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Chiang-shan R. Li - One of the best experts on this subject based on the ideXlab platform.
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Motor Preparation Disrupts Proactive Control in the Stop Signal Task.
Frontiers in Human Neuroscience, 2018Co-Authors: Wuyi Wang, Sheng Zhang, Sien Hu, Simon Zhornitsky, Angela J. Yu, Chiang-shan R. LiAbstract:In a study of the stop signal Task (SST) we employed Bayesian modeling to compute the estimated likelihood of stop signal or P(Stop) trial by trial and identified regional processes of conflict anticipation and response slowing. A higher P(Stop) is associated with prolonged go trial reaction time (goRT)-a form of sequential effect-and reflects proactive control of motor response. However, some individuals do not demonstrate a sequential effect despite similar go and stop success (SS) rates. We posited that motor preparation may disrupt proactive control more in certain individuals than others. Specifically, the time interval between trial and go signal onset-the fore-period (FP)-varies across trials and a longer FP is associated with a higher level of motor preparation and shorter goRT. Greater motor preparatory activities may disrupt proactive control. To test this hypothesis, we compared brain activations and Granger causal connectivities of 81 adults who demonstrated a sequential effect (SEQ) and 35 who did not (nSEQ). SEQ and nSEQ did not differ in regional activations to conflict anticipation, motor preparation, goRT slowing or goRT speeding. In contrast, SEQ and nSEQ demonstrated different patterns of Granger causal connectivities. P(Stop) and FP activations shared reciprocal influence in SEQ but FP activities Granger caused P(Stop) activities unidirectionally in nSEQ, and FP activities Granger caused goRT speeding activities in nSEQ but not SEQ. These findings support the hypothesis that motor preparation disrupts proactive control in nSEQ and provide direct neural evidence for interactive go and stop processes.
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Distinct neural processes support post-success and post-error slowing in the stop signal Task.
Neuroscience, 2017Co-Authors: Yihe Zhang, Sheng Zhang, Sien Hu, Nikola Valchev, Xiaoying Tang, Chiang-shan R. LiAbstract:Abstract Executive control requires behavioral adaptation to environmental contingencies. In the stop signal Task (SST), participants exhibit slower go trial reaction time (RT) following a stop trial, whether or not they successfully interrupt the motor response. In previous fMRI studies, we demonstrated activation of the right-hemispheric ventrolateral prefrontal cortex, in the area of inferior frontal gyrus, pars opercularis (IFGpo) and anterior insula (AI), during post-error slowing (PES). However, in similar analyses we were not able to identify regional activities during post-success slowing (PSS). Here, we revisited this issue in a larger sample of participants ( n = 100) each performing the SST for 40 min during fMRI. We replicated IFGpo/AI activation to PES ( p ≤ 0.05, FWE corrected). Further, PSS engages decreased activation in a number of cortical regions including the left inferior frontal cortex (IFC; p ≤ 0.05, FWE corrected). We employed Granger causality mapping to identify areas that provide inputs each to the right IFGpo/AI and left IFC, and computed single-trial amplitude (STA) of stop trials of these input regions as well as the STA of post-stop trials of the right IFGpo/AI and left IFC. The STAs of the right inferior precentral sulcus and supplementary motor area (SMA) and right IFGpo/AI were positively correlated and the STAs of the left SMA and left IFC were positively correlated (slope > 0, p’s ≤ 0.01, one-sample t test), linking regional responses during stop success and error trials to those during PSS and PES. These findings suggest distinct neural mechanisms to support PSS and PES.
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The effects of methylphenidate on cerebral responses to conflict anticipation and unsigned prediction error in a Stop-Signal Task:
Journal of Psychopharmacology, 2016Co-Authors: Peter Manza, Sheng Zhang, Sien Hu, Olivia M. Farr, Hoi-chung Leung, Chiang-shan R. LiAbstract:To adapt flexibly to a rapidly changing environment, humans must anticipate conflict and respond to surprising, unexpected events. To this end, the brain estimates upcoming conflict on the basis of prior experience and computes unsigned prediction error (UPE). Although much work implicates catecholamines in cognitive control, little is known about how pharmacological manipulation of catecholamines affects the neural processes underlying conflict anticipation and UPE computation. We addressed this issue by imaging 24 healthy young adults who received a 45 mg oral dose of methylphenidate (MPH) and 62 matched controls who did not receive MPH prior to performing the Stop-Signal Task. We used a Bayesian Dynamic Belief Model to make trial-by-trial estimates of conflict and UPE during Task performance. Replicating previous research, the control group showed anticipation-related activation in the presupplementary motor area and deactivation in the ventromedial prefrontal cortex and parahippocampal gyrus, as well ...
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Individual variation in the neural processes of motor decisions in the stop signal Task: the influence of novelty seeking and harm avoidance personality traits
Brain Structure & Function, 2015Co-Authors: Jianping Hu, Sheng Zhang, Sien Hu, Herta Chao, Chiang-shan R. LiAbstract:Personality traits contribute to variation in human behavior, including the propensity to take risk. Extant work targeted risk-taking processes with an explicit manipulation of reward, but it remains unclear whether personality traits influence simple decisions such as speeded versus delayed responses during cognitive control. We explored this issue in an fMRI study of the stop signal Task, in which participants varied in response time trial by trial, speeding up and risking a stop error or slowing down to avoid errors. Regional brain activations to speeded versus delayed motor responses (risk-taking) were correlated to novelty seeking (NS), harm avoidance (HA) and reward dependence (RD), with age and gender as covariates, in a whole brain regression. At a corrected threshold, the results showed a positive correlation between NS and risk-taking responses in the dorsomedial prefrontal, bilateral orbitofrontal, and frontopolar cortex, and between HA and risk-taking responses in the parahippocampal gyrus and putamen. No regional activations varied with RD. These findings demonstrate that personality traits influence the neural processes of executive control beyond behavioral Tasks that involve explicit monetary reward. The results also speak broadly to the importance of characterizing inter-subject variation in studies of cognition and brain functions.
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Conflict anticipation in alcohol dependence - A model-based fMRI study of stop signal Task.
NeuroImage: Clinical, 2015Co-Authors: Sien Hu, Sheng Zhang, Rajita Sinha, Chiang-shan R. LiAbstract:Background Our previous work characterized altered cerebral activations during cognitive control in individuals with alcohol dependence (AD). A hallmark of cognitive control is the ability to anticipate changes and adjust behavior accordingly. Here, we employed a Bayesian model to describe trial-by-trial anticipation of the stop signal and modeled fMRI signals of conflict anticipation in a stop signal Task. Our goal is to characterize the neural correlates of conflict anticipation and its relationship to response inhibition and alcohol consumption in AD.
Rajita Sinha - One of the best experts on this subject based on the ideXlab platform.
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Conflict anticipation in alcohol dependence - A model-based fMRI study of stop signal Task.
NeuroImage: Clinical, 2015Co-Authors: Sien Hu, Sheng Zhang, Rajita Sinha, Chiang-shan R. LiAbstract:Background Our previous work characterized altered cerebral activations during cognitive control in individuals with alcohol dependence (AD). A hallmark of cognitive control is the ability to anticipate changes and adjust behavior accordingly. Here, we employed a Bayesian model to describe trial-by-trial anticipation of the stop signal and modeled fMRI signals of conflict anticipation in a stop signal Task. Our goal is to characterize the neural correlates of conflict anticipation and its relationship to response inhibition and alcohol consumption in AD.
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Gender Differences in Cognitive Control: an Extended Investigation of the Stop Signal Task
Brain Imaging and Behavior, 2009Co-Authors: Chiang-shan R. Li, Sheng Zhang, Rajita Sinha, Jeng-ren Duann, Carolyn M. MazureAbstract:Men and women show important differences in clinical conditions in which deficits in cognitive control are implicated. We used functional magnetic resonance imaging to examine gender differences in the neural processes of cognitive control during a Stop-Signal Task. We observed greater activation in men, compared to women, in a wide array of cortical and sub-cortical areas, during stop success (SS) as compared to stop error (SE). Conversely, women showed greater regional brain activation during SE > SS, compared to men. Furthermore, compared to women, men engaged the right inferior parietal lobule to a greater extent during post-SE go compared to post-go go trials. Women engaged greater posterior cingulate cortical activation than men during post-SS slowing in go trial reaction time (RT) but did not differ during post-SE slowing in go trial RT. These findings extended our previous results of gender differences in regional brain activation during response inhibition. The results may have clinical implications by, for instance, helping initiate studies to understand why women are more vulnerable to depression while men are more vulnerable to impulse control disorders.
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Error-specific medial cortical and subcortical activity during the stop signal Task: A functional magnetic resonance imaging study
Neuroscience, 2008Co-Authors: Chiang-shan R. Li, Rajita Sinha, Prashni Paliwal, Robert Todd Constable, H.h.-a. Chao, Sheng ZhangAbstract:The ability to detect errors and adjust behavior accordingly is essential for maneuvering in an uncertain environment. Errors are particularly prone to occur when multiple, conflicting responses are registered in a situation that requires flexible behavioral outputs. Previous studies have provided evidence indicating the importance of the medial cortical brain regions including the cingulate cortex in processing conflicting information. However, conflicting situations can be successfully resolved, or lead to errors, prompting a behavioral change in the observers. In particular, how does the brain use error signals specifically to adjust behavior on the fly? Here we employ a stop signal Task (SST) to elicit errors approximately half of the time in high-conflict trials despite constant behavioral adjustment of the observers. Using functional magnetic resonance imaging, we show greater and, sequentially, less activation in the medial cortical regions when observers made an error, compared with when they successfully resolved high-conflict responses. Errors also evoked greater activity in the cuneus, retrosplenial cortex, insula, and subcortical structures including the thalamus and the region of the epithalamus (the habenula). We further showed that the error-related medial cortical activities are not correlated with post-error behavioral adjustment, as indexed by post-error slowing (PES) in go trial reaction time. These results delineate an error-specific pattern of brain activation during the SST. The results also suggest that the relationship between error-related activity and post-error behavioral adjustment may be more complicated than has been conceptualized by the conflict monitoring hypothesis.
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Subcortical processes of motor response inhibition during a stop signal Task.
NeuroImage, 2008Co-Authors: Chiang-shan R. Li, Rajita SinhaAbstract:Previous studies have delineated the neural processes of motor response inhibition during a stop signal Task, with most reports focusing on the cortical mechanisms. A recent study highlighted the importance of subcortical processes during stop signal inhibition in 13 individuals and suggested that the subthalamic nucleus (STN) may play a role in blocking response execution (Aron and Poldrack, 2006. Cortical and subcortical contributions to Stop signal response inhibition: role of the subthalamic nucleus. J Neurosci 26, 2424-2433). Here in a functional magnetic resonance imaging (fMRI) study we replicated the finding of greater activation in the STN during stop (success or error) trials, compared to go trials, in a larger sample of subjects (n=30). However, since a contrast between stop and go trials involved processes that could be distinguished from response inhibition, the role of subthalamic activity during stop signal inhibition remained to be specified. To this end we followed an alternative strategy to isolate the neural correlates of response inhibition (Li et al., 2006a. Imaging response inhibition in a stop signal Task--neural correlates independent of signal monitoring and post-response processing. J Neurosci 26, 186-192). We compared individuals with short and long stop signal reaction time (SSRT) as computed by the horse race model. The two groups of subjects did not differ in any other aspects of stop signal performance. We showed greater activity in the short than the long SSRT group in the caudate head during stop successes, as compared to stop errors. Caudate activity was positively correlated with medial prefrontal activity previously shown to mediate stop signal inhibition. Conversely, bilateral thalamic nuclei and other parts of the basal ganglia, including the STN, showed greater activation in subjects with long than short SSRT. Thus, fMRI delineated contrasting roles of the prefrontal-caudate and striato-thalamic activities in mediating motor response inhibition.
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Neural Correlates of Post-error Slowing during a Stop Signal Task: A Functional Magnetic Resonance Imaging Study
Journal of Cognitive Neuroscience, 2008Co-Authors: Chiang-shan Ray Li, Cong Huang, Prashni Paliwal, Robert Todd Constable, Rajita SinhaAbstract:The ability to detect errors and adjust behavior accordingly is essential for maneuvering in an uncertain environment. Errors are particularly prone to occur when multiple, conflicting responses are registered in a situation that requires flexible behavioral outputs; for instance, when a go signal requires a response and a stop signal requires inhibition of the response during a stop signal Task (SST). Previous studies employing the SST have provided ample evidence indicating the importance of the medial cortical brain regions in conflict/error processing. Other studies have also related these regional activations to postconflict/error behavioral adjustment. However, very few studies have directly explored the neural correlates of postconflict/error behavioral adjustment. Here we employed an SST to elicit errors in approximately half of the stop trials despite constant behavioral adjustment of the observers. Using functional magnetic resonance imaging, we showed that prefrontal loci including the ventrolateral prefrontal cortex are involved in post-error slowing in reaction time. These results delineate the neural circuitry specifically involved in error-associated behavioral modifications.
Sheng Zhang - One of the best experts on this subject based on the ideXlab platform.
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Motor Preparation Disrupts Proactive Control in the Stop Signal Task.
Frontiers in Human Neuroscience, 2018Co-Authors: Wuyi Wang, Sheng Zhang, Sien Hu, Simon Zhornitsky, Angela J. Yu, Chiang-shan R. LiAbstract:In a study of the stop signal Task (SST) we employed Bayesian modeling to compute the estimated likelihood of stop signal or P(Stop) trial by trial and identified regional processes of conflict anticipation and response slowing. A higher P(Stop) is associated with prolonged go trial reaction time (goRT)-a form of sequential effect-and reflects proactive control of motor response. However, some individuals do not demonstrate a sequential effect despite similar go and stop success (SS) rates. We posited that motor preparation may disrupt proactive control more in certain individuals than others. Specifically, the time interval between trial and go signal onset-the fore-period (FP)-varies across trials and a longer FP is associated with a higher level of motor preparation and shorter goRT. Greater motor preparatory activities may disrupt proactive control. To test this hypothesis, we compared brain activations and Granger causal connectivities of 81 adults who demonstrated a sequential effect (SEQ) and 35 who did not (nSEQ). SEQ and nSEQ did not differ in regional activations to conflict anticipation, motor preparation, goRT slowing or goRT speeding. In contrast, SEQ and nSEQ demonstrated different patterns of Granger causal connectivities. P(Stop) and FP activations shared reciprocal influence in SEQ but FP activities Granger caused P(Stop) activities unidirectionally in nSEQ, and FP activities Granger caused goRT speeding activities in nSEQ but not SEQ. These findings support the hypothesis that motor preparation disrupts proactive control in nSEQ and provide direct neural evidence for interactive go and stop processes.
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Distinct neural processes support post-success and post-error slowing in the stop signal Task.
Neuroscience, 2017Co-Authors: Yihe Zhang, Sheng Zhang, Sien Hu, Nikola Valchev, Xiaoying Tang, Chiang-shan R. LiAbstract:Abstract Executive control requires behavioral adaptation to environmental contingencies. In the stop signal Task (SST), participants exhibit slower go trial reaction time (RT) following a stop trial, whether or not they successfully interrupt the motor response. In previous fMRI studies, we demonstrated activation of the right-hemispheric ventrolateral prefrontal cortex, in the area of inferior frontal gyrus, pars opercularis (IFGpo) and anterior insula (AI), during post-error slowing (PES). However, in similar analyses we were not able to identify regional activities during post-success slowing (PSS). Here, we revisited this issue in a larger sample of participants ( n = 100) each performing the SST for 40 min during fMRI. We replicated IFGpo/AI activation to PES ( p ≤ 0.05, FWE corrected). Further, PSS engages decreased activation in a number of cortical regions including the left inferior frontal cortex (IFC; p ≤ 0.05, FWE corrected). We employed Granger causality mapping to identify areas that provide inputs each to the right IFGpo/AI and left IFC, and computed single-trial amplitude (STA) of stop trials of these input regions as well as the STA of post-stop trials of the right IFGpo/AI and left IFC. The STAs of the right inferior precentral sulcus and supplementary motor area (SMA) and right IFGpo/AI were positively correlated and the STAs of the left SMA and left IFC were positively correlated (slope > 0, p’s ≤ 0.01, one-sample t test), linking regional responses during stop success and error trials to those during PSS and PES. These findings suggest distinct neural mechanisms to support PSS and PES.
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The effects of methylphenidate on cerebral responses to conflict anticipation and unsigned prediction error in a Stop-Signal Task:
Journal of Psychopharmacology, 2016Co-Authors: Peter Manza, Sheng Zhang, Sien Hu, Olivia M. Farr, Hoi-chung Leung, Chiang-shan R. LiAbstract:To adapt flexibly to a rapidly changing environment, humans must anticipate conflict and respond to surprising, unexpected events. To this end, the brain estimates upcoming conflict on the basis of prior experience and computes unsigned prediction error (UPE). Although much work implicates catecholamines in cognitive control, little is known about how pharmacological manipulation of catecholamines affects the neural processes underlying conflict anticipation and UPE computation. We addressed this issue by imaging 24 healthy young adults who received a 45 mg oral dose of methylphenidate (MPH) and 62 matched controls who did not receive MPH prior to performing the Stop-Signal Task. We used a Bayesian Dynamic Belief Model to make trial-by-trial estimates of conflict and UPE during Task performance. Replicating previous research, the control group showed anticipation-related activation in the presupplementary motor area and deactivation in the ventromedial prefrontal cortex and parahippocampal gyrus, as well ...
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Individual variation in the neural processes of motor decisions in the stop signal Task: the influence of novelty seeking and harm avoidance personality traits
Brain Structure & Function, 2015Co-Authors: Jianping Hu, Sheng Zhang, Sien Hu, Herta Chao, Chiang-shan R. LiAbstract:Personality traits contribute to variation in human behavior, including the propensity to take risk. Extant work targeted risk-taking processes with an explicit manipulation of reward, but it remains unclear whether personality traits influence simple decisions such as speeded versus delayed responses during cognitive control. We explored this issue in an fMRI study of the stop signal Task, in which participants varied in response time trial by trial, speeding up and risking a stop error or slowing down to avoid errors. Regional brain activations to speeded versus delayed motor responses (risk-taking) were correlated to novelty seeking (NS), harm avoidance (HA) and reward dependence (RD), with age and gender as covariates, in a whole brain regression. At a corrected threshold, the results showed a positive correlation between NS and risk-taking responses in the dorsomedial prefrontal, bilateral orbitofrontal, and frontopolar cortex, and between HA and risk-taking responses in the parahippocampal gyrus and putamen. No regional activations varied with RD. These findings demonstrate that personality traits influence the neural processes of executive control beyond behavioral Tasks that involve explicit monetary reward. The results also speak broadly to the importance of characterizing inter-subject variation in studies of cognition and brain functions.
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Conflict anticipation in alcohol dependence - A model-based fMRI study of stop signal Task.
NeuroImage: Clinical, 2015Co-Authors: Sien Hu, Sheng Zhang, Rajita Sinha, Chiang-shan R. LiAbstract:Background Our previous work characterized altered cerebral activations during cognitive control in individuals with alcohol dependence (AD). A hallmark of cognitive control is the ability to anticipate changes and adjust behavior accordingly. Here, we employed a Bayesian model to describe trial-by-trial anticipation of the stop signal and modeled fMRI signals of conflict anticipation in a stop signal Task. Our goal is to characterize the neural correlates of conflict anticipation and its relationship to response inhibition and alcohol consumption in AD.
Jessica A. Turner - One of the best experts on this subject based on the ideXlab platform.
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Cerebellar Contributions to Proactive and Reactive Control in the Stop Signal Task: A Systematic Review and Meta-Analysis of Functional Magnetic Resonance Imaging Studies
Neuropsychology Review, 2020Co-Authors: Sarah V. Clark, Tricia Z. King, Jessica A. TurnerAbstract:The cerebellum facilitates and modulates cognitive functions using forward and inverse internal models to predict and control behavior, respectively. Despite neuroimaging evidence that regions of the cerebellum are active during executive function (EF) Tasks in general, little is known about the cerebellum’s role in specific EFs and their underlying neural networks. Inhibitory control specifically may be facilitated by cerebellar internal models predicting responses during proactive control (withholding), and controlling responses during reactive control (inhibiting). The stop signal Task (SST) is an inhibitory control Task often used in neuroimaging studies to measure neural responses to both proactive and reactive control. Thus, in this review, we examine evidence for the cerebellum’s role in inhibitory control by reviewing studies of healthy adults that utilized the SST in event-related functional magnetic resonance imaging (fMRI) experiments. Twenty-one studies that demonstrated cerebellar results were eligible for review, including 749 participants, 28 contrasts, and 38 cerebellar clusters. We also performed activation likelihood estimation (ALE) meta-analysis of contrasts derived from reviewed studies. This review illustrates evidence for the cerebellum participating in inhibitory control independent of motor control. Most significant cerebellar clusters were located in the left posterior cerebellum, suggesting that it communicates with the established cortical right-lateralized inhibitory control network. Cerebellar activity was most consistently observed for contrasts that measured proactive control, and ALE analysis confirmed that left Crus I is most likely to be activated in studies of proactive control measuring monitoring and anticipation. Results suggest that the left posterior cerebellum may communicate with right frontal and parietal cortices, using forward models to predict appropriate responses. Reactive control contrasts indicated a possible role for cerebellar regions in enhancing inhibition efficiency through inverse models, but ALE meta-analysis did not confirm this hypothesis. Limitations in the current literature, clinical implications, and directions for future research are discussed.
Russell Schachar - One of the best experts on this subject based on the ideXlab platform.
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Dissociation of response inhibition and performance monitoring in the stop signal Task using event‐related fMRI
Human Brain Mapping, 2020Co-Authors: Andre Chevrier, Michael D. Noseworthy, Russell SchacharAbstract:We examined the neural substrate of motor response inhibition and performance monitoring in the stop signal Task (SST) using event-related functional magnetic resonance imaging (fMRI). The SST involves a go Task and the occasional requirement to stop the go response. We posit that both the go and the stop phases of the SST involve components of inhibition and performance monitoring. The goal of this study was to determine whether inhibition and performance monitoring during go and stop phases of the Task activated different networks. We isolated go-phase activities underlying response withholding, monitoring, and sensorimotor processing and contrasted these with successful inhibition to identify the substrate of response inhibition. Error detection activity was isolated using trials in which a stop signal appeared but the response was executed. These trials were modeled as a hand-specific go trial followed by error processing. Cognitive go-phase processes included response withholding and monitoring and activated right prefrontal and midline networks. Response withdrawal additionally activated right inferior frontal gyrus and basal ganglia (caudate). Error detection invoked by failed inhibition activated dorsal anterior cingulate cortex (dACC) and right middle frontal Brodmann's area 9. Our results confirm that there are distinct aspects of inhibition and performance monitoring functions which come into play at various phases within a given trial of the SST, and that these are separable using fMRI.
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Response Time Adjustment in the Stop Signal Task: Development in Children and Adolescents.
Child development, 2018Co-Authors: Annie Dupuis, Andre Chevrier, Maheshan Indralingam, Jennifer Crosbie, Paul Arnold, Christie L Burton, Russell SchacharAbstract:Adjusting speed to maintain fast and accurate performance is critical to goal-directed behavior. This study examined development of response time adjustments in the stop signal Task in 13,709 individuals aged 6-17 years (49.0% Caucasian) across four trial types: correct and incorrect go, successful (stop-inhibit), and failed (stop-respond) trials. People sped more after correct than incorrect go responses and slowed more after failed than successful stop trials. Greater slowing after stop-respond but less slowing after stop-inhibit trials was associated with better response inhibition. Response time adjustments were evident in children as young as age 6, developed throughout childhood, and plateaued by age 10. Results were consistent with the predictions of the error detection and shifting goal priority hypotheses for adjustments.
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Dissociating Two Stages of Preparation in the Stop Signal Task Using fMRI.
PLOS ONE, 2015Co-Authors: Andre Chevrier, Douglas Cheyne, Simon J. Graham, Russell SchacharAbstract:Often we must balance being prepared to act quickly with being prepared to suddenly stop. The stop signal Task (SST) is widely used to study inhibitory control, and provides a measure of the speed of the stop process that is robust to changes in subjects’ response strategy. Previous studies have shown that preparation affects inhibition. We used fMRI to separate activity that occurs after a brief (500 ms) warning stimulus (warning-phase) from activity that occurs during responses that follow (response-phase). Both of these phases could contribute to the preparedness to stop because they both precede stop signals. Warning stimuli activated posterior networks that signal the need for top-down control, whereas response phases engaged prefrontal and subcortical networks that implement top-down control. Regression analyses revealed that both of these phases affect inhibitory control in different ways. Warning-phase activity in the cerebellum and posterior cingulate predicted stop latency and accuracy, respectively. By contrast, response-phase activity in fronto-temporal areas and left striatum predicted go speed and stop accuracy, in pre-supplementary motor area affected stop accuracy, and in right striatum predicted stop latency and accuracy. The ability to separate hidden contributions to inhibitory control during warning-phases from those during response-phases can aid in the study of models of preparation and inhibitory control, and of disorders marked by poor top-down control.
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Inhibitory control and psychopathology: a meta-analysis of studies using the stop signal Task.
Journal of The International Neuropsychological Society, 2010Co-Authors: Jonathan Lipszyc, Russell SchacharAbstract:The Stop Signal Task (SST) is a measure that has been used widely to assess response inhibition. We conducted a meta-analysis of studies that examined SST performance in patients with various psychiatric disorders to determine the magnitude and generality of deficient inhibition. A five-item instrument was used to assess the methodological quality of studies. We found medium deficits in stop signal reaction time (SSRT), reflecting the speed of the inhibitory process, for attention-deficit hyperactivity disorder (ADHD) (g = 0.62), obsessive compulsive disorder (OCD) (g = 0.77) and schizophrenia (SCZ) (g = 0.69). SSRT was less impaired or normal for anxiety disorder (ANX), autism, major depressive disorder (MDD), oppositional defiant disorder/conduct disorder (ODD/CD), pathological gambling, reading disability (RD), substance dependence, and Tourette syndrome. We observed a large SSRT deficit for comorbid ADHD + RD (g = 0.82). SSRT was less than moderately impaired for ADHD + ANX and ADHD + ODD/CD. Study quality did not significantly affect SSRT across ADHD studies. This confirms an inhibition deficit in ADHD, and suggests that comorbid ADHD has different effects on inhibition in patients with ANX, ODD/CD, and RD. Further studies are needed to firmly establish an inhibition deficit in OCD and SCZ.
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Error detection in the stop signal Task.
NeuroImage, 2010Co-Authors: Andre Chevrier, Russell SchacharAbstract:Previous error detection research has focused on error processing functions in the anterior cingulate cortex or on putative reinforcement learning roles of midbrain dopamine pathways. We studied error detection in 14 healthy adult volunteers using a novel fMRI design in the stop signal Task (SST), a Task which invokes numerous errors in performance and frequent instances of post-error slowing. The imaging design accommodated variability immediately before errors (handedness of response) and immediately after (degree of post-error slowing) using distinct within-trial regressors. This approach revealed a whole-brain view of error detection in a reinforcement-learning pathway. Error detection deactivated the midbrain in the vicinity of dorsal substantia nigra where dopamine neurons originate, and the primary targets of dopamine neurons: dorsal striatum and ventral anterior cingulate. Error detection also deactivated posterior hippocampus, which is highly sensitive to long-term synaptic plasticity effects of dopamine. Errors that led to slowed responses deactivated structures in the reciprocal pathway that are known to exert control over dopamine output, and which have been shown to encode error magnitude: ventral midbrain, ventral striatum, and caudal orbitofrontal cortex. Consistent with the role of these structures in modulating dopamine output, post-error slowing also increased activities in the same structures that deactivated on error detection. These results are consistent with the view that errors deactivate structures that receive input from dopamine neurons, followed by deactivations related to requisite behavioral adjustments in structures that exert control over dopamine output.