The neuropsychopharmacology of action inhibition: cross-species translation of the stop-signal and go/no-go tasks

Neurocognitive effects of transcranial direct current stimulation in obsessive-compulsive disorder: a systematic review

Transcranial direct current stimulation (tDCS) has been used with increasing frequency as a therapeutic tool to alleviate clinical symptoms of obsessive compulsive-disorder (OCD). However, little is known about the effects of tDCS on neurocognitive functioning among OCD patients. The aim of this review was to provide a comprehensive overview of the literature examining the effects of tDCS on specific neurocognitive functions in OCD. A literature search following PRISMA guidelines was conducted on the following databases: PubMed, PsycINFO, Embase, the Cochrane Central Register of Controlled Trials (CENTRAL), the Cumulative Index to Nursing and Allied Health Literature (CINAHL), and Web of Science. The search yielded 4 results: one randomized, sham-controlled study (20 patients), one randomized, controlled, partial crossover trial (12 patients), one open-label study (5 patients), and one randomized, double-blind, sham-controlled, parallel-group trial (37 patients). A total of 51 patients received active tDCS with some diversity in electrode montages targeting the dorsolateral prefrontal cortex, the pre-supplementary motor area, or the orbitofrontal cortex. tDCS was associated with improved decision-making in study 1, enhanced attentional monitoring and response inhibition in study 2, improved executive and inhibitory control in study 3, and reduced attentional bias and improved response inhibition and working memory in study 4. Limitations of this review include its small sample, the absence of a sham group in half of the studies, and the heterogeneity in tDCS parameters. These preliminary results highlight the need for future testing in randomized, sham-controlled trials to examine whether and how tDCS induces relevant cognitive benefits in OCD.

A differential impact of action-effect temporal contiguity on different measures of response inhibition in the Go\No-Go and Stop-signal paradigms

Response inhibition refers to suppressing a prepotent motor response and is often studied and discussed as an act of cognitive control. Much less attention was given to the potential contribution of motor control processes to response inhibition. Accumulated empirical findings show that a perceptual effect temporally contiguous with a response improves motor control performance. In the current study, we followed this work by manipulating action-effect temporal contiguity to enhance motor performance and investigated its impact on response selection and inhibition. In two experiments, we integrated a Go/No-Go (GNGT; Experiment 1) and a Stop-signal (SST; Experiment 2) task with the Effect-Motivation task, previously used to capture the facilitating impact of action-effect temporal contiguity on response times (RTs). Replicating previous findings, RTs were shorter following temporally contiguous compared to Lagged action-effect in Go trials in both the GNGT (Experiment 1) and SST (Experiment 2). Notably, an Immediate action-effect improved response inhibition in the GNGT (Experiment 1) but did not modulate Stop-signal reaction time (SSRT) in the SST (Experiment 2). Unexpectedly, the error rate on Go trials was higher in the Immediate effect condition in Experiment 2. We interpret the findings to suggest that an action's (Immediate) perceptual effect may promote response inhibition performance by enhancing selective association between the Go stimuli and the Go response and not by improving cognitive control ability. The findings also imply that an Immediate action-effect may hamper action control (e.g., by increasing general readiness to respond), at least when action control does not benefit from automatic stimulus-response association.

Cognitive trajectories in longitudinally trained 3xTg-AD mice

Preclinical studies in Alzheimer's disease (AD) often rely on cognitively naïve animal models in cross-sectional designs that can fail to reflect the cognitive exposures across the lifespan and heterogeneous neurobehavioral features observed in humans. To determine whether longitudinal cognitive training may affect cognitive capacities in a well-characterized AD mouse model, 3xTg and wild-type mice (n = 20) were exposed daily to a training variant of the Go-No-Go (GNG) operant task from 3 to 9 months old. At 3, 6, and 9 months, performance on a testing variant of the GNG task and anxiety-like behaviors were measured, while long-term recognition memory was also assessed at 9 months. In general, GNG training improved performance with increasing age across genotypes. At 3 months old, 3xTg mice showed slight deficits in inhibitory control that were accompanied by minor improvements in signal detection and decreased anxiety-like behavior, but these differences did not persist at 6 and 9 months old. At 9 months old, 3xTg mice displayed minor deficits in signal detection, and long-term recognition memory capacity was comparable with wild-type subjects. Our findings indicate that longitudinal cognitive training can render 3xTg mice with cognitive capacities that are on par with their wild-type counterparts, potentially reflecting functional compensation in subjects harboring AD genetic mutations.

Impulsivity in adolescent girls diagnosed with trichotillomania: an evaluation of clinical and neuropsychological characteristics

The aim of this study is to compare the clinical and neuropsychological features of impulsivity in adolescent girls with trichotillomania (TTM) and healthy controls, and to assess the relationships between the severity of TTM and the impulsivity/concomitant symptoms of anxiety and depression. The study sample consisted of 43 adolescent girls who were 12 to 18 years old. The Kiddie-Schedule for Affective Disorders and Schizophrenia for School Age Children-Present and Lifetime Version DSM-5 (K-SADS-PL) was administered to the adolescents and their parents. All of the participants completed a sociodemographic data form, the Revised Children's Anxiety and Depression Scale-Child Version (RCADS-CV), the Barratt Impulsiveness Scale-Brief (BIS-Brief), and the Massachusetts General Hospital Hairpulling Scale (MGH-HPS). The Eriksen Flanker task, the Stop Signal Reaction Time (SSRT) task, the Go/No-Go task, and the Balloon Analog Risk Task (BART) were used to assess behavioral impulsivity. The adolescents with TTM reported higher levels of impulsivity and anxiety/depression symptoms than the healthy controls, and they also performed worse on the behavioral tasks. While there were no relationships between clinical and behavioral impulsivity and TTM severity, social anxiety symptoms were the most important predictor of the severity of TTM. It seems important to better understand the role of impulsivity in the onset and persistence of TTM symptoms in adolescents.

Unravelling the dynamics of response force: Investigating motor restraint and motor cancellation through go/no-go and stop-signal tasks

Prior research has found that the go/no-go (GNG) task primarily reflects participants' motor-restraint process, while the stop-signal task (SST) primarily represents participants' motor-cancellation process. However, traditional binary keyboards used in these experiments are unable to capture the subtleties of sub-threshold response-force dynamics. This has led to the neglect of potential sub-threshold motor-inhibition processes. In two experiments, we explored sub-threshold inhibition by using a custom force-sensitive keyboard to record response force in both GNG and SST. In experiment 1, participants displayed increased response force when correctly rejecting no-go targets in the GNG task compared to the baseline. In addition, they exhibited higher response force in hit trials than in false alarms, revealing engagement of both motor-restraint and motor-cancellation processes in GNG. Initially, participants utilised motor restraint, but if it failed to prevent inappropriate responses, they employed motor cancellation to stop responses before reaching the keypress threshold. In experiment 2, we used participants' average response-force amplitude and response-force latency in SST stop trials to characterise the motor-cancellation process. Average amplitude significantly predicted false-alarm rates in the GNG task, but the relationship between response latency and false-alarm rates was insignificant. We hypothesised that response latency reflects reactive inhibition control in motor cancellation, whereas average amplitude indicates proactive inhibition control. Our findings underscore the complexity of motor inhibition.

Success versus failure in cognitive control: Meta-analytic evidence from neuroimaging studies on error processing

Brain mechanisms of error processing have often been investigated using response interference tasks and focusing on the posterior medial frontal cortex, which is also implicated in resolving response conflict in general. Thereby, the role other brain regions may play has remained undervalued. Here, activation likelihood estimation meta-analyses were used to synthesize the neuroimaging literature on brain activity related to committing errors versus responding successfully in interference tasks and to test for commonalities and differences. The salience network and the temporoparietal junction were commonly recruited irrespective of whether responses were correct or incorrect, pointing towards a general involvement in coping with situations that call for increased cognitive control. The dorsal posterior cingulate cortex, posterior thalamus, and left superior frontal gyrus showed error-specific convergence, which underscores their consistent involvement when performance goals are not met. In contrast, successful responding revealed stronger convergence in the dorsal attention network and lateral prefrontal regions. Underrecruiting these regions in error trials may reflect failures in activating the task-appropriate stimulus-response contingencies necessary for successful response execution.

Possible effects of pair bonds on general cognition: Evidence from shared roles of dopamine

Pair bonding builds on preexisting dopamine connectivity to help form and maintain the bond. The involvement of dopaminergic pathways in pair bonding has stimulated research linking pair bonds to other dopamine-dependent processes, like addiction and social cognition (Burkett & Young, 2012; Yetnikoff, Lavezzi, Reichard, & Zahm, 2014). Less studied is the relationship of pair bonding to non-social cognitive processes. The first half of this review will provide an overview of pair bonding and the role of dopamine within social processes. With a thorough review of the literature, the current study will identify the ways the dopaminergic pathways critical for pair bonding also overlap with cognitive processes. Highlighting dopamine as a key player in pair bonds and non-social cognition will provide evidence that pair bonding can alter general cognitive processes like attention, working memory, cognitive flexibility, and impulse control.

The Effect of Cognitive Behavioral Therapy on Impulsivity in Addictive Disorders: a Narrative Review

Purpose of Review

Impulsivity is considered an important construct in the cycle of addiction, yet the effect of evidence-based treatments on impulsivity is unclear. The goal of this paper was to review the evidence regarding the effect of cognitive behavioral therapy (CBT), one of the most studied psychotherapies for addiction, on measures of impulsivity in addictive disorders.

Recent Findings

There is a robust literature implicating impulsivity as risk factor for development of a range of addictions and poorer treatment outcomes. However, this review identified only four randomized controlled trials evaluating CBT for an addictive behavior that included repeated assessment of impulsivity. All four were studies targeting substance use.

Summary

There is limited evidence that CBT has a direct effect on change in measures of impulsivity among individuals being treated for substance use. Future clinical trials should include repeated measurement of impulsivity to examine CBT's effect on the underlying characteristics of addiction.

When not responding to food changes food value: The role of timing

Establishing behavior change toward appetitive foods can be crucial to improve people's health. Food go/no-go training (GNG), in which people respond to some food items and not to other food items depending on the presentation of a go or no-go cue, is a means to establish behavior change. GNG changes the perceived value of food items and food consumption. After GNG, no-go items are rated as less attractive than go and/or untrained items, an empirical phenomenon called the NoGo-devaluation-effect. This effect is not always found, however. One theory-based explanation for these inconsistent results may be found in the timing of the go and no-go cues, which is also inconsistent across studies. Hence, in the present work we conducted two experiments to examine the possible role of go and no-go cue presentation timing in eliciting the NoGo-devaluation-effect. In Experiment 1, we presented the food items before the presentation of go/no-go cues, whereas we reversed this order in Experiment 2. As predicted, the NoGo-devaluation-effect was obtained in Experiment 1. This effect was absent in Experiment 2. Moreover, recognition memory for stimulus-action contingencies moderated the devaluation effect in Experiment 1, but not in Experiment 2. These results show that NoGo devaluation is dependent on the timing of the NoGo cue, which has theoretical and applied implications for understanding how and when go/no-go training influences food consumption. We propose that the value of food items is updated during go/no-go training to minimize prediction errors, and that this updating process is boosted by attention.

Success versus failure in cognitive control: meta-analytic evidence from neuroimaging studies on error processing

Brain mechanisms of error processing have often been investigated using response interference tasks and focusing on the posterior medial frontal cortex, which is also implicated in resolving response conflict in general. Thereby, the role other brain regions may play has remained undervalued. Here, activation likelihood estimation meta-analyses were used to synthesize the neuroimaging literature on brain activity related to committing errors versus responding successfully in interference tasks and to test for commonalities and differences. The salience network and the temporoparietal junction were commonly recruited irrespective of whether responses were correct or incorrect, pointing towards a general involvement in coping with situations that call for increased cognitive control. The dorsal posterior cingulate cortex, posterior thalamus, and left superior frontal gyrus showed error-specific convergence, which underscores their consistent involvement when performance goals are not met. In contrast, successful responding revealed stronger convergence in the dorsal attention network and lateral prefrontal regions. Underrecruiting these regions in error trials may reflect failures in activating the task-appropriate stimulus-response contingencies necessary for successful response execution.

Early life exposure to high fructose diet induces metabolic dysregulation associated with sex-specific cognitive impairment in adolescent rats

The incidence of adolescent mental health disorders is on the rise. Epidemiological studies suggest that poor nutrition is a significant contributor to this public health crisis, specifically through exposure to high level of dietary sugar, including fructose, during critical periods of development. Previous studies have shown that elevated fructose exposure during adolescence disrupts mental health. Despite these data, it is currently unknown how fructose exposure, specifically during infancy, may impact adolescent mental health. We developed a rat experimental protocol to investigate the effects of fructose exposure during infancy on behavioral, cognitive and metabolic endpoints in adolescence. We found that exposing rats to high fructose from birth to weaning resulted in higher circulating glucose, insulin and leptin levels in adolescence. High fructose during infancy also increased bodyweight, disrupted metabolic homeostasis in the basolateral amygdala (BLA) as indicated by decreased activity of the cellular energy sensor AMPK, and impaired attention and impulsivity in a male-specific manner. This impaired attention observed in adolescent male rats following neonatal fructose exposure was partially rescued by viral-mediated, in vivo expression of a constitutively active form of AMPK in principal neurons of the BLA. Our results suggest that exposure to high level of fructose during infancy may impact adolescent mental health in a male-specific manner and that manipulation of AMPK activity may mitigate this impact.

Use of experimental medicine approaches for the development of novel psychiatric treatments based on orexin receptor modulation

Despite progress in understanding the pathological mechanisms underlying psychiatric disorders, translation from animal models into clinical use remains a significant bottleneck. Preclinical studies have implicated the orexin neuropeptide system as a potential target for psychiatric disorders through its role in regulating emotional, cognitive, and behavioral processes. Clinical studies are investigating orexin modulation in addiction and mood disorders. Here we review performance-outcome measures (POMs) arising from experimental medicine research methods which may show promise as markers of efficacy of orexin receptor modulators in humans. POMs provide objective measures of brain function, complementing patient-reported or clinician-observed symptom evaluation, and aid the translation from preclinical to clinical research. Significant challenges include the development, validation, and operationalization of these measures. We suggest that collaborative networks comprising clinical practitioners, academics, individuals working in the pharmaceutical industry, drug regulators, patients, patient advocacy groups, and other relevant stakeholders may provide infrastructure to facilitate validation of experimental medicine approaches in translational research and in the implementation of these approaches in real-world clinical practice.

Sporadic fasting reduces attentional control without altering overall executive function in a binary classification task

Diets with intermittent fasting are an efficient method for producing clinically significant weight loss and preventing the development of obesity. However, individuals following intermittent fasting must face the difficulty of avoiding eating when experiencing the feeling of hunger. In this study, we investigated which aspects of executive function were affected following a prolonged period of food deprivation in participants that have never previously undergone intermittent fasting. Twenty-six participants with normal weight performed two binary classification tasks (Stop Signal (SST) and Go/NoGo) after either a 12 h fasting or a nonfasting period in separate sessions. We measured their performance in several underlying decision-making processes, such as response inhibition and attentional control. In line with previous studies, our results revealed that decision-making processes to resolve the classification task were unaffected by fasting. Response inhibition, as indexed by the stop signal reaction time in the SST, remained as well unaltered after food deprivation. Rather, we observed a higher error rate in NoGo trials following a fasting period, which was associated with disrupted attentional control. Overall, these results indicate that when a hunger feeling reaches consciousness, it induces deficits over certain aspects of attentional control. Our findings hint at the importance of structured behavioral change strategies to cope with fasting-induced difficulties in attentional control, to help achieve weight management goals through successful self-monitoring of food intake.

Explicit and Implicit Devaluation Effects of Food-Specific Response Inhibition Training

The overvaluation of reward-associated stimuli such as energy-dense foods can drive compulsive eating behaviours, including overeating. Previous research has shown that training individuals to inhibit their responses towards appetitive stimuli can lead to their devaluation, providing a potential avenue for behaviour change. Over two preregistered experiments, we investigated whether training participants to inhibit their responses to specific foods would be effective in reducing their evaluations when these were assessed using both explicit and implicit measures. Participants completed an online session of go/no-go training with energy-dense foods that were consistently associated with either responding (go) or inhibiting a response (no-go). An 'explicit' devaluation effect was expected as a reduction in self-reported liking from pre-to post-training for no-go items compared to both go items and foods that were not presented during training (untrained items). An 'implicit' devaluation effect was then measured using the affective priming paradigm, by comparing differences in reaction times for congruent and incongruent trials (i.e., priming effects) between food primes. Experiment 1 revealed conclusive evidence for small-to-medium devaluation effects both in terms of explicit ratings and priming effects. We also observed that the priming effect for no-go items was close to zero. Experiment 2 successfully replicated most of the preregistered and exploratory outcomes from Experiment 1 except for the priming effect for untrained items. Potential explanations for this discrepancy are discussed but overall, these findings provide further support for a devaluation effect of response inhibition training. To our knowledge, our study provides the first evidence that training-induced devaluation can potentially be captured by affective priming measures, but more research is needed to further assess their sensitivity before they can be used to elucidate the mechanisms of action underlying devaluation effects.

Insomnia attenuates response inhibition: Evidence from Go/NoGo research

OBJECTIVE

Varied cognitive dysfunctions including memory, attention, inputs, processing and filtration have been found in insomnia. Meanwhile, evidence from functional neuroimaging have revealed that the abnormal metabolism in prefrontal cortex was associated with probable deficit of executive function. And in our study, we have detected the response inhibition in insomnia patients by Go/NoGo,an Event-related potentials (ERPs) study, in order to explore the impaired executive function, because response inhibition is a hallmark of executive function.

METHODS

We used polysomnography (PSG) to record such objective PSG parameters. Go/NoGo was performed in sequence, different ERP components have been analyzed such as latency or amplitude between insomnia group and control group. And we used Person correlation coefficient R to make analysis between different ERP components and gender, duration, education, BMI and sleep characteristics.

RESULTS

On the behavioral level, we found a little poor performance insomnia participants. On the electrophysiological level, under Go condition, insomnia participants have prolonged latency and smaller amplitude of N2 or P3. While, under NoGo condition, insomnia participants also have longer latency, but higher amplitude of N2 or P3. another major finding was that different correlation was found between gender,anxiety-depression,duration, education,BMI,sleep characteristics and N2 or P3.

DISCUSSION

Our study has revealed that sleep loss may influence the response inhibition ability in insomnia, not only on behavior level, but also on the electrophysiological level. Abnormal changes in inhibition process or inhibition supervision can be represented as N2/P3 components under Go/No-go condition. Additionally, correlation analysis has been found between gender, anxiety-depression, BMI, education, and sleep structure. Thus, sleep loss attenuates response inhibition and impairs executive function in insomnia participants.

Understanding the roles of central and autonomic activity during sleep in the improvement of working memory and episodic memory

The last decade has seen significant progress in identifying sleep mechanisms that support cognition. Most of these studies focus on the link between electrophysiological events of the central nervous system during sleep and improvements in different cognitive domains, while the dynamic shifts of the autonomic nervous system across sleep have been largely overlooked. Recent studies, however, have identified significant contributions of autonomic inputs during sleep to cognition. Yet, there remain considerable gaps in understanding how central and autonomic systems work together during sleep to facilitate cognitive improvement. In this article we examine the evidence for the independent and interactive roles of central and autonomic activities during sleep and wake in cognitive processing. We specifically focus on the prefrontal-subcortical structures supporting working memory and mechanisms underlying the formation of hippocampal-dependent episodic memory. Our Slow Oscillation Switch Model identifies separate and competing underlying mechanisms supporting the two memory domains at the synaptic, systems, and behavioral levels. We propose that sleep is a competitive arena in which both memory domains vie for limited resources, experimentally demonstrated when boosting one system leads to a functional trade-off in electrophysiological and behavioral outcomes. As these findings inevitably lead to further questions, we suggest areas of future research to better understand how the brain and body interact to support a wide range of cognitive domains during a single sleep episode.

Psychopathy and response inhibition: A meta-analysis of go/no-go and stop signal task performance

Traditional and more modern conceptualizations of psychopathy cite problems with impulse control. However, the extent to which these problems represent a cardinal feature of the disorder has been debated. In this study, we conducted a preregistered systematic review and meta-analysis, searching Embase, Medline, PsycINFO, and PubMed, for studies from inception to January 6th, 2022. We included 21 studies, published between 2009 and 2021, that reported on the relationship of psychopathy with performance on the go/no-go or stop signal task. A multilevel random-effects meta-analysis, including 43 effect sizes from 17 studies (total N = 1394), showed a significant pooled association between psychopathy and response inhibition r = -0.143 (95 % CI: -0.250 to -0.034). The relatively small effect size, although statistically significant, calls in to question the extent to which difficulties in response inhibition should be considered a cardinal feature of psychopathic personality. The strength of the relationship did not significantly differ between non-criminal and criminal samples, gender, task type, tasks with or without an affective component, or by psychopathy trait dimension.

Reduction of symptom after a combined behavioral intervention for reward sensitivity and rash impulsiveness in internet gaming disorder: A comparative study

Impulsivity is both a core symptom and a key psychological mechanism in Internet Gaming Disorder (IGD), and therefore interventions for impulsivity in IGD have both theoretical and practical value. However, previous related interventions only tended to focus on a single factor of impulsivity and achieved inconsistent results. In this study, based on the theory of two-factor model of impulsivity (reward sensitivity and rash impulsiveness), four groups of IGD subjects were recruited to investigate whether there were different effects of single rash impulsiveness or reward sensitivity intervention versus a combined intervention. By comparing the different factors of impulsivity of the four groups before and after a 15-day intervention, the results showed that: (1) compared with the control group, subjects in the Go/No-go training group only had a significantly lower level of rash impulsiveness, subjects in the Stimulus-Response Compatibility (SRC) training group only had a significantly lower level of reward sensitivity, and subjects in the combined training group had significantly lower levels of both impulsivity; (2) among the three intervention groups, only the subjects in the combined training group had significantly lower IGD scores in the follow-up measure. This study indicated that the behavioral training of Go/No-go and SRC were effective in improving rash impulsiveness and reward sensitivity in IGD, respectively, but the intervention effect of the combined training was better than that of the single training.

Noradrenaline and Movement Initiation Disorders in Parkinson’s Disease: A Pharmacological Functional MRI Study with Clonidine

Slowness of movement initiation is a cardinal motor feature of Parkinson’s disease (PD) and is not fully reverted by current dopaminergic treatments. This trouble could be due to the dysfunction of executive processes and, in particular, of inhibitory control of response initiation, a function possibly associated with the noradrenergic (NA) system. The implication of NA in the network supporting proactive inhibition remains to be elucidated using pharmacological protocols. For that purpose, we administered 150 μg of clonidine to 15 healthy subjects and 12 parkinsonian patients in a double-blind, randomized, placebo-controlled design. Proactive inhibition was assessed by means of a Go/noGo task, while pre-stimulus brain activity was measured by event-related functional MRI. Acute reduction in noradrenergic transmission induced by clonidine enhanced difficulties initiating movements reflected by an increase in omission errors and modulated the activity of the anterior node of the proactive inhibitory network (dorsomedial prefrontal and anterior cingulate cortices) in PD patients. We conclude that NA contributes to movement initiation by acting on proactive inhibitory control via the α2-adrenoceptor. We suggest that targeting noradrenergic dysfunction may represent a new treatment approach in some of the movement initiation disorders seen in Parkinson’s disease.

Mind Wandering Impedes Response Inhibition by Affecting the Triggering of the Inhibitory Process

Mind wandering is a state in which our mental focus shifts toward task-unrelated thoughts. Although it is known that mind wandering has a detrimental effect on concurrent task performance (e.g., decreased accuracy), its effect on executive functions is poorly studied. Yet the latter question is relevant to many real-world situations, such as rapid stopping during driving. Here, we studied how mind wandering would affect the requirement to subsequently stop an incipient motor response. In healthy adults, we tested whether mind wandering affected stopping and, if so, which component of stopping was affected: the triggering of the inhibitory brake or the implementation of the brake following triggering. We observed that during mind wandering, stopping latency increased, as did the percentage of trials with failed triggering. Indeed, 67% of the variance of the increase in stopping latency was explained by increased trigger failures. Thus, mind wandering primarily affects stopping by affecting the triggering of the brake.

Cortical dopamine reduces the impact of motivational biases governing automated behaviour

Motivations shape our behaviour: the promise of reward invigorates, while in the face of punishment, we hold back. Abnormalities of motivational processing are implicated in clinical disorders characterised by excessive habits and loss of top-down control, notably substance and behavioural addictions. Striatal and frontal dopamine have been hypothesised to play complementary roles in the respective generation and control of these motivational biases. However, while dopaminergic interventions have indeed been found to modulate motivational biases, these previous pharmacological studies used regionally non-selective pharmacological agents. Here, we tested the hypothesis that frontal dopamine controls the balance between Pavlovian, bias-driven automated responding and instrumentally learned action values. Specifically, we examined whether selective enhancement of cortical dopamine either (i) enables adaptive suppression of Pavlovian control when biases are maladaptive; or (ii) non-specifically modulates the degree of bias-driven automated responding. Healthy individuals (n = 35) received the catechol-o-methyltransferase (COMT) inhibitor tolcapone in a randomised, double-blind, placebo-controlled cross-over design, and completed a motivational Go NoGo task known to elicit motivational biases. In support of hypothesis (ii), tolcapone globally decreased motivational bias. Specifically, tolcapone improved performance on trials where the bias was unhelpful, but impaired performance in bias-congruent conditions. These results indicate a non-selective role for cortical dopamine in the regulation of motivational processes underpinning top-down control over automated behaviour. The findings have direct relevance to understanding neurobiological mechanisms underpinning addiction and obsessive-compulsive disorders, as well as highlighting a potential trans-diagnostic novel mechanism to address such symptoms.

Neurobehavioral maturation of motor response inhibition in adolescence - A narrative review

Immature motor response inhibition in adolescence is considered contributory to adolescent risk-taking and externalizing behaviors. We review studies reporting age-related variations in motor response inhibition and MRI measurements from typically-developing adolescents. Reviewed studies measured response inhibition using one of three tasks-the Stop Signal Task, Go/No-Go, and Antisaccade Task. Task reliability appears to be particularly strong for the SST. Across tasks and study designs, results indicate that inhibitory control improves markedly through early adolescence. The trajectory of change in later adolescence and into young adulthood (i.e., linear or plateauing) varies depending on the task design. Neuroimaging studies identify adult-like response inhibition networks that are involved in behavioral development. The pros and cons of each task are discussed, including recommendations to guide future studies. Ongoing studies in large longitudinal datasets offer opportunities for further exploration of the shape of change in response inhibition, related neural regions, and associations with other affective and cognitive processes to identify potential impacts of motor response inhibition immaturities or individual differences on adolescent risk-taking behaviors.

Effects of Noninvasive Cervical Vagal Nerve Stimulation on Cognitive Performance But Not Brain Activation in Healthy Adults

OBJECTIVES

While preliminary evidence suggests that noninvasive vagal nerve stimulation (nVNS) may enhance cognition, to our knowledge, no study has directly assessed the effects of nVNS on brain function and cognitive performance in healthy individuals. The aim of this study was therefore to assess whether nVNS enhances complex visuospatial problem solving in a normative sample. Functional magnetic resonance imaging (fMRI) was used to examine underlying neural substrates.

MATERIAL AND METHODS

Participants received transcutaneous cervical nVNS (N = 15) or sham (N = 15) stimulation during a 3 T fMRI scan. Stimulation lasted for 2 min at 24 V for nVNS and at 4.5 V for sham. Subjects completed a matrix reasoning (MR) task in the scanner and a forced-choice recognition task outside the scanner. An analysis of variance (ANOVA) was used to assess group differences in cognitive performance. And linear mixed effects (LMEs) regression analysis was used to assess main and interaction effects of experimental groups, level of MR task difficulty, and recall accuracy on changes in blood oxygen level-dependent (BOLD) signal.

RESULTS

Subjects who received nVNS showed higher accuracy for both easy (p = 0.017) and hard (p = 0.013) items of the MR task, slower reaction times for hard items (p = 0.014), and fewer false negative errors during the forced-choice recognition task (p = 0.047). MR task difficulty related to increased activation in frontoparietal regions (p < 0.001). No difference between nVNS and sham stimulation was found on BOLD response during performance of the MR task.

CONCLUSIONS

We hypothesize that nVNS increased attention compared to sham, and that this effect led to enhanced executive functions, and consequently to better performance on visuospatial reasoning and recognition tasks. Results provide initial support that nVNS may be a low-risk, low-cost treatment for cognitive disorders.

A Role for Serotonin in Modulating Opposing Drive and Brake Circuits of Impulsivity

Impulsivity generally refers to a deficit in inhibition, with a focus on understanding the neural circuits which constitute the “brake” on actions and gratification. It is likely that increased impulsivity can arise not only from reduced inhibition, but also from a heightened or exaggerated excitatory “drive.” For example, an action which has more vigor, or is fueled by either increased incentive salience or a stronger action-outcome association, may be harder to inhibit. From this perspective, this review focuses on impulse control as a competition over behavioral output between an initially learned response-reward outcome association, and a subsequently acquired opposing inhibitory association. Our goal is to present a synthesis of research from humans and animal models that supports this dual-systems approach to understanding the behavioral and neural substrates that contribute to impulsivity, with a focus on the neuromodulatory role of serotonin. We review evidence for the role of serotonin signaling in mediating the balance of the “drive” and “brake” circuits. Additionally, we consider parallels of these competing instrumental systems in impulsivity within classical conditioning processes (e.g., extinction) in order to point us to potential behavioral and neural mechanisms that may modulate the competing instrumental associations. Finally, we consider how the balance of these competing associations might contribute to, or be extracted from, our experimental assessments of impulsivity. A careful understanding of the underlying behavioral and circuit level contributions to impulsivity is important for understanding the pathogenesis of increased impulsivity present in a number of psychiatric disorders. Pathological levels of impulsivity in such disorders are likely subserved by deficits in the balance of motivational and inhibitory processes.

Dissociation of impulsive traits by subthalamic metabotropic glutamate receptor 4

Behavioral strategies require gating of premature responses to optimize outcomes. Several brain areas control impulsive actions, but the neuronal basis of natural variation in impulsivity between individuals remains largely unknown. Here, by combining a Go/No-Go behavioral assay with resting-state (rs) functional MRI in mice, we identified the subthalamic nucleus (STN), a known gate for motor control in the basal ganglia, as a major hotspot for trait impulsivity. In vivo recorded STN neural activity encoded impulsive action as a separable state from basic motor control, characterized by decoupled STN/substantia nigra pars reticulata (SNr) mesoscale networks. Optogenetic modulation of STN activity bidirectionally controlled impulsive behavior. Pharmacological and genetic manipulations showed that these impulsive actions are modulated by metabotropic glutamate receptor 4 (mGlu4) function in STN and its coupling to SNr in a behavioral trait-dependent manner, and independently of general motor function. In conclusion, STN circuitry multiplexes motor control and trait impulsivity, which are molecularly dissociated by mGlu4. This provides a potential mechanism for the genetic modulation of impulsive behavior, a clinically relevant predictor for developing psychiatric disorders associated with impulsivity.

Modelling ADHD-Like Phenotypes in Zebrafish

The use of multiple species to model complex human psychiatric disorders, such as ADHD, can give important insights into conserved evolutionary patterns underlying multidomain behaviors (e.g., locomotion, attention, and impulsivity). Here we discuss the advantages and challenges in modelling ADHD-like phenotypes in zebrafish (Danio rerio), a vertebrate species that has been widely used in neuroscience and behavior research. Moreover, multiple behavioral tasks can be used to model the core symptoms of ADHD and its comorbidities. We present a critical review of current ADHD studies in zebrafish, and how this species might be used to accelerate the discovery of new drug treatments for this disorder.

The Effects of Drug Treatments for ADHD in Measures of Cognitive Performance

Based on core symptoms of inattention and deficient impulse control, and the identification of effective pharmacotherapies such as amphetamine (AMP; Adderall^®), methylphenidate (MPH; Ritalin^®), and atomoxetine (ATX; Strattera^®), ADHD is a clinical condition which provides opportunity for translational research. Neuropsychological tests such as the 5-Choice and Continuous Performance Tasks, which measure aspects of attention and impulse control in animals and humans, provide scope for both forward (animal to human) and reverse (human to animal) translation. Rodent studies support pro-attentive effects of AMP and MPH and effectiveness in controlling some forms of impulsive behavior. In contrast, any pro-attentive effects of ATX appear to be less consistent, the most reliable effects of ATX are recorded in tests of impulsivity. These differences may account for AMP and MPH being recognized as first-line treatments for ADHD with a higher efficacy relative to ATX. DSM-5 classifies three "presentations" of ADHD: predominantly inattentive type (ADHD-I), predominantly hyperactive/impulsive type (ADHD-HI), or combined (ADHD-C). Presently, it is unclear whether AMP, MPH, or ATX has differential levels of efficacy across these presentation types. Nonetheless, these studies encourage confidence for the forward translation of NCEs in efforts to identify newer pharmacotherapies for ADHD.

The Stop Signal Task for Measuring Behavioral Inhibition in Mice With Increased Sensitivity and High-Throughput Operation

Ceasing an ongoing motor response requires action cancelation. This is impaired in many pathologies such as attention deficit disorder and schizophrenia. Action cancelation is measured by the stop signal task that estimates how quickly a motor response can be stopped when it is already being executed. Apart from human studies, the stop signal task has been used to investigate neurobiological mechanisms of action cancelation overwhelmingly in rats and only rarely in mice, despite the need for a genetic model approach. Contributing factors to the limited number of mice studies may be the long and laborious training that is necessary and the requirement for a very loud (100 dB) stop signal. We overcame these limitations by employing a fully automated home-cage-based setup. We connected a home-cage to the operant box via a gating mechanism, that allowed individual ID chipped mice to start sessions voluntarily. Furthermore, we added a negative reinforcement consisting of a mild air puff with escape option to the protocol. This specifically improved baseline inhibition to 94% (from 84% with the conventional approach). To measure baseline inhibition the stop is signaled immediately with trial onset thus measuring action restraint rather than action cancelation ability. A high baseline allowed us to measure action cancelation ability with higher sensitivity. Furthermore, our setup allowed us to reduce the intensity of the acoustic stop signal from 100 to 70 dB. We constructed inhibition curves from stop trials with daily adjusted delays to estimate stop signal reaction times (SSRTs). SSRTs (median 88 ms) were lower than reported previously, which we attribute to the observed high baseline inhibition. Our automated training protocol reduced training time by 17% while also promoting minimal experimenter involvement. This sensitive and labor efficient stop signal task procedure should therefore facilitate the investigation of action cancelation pathologies in genetic mouse models.

Neurobiological mechanisms of control in alcohol use disorder - moving towards mechanism-based non-invasive brain stimulation treatments

Alcohol use disorder (AUD) is characterized by excessive habitual drinking and loss of control over alcohol intake despite negative consequences. Both of these aspects foster uncontrolled drinking and high relapse rates in AUD patients. Yet, common interventions mostly focus on the phenomenological level, and prioritize the reduction of craving and withdrawal symptoms. Our review provides a mechanistic understanding of AUD and suggests alternative therapeutic approaches targeting the mechanisms underlying dysfunctional alcohol-related behaviours. Specifically, we explain how repeated drinking fosters the development of rigid drinking habits and is associated with diminished cognitive control. These behavioural and cognitive effects are then functionally related to the neurobiochemical effects of alcohol abuse. We further explain how alterations in fronto-striatal network activity may constitute the neurobiological correlates of these alcohol-related dysfunctions. Finally, we discuss limitations in current pharmacological AUD therapies and suggest non-invasive brain stimulation (like TMS and tDCS interventions) as a potential addition/alternative for modulating the activation of both cortical and subcortical areas to help re-establish the functional balance between controlled and automatic behaviour.

Identifying autism spectrum disorder symptoms using response and gaze behavior during the Go/NoGo game CatChicken

Previous studies have found that Autism Spectrum Disorder (ASD) children scored lower during a Go/No-Go task and faced difficulty focusing their gaze on the speaker's face during a conversation. To date, however, there has not been an adequate study examining children's response and gaze during the Go/No-Go task to distinguish ASD from typical children. We investigated typical and ASD children's gaze modulation when they played a version of the Go/No-Go game. The proposed system represents the Go and the No-Go stimuli as chicken and cat characters, respectively. It tracks children's gaze using an eye tracker mounted on the monitor. Statistically significant between-group differences in spatial and auto-regressive temporal gaze-related features for 21 ASD and 31 typical children suggest that ASD children had more unstable gaze modulation during the test. Using the features that differ significantly as inputs, the AdaBoost meta-learning algorithm attained an accuracy rate of 88.6% in differentiating the ASD subjects from the typical ones.

Prenatal PM2.5 exposure in the second and third trimesters predicts neurocognitive performance at age 9-10 years: A cohort study of Mexico City children

INTRODUCTION

Prenatal exposure to fine particulate matter air pollution (PM2.5) is an important, under-studied risk factor for neurodevelopmental dysfunction. We describe the relationships between prenatal PM2.5 exposure and vigilance and inhibitory control, executive functions related to multiple health outcomes in Mexico City children.

METHODS

We studied 320 children enrolled in Programming Research in Obesity, GRowth, Environment and Social Stressors, a longitudinal birth cohort study in Mexico City. We used a spatio-temporal model to estimate daily prenatal PM2.5 exposure at each participant's residential address. At age 9-10 years, children performed three Go/No-Go tasks, which measure vigilance and inhibitory control ability. We used Latent class analysis (LCA) to classify performance into subgroups that reflected neurocognitive performance and applied multivariate regression and distributed lag regression modeling (DLM) to test overall and time-dependent associations between prenatal PM2.5 exposure and Go/No-Go performance.

RESULTS

LCA detected two Go/No-Go phenotypes: high performers (Class 1) and low performers (Class 2). Predicting odds of Class 1 vs Class 2 membership based on prenatal PM2.5 exposure timing, logistic regression modeling showed that average prenatal PM2.5 exposure in the second and third trimesters correlated with increased odds of membership in low-performance Class 2 (OR = 1.59 (1.16, 2.17), p = 0.004). Additionally, DLM analysis identified a critical window consisting of gestational days 103-268 (second and third trimesters) in which prenatal PM2.5 exposure predicted poorer Go/No-Go performance.

DISCUSSION

Increased prenatal PM2.5 exposure predicted decreased vigilance and inhibitory control at age 9-10 years. These findings highlight the second and third trimesters of gestation as critical windows of PM2.5 exposure for the development of vigilance and inhibitory control in preadolescent children. Because childhood development of vigilance and inhibitory control informs behavior, academic performance, and self-regulation into adulthood, these results may help to describe the relationship of prenatal PM2.5 exposure to long-term health and psychosocial outcomes. The integrative methodology of this study also contributes to a shift towards more holistic analysis.

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

The ability to stop already-initiated actions is a key cognitive control ability. Recent work on human action-stopping has been dominated by two controversial debates. First, the contributions (and neural signatures) of attentional orienting and motor inhibition after stop-signals are near-impossible to disentangle. Second, the timing of purportedly inhibitory (neuro)physiological activity after stop-signals has called into question which neural signatures reflect processes that actually contribute to action-stopping. Here, we propose that a two-stage model of action-stopping - proposed by Schmidt and Berke (2017) based on subcortical rodent recordings - may resolve these controversies. Translating this model to humans, we first argue that attentional orienting and motor inhibition are inseparable because orienting to salient events like stop-signals automatically invokes broad motor inhibition, reflecting a fast-acting, ubiquitous Pause process. We then argue that inhibitory signatures after stop-signals differ in latency because they map onto two sequential stages: the salience-related Pause and a slower, stop-specific Cancel process. We formulate the model, discuss recent supporting evidence in humans, and interpret existing data within its context.

The role of inhibitory control in shoot/don't-shoot decisions

Previous work has demonstrated a link between cognitive abilities, specifically inhibitory control and lethal force decision-making performance. However, many previously used approaches to simulating shoot/don't shoot scenarios have lacked ecological validity. There is a need to investigate how inhibitory control impacts shoot/don't decisions using realistic simulations to better translate the findings to military and law enforcement settings. This study used multiple cognitive control tasks incorporating discrete judgements in go/no-go and stop signal tasks as well as subjective judgements in go/no-go tasks with both colour stimuli and emotional faces. These combined tasks provided a comprehensive evaluation of inhibitory control abilities. To ensure ecological validity in shooting performance, existing military training scenarios incorporated realistic weaponry and aiming behaviours across different shoot/don't-shoot simulations. The inhibitory control battery identified five principal components from the various tasks, including: stopping ability, response speed, emotion detection, colour detection, and emotional biases. These principal inhibitory control components were entered into hierarchical linear regressions with the dependent variables of unintended casualties inflicted and lethal rounds fired, respectively. Stopping ability better predicted the likelihood of inflicting an unintended casualty, whereas response speed better predicted the number of lethal rounds fired. These regression models included baseline metrics of marksmanship and shots fired, which supports a role for inhibitory control above and beyond basic shooting abilities or strategy. These collective findings provide mechanistic support for the relationship between inhibitory control and errors in shoot/don't-shoot decision-making while using realistic military training scenarios.

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.

The role of noradrenaline in cognition and cognitive disorders

Many aspects of cognition and behaviour are regulated by noradrenergic projections to the forebrain originating from the locus coeruleus, acting through alpha and beta adrenoreceptors. Loss of these projections is common in neurodegenerative diseases and contributes to their cognitive and behavioural deficits. We review the evidence for a noradrenergic modulation of cognition in its contribution to Alzheimer's disease, Parkinson's disease and other cognitive disorders. We discuss the advances in human imaging and computational methods that quantify the locus coeruleus and its function in humans, and highlight the potential for new noradrenergic treatment strategies.

Relating Response Inhibition, Brain Connectivity, and Freezing of Gait in People with Parkinson's Disease

OBJECTIVE

Freezing of gait (FoG) in Parkinson's disease (PD) has been associated with response inhibition. However, the relationship between response inhibition, neural dysfunction, and PD remains unclear. We assessed response inhibition and microstructural integrity of brain regions involved in response inhibition [right hemisphere inferior frontal cortex (IFC), bilateral pre-supplementary motor areas (preSMA), and subthalamic nuclei (STN)] in PD subjects with and without FoG and elderly controls.

METHOD

Twenty-one people with PD and FoG (PD-FoG), 18 without FoG (PD-noFoG), and 19 age-matched controls (HC) completed a Stop-Signal Task (SST) and MRI scan. Probabilistic fiber tractography assessed structural integrity (fractional anisotropy, FA) among IFC, preSMA, and STN regions.

RESULTS

Stop-signal performance did not differ between PD and HC, nor between PD-FoG and PD-noFoG. Differences in white matter integrity were observed across groups (.001 < p < .064), but were restricted to PD versus HC groups; no differences in FA were observed between PD-FoG and PD-noFoG (p > .096). Interestingly, worse FoG was associated with higher (better) mean FA in the r-preSMA, (β = .547, p = .015). Microstructural integrity of the r-IFC, r-preSMA, and r-STN tracts correlated with stop-signal performance in HC (p ≤ .019), but not people with PD.

CONCLUSION

These results do not support inefficient response inhibition in PD-FoG. Those with PD exhibited white matter loss in the response inhibition network, but this was not associated with FoG, nor with response inhibition deficits, suggesting FoG-specific neural changes may occur outside the response inhibition network. As shown previously, white matter loss was associated with response inhibition in elderly controls, suggesting PD may disturb this relationship.

Segregating domain-general from emotional context-specific inhibitory control systems - ventral striatum and orbitofrontal cortex serve as emotion-cognition integration hubs

Inhibitory control hierarchically regulates cognitive and emotional systems in the service of adaptive goal-directed behavior across changing task demands and environments. While previous studies convergently determined the contribution of prefrontal-striatal systems to general inhibitory control, findings on the specific circuits that mediate emotional context-specific impact on inhibitory control remained inconclusive. Against this background we combined an evaluated emotional Go/No Go task with fMRI in a large cohort of subjects (N=250) to segregate brain systems and circuits that mediate domain-general from emotion-specific inhibitory control. Particularly during a positive emotional context, behavioral results showed a lower accuracy for No Go trials and a faster response time for Go trials. While the dorsal striatum and lateral frontal regions were involved in inhibitory control irrespective of emotional context, activity in the ventral striatum (VS) and medial orbitofrontal cortex (mOFC) varied as a function of emotional context. On the voxel-wise whole-brain network level, limbic and striatal systems generally exhibited highest changes in global brain connectivity during inhibitory control, while global brain connectivity of the left mOFC was less decreased during emotional contexts. Functional connectivity analyses moreover revealed that negative coupling between the VS with inferior frontal gyrus (IFG)/insula and mOFC varied as a function of emotional context. Together these findings indicate separable domain- general as well as emotional context-specific inhibitory brain systems which specifically encompass the VS and its connections with frontal regions.

Transcutaneous vagus nerve stimulation in patients with attention-deficit/hyperactivity disorder: A viable option?

Individuals with attention-deficit/hyperactivity disorder (ADHD) suffer from a range of cognitive and behavioral problems that severely impair their educational and occupational attainment. ADHD symptoms have been linked to structural and functional changes within and between different brain regions, particularly the prefrontal cortex. At the system level, reduced availability of the neurotransmitters dopamine (DA) and norepinephrine (NE) but also γ-aminobutyric acid (GABA) have been repeatedly demonstrated. Recently, non-invasive brain stimulation (NIBS) techniques have been explored as treatment alternatives to alter dysfunctional activation patterns in specified brain areas or networks. In the current paper, we introduce transcutaneous vagus nerve stimulation (tVNS) as a systemic approach to directly affect NE and GABA neurotransmission. TVNS is a non-drug intervention with low risk and proven efficacy in improving cognitive particularly executive functions. It is easy to apply and therefore well-suited to provide home-based or mobile treatment options allowing a significant increase in treatment intensity and providing easier access to medical care for individuals who are unable to regularly visit a clinician. We describe in detail the underlying mechanisms of tVNS and current fields of application and discuss its potential as an adjuvant treatment for ADHD.

Rationale and validation of a novel mobile application probing motor inhibition: Proof of concept of CALM-IT

Identification of behavioral mechanisms underlying psychopathology is essential for the development of novel targeted therapeutics. However, this work relies on rigorous, time-intensive, clinic-based laboratory research, making it difficult to translate research paradigms into tools that can be used by clinicians in the community. The broad adoption of smartphone technology provides a promising opportunity to bridge the gap between the mechanisms identified in the laboratory and the clinical interventions targeting them in the community. The goal of the current study is to develop a developmentally appropriate, engaging, novel mobile application called CALM-IT that probes a narrow biologically informed process, inhibitory control. We aim to leverage the rigorous and robust methods traditionally used in laboratory settings to validate this novel mechanism-driven but easily disseminatable tool that can be used by clinicians to probe inhibitory control in the community. The development of CALM-IT has significant implications for the ability to screen for inhibitory control deficits in the community by both clinicians and researchers. By facilitating assessment of inhibitory control outside of the laboratory setting, researchers could have access to larger and more diverse samples. Additionally, in the clinical setting, CALM-IT represents a novel clinical screening measure that could be used to determine personalized courses of treatment based on the presence of inhibitory control deficits.

Assessing Impulsivity in Humans and Rodents: Taking the Translational Road

Impulsivity is a multidimensional construct encompassing domains of behavioral inhibition as well as of decision making. It is often adaptive and associated with fast responses, being in that sense physiological. However, abnormal manifestations of impulsive behavior can be observed in contexts of drug abuse and attention-deficit/hyperactivity disorder (ADHD), among others. A number of tools have therefore been devised to assess the different facets of impulsivity in both normal and pathological contexts. In this narrative review, we systematize behavioral and self-reported measures of impulsivity and critically discuss their constructs and limitations, establishing a parallel between assessments in humans and rodents. The first rely on paradigms that are typically designed to assess a specific dimension of impulsivity, within either impulsive action (inability to suppress a prepotent action) or impulsive choice, which implies a decision that weighs the costs and benefits of the options. On the other hand, self-reported measures are performed through questionnaires, allowing assessment of impulsivity dimensions that would be difficult to mimic in an experimental setting (e.g., positive/negative urgency and lack of premeditation) and which are therefore difficult (if not impossible) to measure in rodents.

Mapping local and long-distance resting connectivity markers of TMS-related inhibition reduction in schizophrenia

Short interval intracortical inhibition (SICI) is a biomarker for altered motor inhibition in schizophrenia, but the manner in which distant sites influence the inhibitory cortical-effector response remains elusive. Our study investigated local and long-distance resting state functional connectivity (rsFC) markers of SICI in a sample of N = 23 patients with schizophrenia and N = 29 controls. Local functional connectivity was quantified using regional homogeneity (ReHo) analysis and long-range connectivity was estimated using seed-based rsFC analysis. Direct and indirect effects of connectivity measures on SICI were modeled using mediation analysis. Higher SICI ratios (indicating reduced inhibition) in patients were associated with lower ReHo in the right insula. Follow-up rsFC analyses showed that higher SICI scores (indicating reduced inhibition) were associated with reduced connectivity between right insula and hubs of the corticospinal pathway: sensorimotor cortex and basal ganglia. Mediation analysis supported a model in which the direct effect of local insular connectivity strength on SICI is mediated by the interhemispheric connectivity between insula and left sensorimotor cortex. The broader clinical implications of these findings are discussed with emphasis on how these preliminary findings might inform novel interventions designed to restore or improve SICI in schizophrenia and deepen our understanding of motor inhibitory control and impact of abnormal signaling in motor-inhibitory pathways in schizophrenia.

A meta-analytic investigation of the role of reward on inhibitory control

Contemporary theories predict that inhibitory control (IC) can be improved when rewards are available for successfully inhibiting. In non-clinical samples empirical research has demonstrated some support; however, "null" findings have also been published. The aim of this meta-analysis was to clarify the magnitude of the effect of reward on IC and identify potential moderators. A total of 73 articles (contributing k = 80 studies) were identified from PubMed, PsycInfo, and Scopus, published between 1997 and 2020, using a systematic search strategy. A random effects meta-analysis was performed on effect sizes generated from IC tasks, which included rewarded and non-rewarded inhibition trials. Moderator analyses were conducted on clinical samples (vs "healthy controls"), task type (go/no-go vs stop signal vs Flanker vs Simon vs Stroop vs Anti-saccade), reward type (monetary vs points vs other), and age (adults vs children). The prospect of reward for successful inhibition significantly improved IC (SMD = 0.429, 95% CI = 0.288, 0.570, I² = 96.7%) compared with no reward conditions/groups. This finding was robust against influential cases and outliers. The significant effect was present across all IC tasks. There was no evidence of the effect moderated by type of reward, age, or clinical samples. Moderator analyses did not resolve the considerable heterogeneity. The findings suggest that IC is a transient state that fluctuates in response to motivations driven by reward. Future research might examine the potential of improving IC through rewards as a behavioural intervention.

Brain activation patterns in medicated versus medication-naïve adults with attention-deficit hyperactivity disorder during fMRI tasks of motor inhibition and cognitive switching

Background

Adult-attention-deficit-hyperactive-disorder (ADHD) is often unrecognized condition. FMRI examination along with neuropsychological testing might strengthen the diagnosis. We hypothesized that ADHD-adults with and without medication would show different fMRI pattern compared to healthy controls while testing tasks of motor inhibition and cognitive switching.

Methods

45 subjects in three age-matched groups: (1) controls, (2) ADHD-adults under medication (ADHD+) and (3) medication-naïve adults with ADHD (ADHD−) underwent fMRI and neuropsychological testing. Group analysis and population-based statistics were performed.

Results

DTVP-A, intellectual ability as well as attention capability, visual-perceptual and visual-motor abilities showed no significant differences between the groups. However, fMRI revealed statistically significant differences between the ADHD+, ADHD− and control groups on tasks of motor inhibition and cognitive switching on adults in bilateral fronto-striatal brain regions, inferior fronto-frontal, fronto-cingulate and fronto-parietal networks as well as in the parietal lobe (p < 0.05).

Conclusions

fMRI offers the potential to differentiate between the ADHD+, ADHD− and control groups. FMRI possibly opens a new window for monitoring the therapeutic effect of ADHD medication.

Trial registration

NCT02578342, registered at August 2015 to clinical trial registry (https://ichgcp.net/clinical-trials-registry/NCT02578342).

Electrocortical correlates of impaired motor inhibition and outcome processing are related in high binge-watching

Models posit problematic binge-watching to involve a vicious circle of low motivation for alternative activities, low sensitivity for the consequences of neglected goals, and low self-control. As such, simultaneously impaired feedback and inhibitory functioning might contribute to binge-watching. We tested the hypothesis that blunted feedback-related brain activity is coupled with attenuated inhibitory brain activity in binge-watchers. High (n = 32) and non-binge-watchers (n = 31) performed go/nogo (inhibition) and stop signal (stopping) tasks and a flanker paradigm with performance feedback during electroencephalography. We examined how neural correlates of inhibition and stopping were associated with outcome processing in each group. We assessed the temporospatial relationship using a single-trial regression approach. High binge-watchers, but not non-binge-watchers, who differentiated less between gains and losses at the neural level (feedback-P3b) also recruited less brain activity during both inhibition and stopping (inhibition-P3 and stopping-P3). Exploratory analyses suggested that these relationships were most prominent in high binge-watchers with high loss of control over watching. Main effects of the group in performance or EEG did not emerge. These results suggest a potentially problematic interaction between outcome and inhibitory functions in binge-watchers. Insensitivity to behavioral consequences along with inhibitory impairments may also confer a long-term risk for compulsive watching. Our multi-modal approach may be particularly suited to detect such an underlying risk marker.

Pharmacological enhancing agents targeting cognition in patients with alcohol-induced neurocognitive disorders: A systematic review

Debilitating neurocognitive deficits are seen in alcohol use disorders (AUD) and Wernicke-Korsakoff's syndrome (WKS). These shared characteristics suggest a spectrum of alcohol-induced neurocognitive disorders (AIND). Cognitive pharmacological enhancing agents (CPEA) have been examined in the treatment of other psychiatric disorders, but little is known about the effects of these agents on AINDs. Our aim was to synthesize the evidence for the effectiveness of CPEAs on AINDs. Databases were searched for controlled trials examining CPEAs on AUD, WKS, and alcohol-related dementia (ARD). Eligible studies were included in a qualitative synthesis and a quality assessment was conducted. The search identified 23 studies (4 ≤ ns ≤ 98). Evidence suggests that modafinil may improve executive functions in AUD and ARD, but this effect may only be present in patients with severe deficits. The studies were rated as having a moderate risk of bias. Despite the promising effects of modafinil, small samples and inconsistent evidence deem the results preliminary. More research is warranted examining the effects of transdiagnostic CPEAs on deficits across AINDs.

Inhibitory control dysfunction in parkinsonian impulse control disorders

Impulse control disorders (ICDs) in Parkinson's disease have been associated with dysfunctions in the control of value- or reward-based responding (choice impulsivity) and abnormalities in mesocorticolimbic circuits. The hypothesis that dysfunctions in the control of response inhibition (action impulsivity) also play a role in Parkinson's disease ICDs has recently been raised, but the underlying neural mechanisms have not been probed directly. We used high-resolution EEG recordings from 41 patients with Parkinson's disease with and without ICDs to track the spectral and dynamical signatures of different mechanisms involved in inhibitory control in a simple visuomotor task involving no selection between competing responses and no reward to avoid potential confounds with reward-based decision. Behaviourally, patients with Parkinson's disease with ICDs proved to be more impulsive than those without ICDs. This was associated with decreased beta activity in the precuneus and in a region of the medial frontal cortex centred on the supplementary motor area. The underlying dynamical patterns pinpointed dysfunction of proactive inhibitory control, an executive mechanism intended to gate motor responses in anticipation of stimulation in uncertain contexts. The alteration of the cortical drive of proactive response inhibition in Parkinson's disease ICDs pinpoints the neglected role the precuneus might play in higher order executive functions in coordination with the supplementary motor area, specifically for switching between executive settings. Clinical perspectives are discussed in the light of the non-dopaminergic basis of this function.

Dimensions of Impulsivity in Healthy People, Patients with Borderline Personality Disorder, and Patients with Attention-Deficit/Hyperactivity Disorder

Objective: Impulsivity, observed in patients with various psychiatric disorders, is a heterogeneous construct with different behavioral manifestations. Through confirmatory factor analysis (CFA), this study tests hypotheses about relationships between dimensions of impulsivity measured using personality questionnaires and behavioral tests. Method: The study included 200 healthy people, 40 patients with borderline personality disorder, and 26 patients with attention-deficit/hyperactivity disorder (ADHD) who underwent a comprehensive impulsivity test battery including the Barratt Impulsiveness Scale (BIS), UPPS-P Impulsive Behavior Scale, a Go-NoGo task, a stop-signal task, and a delay discounting task. Results: A CFA model comprising three self-reported and three behavioral latent variables reached a good fit. Both patient groups scored higher in the self-reported dimensions and impulsive choice; only the ADHD patients displayed impaired waiting and stopping impulsivity. Conclusions: Using the developed CFA model, it is possible to describe relations between impulsivity dimensions and show different impulsivity patterns in patient populations.