Stop-signal Reaction Time Research Articles

A Bayesian Mixture Modelling of Stop Signal Reaction Time Distributions: The Second Contextual Solution for the Problem of Aftereffects of Inhibition on SSRT Estimations.

The distribution of single Stop Signal Reaction Times (SSRT) in the stop signal task (SST) has been modelled with two general methods: a nonparametric method by Hans Colonius (1990) and a Bayesian parametric method by Dora Matzke, Gordon Logan and colleagues (2013). These methods assume an equal impact of the preceding trial type (go/stop) in the SST trials on the SSRT distributional estimation without addressing the relaxed assumption. This study presents the required model by considering a two-state mixture model for the SSRT distribution. It then compares the Bayesian parametric single SSRT and mixture SSRT distributions in the usual stochastic order at the individual and the population level under ex-Gaussian (ExG) distributional format. It shows that compared to a single SSRT distribution, the mixture SSRT distribution is more varied, more positively skewed, more leptokurtic and larger in stochastic order. The size of the results’ disparities also depends on the choice of weights in the mixture SSRT distribution. This study confirms that mixture SSRT indices as a constant or distribution are significantly larger than their single SSRT counterparts in the related order. This result offers a vital improvement in the SSRT estimations.

Investigating the sex-dependent effects of prefrontal cortex stimulation on response execution and inhibition

Context-dependent execution or inhibition of a response is an important aspect of executive control, which is impaired in neuropsychological and addiction disorders. Transcranial direct current stimulation (tDCS) of the dorsolateral prefrontal cortex (DLPFC) has been considered a remedial approach to address deficits in response control; however, considerable variability has been observed in tDCS effects. These variabilities might be related to contextual differences such as background visual-auditory stimuli or subjects' sex. In this study, we examined the interaction of two contextual factors, participants' sex and background acoustic stimuli, in modulating the effects of tDCS on response inhibition and execution. In a sham-controlled and cross-over (repeated-measure) design, 73 participants (37 females) performed a Stop-Signal Task in different background acoustic conditions before and after tDCS (anodal or sham) was applied over the DLPFC. Participants had to execute a speeded response in Go trials but inhibit their response in Stop trials. Participants' sex was fully counterbalanced across all experimental conditions (acoustic and tDCS). We found significant practice-related learning that appeared as changes in indices of response inhibition (stop-signal reaction time and percentage of successful inhibition) and action execution (response time and percentage correct). The tDCS and acoustic stimuli interactively influenced practice-related changes in response inhibition and these effects were uniformly seen in both males and females. However, the effects of tDCS on response execution (percentage of correct responses) were sex-dependent in that practice-related changes diminished in females but heightened in males. Our findings indicate that participants' sex influenced the effects of tDCS on the execution, but not inhibition, of responses.

Pain and executive function: no association between remote exercise-induced hypoalgesia and cognitive inhibition in pain-free participants.

Cognitive inhibition, which denotes the ability to suppress predominant or automatic responses, has been associated with lower pain sensitivity and larger conditioned pain modulation in humans. Studies exploring the association between cognitive inhibition and other pain inhibitory phenomena, like exercise-induced hypoalgesia (EIH), are scarce. The primary aim was to explore the association between cognitive inhibition and EIH at exercising (local) and non-exercising (remote) muscles after isometric exercise. The secondary aim was to explore the association between cognitive inhibition and pressure pain sensitivity. Sixty-six pain-free participants (28.3±8.9 years old, 34 women) completed two cognitive inhibition tasks (stop-signal task and Stroop Colour-Word task), a 3-min isometric wall squat exercise, and a quiet rest control condition with pre- and post-assessments of manual pressure pain thresholds at a local (thigh) and a remote site (shoulder). In addition, cuff pressure pain thresholds, pain tolerance and temporal summation of pain were assessed at baseline. No association was found between remote EIH and cognitive inhibition (Stroop interference score: r=0.12, [-0.15; 0.37], p=0.405, BF01=6.70; stop-signal reaction time: r=-0.08, [-0.32; 0.17], p=0.524, BF01=8.32). Unexpectedly, individuals with worse performance on the Stroop task, as indicated by a higher Stroop interference score, showed higher local EIH (r=0.33; [0.10; 0.53], p=0.007, BF01=0.29). No associations were observed between pain sensitivity and any of the cognitive inhibition performance parameters. The present findings do not support previous evidence on positive associations between exercise-induced hypoalgesia and cognitive inhibition, as well as baseline pain sensitivity and cognitive inhibition.

Causal Prefrontal Contributions to Stop-Signal Task Performance in Humans.

The frontal lobes have long been implicated in inhibitory control, but a full understanding of the underlying mechanisms remains elusive. The stop-signal task has been widely used to probe instructed response inhibition in cognitive neuroscience. The processes involved have been modeled and related to putative brain substrates. However, there has been surprisingly little human lesion research using this task, with the few existing studies implicating different prefrontal regions. Here, we tested the effects of focal prefrontal damage on stop-signal task performance in a large sample of people with chronic focal damage affecting the frontal lobes (n = 42) and demographically matched healthy individuals (n = 60). Patients with damage to the left lateral, right lateral, dorsomedial, or ventromedial frontal lobe had slower stop-signal RT compared to healthy controls. There were systematic differences in the patterns of impairment across frontal subgroups: Those with damage to the left or right lateral and dorsomedial frontal lobes, but not those with ventromedial frontal damage, were slower than controls to "go" as well as to stop. These findings suggest that multiple prefrontal regions make necessary but distinct contributions to stop-signal task performance. As a consequence, stop-signal RT slowing is not strongly localizing within the frontal lobes.

Comparing Stop Signal Reaction Times in Alzheimer's and Parkinson's Disease.

To investigate the relative contributions of cerebral cortex and basal ganglia to movement stopping, we tested the optimum combination Stop Signal Reaction Time (ocSSRT) and median visual reaction time (RT) in patients with Alzheimer's disease (AD) and Parkinson's disease (PD) and compared values with data from healthy controls. Thirty-five PD patients, 22 AD patients, and 29 healthy controls were recruited to this study. RT and ocSSRT were measured using a hand-held battery-operated electronic box through a stop signal paradigm. The mean ocSSRT was found to be 309 ms, 368 ms, and 265 ms in AD, PD, and healthy controls, respectively, and significantly prolonged in PD compared to healthy controls (p = 0.001). The ocSSRT but not RT could separate AD from PD patients (p = 0.022). Our data suggest that subcortical networks encompassing dopaminergic pathways in the basal ganglia play a more important role than cortical networks in movement-stopping. Combining ocSSRT with other putative indices or biomarkers of AD (and other dementias) could increase the accuracy of early diagnosis.

Cortical silent period reflects individual differences in action stopping performance

Inhibitory control is the ability to suppress inappropriate movements and unwanted actions, allowing to regulate impulses and responses. This ability can be measured via the Stop Signal Task, which provides a temporal index of response inhibition, namely the stop signal reaction time (SSRT). At the neural level, Transcranial Magnetic Stimulation (TMS) allows to investigate motor inhibition within the primary motor cortex (M1), such as the cortical silent period (CSP) which is an index of GABAB-mediated intracortical inhibition within M1. Although there is strong evidence that intracortical inhibition varies during action stopping, it is still not clear whether differences in the neurophysiological markers of intracortical inhibition contribute to behavioral differences in actual inhibitory capacities. Hence, here we explored the relationship between intracortical inhibition within M1 and behavioral response inhibition. GABABergic-mediated inhibition in M1 was determined by the duration of CSP, while behavioral inhibition was assessed by the SSRT. We found a significant positive correlation between CSP’s duration and SSRT, namely that individuals with greater levels of GABABergic-mediated inhibition seem to perform overall worse in inhibiting behavioral responses. These results support the assumption that individual differences in intracortical inhibition are mirrored by individual differences in action stopping abilities.

Inter-individual performance differences in the stop-signal task are associated with fibre-specific microstructure of the fronto-basal-ganglia circuit in healthy children

Previous Diffusion Tensor Imaging (DTI) studies in children suggest that developmental improvements in inhibitory control is largely mediated by the degree of white matter organisation within a right-lateralised network of fronto-basal-ganglia regions. Recent advances in diffusion imaging analysis now permit greater biological specificity, both in identifying specific fibre populations within a voxel, as well as in the underlying microstructural properties of that white matter. In the present work, employing a novel fixel-based analysis (FBA) framework, we aimed to comprehensively investigate microstructure within the fronto-basal-ganglia circuit in childhood, and its contribution to inhibition performance. Diffusion MRI data were obtained from 43 healthy children and adolescents aged 9–11 years (10.42 ± .41 years, 18 females). Response inhibition for each participant was assessed using the Stop-signal Task (SST) and quantified as a Stop–Signal Reaction Time (SSRT). All steps relevant to FBA were implemented in MRtrix3Tissue, a fork of the MRtrix3 software library. The fronto-basal-ganglia circuit were delineated using probabilistic tractography to identify the tracts connecting the subthalamic nucleus, pre-supplementary motor area and the inferior frontal gyrus. Connectivity-based fixel enhancement (CFE) was then used to assess the association between fibre density (FD) and fibre cross-section (FC) with inhibitory ability. Significant negative associations were identified for FD in both the right and left fronto-basal-ganglia circuit whereby greater FD was associated with better inhibition performance (e.g., reduced SSRTs). This effect was specifically localised to clusters of fixels within white matter proximal to the right subthalamic nucleus. We did not report any meaningful associations between SSRT and FC. Whilst findings are broadly consistent with prior DTI evidence, current results suggest that SSRT is predominantly facilitated by subcortical microstructure of the connections projecting from the subthalamic nucleus to the cortical regions of the network. Our findings extend current understanding of the role of white matter in childhood response inhibition.

Effects of Trait Anxiety on Error Processing and Post-error Adjustments: An Event-Related Potential Study With Stop-Signal Task

The present study aimed to use event-related potentials with the stop-signal task to investigate the effects of trait anxiety on inhibitory control, error monitoring, and post-error adjustments. The stop-signal reaction time (SSRT) was used to evaluate the behavioral competence of inhibitory control. Electrophysiological signals of error-related negativity (ERN) and error positivity (Pe) were used to study error perception and error awareness, respectively. Post-error slowing (PES) was applied to examine the behavioral adjustments after making errors. The results showed that SSRT and PES did not differ significantly between individuals with high trait anxiety (HTA) and those with low trait anxiety (LTA). However, individuals with HTA demonstrated reduced ERN amplitudes and prolonged Pe latencies than those with LTA. Prolonged Pe latencies were also significantly associated with poorer post-error adjustments. In conclusion, HTA led to reduced cortical responses to error monitoring. Furthermore, inefficient conscious awareness of errors might lead to maladaptive post-error adjustments.

Selective Inhibitory Control in Middle Childhood.

The main aim of this study was to investigate the development of selective inhibitory control in middle childhood, a critical period for the maturation of inhibition-related processes. To this end, 64 children aged 6–7 and 56 children aged 10–11 performed a stimulus-selective stop-signal task, which allowed us to estimate not only the efficiency of response inhibition (the stop-signal reaction time or SSRT), but also the strategy adopted by participants to achieve task demands. We found that the adoption of a non-selective (global) strategy characterized by stopping indiscriminately to all stimuli decreased in older children, so that most of them were able to interrupt their ongoing responses selectively at the end of middle childhood. Moreover, compared to younger children, older children were more efficient in their ability to cancel an initiated response (indexed by a shorter SSRT), regardless of which strategy they used. Additionally, we found improvements in other forms of impulsivity, such as the control of premature responding (waiting impulsivity), and attentional-related processes, such as intra-individual variability and distractibility. The present results suggest that middle childhood represents a milestone in the development of crucial aspects of inhibitory control, including selective stopping.

The development of cognitive control in children with autism spectrum disorder or obsessive-compulsive disorder: A longitudinal fMRI study

Repetitive behavior is a core symptom of Autism Spectrum Disorder (ASD) and Obsessive-Compulsive Disorder (OCD), and has been associated with impairments in cognitive control. However, it is unclear how cognitive control and associated neural circuitry relate to the development of repetitive behavior in children with these disorders. In a multicenter, longitudinal study (TACTICS; Translational Adolescent and Childhood Therapeutic Interventions in Compulsive Syndromes), the development of cognitive control was assessed during late childhood using a longitudinal fMRI design with a modified stop-signal task in children with ASD or OCD, and typically developing (TD) children (baseline: N = 95 (8-12 y), follow-up: N = 53 (10-14 y), average interval: 1.48 y (sd: 0.36, range: 0.98–2.52 y). Stop-signal reaction time (SSRT) decreased over development, regardless of diagnosis. Repetitive behavior in children with ASD and OCD was not associated with performance on the stop-signal task. There were no whole-brain between-group differences in brain activity, but ROI-analyses showed increases in activity in right precentral gyrus over development for children with OCD. In sum, even though subtle differences were observed in the development of brain activity in children with OCD, overall the findings suggest that the development of cognitive control, as assessed by the stop signal task, is similar to typical in children with ASD and OCD.

Relationship between Speed of Response Inhibition and Ability to Suppress a Step in Midlife and Older Adults.

In young adults, performance on a test of response inhibition was recently found to be correlated with performance on a reactive balance test where automated stepping responses must occasionally be inhibited. The present study aimed to determine whether this relationship holds true in older adults, wherein response inhibition is typically deficient and the control of postural equilibrium presents a greater challenge. Ten participants (50+ years of age) completed a seated cognitive test (stop signal task) followed by a reactive balance test. Reactive balance was assessed using a modified lean-and-release system where participants were required to step to regain balance following perturbation, or suppress a step if an obstacle was present. The stop signal task is a standardized cognitive test that provides a measure of the speed of response inhibition called the Stop Signal Reaction Time (SSRT). Muscle responses in the legs were compared between conditions where a step was allowed or blocked to quantify response inhibition of the step. The SSRT was significantly related to leg muscle suppression during balance recovery in the stance leg. Thus, participants that were better at inhibiting their responses in the stop signal task were also better at inhibiting an unwanted leg response in favor of grasping a supportive handle. The relationship between a seated cognitive test using finger responses and leg muscle suppression when a step was blocked indicates a context-independent, generalized capacity for response inhibition. This suggests that a simple cognitive test such as the stop signal task could be used clinically to predict an individual’s capacity for adapting balance reactions and fall risk. The present results provide support for future studies, with larger samples, to verify this relationship between stop signal reaction time and leg response during balance recovery.

Right prefrontal activation predicts ADHD and its severity: A TMS-EEG study in young adults

ObjectiveHere we bring a neurophysiological diagnostic tool, based on pathophysiologically-relevant brain region, that is critical for reducing the variability between clinicians, and necessary for quantitative measures of ADHD severity. Methods54 healthy and 57 ADHD adults participated in the study. Electroencephalography (EEG) was recorded when combined with transcranial magnetic stimulation (TMS) over the right prefrontal cortex and also recorded during the Stop Signal task. ResultsTMS evoked potentials (TEPs) and the event related potential (ERP) components in the Stop Signal task were found to be significantly reduced in ADHD relative to the matched healthy controls. Stop signal reaction time (SSRT) and stopping accuracy was found to correlate with the ERP signal, and ADHD severity correlated with the TEP signal. Cortical activity (early TEP and Stop Signal ERP) diagnostic model yielded accuracy of 72%. ConclusionTEPs and ERPs reveal that right PFC excitability was associated with ADHD severity, and with behavioral impulsivity – as a hallmark of ADHD pathology. This electrophysiological biomarker supports the potential of objective diagnosis for ADHD. SignificanceSuch tools would allow better assessment of treatment efficacy and prognosis, may advance understanding of the pathophysiology of the disease and better the public's attitudes and stigma towards ADHD.Trial Registration: Trial to Evaluate the Efficacy of the HLPFC Coil Deep Transcranial Magnetic Stimulation System in Treating Attention Deficit and Hyperactivity Disorder (ADHD) in Adults, https://clinicaltrials.gov/ct2/show/NCT01737476, ClinicalTrials.govnumberNCT01737476

Volume of β-Bursts, But Not Their Rate, Predicts Successful Response Inhibition.

In humans, impaired response inhibition is characteristic of a wide range of psychiatric diseases and of normal aging. It is hypothesized that the right inferior frontal cortex (rIFC) plays a key role by inhibiting the motor cortex via the basal ganglia. The electroencephalography (EEG)-derived β-rhythm (15-29 Hz) is thought to reflect communication within this network, with increased right frontal β-power often observed before successful response inhibition. Recent literature suggests that averaging spectral power obscures the transient, burst-like nature of β-activity. There is evidence that the rate of β-bursts following a Stop signal is higher when a motor response is successfully inhibited. However, other characteristics of β-burst events, and their topographical properties, have not yet been examined. Here, we used a large human (male and female) EEG Stop Signal task (SST) dataset (n = 218) to examine averaged normalized β-power, β-burst rate, and β-burst "volume" (which we defined as burst duration × frequency span × amplitude). We first sought to optimize the β-burst detection method. In order to find predictors across the whole scalp, and with high temporal precision, we then used machine learning to (1) classify successful versus failed stopping and to (2) predict individual stop signal reaction time (SSRT). β-burst volume was significantly more predictive of successful and fast stopping than β-burst rate and normalized β-power. The classification model generalized to an external dataset (n = 201). We suggest β-burst volume is a sensitive and reliable measure for investigation of human response inhibition.SIGNIFICANCE STATEMENT The electroencephalography (EEG)-derived β-rhythm (15-29 Hz) is associated with the ability to inhibit ongoing actions. In this study, we sought to identify the specific characteristics of β-activity that contribute to successful and fast inhibition. In order to search for the most relevant features of β-activity, across the whole scalp and with high temporal precision, we employed machine learning on two large datasets. Spatial and temporal features of β-burst "volume" (duration × frequency span × amplitude) predicted response inhibition outcomes in our data significantly better than β-burst rate and normalized β-power. These findings suggest that multidimensional measures of β-bursts, such as burst volume, can add to our understanding of human response inhibition.

Is motor inhibition involved in the processing of sentential negation? An assessment via the Stop-Signal Task

In the last decades, the embodied approach to cognition and language gained momentum in the scientific debate, leading to evidence in different aspects of language processing. However, while the bodily grounding of concrete concepts seems to be relatively not controversial, abstract aspects, like the negation logical operator, are still today one of the main challenges for this research paradigm. In this framework, the present study has a twofold aim: (1) to assess whether mechanisms for motor inhibition underpin the processing of sentential negation, thus, providing evidence for a bodily grounding of this logic operator, (2) to determine whether the Stop-Signal Task, which has been used to investigate motor inhibition, could represent a good tool to explore this issue. Twenty-three participants were recruited in this experiment. Ten hand-action-related sentences, both in affirmative and negative polarity, were presented on a screen. Participants were instructed to respond as quickly and accurately as possible to the direction of the Go Stimulus (an arrow) and to withhold their response when they heard a sound following the arrow. This paradigm allows estimating the Stop Signal Reaction Time (SSRT), a covert reaction time underlying the inhibitory process. Our results show that the SSRT measured after reading negative sentences are longer than after reading affirmative ones, highlighting the recruitment of inhibitory mechanisms while processing negative sentences. Furthermore, our methodological considerations suggest that the Stop-Signal Task is a good paradigm to assess motor inhibition’s role in the processing of sentence negation.

An ERP study on proactive and reactive response inhibition in individuals with schizotypy

Schizotypy, a subclinical group at risk for schizophrenia, has been found to show impairments in response inhibition. However, it remains unclear whether this impairment is accompanied by outright stopping (reactive inhibition) or preparation for stopping (proactive inhibition). We recruited 20 schizotypy and 24 non-schizotypy individuals to perform a modified stop-signal task with electroencephalographic (EEG) data recorded. This task consists of three conditions based on the probability of stop signal: 0% (no stop trials, only go trials), 17% (17% stop trials), and 33% (33% stop trials), the conditions were indicated by the colour of go stimuli. For proactive inhibition (go trials), individuals with schizotypy exhibited significantly lesser increase in go response time (RT) as the stop signal probability increasing compared to non-schizotypy individuals. Individuals with schizotypy also exhibited significantly increased N1 amplitude on all levels of stop signal probability and increased P3 amplitude in the 17% stop condition compared with non-schizotypy individuals. For reactive inhibition (stop trials), individuals with schizotypy exhibited significantly longer stop signal reaction time (SSRT) in both 17% and 33% stop conditions and smaller N2 amplitude on stop trials in the 17% stop condition than non-schizotypy individuals. These findings suggest that individuals with schizotypy were impaired in both proactive and reactive response inhibition at behavioural and neural levels.

Inhibitory Control on a Stop Signal Task in Tourette Syndrome before and after Deep Brain Stimulation of the Internal Segment of the Globus Pallidus.

As part of the first randomized double-blind trial of deep brain stimulation (DBS) of the globus pallidus (GPi) in Tourette syndrome, we examined the effect of stimulation on response initiation and inhibition. A total of 14 patients with severe Tourette syndrome were recruited and tested on the stop signal task prior to and after GPi-DBS surgery and compared to eight age-matched healthy controls. Tics were significantly improved following GPi-DBS. The main measure of reactive inhibition, the stop signal reaction time did not change from before to after surgery and did not differ from that of healthy controls either before or after GPi-DBS surgery. This suggests that patients with Tourette syndrome have normal reactive inhibition which is not significantly altered by GPi-DBS.

Adults with adhd symptoms express a better inhibitory capacity when the perceptual load is higher

IntroductionADHD is associated with impairments in different inhibitory functions, including suppression of an already initiated response and inhibition of distracting information. This work used a protocol that combines the Stroop-matched and stop-signal tasks to examine the association between the frequency of ADHD symptoms and different inhibitory abilities in a young adult.ObjectivesTo investigate how the symptoms of inattention and hyperactivity / impulsivity are associated with three forms of inhibition evaluated by the Stroop-matched / stop-signal task: inhibiting an automatic response, controlling interference and canceling a response.Methods38 participants (33 women; mean age = 23.3; SD = 5.17) completed Adult ADHD Self-Report Scale (ASRS) assessing ADHD symptoms before performing the task. Reaction times, accuracy and stop-signal reaction time (SSRT; the latency of the inhibitory process of response cancellation) were calculated for each task condition.ResultsThere was a significant correlation of ADHD symptoms and SSRT in the condition with the higher perceptual load (i.e., a greater number of colors presented in the same test). This correlation was negative (r = - .36, p <.05), which indicates that participants with higher ADHD symptoms frequency had more efficient inhibitory processes in this condition.Conclusions(1) the perceptual load of the task influences the cancellation of responses; (2) individuals with higher frequency of ADHD symptoms may have a better inhibitory capacity when the perceptual load is high, possibly reflecting a lower availability of attentional resources to process distracting information.DisclosureNo significant relationships.

Locus coeruleus integrity and the effect of atomoxetine on response inhibition in Parkinson's disease.

Cognitive decline is a common feature of Parkinson's disease, and many of these cognitive deficits fail to respond to dopaminergic therapy. Therefore, targeting other neuromodulatory systems represents an important therapeutic strategy. Among these, the locus coeruleus-noradrenaline system has been extensively implicated in response inhibition deficits. Restoring noradrenaline levels using the noradrenergic reuptake inhibitor atomoxetine can improve response inhibition in some patients with Parkinson's disease, but there is considerable heterogeneity in treatment response. Accurately predicting the patients who would benefit from therapies targeting this neurotransmitter system remains a critical goal, in order to design the necessary clinical trials with stratified patient selection to establish the therapeutic potential of atomoxetine. Here, we test the hypothesis that integrity of the noradrenergic locus coeruleus explains the variation in improvement of response inhibition following atomoxetine. In a double-blind placebo-controlled randomized crossover design, 19 patients with Parkinson's disease completed an acute psychopharmacological challenge with 40 mg of oral atomoxetine or placebo. A stop-signal task was used to measure response inhibition, with stop-signal reaction times obtained through hierarchical Bayesian estimation of an ex-Gaussian race model. Twenty-six control subjects completed the same task without undergoing the drug manipulation. In a separate session, patients and controls underwent ultra-high field 7 T imaging of the locus coeruleus using a neuromelanin-sensitive magnetization transfer sequence. The principal result was that atomoxetine improved stop-signal reaction times in those patients with lower locus coeruleus integrity. This was in the context of a general impairment in response inhibition, as patients on placebo had longer stop-signal reaction times compared to controls. We also found that the caudal portion of the locus coeruleus showed the largest neuromelanin signal decrease in the patients compared to controls. Our results highlight a link between the integrity of the noradrenergic locus coeruleus and response inhibition in patients with Parkinson's disease. Furthermore, they demonstrate the importance of baseline noradrenergic state in determining the response to atomoxetine. We suggest that locus coeruleus neuromelanin imaging offers a marker of noradrenergic capacity that could be used to stratify patients in trials of noradrenergic therapy and to ultimately inform personalized treatment approaches.

Short intracortical facilitation associates with motor-inhibitory control

The ability of motor-inhibitory control is important in daily life. Inhibitory control deficits are commonly observed in psychiatric conditions with enhanced impulsivity. The physiological mechanisms underlying the inhibitory control deficits are not well elucidated. We systematically investigated the relationship between resting-state intracortical inhibition or facilitation and inhibitory control (indicated by stop signal reaction time, SSRT) to determine whether reduced intracortical inhibition or increased intracortical facilitation was related to the poorer inhibitory control. Thirty-three healthy subjects (age: 21.46 ± 1.40 years) participated in this study. We used paired-pulse transcranial magnetic stimulation to induce short intracortical inhibition, intracortical facilitation, long intracortical inhibition, and short intracortical facilitation at rest. SSRT was derived from stop signal task. We performed all measurements in two repeat sessions conducted two weeks apart. A negative correlation between short intracortical inhibition and SSRT was only observed in session 1; however, the correlation did not persist after controlling for short intracortical facilitation. Positive correlation between short intracortical facilitation and SSRT was observed in both sessions, indicating that individuals with greater resting-state short intracortical facilitation tend to have less efficient stopping performance. Our results help explain the inconsistency with respect to the relationship between short intracortical inhibition and SSRT in the existing literature. Short intracortical facilitation may be used as a potential physiological biomarker for motor-inhibitory control, which may have clinical implications for disorders associated with inhibitory control deficits.

Face the (trigger) failure: Trigger failures strongly drive the effect of reward on response inhibition

Response inhibition is typically understood as the ability to stop inappropriate actions and is often investigated using the stop-signal task, in which a go response, triggered by a go signal, has to be inhibited upon the onset of a stop signal. In this task, response inhibition has been formalized as a race between a go and a stop process, which allows the latency of the stop process (stop-signal reaction time; SSRT) to be estimated. Yet, non-parametric SSRT estimations assume that the stop process is initiated without fail, which appears problematic as it is known that participants fail to do so on a subset of trials (“trigger failures”). Importantly, non-parametric methods systematically overestimate SSRT when trigger failures are present, and a growing literature is demonstrating that reported SSRT differences between groups and individuals are also (or rather) driven by differential trigger-failure rates. In the present study, we extend this line of research to a within-individual manipulation, namely the influence of reward on stop performance. We first reanalyzed four data sets of studies that had reported a facilitating effect of stimulus-based reward on SSRTs. Reanalyzing this data, we found that reward decreased the rates of trigger failures. When accounting for these differential trigger-failure rates, the effect of reward on SSRTs (i.e., stop latency) appeared to be virtually abolished. We then conducted a preregistered online follow-up study, implementing a typical block-based reward manipulation. The results of this study indicated simultaneous reward effects on trigger-failure rates and on SSRT. In sum, the present results indicate that trigger failures are an important source of variance in response inhibition, dovetailing with an evolving multicomponential view of response inhibition.