types of motor inhibition after action errors in humans

“…Here, we applied the same analysis logic (using the same functionally localized stop-signal P3 components from the stop-signal task portion of each participant’s data) and interrogated the activity of these components on correct post-error trials. Based on the results from TMS Experiments 3 and 4 of the current study, we predicted that the independent component that explained the stop-signal P3 would show activity during that same time period and relate to PES (as the stop-signal P3 has recently been proposed to reflect a selective, specific inhibitory process that purportedly underlies selective CSE inhibition, c.f., Diesburg & Wessel, 2021).…”

Cortical sensorimotor activity in the execution and suppression of discrete and rhythmic movements

“…This finding is in line with the Mu rhythm being independent of the movement outcome, which may be the case if the Mu rhythm encodes the processing of sensorimotor integration in an open-loop control of discrete actions. Notably, the reactive inhibition of discrete actions has been coherently conceptualized as a dual-step process encompassing attention reorientation (by the STOP signal) and prepared-movement cancellation 86 – 88 . The reorientation of attention is not specific to action inhibition but generalizes to multiple situations implicating goal redirection, including the reaction to a GO stimulus 88 .…”

“…Notably, the reactive inhibition of discrete actions has been coherently conceptualized as a dual-step process encompassing attention reorientation (by the STOP signal) and prepared-movement cancellation 86 – 88 . The reorientation of attention is not specific to action inhibition but generalizes to multiple situations implicating goal redirection, including the reaction to a GO stimulus 88 . Following the hypothesis that the Mu rhythm is an alpha-like oscillation that links perception and action 49 , 50 , a Mu ERD is expected to occur when cortical motor activity is modulated following attentional reorientation, which includes both discrete GO D and STOP D trials.…”