Interacting sources of interference during sensorimotor integration processes

EEG tensor decomposition delineates neurophysiological principles underlying conflict-modulated action restraint and action cancellation

Executive functions are essential for adaptive behavior. One executive function is the so-called 'interference control' or conflict monitoring another one is inhibitory control (i.e., action restraint and action cancelation). Recent evidence suggests an interplay of these processes, which is conceptually relevant given that newer conceptual frameworks imply that nominally different action/response control processes are explainable by a small set of cognitive and neurophysiological processes. The existence of such overarching neural principles has as yet not directly been examined. In the current study, we therefore use EEG tensor decomposition methods, to look into possible common neurophysiological signatures underlying conflict-modulated action restraint and action cancelation as mechanism underlying response inhibition. We show how conflicts differentially modulate action restraint and action cancelation processes and delineate common and distinct neural processes underlying this interplay. Concerning the spatial information modulations are similar in terms of an importance of processes reflected by parieto-occipital electrodes, suggesting that attentional selection processes play a role. Especially theta and alpha activity seem to play important roles. The data also show that tensor decomposition is sensitive to the manner of task implementation, thereby suggesting that switch probability/transitional probabilities should be taken into consideration when choosing tensor decomposition as analysis method. The study provides a blueprint of how to use tensor decomposition methods to delineate common and distinct neural mechanisms underlying action control functions using EEG data.

Interactions of catecholamines and GABA+ in cognitive control: Insights from EEG and 1H-MRS

Catecholamines and amino acid transmitter systems are known to interact, the exact links and their impact on cognitive control functions have however remained unclear. Using a multi-modal imaging approach combining EEG and proton-magnetic resonance spectroscopy (1H-MRS), we investigated the effect of different degrees of pharmacological catecholaminergic enhancement onto theta band activity (TBA) as a measure of interference control during response inhibition and execution. It was central to our study to evaluate the predictive impact of in-vivo baseline GABA+ concentrations in the striatum, the anterior cingulate cortex (ACC) and the supplemental motor area (SMA) of healthy adults under varying degrees of methylphenidate (MPH) stimulation. We provide evidence for a predictive interrelation of baseline GABA+ concentrations in cognitive control relevant brain areas onto task-induced TBA during response control stimulated with MPH. Baseline GABA+ concentrations in the ACC, the striatum, and the SMA had a differential impact on predicting interference control-related TBA in response execution trials. GABA+ concentrations in the ACC appeared to be specifically important for TBA modulations when the cognitive effort needed for interference control was high - that is when no prior task experience exists, or in the absence of catecholaminergic enhancement with MPH. The study highlights the predictive role of baseline GABA+ concentrations in key brain areas influencing cognitive control and responsiveness to catecholaminergic enhancement, particularly in high-effort scenarios.

Effects of Catecholaminergic and Transcranial Direct Current Stimulation on Response Inhibition

BACKGROUND

The principle of gain control determines the efficiency of neuronal processing and can be enhanced with pharmacological or brain stimulation methods. It is a key factor for cognitive control, but the degree of how much gain control may be enhanced underlies a physical limit.

METHODS

To investigate whether methylphenidate (MPH) and transcranial direct current stimulation (tDCS) share common underlying mechanisms and cognitive effects, we administered MPH and anodal tDCS (atDCS) over the right inferior frontal gyrus both separately and combined, while healthy adult participants (n = 104) performed a response selection and inhibition task. The recorded EEG data were analyzed with a focus on theta band activity, and source estimation analyses were conducted.

RESULTS

The behavioral data show that MPH and atDCS revealed interactive effects on the ability to inhibit responses. Both MPH and atDCS modulated task-related theta oscillations in the supplementary motor area when applied separately, making a common underlying mechanism likely. When both stimulation methods were combined, there was no doubling of effects in the supplementary motor area but a shift to inferior frontal areas in the cortical network responsible for theta-driven processing.

CONCLUSIONS

The results indicate that both MPH and atDCS likely share a common underlying neuronal mechanism, and interestingly, they demonstrate interactive effects when combined, which are most likely due to the physical limitations of gain control increases. The current study provides critical groundwork for future combined applications of MPH and non-invasive brain stimulation.

Neural oscillations guiding action during effects imagery

Goal-directed acting requires the integration of sensory information but can also be performed without direct sensory input. Examples of this can be found in sports and can be conceptualized by feedforward processes. There is, however, still a lack of understanding of the temporal neural dynamics and neuroanatomical structures involved in such processes. In the current study, we used EEG beamforming methods and examined 37 healthy participants in two well-controlled experiments varying the necessity of anticipatory processes during goal-directed action. We found that alpha and beta activity in the medial and posterior cingulate cortex enabled feedforward predictions about the position of an object based on the latest sensorimotor state. On this basis, theta band activity seems more related to sensorimotor representations, while beta band activity would be more involved in setting up the structure of the neural representations themselves. Alpha band activity in sensory cortices reflects an intensified gating of the anticipated perceptual consequences of the to-be-executed action. Together, the findings indicate that goal-directed acting through the anticipation of the predicted state of an effector is based on accompanying processes in multiple frequency bands in midcingulate and sensory brain regions.

Tracing conflict-induced cognitive-control adjustments over time using aperiodic EEG activity

Cognitive-control theories assume that the experience of response conflict can trigger control adjustments. However, while some approaches focus on adjustments that impact the selection of the present response (in trial N), other approaches focus on adjustments in the next upcoming trial  (N + 1). We aimed to trace control adjustments over time by quantifying cortical noise by means of the fitting oscillations and one over f algorithm, a measure of aperiodic activity. As predicted, conflict trials increased the aperiodic exponent in a large sample of 171 healthy adults, thus indicating noise reduction. While this adjustment was visible in trial N already, it did not affect response selection before the next trial. This suggests that control adjustments do not affect ongoing response-selection processes but prepare the system for tighter control in the next trial. We interpret the findings in terms of a conflict-induced switch from metacontrol flexibility to metacontrol persistence, accompanied or even implemented by a reduction of cortical noise.

Response stopping under conflict: The integrative role of representational dynamics associated with the insular cortex

Coping with distracting inputs during goal-directed behavior is a common challenge, especially when stopping ongoing responses. The neural basis for this remains debated. Our study explores this using a conflict-modulation Stop Signal task, integrating group independent component analysis (group-ICA), multivariate pattern analysis (MVPA), and EEG source localization analysis. Consistent with previous findings, we show that stopping performance is better in congruent (nonconflicting) trials than in incongruent (conflicting) trials. Conflict effects in incongruent trials compromise stopping more due to the need for the reconfiguration of stimulus-response (S-R) mappings. These cognitive dynamics are reflected by four independent neural activity patterns (ICA), each coding representational content (MVPA). It is shown that each component was equally important in predicting behavioral outcomes. The data support an emerging idea that perception-action integration in action-stopping involves multiple independent neural activity patterns. One pattern relates to the precuneus (BA 7) and is involved in attention and early S-R processes. Of note, three other independent neural activity patterns were associated with the insular cortex (BA13) in distinct time windows. These patterns reflect a role in early attentional selection but also show the reiterated processing of representational content relevant for stopping in different S-R mapping contexts. Moreover, the insular cortex's role in automatic versus complex response selection in relation to stopping processes is shown. Overall, the insular cortex is depicted as a brain hub, crucial for response selection and cancellation across both straightforward (automatic) and complex (conditional) S-R mappings, providing a neural basis for general cognitive accounts on action control.

Neurophysiological processes reflecting the effects of the immediate past during the dynamic management of actions

In recent years, there has been many efforts to establish a comprehensive theoretical framework explaining the working mechanisms involved in perception-action integration. This framework stresses the importance of the immediate past on mechanisms supporting perception-action integration. The present study investigates the neurophysiological principles of dynamic perception-action bindings, particularly considering the influence of the immediate history on action control mechanisms. For this purpose, we conducted an established stimulus-response binding paradigm during EEG recording. The SR-task measures stimulus-response binding in terms of accuracy and reaction time differences depending on the degree of feature overlap between conditions. Alpha, beta and theta band activity in distinct time domains as well as associated brain regions were investigated applying time-frequency analyses, a beamforming approach as well as correlation analyses. We demonstrate, for the first time, interdependencies of neuronal processes relying on the immediate past. The reconfiguration of an action seems to overwrite immediately preceding processes. The analyses revealed modulations of theta (TBA), alpha (ABA) and beta band activity (BBA) in connection with fronto-temporal structures supporting the theoretical assumptions of the considered conceptual framework. The close interplay of attentional modulation by gating irrelevant information (ABA) and binding and retrieval processes (TBA) is reflected by the correlation of ABA in all pre-probe-intervals with post-probe TBA. Likewise, the role of BBA in maintaining the event file until retrieval is corroborated by BBA preceding the TBA-associated retrieval of perception-action codes. Following action execution, TBA shifted towards visual association cortices probably reflecting preparation for upcoming information, while ABA and BBA continue to reflect processes of attentional control and information selection for goal-directed behavior. The present work provides the first empirical support for concepts about the neurophysiological mechanisms of dynamic management of perception and action.

The Ability to Voluntarily Regulate Theta Band Activity Affects How Pharmacological Manipulation of the Catecholaminergic System Impacts Cognitive Control

BACKGROUND

The catecholaminergic system influences response inhibition, but the magnitude of the impact of catecholaminergic manipulation is heterogeneous. Theoretical considerations suggest that the voluntary modulability of theta band activity can explain this variance. The study aimed to investigate to what extent interindividual differences in catecholaminergic effects on response inhibition depend on voluntary theta band activity modulation.

METHODS

A total of 67 healthy adults were tested in a randomized, double-blind, cross-over study design. At each appointment, they received a single dose of methylphenidate or placebo and performed a Go/Nogo task with stimuli of varying complexity. Before the first appointment, the individual's ability to modulate theta band activity was measured. Recorded EEG data were analyzed using temporal decomposition and multivariate pattern analysis.

RESULTS

Methylphenidate effects and voluntary modulability of theta band activity showed an interactive effect on the false alarm rates of the different Nogo conditions. The multivariate pattern analysis revealed that methylphenidate effects interacted with voluntary modulability of theta band activity at a stimulus processing level, whereas during response selection methylphenidate effects interacted with the complexity of the Nogo condition.

CONCLUSIONS

The findings reveal that the individual's theta band modulability affects the responsiveness of an individual's catecholaminergic system to pharmacological modulation. Thus, the impact of pharmacological manipulation of the catecholaminergic system on cognitive control most likely depends on the existing ability to self-modulate relevant brain oscillatory patterns underlying the cognitive processes being targeted by pharmacological modulations.

Common and distinct BOLD correlates of Simon and flanker conflicts which can(not) be reduced to time-on-task effects

The ability to identify and resolve conflicts between standard, well-trained behaviors and behaviors required by the current context is an essential feature of cognitive control. To date, no consensus has been reached on the brain mechanisms involved in exerting such control: while some studies identified diverse patterns of activity across different conflicts, other studies reported common resources across conflict tasks or even across simple tasks devoid of the conflict component. The latter reports attributed the entire activity observed in the presence of conflict to longer time spent on the task (i.e., to the so-called time-on-task effects). Here, we used an extended Multi-Source Interference Task (MSIT) which combines Simon and flanker types of interference to determine shared and conflict-specific mechanisms of conflict resolution in fMRI and their separability from the time-on-task effects. Large portions of the activity in the dorsal attention network and decreases of activity in the default mode network were shared across the tasks and scaled in parallel with increasing reaction times. Importantly, the activity in the sensory and sensorimotor cortices, as well as in the posterior medial frontal cortex (pMFC) - a key region implicated in conflict processing - could not be exhaustively explained by the time-on-task effects.

Altered age-related alpha and gamma prefrontal-occipital connectivity serving distinct cognitive interference variants

The presence of conflicting stimuli adversely affects behavioral outcomes, which could either be at the level of stimulus (Flanker), response (Simon), or both (Multisource). Briefly, flanker interference involves conflicting stimuli requiring selective attention, Simon interference is caused by an incongruity between the spatial location of the task-relevant stimulus and prepotent motor mapping, and multisource is combination of both. Irrespective of the variant, interference resolution necessitates cognitive control to filter irrelevant information and allocate neural resources to task-related goals. Though previously studied in healthy young adults, the direct quantification of changes in oscillatory activity serving such cognitive control and associated inter-regional interactions in healthy aging are poorly understood. Herein, we used an adapted version of the multisource interference task and magnetoencephalography to investigate age-related alterations in the neural dynamics governing both divergent and convergent cognitive interference in 78 healthy participants (age range: 20-66 years). We identified weaker alpha connectivity between bilateral visual and right dorsolateral prefrontal cortices (DLPFC) and left dorsomedial prefrontal cortices (dmPFC), as well as weaker gamma connectivity between bilateral occipital regions and the right dmPFC during flanker interference with advancing age. Further, an age-related decrease in gamma power was observed in the left cerebellum and parietal region for Simon and differential interference effects (i.e., flanker-Simon), respectively. Moreover, the superadditivity model showed decreased gamma power in the right temporoparietal junction (TPJ) with increasing age. Overall, our findings suggest age-related declines in the engagement of top-down attentional control secondary to reduced alpha and gamma coupling between prefrontal and occipital cortices.

The neurophysiology of continuous action monitoring

Monitoring actions is essential for goal-directed behavior. However, as opposed to short-lasting, and regularly reinstating monitoring functions, the neural processes underlying continuous action monitoring are poorly understood. We investigate this using a pursuit-tracking paradigm. We show that beta band activity likely maintains the sensorimotor program, while theta and alpha bands probably support attentional sampling and information gating, respectively. Alpha and beta band activity are most relevant during the initial tracking period, when sensorimotor calibrations are most intense. Theta band shifts from parietal to frontal cortices throughout tracking, likely reflecting a shift in the functional relevance from attentional sampling to action monitoring. This study shows that resource allocation mechanisms in prefrontal areas and stimulus-response mapping processes in the parietal cortex are crucial for adapting sensorimotor processes. It fills a knowledge gap in understanding the neural processes underlying action monitoring and suggests new directions for examining sensorimotor integration in more naturalistic experiments.

A dissociable functional relevance of theta- and beta-band activities during complex sensorimotor integration

Sensorimotor integration processes play a central role in daily life and require that different sources of sensory information become integrated: i.e. the information related to the object being under control of the agent (i.e. indicator) and the information about the goal of acting. Yet, how this is accomplished on a neurophysiological level is contentious. We focus on the role of theta- and beta-band activities and examine which neuroanatomical structures are involved. Healthy participants (n = 41) performed 3 consecutive pursuit-tracking EEG experiments in which the source of visual information available for tracking was varied (i.e. that of the indicator and the goal of acting). The initial specification of indicator dynamics is determined through beta-band activity in parietal cortices. When information about the goal was not accessible, but operating the indicator was required nevertheless, this incurred increased theta-band activity in the superior frontal cortex, signaling a higher need for control. Later, theta- and beta-band activities encode distinct information within the ventral processing stream: Theta-band activity is affected by the indicator information, while beta-band activity is affected by the information about the action goal. Complex sensorimotor integration is realized through a cascade of theta- and beta-band activities in a ventral-stream-parieto-frontal network.

Does chronic use of amphetamine-type stimulants impair interference control? - A meta-analysis

In substance use and addiction, inhibitory control is key to ignoring triggers, withstanding craving and maintaining abstinence. In amphetamine-type stimulant (ATS) users, most research focused on behavioral inhibition, but largely neglected the equally important subdomain of cognitive interference control. Given its crucial role in managing consumption, we investigated the relationship between interference control and chronic ATS use in adults. A database search (Pubmed & Web of Science) and relevant reviews were used to identify eligible studies. Effect sizes were estimated with random effects models. Subgroup, meta-regression, and sensitivity analyses explored heterogeneity in effect sizes. We identified 61 studies (53 datasets) assessing interference control in 1873 ATS users and 1905 controls. Findings revealed robust small effect sizes for ATS-related deficits in interference control, which were mainly seen in methamphetamine, as compared to MDMA users. The differential effects are likely due to tolerance-induced dopaminergic deficiencies (presumably most pronounced in methamphetamine users). Similarities between different ATS could be due to noradrenergic deficiencies; but elucidating their functional role in ATS users requires further/more research.

Alcohol-induced deficits in reactive control of response selection and inhibition are counteracted by a seemingly paradox increase in proactive control

High-dose alcohol intoxication reduces cognitive control, including inhibition. Although inhibition deficits may contribute to the behavioral deficits commonly observed in alcohol use disorder (AUD), many questions about potentially modulating factors have remained unanswered. We examined the effects of experimentally induced high-dose alcohol intoxication (~ 1.1 ‰) on the interplay between controlled vs. automatic response selection and inhibition in healthy young men. A holistic EEG-based theta activity analysis that considered both reactive control during task performance and preceding proactive control processes was run. It revealed a previously unknown seesaw relationship, with decreased reactive control, but paradoxically increased proactive control. Most importantly, alcohol-induced increases in proactive occipital theta band power were associated with reductions in negative alcohol effects on reactive control processes associated with decreased activity in the SMA and medial frontal cortex. Our findings demonstrate that research should not solely focus on immediate effects during task performance. Aside from differential neurobiochemical and neuroanatomical effects of alcohol, it is also conceivable that proactive control may have been recruited in a (secondary) response to compensate for alcohol-induced impairments in reactive control. Against this background, it could be promising to investigate changes in such compensatory mechanisms in pronounced alcohol-associated inhibition deficits, like in AUD patients.

The role of visual association cortices during response selection processes in interference-modulated response stopping

Response inhibition and the ability to navigate distracting information are both integral parts of cognitive control and are imperative to adaptive behavior in everyday life. Thus far, research has only inconclusively been able to draw inferences regarding the association between response stopping and the effects of interfering information. Using a novel combination of the Simon task and a stop signal task, the current study set out to investigate the behavioral as well as the neurophysiological underpinnings of the relationship between response stopping and interference processing. We tested n = 27 healthy individuals and combined temporal EEG signal decomposition with source localization methods to delineate the precise neurophysiological dynamics and functional neuroanatomical structures associated with conflict effects on response stopping. The results showed that stopping performance was compromised by conflicts. Importantly, these behavioral effects were reflected by specific aspects of information coded in the neurophysiological signal, indicating that conflict effects during response stopping are not mediated via purely perceptual processes. Rather, it is the processing of specific, stop-relevant stimulus features in the sensory regions during response selection, which underlies the emergence of conflict effects in response stopping. The findings connect research regarding response stopping with overarching theoretical frameworks of perception-action integration.

Evidence for independent representational contents in inhibitory control subprocesses associated with frontoparietal cortices

Inhibitory control processes have intensively been studied in cognitive science for the past decades. Even though the neural dynamics underlying these processes are increasingly better understood, a critical open question is how the representational dynamics of the inhibitory control processes are modulated when engaging in response inhibition in a relatively automatic or a controlled mode. Against the background of an overarching theory of perception-action integration, we combine temporal and spatial EEG signal decomposition methods with multivariate pattern analysis and source localization to obtain fine-grained insights into the neural dynamics of the representational content of response inhibition. For this purpose, we used a sample of N = 40 healthy adult participants. The behavioural data suggest that response inhibition was better in a more controlled than a more automated response execution mode. Regarding neural dynamics, effects of response inhibition modes relied on a concomitant coding of stimulus-related information and rules of how stimulus information is related to the appropriate motor programme. Crucially, these fractions of information, which are encoded at the same time in the neurophysiological signal, are based on two independent spatial neurophysiological activity patterns, also showing differences in the temporal stability of the representational content. Source localizations revealed that the precuneus and inferior parietal cortex regions are more relevant than prefrontal areas for the representation of stimulus-response selection codes. We provide a blueprint how a concatenation of EEG signal analysis methods, capturing distinct aspects of neural dynamics, can be connected to cognitive science theory on the importance of representations in action control.

Influence of Bilingualism on Behavioral and Electrophysiological Parameters of Cognitive Control

Abstract. Bilingualism has been associated with better cognitive control as compared to monolingualism. However, the robustness of the respective findings is subject to a recent debate, and moderators should be taken into consideration. We reasoned that groups immersed in their second language should show a greater bilingual advantage in cognitive control as compared to non-immersed participants. Further, stimulus language (first or second language), word similarity in the two languages (similar or dissimilar), as well as congruency between ink and word were varied. Forty-five participants from three different language groups (Romance, Slavic, and German) conducted a Stroop task while EEG was recorded. Higher cognitive control demand was operationalized as (1) longer reaction times, (2) higher error rates, (3) stronger N400, (4) increased Late Positive Complex (LPC), and (5) stronger Frontal Midline Theta activity. The classical Stroop interference effect was replicated for all dependent variables. Contrary to expectation, participants immersed in their second language did not exhibit any inhibition advantage in the Stroop task. Moreover, higher script similarity between first and second languages led to faster response times in general. Results are discussed in light of the current debate on the existence of a bilingual advantage in cognitive control.

Superior frontal regions reflect the dynamics of task engagement and theta band-related control processes in time-on task effects

Impairment of cognitive performance is often observed in time-on tasks. Theoretical considerations suggest that especially prefrontal cortex cognitive control functions is affected by time-on-task effects, but the role of effort/task engagement is not understood. We examine time-on-task effects in cognitive control on a neurophysiological level using a working-memory modulated response inhibition task and inter-relate prefrontal neuroanatomical region-specific theta-band activity with pupil diameter data using EEG-beamforming approaches. We show that task performance declines with time-on tasks, which was paralleled by a concomitant decreases of task-evoked superior frontal gyrus theta-band activity and a reduction in phasic pupil diameter modulations. A strong relation between cognitive control-related superior frontal theta-band activity and effort/task engagement indexed by phasic pupil diameter modulations was observed in the beginning of the experiment, especially for tasks requiring inhibitory controls and demanding high working memory. This strong relation vanished at the end of the experiment, suggesting a decoupling of cognitive control resources useable for a task and effort invested that characterizes time-on-task effects in prefrontal cortical structures.

A role of the norepinephrine system or effort in the interplay of different facets of inhibitory control

Inhibitory control has multiple facets, and one possible distinction can be made between 'inhibition of interferences' and the 'inhibition of actions'. Both facets of inhibitory control show an interdependency. Even though some neurophysiological processes underlying this interdependency have been examined, the role of neuro-modulatory processes in their interplay are not understood. In the current study, we examine the role of the norepinephrine (NE) system in these processes. We did so by combining a Go/Nogo and Simon task. We recorded the EEG and pupil diameter data as an indirect index of NE system activity during the task. EEG theta band activity data and pupil diameter data were then integrated after conducting a temporal signal decomposition of the EEG data. We show that particularly theta band activity coding stimulus-response translation processes associated with middle frontal cortices, but not stimulus-driven processes are modulated by the interplay between the 'inhibition of interferences' and the 'inhibition of actions'. Modulations in stimulus-response translation processes were systematically correlated with pupil-diameter responses. The pattern of correlations suggests that phasic NE system activity particularly modulates stimulus-response mapping processes during conflict monitoring in incongruent Nogo trials, which may explain behavioral performance effects. Phasic NE system activity reflects essential modulators of the interplay between the 'inhibition of interferences' and the 'inhibition of actions'.

Neural correlates of abnormal cognitive conflict resolution in major depression: An event-related potential study

Abnormal cognitive conflict resolution has been considered as a critical element of executive dysfunctions inpatient with major depression (MD). Further clarifying whether there was a deficit at perceptual encoding stage or the early response-execution stage in conflict control function by event-related potential (ERP) technique in MD would be helpful in understanding the neural mechanism of MD. Participants included twenty-six depressed patients and twenty-six healthy controls (HCs). All participants measured with Hamilton Depression Scale (17-item edition, HAMD) and a Simon task. Electroencephalograms were synchronously recorded when performing the Simon task. The method of residue iteration decomposition was used to analyze the lateralized readiness potential (LRP) and P300 components, which contributed to divides ERP components into a stimulus-locked component (S-cluster), a response-locked component (R-cluster) and an intermediate component cluster (C-cluster) by using latency variability and time markers. Results showed that reactive times (RTs) for both groups were fastest in congruent trials, and slowest in incongruent trials; however, there is no difference in RTs under the three conditions between two groups. Accuracy Rate (ACC) for both groups were the highest in neutral trials, and the lowest in incongruent trials; ACC in MD group were all lower than that of HC group under three conditions. ERP data analyses showed that depressed patients had a deficit in activating the correct response, as reflected by reduced amplitudes of R-LRP, but no abnormality in LRP-S and P300-C. In conclusion, patients with MD present conflict control dysfunction (i.e., abnormal cognitive conflict resolution) at the early response-execution stage, not at perceptual encoding stage, which may be reflected by the reduced R-LRP amplitudes. The abnormal cognitive conflict resolution in activating the correct response might constitute an interesting treatment target.

Inhibition of return in time-lapse: Brain Rhythms during grip force control for spatial attention

The inhibition of return (IoR) is the observable slowed response to a target at a cued position for cue-target intervals of longer than 300 ms; when there has been enough time to disengage from a previously-cued location, an inhibitory after-effect can be observed. Studies aimed at understanding whether mechanisms underlying IoR act at a perceptual/attentional or a later response-execution stage have offered divergent results. Though focusing on the brain's responses to cue-target intervals can offer significant information on the nature of IoR, few studies have investigated neural activity during this interval; these studies suggest the generation of inhibitory tags on the spatial coordinates of the previously attended position which, in turn, inhibit motor programming toward that position. As such, a cue-target task was administered in this study; the rhythmic activity of EEG signals on the entire cue-target interval was measured to determine whether IoR is referred to early or late response processing stages. A visually-guided force variation during isometric contraction, instead of a key press response, was required to reduce the effect of motor response initiation. Our results indicated the prominent involvement of the fronto-parietal and occipital cortical areas post-cue appearance, with a peculiar theta band modulation characterizing the posterior parietal cortex. Theta activity in this region was enhanced post-cue onset, decreased over time, and was enhanced again when a target appeared in an unexpected location rather than in a cued position. This suggests that the mechanism that generates IoR sequentially affects perceptual/attentional processing and motor preparation rather than response execution.

Distinguishing Multiple Coding Levels in Theta Band Activity During Working Memory Gating Processes

Cognitive control and working memory (WM) processes are essential for goal-directed behaviour. Cognitive control and WM are probably based on overlapping neurophysiological mechanisms. For example, theta-band activity (TBA) plays an important role in both functions. For cognitive control processes, it is known that different aspects of information about stimulus content, motor processes and stimulus-response relationships are encoded simultaneously in the TBA. All this information is probably processed during WM gating processes and must be controlled during them. However, direct data for this are lacking. This question is investigated in this study by combining methods of EEG temporal signal decomposition, time-frequency decomposition and beamforming. We show that portions of stimulus-related information, motor response-related information and information related to the interaction between the stimulus and motor responses in the TBA are influenced in parallel and to a similar extent by WM gate opening and gate closing processes. Nevertheless, it is stimulus-related information in the theta signal in particular that modulates behavioural performance in WM-gating. The data suggest that the identified processes are implemented in specific neuroanatomical structures. In particular, the medial frontal cortex, temporal cortical regions and insular cortex are involved in these dynamics. The study shows that principles of information coding relevant to cognitive control processes are also crucial for understanding WM gating.

Distinct Brain-Oscillatory Neuroanatomical Architecture of Perception-Action Integration in Adolescents With Tourette Syndrome

Background

Gilles de la Tourette Syndrome (GTS) is a neurodevelopmental disorder with a peak of symptom severity around late childhood and early adolescence. Previous findings in adult GTS suggest that changes in perception-action integration, as conceptualized in the theory of event coding framework, are central for the understanding of GTS. However, the neural mechanisms underlying these processes in adolescence are elusive.

Methods

A total of 59 children/adolescents aged 9 to 18 years (n = 32 with GTS, n = 27 typically developing youths) were examined using a perception-action integration task (event file task) derived from the theory of event coding. Event-related electroencephalogram recordings (theta and beta band activity) were analyzed using electroencephalogram–beamforming methods.

Results

Behavioral data showed robust event file binding effects in both groups without group differences. Neurophysiological data showed that theta and beta band activity were involved in event file integration in both groups. However, the functional neuroanatomical organization was markedly different for theta band activity between the groups. The typically developing group mainly relied on superior frontal regions, whereas the GTS group engaged parietal and inferior frontal regions. A more consistent functional neuroanatomical activation pattern was observed for the beta band, engaging inferior parietal and temporal regions in both groups.

Conclusions

Perception-action integration processes lag behind in persisting GTS but not in the GTS population as a whole, underscoring differences in developmental trajectories and the importance of longitudinal investigations for the understanding of GTS. The findings corroborate known differences in the functional/structural brain organization in GTS and suggest an important role of theta band activity in these patients.

Event-related synchronization/desynchronization and functional neuroanatomical regions associated with fatigue effects on cognitive flexibility

Cognitive flexibility is an essential prerequisite for goal-directed behavior, and daily observations already show that it deteriorates when one is engaged in a task for a (too) long time. Yet, the neural mechanisms underlying such fatigability effect in cognitive flexibility are poorly understood. We examined how theta, alpha, and beta frequency event-related synchronization and desynchronization processes during cued memory-based task switching are modulated by time-on-task effects. We put special emphasis on the examination of functional neuroanatomical regions being associated with these modulations, using EEG beamforming. We show clear declines in task switching performance (increased switch costs) with time on task. For processes occurring before rule switching or repetition processes, we show that anticipatory attentional sampling and selection mechanisms associated with fronto-parietal structures are modulated by time-on-task effects but sensory areas (occipital cortex) also show fatigability-dependent modulations. After target stimulus presentation, the allocation of processing resources for response selection as reflected by theta-related activity in parietal cortices is compromised with time on task and similarly a concomitant increase in alpha and beta band-related attentional processing or gating mechanisms in frontal and occipital regions. Yet, considering the behavioral data showing an apparent decline in performance, this probably compensatory increase is still insufficient to allow reasonable performance. The same is likely the case for processes occurring before rule switching or repetition processes. Comparative analyses show that modulations of alpha band activity are as strongly modulated by fatigability as theta band activity. Implications of these findings for theoretical concepts on fatigability are discussed.NEW & NOTEWORTHY We examine the neurophysiological and functional neuroanatomical basis of fatigability in cognitive flexibility. We show that alpha and theta modulations in fronto-parietal and primary sensory areas are central for the understanding of fatigability effects in cognitive flexibility.

Anodal tDCS modulates specific processing codes during conflict monitoring associated with superior and middle frontal cortices

Conflict monitoring processes are central for cognitive control. Neurophysiological correlates of conflict monitoring (i.e. the N2 ERP) likely represent a mixture of different cognitive processes. Based on theoretical considerations, we hypothesized that effects of anodal tDCS (atDCS) in superior frontal areas affect specific subprocesses in neurophysiological activity during conflict monitoring. To investigate this, young healthy adults performed a Simon task while EEG was recorded. atDCS and sham tDCS were applied in a single-blind, cross-over study design. Using temporal signal decomposition in combination with source localization analyses, we demonstrated that atDCS effects on cognitive control are very specific: the detrimental effect of atDCS on response speed was largest in case of response conflicts. This however only showed in aspects of the decomposed N2 component, reflecting stimulus-response translation processes. In contrast to this, stimulus-related aspects of the N2 as well as purely response-related processes were not modulated by atDCS. EEG source localization analyses revealed that the effect was likely driven by activity modulations in the superior frontal areas, including the supplementary motor cortex (BA6), as well as middle frontal (BA9) and medial frontal areas (BA32). atDCS did not modulate effects of proprioceptive information on hand position, even though this aspect is known to be processed within the same brain areas. Physiological effects of atDCS likely modulate specific aspects of information processing during cognitive control.

Spatiotemporal Characteristics of Neural Dynamics in Theta Oscillations Related to the Inhibition of Habitual Behavior

The human brain carries out cognitive control for the inhibition of habitual behaviors by suppressing some familiar but inappropriate behaviors instead of engaging specific goal-directed behavior flexibly in a given situation. To examine the characteristics of neural dynamics related to such inhibition of habitual behaviors, we used a modified rock–paper–scissors (RPS) task that consisted of a basic, a lose-, and a win-conditioned game. Spectral and phase synchrony analyses were conducted to examine the acquired electroencephalogram signals across the entire brain during all RPS tasks. Temporal variations in frontal theta power activities were directly in line with the stream of RPS procedures in accordance with the task conditions. The lose-conditioned RPS task gave rise to increases in the local frontal power and global phase-synchronized pairs of theta oscillations. The activation of the global phase-synchronized network preceded the activation of frontal theta power. These results demonstrate that the frontal regions play a pivotal role in the inhibition of habitual behaviors—stereotyped and ingrained stimulus–response mappings that have been established over time. This study suggests that frontal theta oscillations may be engaged during the cognitive inhibition of habitual behaviors and that these oscillations characterize the degree of cognitive load required to inhibit habitual behaviors.

Behavioral and electrophysiological correlates of Simon and flanker conflict interference in younger and older adults

Conflict processing and interference control have been popular topics of research in the study of pathological brain aging. However, there remains much to be learned about how these cognitive processes are altered in the course of healthy brain aging. Moreover, few studies have combined multiple measures of interference control using factorial designs. The aim of this study was to determine the nature of age-related changes in behavioral and electroencephalographic correlates of interference control using a factorial combination of the Simon and flanker interference conditions. Data were collected from a group of younger and high-functioning older adults. Behavioral results indicated the presence of conflict interference effects in both groups, that both Simon and flanker conflict effects are increased in high-functioning older adults, that the two types of conflict interference interact superadditively, and that older adults are more susceptible to the superadditive costs of multiple conflict types. ERP analyses revealed that early perceptual and response-selection processes are differentially modulated by flanker and Simon conflict respectively, however, there was no evidence that these early processes were impaired in older adults. Later components of the ERP in the P3 time range mirrored behavioral results, reflecting the increased susceptibility to flanker and Simon conflict in older adults.

Resting theta activity is associated with specific coding levels in event-related theta activity during conflict monitoring

Brain electrical activity in the theta frequency band is essential for cognitive control (e.g., during conflict monitoring), but is also evident in the resting state. The link between resting state theta activity and its relevance for theta-related neural mechanisms during cognitive control is still undetermined. Yet, theoretical considerations suggest that there may be a connection. To examine the link between resting state theta activity and conflict-related theta activity, we combined temporal EEG signal decomposition methods with time-frequency decomposition and beamforming methods in N = 86 healthy participants. Results indicate that resting state theta activity is closely associated with the strength of conflict-related neural activity at the level of ERPs and total theta power (consisting of phase-locked and nonphase-locked aspects of theta activity). The data reveal that resting state theta activity is related to a specific aspect of conflict-related theta activity, mainly in superior frontal regions and in the supplemental motor area (SMA, BA6) in particular. The signal decomposition showed that only stimulus-related, but not motor-response-related coding levels in the EEG signal and the event-related total theta activity were associated with resting theta activity. This specificity of effects may explain why the association between resting state theta activity and overt conflict monitoring performance may not be as strong as often assumed. The results suggest that resting state theta activity is particularly important to consider for input integration processes during cognitive control.

A review on the electroencephalography markers of Stroop executive control processes

The present article on executive control addresses the issue of the locus of the Stroop effect by examining neurophysiological components marking conflict monitoring, interference suppression, and conflict resolution. Our goal was to provide an overview of a series of determining neurophysiological findings including neural source reconstruction data on distinct executive control processes and sub-processes involved in the Stroop task. Consistently, a fronto-central N2 component is found to reflect conflict monitoring processes, with its main neural generator being the anterior cingulate cortex (ACC). Then, for cognitive control tasks that involve a linguistic component like the Stroop task, the N2 is followed by a centro-posterior N400 and subsequently a late sustained potential (LSP). The N400 is mainly generated by the ACC and the prefrontal cortex (PFC) and is thought to reflect interference suppression, whereas the LSP plausibly reflects conflict resolution processes. The present overview shows that ERP constitute a reliable methodological tool for tracing with precision the time course of different executive processes and sub-processes involved in experimental tasks involving a cognitive conflict. Future research should shed light on the fine-grained mechanisms of control respectively involved in linguistic and non-linguistic tasks.

Non-invasive Brain Stimulation for the Treatment of Gilles de la Tourette Syndrome

Gilles de la Tourette Syndrome is a multifaceted neuropsychiatric disorder typically commencing in childhood and characterized by motor and phonic tics. Its pathophysiology is still incompletely understood. However, there is convincing evidence that structural and functional abnormalities in the basal ganglia, in cortico-striato-thalamo-cortical circuits, and some cortical areas including medial frontal regions and the prefrontal cortex as well as hyperactivity of the dopaminergic system are key findings. Conventional therapeutic approaches in addition to counseling comprise behavioral treatment, particularly habit reversal therapy, oral pharmacotherapy (antipsychotic medication, alpha-2-agonists) and botulinum toxin injections. In treatment-refractory Tourette syndrome, deep brain stimulation, particularly of the internal segment of the globus pallidus, is an option for a small minority of patients. Based on pathophysiological considerations, non-invasive brain stimulation might be a suitable alternative. Repetitive transcranial magnetic stimulation appears particularly attractive. It can lead to longer-lasting alterations of excitability and connectivity in cortical networks and inter-connected regions including the basal ganglia through the induction of neural plasticity. Stimulation of the primary motor and premotor cortex has so far not been shown to be clinically effective. Some studies, though, suggest that the supplementary motor area or the temporo-parietal junction might be more appropriate targets. In this manuscript, we will review the evidence for the usefulness of repetitive transcranial magnetic stimulation and transcranial electric stimulation as treatment options in Tourette syndrome. Based on pathophysiological considerations we will discuss the rational for other approaches of non-invasive brain stimulation including state informed repetitive transcranial magnetic stimulation.

EEG Signal Decomposition Evidence for a Role of Perceptual Processes during Conflict-related Behavioral Adjustments in Middle Frontal Regions

Conflict monitoring processes are central to cope with fluctuating environmental demands. However, the efficacy of these processes depends on previous trial history/experience, which is reflected in the "congruency sequence effect" (CSE). Several theoretical accounts have been put forward to explain this effect. Some accounts stress the role of perceptual processes in the emergence of the CSE. As yet, it is elusive how these perceptual processes are implemented on a neural level. We examined this question using a newly developed moving dots flanker task. We combine decomposition methods of EEG data and source localization. We show that perceptual processes modulate the CSE and can be isolated in neurophysiological signals, especially in the N2 ERP time window. However, mechanisms relating perception to action are also coded and modulated in this time window. We show that middle frontal regions (BA 6) are associated with processes dealing with purely perceptual processes. Inferior frontal regions (BA 45) are associated with processes dealing with stimulus-response transition processes. Likely, the neurophysiological modulations reflect unbinding processes at the perceptual level, and stimulus-response translation level needed to respond correctly on the presented (changed) stimulus-response relationships. The data establish a direct relationship between psychological concepts focusing on perceptual processes during conflict monitoring and neurophysiological processes using signal decomposition.

Applying deep learning to single-trial EEG data provides evidence for complementary theories on action control

Efficient action control is indispensable for goal-directed behaviour. Different theories have stressed the importance of either attention or response selection sub-processes for action control. Yet, it is unclear to what extent these processes can be identified in the dynamics of neurophysiological (EEG) processes at the single-trial level and be used to predict the presence of conflicts in a given moment. Applying deep learning, which was blind to cognitive theory, on single-trial EEG data allowed to predict the presence of conflict in ~95% of subjects ~33% above chance level. Neurophysiological features related to attentional and motor response selection processes in the occipital cortex and the superior frontal gyrus contributed most to prediction accuracy. Importantly, deep learning was able to identify predictive neurophysiological processes in single-trial neural dynamics. Hence, mathematical (artificial intelligence) approaches may be used to foster the validation and development of links between cognitive theory and neurophysiology of human behavior.

Vahid et al. use a deep-learning approach to analyze single-trial EEG data to examine theories on action control. Their approach enables the identification of spatial and temporal neurophysiological features that are predictive of the response control during the Simon task. The results confirm cognitive theory-driven approaches on the relationship between neurophysiology and human behavior.

Low and high stimulation frequencies differentially affect automated response selection in the superior parietal cortex - implications for somatosensory area processes

Response inhibition as a central facet of executive functioning is no homogeneous construct. Interference inhibition constitutes a subcomponent of response inhibition and refers to inhibitory control over responses that are automatically triggered by irrelevant stimulus dimensions as measured by the Simon task. While there is evidence that the area-specific modulation of tactile information affects the act of action withholding, effects in the context of interference inhibition remain elusive. We conducted a tactile version of the Simon task with stimuli designed to be predominantly processed in the primary (40 Hz) or secondary (150 Hz) somatosensory cortex. On the basis of EEG recordings, we performed signal decomposition and source localization. Behavioral results reveal that response execution is more efficient when sensory information is mainly processed via SII, compared to SI sensory areas during non-conflicting trials. When accounting for intermingled coding levels by temporally decomposing EEG data, the results show that experimental variations depending on sensory area-specific processing differences specifically affect motor and not sensory processes. Modulations of motor-related processes are linked to activation differences in the superior parietal cortex (BA7). It is concluded that the SII cortical area supporting cognitive preprocessing of tactile input fosters automatic tactile information processing by facilitating stimulus-response mapping in posterior parietal regions.

Acute Alcohol Effects on Response Inhibition Depend on Response Automatization, but not on GABA or Glutamate Levels in the ACC and Striatum

Alcohol increases GABAergic signaling and decreases glutamatergic signaling in the brain. Variations in these neurotransmitter levels may modulate/predict executive functioning. Matching this, strong impairments of response inhibition are one of the most consistently reported cognitive/behavioral effects of acute alcohol intoxication. However, it has never been investigated whether baseline differences in these neurotransmitters allow to predict how much alcohol intoxication impairs response inhibition, and whether this is reflected in neurophysiological measures of cognitive control. We used MR spectroscopy to assess baseline (i.e., sober) GABA and glutamate levels in the anterior cingulate cortex (ACC) and striatum in n = 30 healthy young males, who were subsequently tested once sober and once intoxicated (1.01 permille). Inhibition was assessed with the sustained attention to response task (SART). This paradigm also allows to examine the effect of different degrees of response automatization, which is a known modulator for response inhibition, but does not seem to be substantially impaired during acute intoxication. As a neurophysiological correlate of response inhibition and control, we quantified EEG-derived theta band power and located its source using beamforming analyses. We found that alcohol-induced response inhibition deficits only occurred in the case of response automatization. This was reflected by decreased theta band activity in the left supplementary motor area (SMA), which may reflect modulations in the encoding of a surprise signal in response to inhibition cues. However, we did not find that differences in baseline (i.e., sober) GABA or glutamate levels significantly modulated differences in the size of alcohol-induced inhibition deficits.

Static magnetic field stimulation of the supplementary motor area modulates resting-state activity and motor behavior

Focal application of a strong static magnetic field over the human scalp induces measurable local changes in brain function. Whether it also induces distant effects across the brain and how these local and distant effects collectively affect motor behavior remains unclear. Here we applied transcranial static magnetic field stimulation (tSMS) over the supplementary motor area (SMA) in healthy subjects. At a behavioral level, tSMS increased the time to initiate movement while decreasing errors in choice reaction-time tasks. At a functional level, tSMS increased SMA resting-state fMRI activity and bilateral functional connectivity between the SMA and both the paracentral lobule and the lateral frontotemporal cortex, including the inferior frontal gyrus. These results suggest that tSMS over the SMA can induce behavioral aftereffects associated with modulation of both local and distant functionally-connected cortical circuits involved in the control of speed-accuracy tradeoffs, thus offering a promising protocol for cognitive and clinical research.

How non-veridical perception drives actions in healthy humans: evidence from synaesthesia

We continually perform actions that are driven by our perception and it is a commonly held view that only objectively perceived changes within the 'real' world affect behaviour. Exceptions are generally only made for mental health disorders associated with delusions and hallucinations where behaviour may be triggered by the experience of objectively non-existent percepts. Here, we demonstrate, using synaesthesia as a model condition (in N = 19 grapheme-colour synaesthetes), how objectively non-existent (i.e. non-veridical) but still non-pathological perceptions affect actions in healthy humans. Using electroencephalography, we determine whether early-stage perceptual processes (reflected by P1 and N1 event-related potential (ERP) components), or late-stage-integration processes (reflected by N2 component), underlie the effects of non-veridical perceptions on action control. ERP analysis suggests that even though the examined peculiarities and experimental variations are perceptual in nature, it is not early-stage perceptual processes, but rather higher-order executive control processes linking perceptions to the appropriate motor response underlying this effect. Source localization analysis implicates activation within medial frontal cortices in the effect of how irrelevant non-veridical perceptions modulate behaviour. Our results challenge common conceptions about the determinants of human behaviour but can be explained by well-established theoretical frameworks detailing the link between perception and action. This article is part of a discussion meeting issue 'Bridging senses: novel insights from synaesthesia'.

The Simon Effect Based on Allocentric and Egocentric Reference Frame: Common and Specific Neural Correlates

An object's location can be represented either relative to an observer's body effectors (egocentric reference frame) or relative to another external object (allocentric reference frame). In non-spatial tasks, an object's task-irrelevant egocentric position conflicts with the side of a task-relevant manual response, which defines the classical Simon effect. Growing evidence suggests that the Simon effect occurs not only based on conflicting positions within the egocentric but also within the allocentric reference frame. Although neural mechanisms underlying the egocentric Simon effect have been extensively researched, neural mechanisms underlying the allocentric Simon effect and their potential interaction with those underlying its egocentric variant remain to be explored. In this fMRI study, spatial congruency between the task-irrelevant egocentric and allocentric target positions and the task-relevant response hand was orthogonally manipulated. Behaviorally, a significant Simon effect was observed for both reference frames. Neurally, three sub-regions in the frontoparietal network were involved in different aspects of the Simon effect, depending on the source of the task-irrelevant object locations. The right precentral gyrus, extending to the right SMA, was generally activated by Simon conflicts, irrespective of the spatial reference frame involved, and showed no additive activity to Simon conflicts. In contrast, the right postcentral gyrus was specifically involved in Simon conflicts induced by task-irrelevant allocentric, rather than egocentric, representations. Furthermore, a right lateral frontoparietal network showed increased neural activity whenever the egocentric and allocentric target locations were incongruent, indicating its functional role as a mismatch detector that monitors the discrepancy concerning allocentric and egocentric object locations.

How perceptual ambiguity affects response inhibition processes

The ability to inhibit responses is a central requirement for goal-directed behavior but has been dominated by a top-down or cognitive control view. Only recently, the role of bottom-up perceptual factors were focused in research. However, studies usually use clearly distinguishable stimulus categories to trigger response execution or inhibition. In the current study, we present a novel Gabor patch Go/No-go task to induce perceptual ambiguity during response inhibition. To examine the neurophysiological processes in detail, we use EEG recordings and combined temporal EEG signal decomposition methods with source localization analyses. We show that perceptual similarity between Go and No-go trials compromises response inhibition performance. Interestingly, the EEG data show that this is due to a modulation of stimulus-response transition or decision processes, and not purely stimulus-related processes. This was possible by applying a temporal EEG decomposition method. We provide evidence that a prefrontal P2 (pP2) likely reflects decision processes on action execution using stimulus information. These processes were associated with superior and middle prefrontal regions (BA8). When these processes fail, occasions to execute a response become misinterpreted as occasions to inhibit a response. Successful and unsuccessful decisions to inhibit a response under high perceptual ambiguity seem to further depend on how well "what-decisions," supported by neural mechanisms in BA19, can be processed. However, these what-decisions seem to be closely linked to the specification of the required action. Stimulus processing is closely linked to response programming so that response control is already informed when uncertainty with regard to stimulus identity is detected.NEW & NOTEWORTHY This study introduces a novel Go/No-go paradigm and shows what neurophysiological subprocesses and functional neuroanatomical are involved during inhibitory control when ambiguous stimulus input is provided. The results show that bottom-up perceptual processes are important to consider during top-down controlled response inhibition. Stimulus processing is closely linked to response programming so that response control is already informed when uncertainty with regard to stimulus identity is detected.

On the relevance of EEG resting theta activity for the neurophysiological dynamics underlying motor inhibitory control

The modulation of theta frequency activity plays a major role in inhibitory control processes. However, the relevance of resting theta band activity and of the ability to spontaneously modulate this resting theta activity for neural mechanisms underlying inhibitory control is elusive. Various theoretical conceptions suggest to take these aspects into consideration. In the current study, we examine whether the strength of resting theta band activity or the ability to modulate the resting state theta activity affects response inhibition. We combined EEG-time frequency decomposition and beamforming in a conflict-modulated Go/Nogo task. A sample of N = 66 healthy subjects was investigated. We show that the strength of resting state theta activity modulates the effects of conflicts during motor inhibitory control. Especially when resting theta activity was low, conflicts strongly affected response inhibition performance and total theta band activity during Nogo trials. These effects were associated with theta-related activity differences in the superior (BA7) and inferior parietal cortex (BA40). The results were very specific for total theta band activity since evoked theta activity and measures of intertrial phase coherency (phase-locking factor) were not affected. The data suggest that the strength of resting state theta activity modulates processing of a theta-related alarm or surprise signal during inhibitory control. The ability to voluntarily modulate theta band activity did not affect conflict-modulated inhibitory control. These findings have important implications for approaches aiming to optimize human cognitive control.

The Presynaptic Regulation of Dopamine and Norepinephrine Synthesis Has Dissociable Effects on Different Kinds of Cognitive Conflicts

Goal-directed behavior requires the ability to resolve subliminally or consciously induced response conflicts, both of which may benefit from catecholamine-induced increases in gain control. We investigated the effects of presynaptic differences in dopamine and norepinephrine synthesis with the help of the tyrosine hydroxylase (TH) rs10770141 and the dopamine-β-hydroxylase (DBH) rs1611115, rs6271, and rs1611122 polymorphisms. Conscious and subliminal response conflicts were induced with flanker and prime distractors in (n = 207) healthy young participants while neurophysiological data (EEG) was recorded. The results demonstrated that the increased presynaptic catecholamine synthesis associated with the TH rs10770141 TT genotype improves cognitive control in case of consciously perceived (flanker) conflicts, but not in case of subliminally processed (prime) conflicts. Only norepinephrine seemed to also modulate subliminal conflict processing, as evidenced by better performance of the DBH rs1611122 CC genotype in case of high subliminal conflict load. Better performance was linked to larger conflict-induced modulations in post-response alpha band power arising from parietal and inferior frontal regions, which likely helps to suppress the processing of distracting information. In summary, presynaptic catecholamine synthesis benefits consciously perceived conflicts by improving the suppression of distracting information following a conflict. Subliminal conflicts were modulated via the same mechanism, but only by norepinephrine.

Paradoxical response inhibition advantages in adolescent obsessive compulsive disorder result from the interplay of automatic and controlled processes

Response inhibition deficits have often been described in obsessive compulsive disorder (OCD). Yet, research on response inhibition in OCD focusses on “top-down” controlled mechanisms, and it has been neglected that response inhibition performance depends on the interplay of controlled and automatic processes during response selection. Based on pathophysiological considerations we test the counterintuitive hypothesis that OCD patients show superior inhibitory control when automatic mechanisms govern processes involved in response inhibition. We examined a group of adolescent OCD patients (n = 27) and healthy controls (n = 27) using a combined Simon-Go/NoGo task. This task is able to examine conjoint effects of automatic and controlled processes during response inhibition. EEG and source localization analyses were applied to examine the underlying neural mechanisms. OCD patients committed fewer false alarms than healthy controls (HC) in the congruent Simon-NoGo condition, which is dominated by automatic response selection mechanisms. On a neurophysiological (EEG) level, these effects were reflected by intensified correlates of ‘braking’ processes associated with modulation of right inferior prefrontal regions. There is no general response inhibition deficit in adolescent OCD. When considering conjoint effects of automatic and controlled processes during the inhibition of responses paradoxical response inhibition advantages can emerge in OCD. This is likely a result of otherwise pathological fronto-striatal hyperactivity and loss of a situation-specific modulation of response selection mechanisms in OCD.

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Effects of automatic/controlled processes on response inhibition (RI) are studied.

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OCD patients show better performance in automatic vs. controlled RI.

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Underlying neurophysiological (EEG) processes are delineated.

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Activation differences in the rIFG are associated with this effect.

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Effects are discussed in neurobiological frameworks of OCD.

RETRACTED: Neurophysiological mechanisms underlying the modulation of cognitive control by simultaneous conflicts

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal) This article has been retracted at the request of the Editor-in-Chief with the agreement of the authors. In a previous version of the paper reviewed in another journal, the reviewer suggested changing the filter settings because the setting used (reported hp 0.5) can produce serious artifactual effects on the ERP components (N200, N400 and P300) that the authors were interested in. In this published version of the article a different filter (0.2Hz HP) setting is reported in the methods. However, the results sections are identical. A change in filter setting should have led to different results. There is reasonable doubt that the reported filter settings were indeed applied on the reported data. However, there is consensus that this was due to an error, acknowledged by the authors who fully co-operated with the investigation and agreed with the decision. There is no indication of any fraudulent motivation.

Neuronal networks underlying the conjoint modulation of response selection by subliminal and consciously induced cognitive conflicts

Goal-directed behavior has been shown to be affected by consciously and subliminally induced conflicts. Both types of conflict conjointly modulate behavioral performance, but the underlying neuronal mechanisms have remained unclear. While cognitive control is linked to oscillations in the theta frequency band, there are several mechanisms via which theta oscillations may enable cognitive control: via the coordination and synchronization of a large and complex neuronal network and/or via local processes within the medial frontal cortex. We, therefore, investigated this issue with a focus on theta oscillations and the underlying neuronal networks. For this purpose, n = 40 healthy young participants performed a conflict paradigm that combines conscious and subliminal distractors while an EEG was recorded. The data show that separate processes modulate the theta-based activation and organization of cognitive control networks: EEG beamforming analyses showed that variations in theta band power generated in the supplementary motor area reflected the need for control and task-relevant goal shielding, as both conflicts as well as their conjoint effect on behavior increased theta power. Yet, large networks were not modulated by this and graph theoretical analyses of the efficiency (i.e. small worldness) of theta-driven networks did not reflect the need for control. Instead, theta network efficiency was decreased by subliminal conflicts only. This dissociation suggests that while both kinds of conflict require control and goal shielding, which are induced by an increase in theta band power and modulate processes in the medial frontal cortex, only non-conscious conflicts diminish the efficiency of theta-driven large-scale networks.

Evidence for an altered architecture and a hierarchical modulation of inhibitory control processes in ADHD

Inhibitory control deficits are a hallmark in ADHD. Yet, inhibitory control includes a multitude of entities (e.g. ‘inhibition of interferences’ and ‘action inhibition’). Examining the interplay between these kinds of inhibitory control provides insights into the architecture of inhibitory control in ADHD. Combining a Simon task and a Go/Nogo task, we assessed the interplay of ‘inhibition of interferences’ and ‘action inhibition’. This was combined with EEG recordings, EEG data decomposition and source localization. Simon interference effects in Go trials were larger in ADHD. At the neurophysiological level, this insufficient inhibition of interferences in ADHD related to the superior parietal cortex. Simon interference effects were absent in action inhibition (Nogo) trials in ADHD, compared to controls. This was supported by bayesian statistics. The power of effects was higher than 95%. The differential effects between the groups were associated with modulations of neurophysiological response selection processes in the superior frontal gyrus. ADHD is not only associated with deficits in inhibitory control. Rather, the organization and architecture of the inhibitory control system is different in ADHD. Distinguishable inhibitory control processes operate on a hierarchical ‘first come, first serve’ basis and are not integrated in ADHD. This is a new facet of ADHD.

On the effects of tyrosine supplementation on interference control in a randomized, double-blind placebo-control trial

Exerting cognitive control is an effortful endeavor that is strongly modulated by the availability of dopamine (DA) and norepinephrine (NE), which are both synthesized from the amino acid precursor tyrosine. Supplementing tyrosine may increase the synthesis of both catecholamines. This has been suggested to improve executive functioning and potentially even counteract depletion effects in this domain. Yet, it has remained unclear whether tyrosine also improves interference control and whether subliminally and consciously triggered response conflicts are subject to the same modulation. We investigated this question in a double-blind intra-individual study design. N = 26 young healthy subjects performed two consecutive cognitive control tasks that triggered automatic incorrect response tendencies; once with tyrosine supplementation and once with a placebo. The results show that tyrosine decreased the size of consciously perceived conflicts in a Simon Task, but not a Flanker task, thus suggesting that stimulus-response conflicts might be modulated differently from stimulus-stimulus conflicts. At the same time, tyrosine supplementation increased the size of subliminally triggered conflicts whenever a different, consciously perceived conflict was also present. This suggests that control-related DA and NE release may increase visuo-motor priming, especially when no conflict-specific top-down control may be triggered to counteract subliminal priming effects. Also, these subliminal conflicts might be aggravated by concurrent control investments in other kinds of conflict. Taken together, our data suggest that beneficial effects of tyrosine supplementation do not require depletion effects, but may be limited to situations where we consciously perceive a conflict and the associated need for conflict-specific control.

Evidence for a neural dual-process account for adverse effects of cognitive control

Advantageous effects of cognitive control are well-known, but cognitive control may also have adverse effects, for example when it suppresses the implicit processing of stimulus-response (S-R) bindings that could benefit task performance. Yet, the neurophysiological and functional neuroanatomical structures associated with adverse effects of cognitive control are poorly understood. We used an extreme group approach to compare individuals who exhibit adverse effects of cognitive control to individuals who do not by combining event-related potentials (ERPs), source localization, time-frequency analysis and network analysis methods. While neurophysiological correlates of cognitive control (i.e. N2, N450, theta power and theta-mediated neuronal network efficiency) and task-set updating (P3) both reflect control demands and implicit information processing, differences in the degree of adverse cognitive control effects are associated with two independent neural mechanisms: Individuals, who show adverse behavioral effects of cognitive control, show reduced small-world properties and thus reduced efficiency in theta-modulated networks when they fail to effectively process implicit information. In contrast to this, individuals who do not display adverse control effects show enhanced task-set updating mechanism when effectively processing implicit information, which is reflected by the P3 ERP component and associated with the temporo-parietal junction (TPJ, BA 40) and medial frontal gyrus (MFG; BA 8). These findings suggest that implicit S-R contingencies, which benefit response selection without cognitive control, are always 'picked up', but may fail to be integrated with task representations to guide response selection. This provides evidence for a neurophysiological and functional neuroanatomical "dual-process" account of adverse cognitive control effects.