Biology subjects

Salomoni, S.

Publications and source records attributed to Salomoni, S..

3 recordsLinked to original sources

bioRxiv2025

The Stop Signal Stepping Task: how action cancellation commands disrupt step initiation in young and healthy older adults

Action cancellation - the ability to rapidly cancel an initiated movement in response to unexpected events - has been extensively studied in the upper limb using the stop signal task (SST). During gait, action cancellation is needed to stop and modify steps to avoid hazards and prevent falls. By adapting the SST to step initiation, this study investigated how the anticipatory postural adjustment (APA) and foot-lift phases of forward stepping were affected by action cancellation commands, and whether this changed with healthy ageing. The SST was performed in stepping, foot tap, and finger button conditions in 27 young (Mage = 28.7 years) and 29 healthy older adults (Mage = 70.1 years). Across conditions, older adults exhibited slower response speed compared to young adults and greater proactive slowing of responses when stop cues were anticipated. However, there was no significant difference in stopping speed between young and older adults. Stopping speed was fastest in the finger tap condition, and slowest in the step condition. When an APA was initiated in a step cancellation trial, the magnitude of the weight shift toward the step leg did not differ between successful and unsuccessful foot-lift cancellations. Foot-lift could be cancelled when stop cues were presented at similar phases of step preparation for young and older adults. These results suggest that the initial loading of the step leg is a ballistic process, however as weight is shifted toward the stance leg, action cancellation commands responding to external stimuli can decouple the APA and foot-lift step phases. Key PointsO_LIThe stop signal task (SST) - which allows an estimation of stopping speed independently of response speed - was applied to voluntary stepping in young and older adults. C_LIO_LIWhile response speed was slower for older than young adults, stopping speed was not significantly different between age groups in the upper limb, lower limb when seated, and during forward stepping. C_LIO_LIWhen stop cues were introduced, response speed slowed more in older than young adults, and more in the upper than the lower limb (i.e., Foot Tap and Step conditions). C_LIO_LIThe initial preparatory weight shift toward the stepping foot was not significantly different between successfully cancelled steps and normal steps, highlighting the ballistic nature of the early phase of step preparation. C_LIO_LIPrior to foot-lift, action cancellation commands could decouple the preparatory weight shift phase from foot-lift at similar stages of step initiation in young and healthy older adults. C_LI

neuroscience↗

bioRxiv2024

Cortical contributions to attentional orienting and response cancellation in action stopping

Action cancellation involves the termination of planned or initiated movement. Contemporary models of action cancellation, such as the Pause-then-Cancel model, propose that this occurs via a two-stage process, initiated in the cortex by the pre-supplementary motor area (preSMA) and inferior frontal gyrus (IFG). Previous experimental work using electromyography (EMG) has identified that the cancellation of actions can involve the partial activation of the responding muscles, which does not result in an overt behavioural response. In this study, we used functional near-infrared spectroscropy (fNIRS) to investigate the neural correlates of these partial responses in a modified stopping task (a response- and stimulus-selective stop-signal task), controlling for the attentional effects that have long confounded action cancellation research by comparing responses to stop stimuli with those to ignore stimuli. We identified stopping-related activity in the preSMA but not the IFG, consistent with predictions of the Pause-then-Cancel model. Additionally, we observed increased preSMA activity in trials where no partial responses occurred, potentially due to the cumulative effect of different inhibitory processes in those trials. This study also highlights the utility of combining fNIRS and EMG in examining the cortical correlates and dynamic processes involved in action cancellation.

neuroscience↗

bioRxiv2022

Dissociating Attentional Capture from Action Cancellation in the Stop Signal Task

Inhibiting ongoing responses when environmental demands change is a critical component of human motor control. Experimentally, the stop signal task (SST) represents the gold standard response inhibition paradigm. However, an emerging body of evidence suggests that the SST conflates two dissociable sources of inhibition, namely an involuntarily pause associated with attentional capture and the (subsequent) voluntary cancellation of action. The extent to which these processes also occur in other response tasks is unknown. 24 younger (20-35 years) and 23 older (60-85 years) adults completed a series of tasks involving rapid unimanual or bimanual responses to a visual stimulus. A subset of trials required cancellation of one component of an initial bimanual response (i.e., selective stop task; stop left response, continue with right response) or enacting an additional response (e.g., press left button as well as right button). Critically, both tasks involved some infrequent stimuli which bore no behavioural imperative (i.e., they had to be ignored). EMG recordings of voluntary responses during the stopping tasks revealed bimanual covert responses (i.e., muscle activation which was suppressed before a button press ensued), consistent with a pause process, following both stop and ignore stimuli, before the required response was subsequently enacted. Critically, we also observed the behavioural consequences of a similar involuntary pause in trials where action cancellation was not part of the response set (i.e., when the additional stimulus required additional action or ignoring, but not inhibition). The findings shed new light on the mechanisms of inhibition and their generalisability to other task contexts.

neuroscience↗