Successful Response Inhibition Research Articles

Anxiety may alter the role of fronto-striatal circuitry in adolescent risky decision-making

BackgroundAnxiety disorders often emerge in adolescence and are associated with risk aversion. Risk aversion conflicts with the typical adolescent approach-motivated phenotype and can interfere with learning and contribute to symptom maintenance. MethodsWe investigated the neural and behavioral correlates of risk avoidance in a diverse sample of adolescents (N = 137; MAge = 11.3; 34.3 % white, 22.1 % Latino, 20 % Asian, 14.3 % Black, 9.3 % Mixed Race) as they completed a task involving risky decision-making and response inhibition during fMRI. Voluntary cautious choice was compared to successful response inhibition to isolate the neural systems underlying the decision to avoid a risk and identify their relation to risk-taking and anxiety in adolescents. ResultsAnxious adolescents self-reported more avoidance but demonstrated normative risk-taking on the laboratory task. Interestingly, they responded quickly during response inhibition but took longer to decide in the face of risk. All youth showed widespread recruitment of decision-making and salience network regions when deciding to avoid risk. The neural mechanisms driving avoidance differed based on anxiety such that left inferior frontal gyrus (IFG) activation was linked to risk avoidance in adolescents with low anxiety and risk-taking in anxious adolescents, while striatal connectivity was linked to risk avoidance in anxious adolescents and risk-taking in those with low anxiety. LimitationsThis work is cross-sectional and therefore cannot speak to causality or directionality of effects. ConclusionsThese results suggest that the neural mechanisms contributing to adolescent risk-taking may function to promote avoidance in anxious youth, increasing vulnerability to maladaptive avoidance and further anxiety development.

The effects of age bias on neural correlates of successful and unsuccessful response inhibition in younger and older adults

Facilitating communication between generations has become increasingly important. However, individuals often demonstrate a preference for their own age group, which can impact social interactions, and such bias in young adults even extends to inhibitory control. To assess whether older adults also experience this phenomenon, a group of younger and older adults completed a Go/NoGo task incorporating young and old faces, while undergoing functional magnetic resonance imaging. Within the networks subserving successful and unsuccessful response inhibition, patterns of activity demonstrated distinct neural age bias effects in each age group. During successful inhibition, the older adult group demonstrated significantly increased activity to other-age faces, whereas unsuccessful inhibition in the younger group produced significantly enhanced activity to other-age faces. Consequently, the findings of the study confirm that neural responses to successful and unsuccessful inhibition can be contingent on the stimulus-specific attribute of age in both younger and older adults. These findings have important implications in regard to minimizing the emergence of negative consequences, such as ageism, as a result of related implicit biases.

Prepared to stop: how sense of agency in a preceding trial modulates inhibitory control in the current trial.

Feeling in control of actions and events can enhance motivation for further actions. How this sense of agency (SoA) in fact influences flexible motor control remains poorly understood. Here, we investigated the effect of SoA on subsequent response inhibition in a modified go/no-go task with EEG recordings. We manipulated participants' SoA by varying the presence, predictability, and emotional valence of a visual outcome for a given motor action. When participants unexpectedly did not receive any visible outcome following their action on trial n-1, they exhibited slower responses and lower hit rates to the go signal but higher rates of successful inhibition to the no-go signal on trial n, regardless of the emotional valence of the expected action outcome. Furthermore, enhanced inhibitory tendencies were accompanied by reduced N2 and P3 amplitudes, midfrontal theta power, and theta synchronization between midfrontal and medial to parietal areas, indicating that less top-down control is required for successful response inhibition on trial n after experiencing low SoA on trial n-1. These findings suggest that feeling less in control in a preceding trial makes it easier to implement inhibitory control in the current trial, thereby providing new insights into the role of SoA in goal-directed behavior.

The effectiveness of a school mindfulness-based intervention on the neural correlates of inhibitory control in children at risk: A randomized control trial.

Interest in the applications of mindfulness practice in education is growing in the scientific community. Recent research has shown that mindfulness practice in schools may be beneficial for executive functions (EFs) which are abilities crucial for healthy development. The study of the effects of mindfulness practices on children's neural correlates of EFs, particularly inhibitory control, may provide relevant information about the impact and mechanisms of mindfulness-based interventions (MBIs) in children. The aim of the present study was to investigate the effects of a MBI in elementary school children on the neural correlates of inhibitory control via a randomized controlled trial. Children from two 4th grade classrooms and two 5th grade classrooms located in a school identified as having low socioeconomic status in Santiago de Chile were randomly assigned to either receive a MBI or serve as active controls and receive a social skills program. Both before and after the interventions, electroencephalographic activity was recorded during a modified version of the Go/Nogo task in a subsample of children in each group. Additionally, teachers completed questionnaires of students' EFs and students completed self-report measures. Results revealed increases in EFs assessed by questionnaires together with improved P3 amplitude associated with successful response inhibition in children who received the MBI compared to active controls. These results contribute to the understanding of the ways in which mindfulness practices can promote the development of inhibitory control together with EF improvement, factors identified as critical for children's social and emotional development and positive mental health. RESEARCH HIGHLIGHTS: This study investigated the effects of a mindfulness-based intervention in children from a low socioeconomic status school on neural correlates of EFs. Children performed a Go/Nogo task while electroencephalographic activity was recorded and completed questionnaires before and after a MBI or an active control program. Improvements in EFs assessed by questionnaires together with an increased Nogo-P3 activity associated with successful inhibition in children who received the MBI were found. The results could contribute to understand how mindfulness practice can promote the development of inhibitory control in children from vulnerable populations.

Structural and functional variations in the prefrontal cortex are associated with learning in pre-adolescent common marmosets (Callithrix jacchus)

There is substantial evidence linking the prefrontal cortex (PFC) to a variety of cognitive abilities, with adolescence being a critical period in its development. In the current study, we investigated the neural basis of differences in learning in pre-adolescent common marmosets. At 8 months old, marmosets were given anatomical and resting state MRI scans (n = 24). At 9 months old, association learning and inhibitory control was tested using a ‘go/no go’ visual discrimination (VD) task. Marmosets were grouped into ‘learners’ (n = 12) and “non-learners” (n = 12), and associations between cognitive performance and sub-regional PFC volumes, as well as PFC connectivity patterns, were investigated. “Learners” had significantly (p < 0.05) larger volumes of areas 11, 25, 47 and 32 than ‘non-learners’, although ‘non-learners’ had significantly larger volumes of areas 24a and 8 v than “learners”. There was also a significant correlation between average % correct responses to the ‘punished’ stimulus and volume of area 47. Further, ‘non-learners’ had significantly greater global PFC connections, as well as significantly greater numbers of connections between the PFC and basal ganglia, cerebellum and hippocampus, compared to ‘learners’. These results suggest that larger sub-regions of the orbitofrontal cortex and ventromedial PFC, as well more refined PFC connectivity patterns to other brain regions associated with learning, may be important in successful response inhibition. This study therefore offers new information on the neurodevelopment of individual differences in cognition during pre-adolescence in non-human primates.

Perceptual Uncertainty Alternates Top-down and Bottom-up Fronto-Temporal Network Signaling during Response Inhibition.

Response inhibition is a primary executive control function that allows the withholding of inappropriate responses, and requires appropriate perception of the external environment to achieve a behavioral goal. It remains unclear, however, how response inhibition is achieved when goal-relevant information involves perceptual uncertainty. Twenty-six human participants of both sexes performed a go/no-go task where visually presented random-dot motion stimuli involved perceptual uncertainties. The right inferior frontal cortex (rIFC) was involved in response inhibition, and the middle temporal (MT) region showed greater activity when dot motions involved less uncertainty. A neocortical temporal region in the superior temporal sulcus (STS) specifically showed greater activity during response inhibition in more perceptually certain trials. In this STS region, activity was greater when response inhibition was successful than when it failed. Directional effective connectivity analysis revealed that, in more coherent trials, the MT and STS regions showed enhanced connectivity to the rIFC, whereas in less coherent trials, the signal direction was reversed. These results suggest that a reversible fronto-temporal functional network guides response inhibition and perceptual decision-making under perceptual uncertainty, and in this network, perceptual information in the MT is converted to control information in the rIFC via STS, enabling achievement of response inhibition.SIGNIFICANCE STATEMENT Response inhibition refers to withholding inappropriate behavior and is important for achieving goals. Often, however, decision must be made based on limited environmental evidence. We showed that successful response inhibition is guided by a neocortical temporal region that plays a hub role in converting perceived information coded in a posterior temporal region to control information coded in the PFC. Interestingly, when a perceived stimulus becomes more uncertain, the PFC supplements stimulus encoding in the temporal regions. Our results highlight fronto-temporal mechanisms of response inhibition in which conversion of stimulus-control information is regulated based on the uncertainty of environmental evidence.

The effects of age-bias on neural correlates of successful and unsuccessful response inhibition

Response inhibition is important for adherence to social norms, especially when norms conflict with biases based on one’s social identity. While previous studies have shown that in-group bias generally modulates neural activity related to stimulus appraisal, it is unclear whether and how an in-group bias based on age affects neural information processing during response inhibition. To assess this potential influence, young adults completed a Go/NoGo task incorporating younger face (in-group) and older face (out-group) stimuli while undergoing functional magnetic resonance imaging (fMRI). Our results replicated previous findings by demonstrating higher accuracy in successful Go compared to NoGo trials, as well as the engagement of nodes of the response inhibition network during successful response inhibition, and brain regions comprising the salience network during unsuccessful response inhibition. Importantly, despite a lack of behavioural differences, our results showed that younger and older face stimuli modulated activity in the response inhibition and salience networks during successful and unsuccessful inhibition, respectively. Interestingly, these effects were not uniform across networks. During successful response inhibition, in-group stimuli increased activity in medial prefrontal cortex and temporo-parietal junction, whereas out-group stimuli more strongly engaged pre-supplemental motor area. During unsuccessful response inhibition, in-group stimuli increased activity in posterior insula, whereas out-group stimuli more strongly engaged angular gyrus and intraparietal sulcus. Consequently, the results infer the presence of an age-bias effect in the context of inhibitory control, which has substantial implications for future experimental design and may also provide the means of investigating the neural correlates of implicit beliefs that contribute to ageism.

Alcohol-related stimuli modulate functional connectivity during response inhibition in young binge drinkers.

Binge drinking is a pattern of intermittent excessive alcohol consumption that is highly prevalent in young people. Neurocognitive dual-process models have described substance abuse and adolescence risk behaviours as the result of an imbalance between an overactivated affective-automatic system (related to motivational processing) and damaged and/or immature reflective system (related to cognitive control abilities). Previous studies have evaluated the reflective system of binge drinkers (BDs) through neutral response inhibition tasks and have reported anomalies in theta (4-8 Hz) and beta (12-30 Hz) bands. The present study aimed to investigate the influence of the motivational value of alcohol-related stimuli on brain functional networks devoted to response inhibition in young BDs. Sixty eight BDs and 78 control participants performed a beverage Go/NoGo task while undergoing electrophysiological recording. Whole cortical brain functional connectivity (FC) was evaluated during successful response inhibition trials (NoGo). BDs exhibited fast-beta and theta hyperconnectivity in regions related to cognitive control. These responses were modulated differently depending on the motivational content of the stimuli. The increased salience of alcohol-related stimuli may lead to overactivation of the affective-automatic system in BDs, and compensatory neural resources of the reflective system will thus be required during response inhibition. In BDs, inhibition of the response to alcohol stimuli may require higher theta FC to facilitate integration of information related to the task goal (withholding a response), while during inhibition of the response to no-alcoholic stimuli, higher fast-beta FC would allow to apply top-down inhibitory control of the information related to the prepotent response.

Uncontrolled eating in healthy women has limited influence on food cue reactivity and food-related inhibitory control

Uncontrolled eating—in the general population—is characterized by overeating, hedonic hunger and being drawn towards palatable foods. Theoretically, it is the result of a strong food reward signal in relation to a poor ability to exert inhibitory control. How food consumption influences inhibitory control and food cue sensitivity, and how this relates to the continued urge to eat, remains unclear. We used fMRI in order to investigate the neural mechanism underlying food cue reactivity and food-specific response inhibition (go-nogo task), by comparing women reporting high (n = 21) versus low/average (n = 19) uncontrolled eating across two sessions: during an inter-meal state and after consumption of a high-caloric snack. We found no effects of individual differences in uncontrolled eating, food consumption, nor their interaction on food cue reactivity. Differences in uncontrolled eating and food consumption did interact in modulating activity in an occipital-parietal network, extending from left lateral superior occipital cortex to visual cortex, cuneal cortex, and precuneus during response inhibition of non-food stimuli, areas previously associated with successful nogo-vs. go-trials. Yet, behavioural performance on the go-nogo task was not modulated by uncontrolled eating nor food consumption. Women with a low/average tendency for uncontrolled eating may need more cognitive resources to support successful response inhibition of non-food stimuli during food ‘go’ blocks in an inter-meal state, whereas women with a high tendency for uncontrolled eating showed this after food consumption. However, considering current and previous findings, it seems that individual differences in uncontrolled eating in healthy women have only limited influence on food cue reactivity and food-related inhibitory control.

Attenuated neuronal and autonomic responses during error processing in anorexia nervosa.

IntroductionAnorexia nervosa (AN) is a severe psychiatric illness with alarming mortality rates. Nevertheless, despite former and recent research results, the etiology of AN is still poorly understood. Of particular interest is that, despite exaggerated response control and increased perfectionism scores, patients with AN seem not to perform better that those unaffected in tasks that require inhibitory control. One reason might be aberrant processing of errors. The objective of our study was thus to obtain further insight into the pathopsychology of AN. We were particularly interested in neuronal and autonomic responses during error processing and their association with behavior.MethodsWe analyzed 16 acute patients suffering from restrictive type AN and 21 healthy controls using functional magnetic resonance imaging (fMRI) with simultaneous physiological recordings during a Go/Nogo response inhibition task. Data were corrected for noise due to cardiac and respiratory influence.ResultsPatients and controls had similarly successful response inhibition in Nogo trials. However, in failed Nogo trials, controls had significantly greater skin conductance responses (SCR) than in correct Nogo trials. Patients did not exhibit elevated SCR to errors. Furthermore, we found significantly increased neuronal responses, especially in the amygdala and hippocampus, in controls compared to patients during error trials. We also found significant positive correlations in controls but not in patients between Nogo performance and activation in the salience network core regions after errors.ConclusionAcute restrictive type AN patients seem to lack neuronal and autonomic responses to errors that might impede a flexible behavior adaption.

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.

Response Inhibition Circuit Dysregulation in Substance Use Disorders Identified With Event-Related Potential-Derived Functional Connectivity

Dysregulated region-to-region activity in brain circuits that underlie successful response inhibition is common among substance use disorders (SUDs). Specific to response inhibition is the circuit (i.e., functional connectivity [FC]) between the anterior cingulate cortex (ACC) and bi-lateral dorsolateral prefrontal cortex (dlPFC), often measured with functional magnetic resonance imaging (fMRI). Inter-Channel Phase Synchrony (ICPS) analysis in the theta frequency range is a novel technique to identify FC from event-related potentials (ERPs).

Evoked Potentials Differentiate Developmental Coordination Disorder From Attention-Deficit/Hyperactivity Disorder in a Stop-Signal Task: A Pilot Study.

Developmental Coordination Disorder and Attention-Deficit/Hyperactivity Disorder are unique neurodevelopmental disorders with overlaps in executive functions and motor control. The conditions co-occur in up to 50% of cases, raising questions of the pathological mechanisms of DCD versus ADHD. Few studies have examined these overlaps in adults with DCD and/or ADHD. Therefore, to provide insights about executive functions and motor control between adults with DCD, ADHD, both conditions (DCD + ADHD), or typically developed controls, this study used a stop-signal task and parallel EEG measurement. We assessed executive performance via go accuracy and go reaction time, as well as motor response inhibition via stop-signal reaction time. This was complemented with analysis of event-related potentials (ERPs). Based on existing investigations of adults with DCD or ADHD, we expected (1) groups would not differ in behavioral performance on stop and go trials, but (2) differences in ERPs, particularly in components N200 (index of cognitive control) and P300 (index of attention and inhibition) would be evident. The sample included N = 50 adults with DCD (n = 12), ADHD (n = 9), DCD + ADHD (n = 7), and control participants (n = 22). We replicated that there were no between-group differences for behavioral-level executive performance and motor response inhibition. However, on a physiological level, ERP components N200 and P300 differed between groups, particularly during successful response inhibition. These ERPs reflect potential endophenotypic differences not evident in overt behavior of participants with ADHD and/or DCD. This suggests a disorder specific employment of inhibition or general executive functions in groups of adults with DCD, DCD + ADHD, ADHD, or control participants.

Alcohol-related context modulates neural correlates of inhibitory control in alcohol dependent patients: Preliminary data from an fMRI study using an alcohol-related Go/NoGo-task

Alcohol use disorder (AUD) is characterized by both impaired inhibitory control and heightened cue reactivity, including enhanced craving and drinking urges in response to alcohol-related stimuli. The interaction between these two mechanisms is thought to be crucial in the maintenance of addiction and relapse. The present study used a newly developed alcohol-related Go/NoGo-task to investigate how exposure to alcohol-related cues affects neural processing of inhibitory control in subjects with AUD.Functional magnetic resonance imaging (fMRI) was recorded during performance of a Go/NoGo task, which incorporated alcohol-related and neutral stimuli as Go and NoGo trials in abstinent AUD patients and healthy controls (HC).AUD patients exhibited increased activation of a fronto-striatal-parietal network during successful response inhibition relative to HC. Within the AUD group, activation for alcohol-related (relative to neutral) inhibition was enhanced in regions including bilateral anterior cingulate cortex (ACC), right medial frontal and precentral gyri, and right putamen. Activation differences in the right ACC increased with subjective craving.These preliminary findings suggest that AUD patients need to recruit enhanced neuronal resources for successful inhibition. In parts of the inhibitory network, this hyperactivation is enhanced when inhibition takes place in an alcohol-related context. Activation in the ACC increased stronger in patients experiencing high craving, possibly because of an enhanced conflict.The task introduced here thus allows to investigate neural processing of alcohol-related inhibition in an AUD sample. The preliminary results suggest that exposure to alcohol-related cues intensifies the demand on an already challenged inhibitory system in recently abstinent patients with AUD.

Adolescent sex differences in cortico-subcortical functional connectivity during response inhibition.

Numerous lines of evidence have shown that cognitive processes engaged during response inhibition tasks are associated with structure and functional integration of regions within fronto-parietal networks. However, while prior studies have started to characterize how intrinsic connectivity during resting state differs between boys and girls, comparatively less is known about how functional connectivity differs between males and females when brain function is exogenously driven by the processing demands of typical Go/No-Go tasks that assess both response inhibition and error processing. The purpose of this study was to characterize adolescent sex differences and possible changes in sexually dimorphic regional functional connectivity across adolescent development in both cortical and subcortical brain connectivity elicited during a visual Go/No-Go task. A total of 130 healthy adolescents (ages 12-25 years) performed a Go/No-Go task during functional magnetic resonance imaging. High model-order group independent component analysis was used to characterize whole-brain network functional connectivity during response inhibition and then a univariate technique used to evaluate differences related to sex and age. As predicted and similar to previously described findings from non-task-driven resting state connectivity studies, functional connectivity sex differences were observed in several subcortical regions, including the amygdala, caudate, thalamus, and cortical regions, including inferior frontal gyrus engaged most strongly during successful response inhibition and/or error processing. Importantly, adolescent boys and girls exhibited different normative profiles of age-related changes in several default mode networks of regions and anterior cingulate cortex. These results suggest that cortical-subcortical functional networks supporting response inhibition operate differently between sexes during adolescence.

Binge drinking is associated with attenuated frontal and parietal activation during successful response inhibition in fearful context.

Binge drinking is associated with increased impulsivity and altered emotional processing. This study investigated, in a group of university students who differed in their level of binge drinking, whether the ability to inhibit a pre-potent response and to delay gratification is disrupted in the presence of emotional context. We further tested whether functional connectivity within intrinsic resting-state networks was associated with alcohol use. Higher incidence of binge drinking was associated with enhanced activation of the lateral occipital cortex, angular gyrus, the left frontal pole during successful response inhibition irrespective of emotional context. This observation suggests a compensatory mechanism. However, higher binge drinking attenuated frontal and parietal activation during successful response inhibition within a fearful context, indicating the selective emotional facilitation of inhibitory control. Similarly, higher binge drinking was associated with attenuated frontopolar activation when choosing a delayed reward over an immediate reward within the fearful, relative to the neutral, context. Resting-state functional data analysis revealed that binge drinking decreased coupling between the right supramarginal gyrus and Ventral Attention Network, indicating alcohol-associated disruption of functional connectivity within brain substrates directing attention. Together, our results suggest that binge drinking makes response inhibition more effortful, yet emotional (more arousing) contexts may mitigate this; disrupted functional connectivity between regions underlying adaptive attentional control, is a likely mechanism underlying these response inhibition effects associated with binge drinking.

Towards response success prediction: An integrative approach using high-resolution fMRI and autonomic indices

Brainstem and midbrain nuclei are closely linked to effective cognitive performance and autonomic function. In the present study, we aimed to investigate indices of successful and unsuccessful response inhibition paying particular attention to the interplay between locus coeruleus (LC), ventral tegmental area (VTA)/substantia nigra (SN) and, most importantly, peripheral markers. We aimed to get insight in the predictive value of neural and physiological signals in response inhibition.A total of 35 healthy controls were recruited from the local community and a typical task of behavioral response inhibition (Go/No-Go paradigm) was applied. We used high-resolution fMRI, advanced brainstem analyses and specifically corrected for respiratory signal and cardiac noise.Our main results characterize specific neural activation patterns during successful and unsuccessful response inhibition especially comprising the anterior cingulate as well as the medial and lateral prefrontal cortex. A significant activation of the dopaminergic nuclei (VTA/SN) was found during error processing, but not during response inhibition. Most remarkably, specific neural activation patterns (i.e., dorsal anterior cingulate cortex) as well as accompanying autonomic indices (i.e., skin conductance response (SCR)) were identified to hold predictive information on an individual's performance.In summary, the importance of the VTA/SN during error processing was shown. Furthermore, autonomic indices and specific neural activation patterns may contain valuable information to predict task performance.

Response selection codes in neurophysiological data predict conjoint effects of controlled and automatic processes during response inhibition.

The inhibition of prepotent responses is a requirement for goal-directed behavior and several factors determine corresponding successful response inhibition processes. One factor relates to the degree of automaticity of pre-potent response tendencies and another factor relates to the degree of cognitive control that is exerted during response inhibition. However, both factors can conjointly modulate inhibitory control. Cognitive theoretical concepts suggest that codings of stimulus-response translations may underlie such conjoint effects. Yet, it is unclear in how far such specific codes, as assumed in cognitive psychological concepts, are evident in neurophysiological processes and whether there are specific functional neuroanatomical structures associated with the processing of such codes. Applying a temporal decomposition method of EEG data in combination with source localization methods we show that there are different, intermingled codes (i.e., "stimulus codes" and "response selection codes") at the neurophysiological level during conjoint effects of "automatic" and "controlled" processes in response inhibition. Importantly, only "response selection codes" predict behavioral performance, and are subject to conjoint modulations by "automatic" and "controlled" processes. These modulations are associated with inferior and superior parietal areas (BA40/BA7), possibly reflecting an updating of internal representations when information is complex and probably difficult to categorize, but essential for behavioral control. Codes proposed by cognitive, psychological concepts seem to have a neurophysiological analogue that fits into current views on functions of inferior and superior parietal regions.

Striatal activity during reactive inhibition is related to the expectation of stop-signals

Successful response inhibition relies on the suppression of motor cortex activity. The striatum has previously been linked to motor cortex suppression during the act of inhibition (reactive), but activation was also seen during anticipation of stop signals (proactive). More specifically, striatal activation increased with a higher stop probability. Using functional magnetic resonance imaging with specific regions of interest, we investigate for the first time whether activation in the striatum during reactive inhibition is related to previously formed expectations. We used a modified stop-signal response task in which subjects were asked trial by trial, after being presented a stop-signal probability cue, whether they actually expected a stop to occur. This enabled us to investigate the subjective expectation of a stop signal during each trial. We found that striatal activity during reactive inhibition was higher when subjects expected stop signals. These results help explain conflicting findings of previous studies on the association between striatal activation and inhibition, since we demonstrate a crucial role of the subjects’ expectation of a stop signal and thus their ability to prepare for a stop in advance. In conclusion, the current results show for the first time that striatal contributions to reactive response inhibition are, in part, related to subjective anticipation.

Impact of a Common Genetic Variation Associated With Putamen Volume on Neural Mechanisms of Attention-Deficit/Hyperactivity Disorder

In a recent genomewide association study of subcortical brain volumes, a common genetic variation at rs945270 was identified as having the strongest effect onputamen volume, a brain measurement linked to familial risk for attention-deficit/hyperactivity disorder (ADHD). To determine whether rs945270 might be a genetic determinant of ADHD, its effects on ADHD-related symptoms and neural mechanisms of ADHD, such as response inhibition and reward sensitivity, were explored. A large population sample of 1,834 14-year-old adolescents was used to test the effects of rs945270 on ADHD symptoms assessed through the Strengths and Difficulties Questionnaire and region-of-interest analyses of putamen activation by functional magnetic resonance imaging using the stop signal and monetary incentive delay tasks, assessing response inhibition and reward sensitivity, respectively. There was a significant link between rs945270 and ADHD symptom scores, with the C allele associated with lower symptom scores, most notably hyperactivity. In addition, there were sex-specific effects of this variant on the brain. In boys, the C allele was associated with lower putamen activity during successful response inhibition, a brain response that was not associated withADHD symptoms. In girls, putamen activation during reward anticipation increased with the number of Calleles, most significantly in the right putamen. Remarkably, right putamen activation during reward anticipation tended to negatively correlate with ADHD symptoms. These results indicate that rs945270 might contribute to the genetic risk of ADHD partly through itseffects on hyperactivity and reward processing in girls.