Effects of binge drinking on action cascading processes: an EEG study

Pilot study on the influence of acute alcohol exposure on biophysical parameters of leukocytes

Objective: This pilot study explores the influence of acute alcohol exposure on cell mechanical properties of steady-state and activated leukocytes conducted with real-time deformability cytometry. Methods: Nineteen healthy male volunteers were enrolled to investigate the effect of binge drinking on biophysical properties and cell counts of peripheral blood leukocytes. Each participant consumed an individualized amount of alcohol to achieve a blood alcohol concentration of 1.2 ‰ as a mean peak. In addition, we also incubated whole blood samples from healthy donors with various ethanol concentrations and performed stimulation experiments using lipopolysaccharide and CytoStim™ in the presence of ethanol. Results: Our findings indicate that the biophysical properties of steady-state leukocytes are not significantly affected by a single episode of binge drinking within the first two hours. However, we observed significant alterations in relative cell counts and a shift toward a memory T cell phenotype. Moreover, exposure to ethanol during stimulation appears to inhibit the cytoskeleton reorganization of monocytes, as evidenced by a hindered increase in cell deformability. Conclusion: Our observations indicate the promising potential of cell mechanical analysis in understanding the influence of ethanol on immune cell functions. Nevertheless, additional investigations in this field are warranted to validate biophysical properties as biomarkers or prognostic indicators for alcohol-related changes in the immune system.

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.

Alcohol and Neural Dynamics: A Meta-analysis of Acute Alcohol Effects on Event-Related Brain Potentials

BACKGROUND

An understanding of alcohol's acute neural effects could augment our knowledge of mechanisms underlying alcohol-related cognitive/motor impairment and inform interventions for addiction. Focusing on studies employing event-related brain potential methods, which offer a direct measurement of neural activity in functionally well-characterized brain networks, we present the first meta-analysis to explore acute effects of alcohol on the human brain.

METHODS

Databases were searched for randomized laboratory alcohol-administration trials assessing brain activity using event-related potentials. Hedges' g coefficients were pooled using 3-level random-effects meta-regression.

RESULTS

Sixty independent randomized controlled trials met inclusion (total N = 2149). Alcohol's effects varied significantly across neural systems, with alcohol leading to reductions in event-related potential components linked with attention (P3b), g = -0.40, 95% CI (-0.50, -0.29), automatic auditory processing (mismatch negativity), g = -0.44, 95% CI (-0.66, -0.22), and performance monitoring (error-related negativity), g = -0.56, 95% CI (-0.79, -0.33). These effects were moderated by alcohol dose, emerging as significant at doses as low as 0.026% blood alcohol concentration and increasing to moderate/large at 0.12%. In contrast, irrespective of dose, relatively small or nonsignificant alcohol effects emerged in other processing domains, including those linked to executive control (N2b responses) and stimulus classification (N2c responses).

CONCLUSIONS

Contrary to traditional conceptualizations of alcohol as a "dirty drug" with broad central nervous system depressant effects, results instead support accounts positing targeted alcohol effects in specific processing domains. By identifying alcohol effects on brain systems involved in performance monitoring and attention, results move toward the identification of mechanisms underlying alcohol-related impairment as well as factors reinforcing addiction.

Automatic aspects of response selection remain unchanged during high-dose alcohol intoxication

Regular binge-drinking increases the risk of developing alcohol use disorder (AUD) and induces similar acute effects on behavioral control, particularly in case of response selection conflicts. No such effects have been reported for automatic/bottom-up response selection, even though AUD alters automaticity. However, it has never been reliably tested whether this domain is truly unchanged during high-dose alcohol intoxication. To investigate this question with the help of Bayesian analyses, we subjected n=31 young healthy male participants to a within-subject design, where each participant was tested twice in a counter-balanced order (ie, once sober and once intoxicated at 1.1‰). On each appointment, the participants performed the S-R paradigm, which assesses automatic stimulus-response (S-R) binding within the framework of the theory of event coding (TEC). In short, the TEC states that stimulus features and responses become encoded in an event file when they occur simultaneously. These event files will be reactivated by any matching stimulus feature, thus facilitating the encoded response (and hampering different responses). Alcohol led to a general decrease in behavioral performance, as demonstrated by significant main effects of intoxication status on accuracy and response times (all P ≤ .009). We also reproduced typical task effects, but did not find any significant interactions with the intoxication factor (all P ≥ .099). The latter was further substantiated by Bayesian analyses providing positive to strong evidence for the null hypothesis. Taken together, our results demonstrate that even high-dose alcohol intoxication does not impair automatic response selection/S-R associations.

High-dose ethanol intoxication decreases 1/f neural noise or scale-free neural activity in the resting state

Binge drinking is a frequent phenomenon in many western societies and has been associated with an increased risk of developing alcohol use disorder later in life. Yet, the effects of high-dose alcohol intoxication on neurophysiological processes are still quite poorly understood. This is particularly the case given that neurophysiological brain activity not only contains recurring (oscillatory) patterns of activity, but also a significant fraction of "scale-free" or arrhythmic dynamics referred to as 1/f type activity, pink noise, or 1/f neural noise. Neurobiological considerations suggest that it should be modulated by alcohol intoxication. To investigate this assumption, we collected resting state EEG data from n = 23 healthy young male subjects in a crossover design, where each subject was once tested sober and once tested while intoxicated (mean breath alcohol concentration of 1.1 permille ±0.2). Analyses of the 1/f neural dynamics showed that ethanol intoxication decreased resting state 1/f neural noise, as compared with a sober state. The effects were strongest when the eyes were closed and particularly reliable in the beta frequency band. Given that the dynamics of the beta band have been shown to strongly depend on GABA_A receptor neural transmission, this finding nicely aligns with the fact that ethanol increases GABAergic signaling. The study reveals a currently unreported effect of binge drinking on neurophysiological dynamics, which likely revealed a higher sensitivity for ethanol effects than most commonly considered measures of power in neural oscillations. Implications and applicability of these findings are discussed.

Alcohol Hangover Does Not Alter the Application of Model-Based and Model-Free Learning Strategies

Frequent alcohol binges shift behavior from goal-directed to habitual processing modes. This shift in reward-associated learning strategies plays a key role in the development and maintenance of alcohol use disorders and seems to persist during (early stages of) sobriety in at-risk drinkers. Yet still, it has remained unclear whether this phenomenon might be associated with alcohol hangover and thus also be found in social drinkers. In an experimental crossover design, n = 25 healthy young male participants performed a two-step decision-making task once sober and once hungover (i.e., when reaching sobriety after consuming 2.6 g of alcohol per estimated liter of total body water). This task allows the separation of effortful model-based and computationally less demanding model-free learning strategies. The experimental induction of alcohol hangover was successful, but we found no significant hangover effects on model-based and model-free learning scores, the balance between model-free and model-based valuation (ω), or perseveration tendencies (π). Bayesian analyses provided positive evidence for the null hypothesis for all measures except π (anecdotal evidence for the null hypothesis). Taken together, alcohol hangover, which results from a single binge drinking episode, does not impair the application of effortful and computationally costly model-based learning strategies and/or increase model-free learning strategies. This supports the notion that the behavioral deficits observed in at-risk drinkers are most likely not caused by the immediate aftereffects of individual binge drinking events.

A literature review on the neurophysiological underpinnings and cognitive effects of transcutaneous vagus nerve stimulation: challenges and future directions

Brain stimulation approaches are important to gain causal mechanistic insights into the relevance of functional brain regions and/or neurophysiological systems for human cognitive functions. In recent years, transcutaneous vagus nerve stimulation (tVNS) has attracted considerable popularity. It is a noninvasive brain stimulation technique based on the stimulation of the vagus nerve. The stimulation of this nerve activates subcortical nuclei, such as the locus coeruleus and the nucleus of the solitary tract, and from there, the activation propagates to the cortex. Since tVNS is a novel stimulation technique, this literature review outlines a brief historical background of tVNS, before detailing underlying neurophysiological mechanisms of action, stimulation parameters, cognitive effects of tVNS on healthy humans, and, lastly, current challenges and future directions of tVNS research in cognitive functions. Although more research is needed, we conclude that tVNS, by increasing norepineprine (NE) and gamma-aminobutyric acid (GABA) levels, affects NE- and GABA-related cognitive performance. The review provides detailed background information how to use tVNS as a neuromodulatory tool in cognitive neuroscience and outlines important future leads of research on tVNS.

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.

How high-dose alcohol intoxication affects the interplay of automatic and controlled processes

Binge drinking is an increasingly prevalent pattern of alcohol consumption that impairs top-down cognitive control to a much stronger degree than automatic response generation. Even though an imbalance of those two antagonistic processes fosters the development and maintenance of alcohol use disorders (AUDs), it has never been directly investigated how binge drinking affects the interaction of those two processes. We therefore assessed a sample of n = 35 healthy young men who were asked to perform a newly developed Simon Nogo paradigm once sober and once intoxicated (~1.2‰) in a balanced within-subject design. Additionally, an EEG was recorded to dissociate controlled and automatic cognitive subprocesses. The results demonstrate that alcohol seems to reduce top-down cognitive control. This control impairment was associated with changes in S-R mapping (reflected by a reduced parietal P3 amplitude), top-down response selection (reflected by modulations of lateralized readiness potentials), and (the evaluation of) response inhibition (reflected by modulations of the Nogo P3). In sharp contrast to this, automatic processing does not seem to be equally altered, as we found neither increases nor decreases in this domain. Most importantly, we also found that the interaction between control and automatisms might be less impaired by alcohol than control alone, which may help to overcome alcohol-induced response inhibition deficits. These "carryover" effects of control from one domain to the other could potentially prove beneficial in AUDs.

Young frequent binge drinkers show no behavioral deficits in inhibitory control and cognitive flexibility

Alcohol intoxication and abuse are well-known to cause impairments in executive functioning and control. Still, we know surprisingly little about individuals engaging in frequent binge drinking, even though they have an increased risk to develop an alcohol use disorder (AUD) later in life. As this risk has been suggested to be linked to (premorbid) executive deficits, we assessed changes in cognitive flexibility and inhibition with the help of a switching task and a stop-change task. Both paradigms had previously been shown to be modulated by alcohol, as well as by functional variations in dopaminergic and GABAergic neurotransmission. We employed an extreme group approach, where we compared pre-selected samples of frequent binge drinkers and non-frequent binge drinkers, all of which had stably pursued their respective consumption pattern for at least 3 years. In combination with Bayes analyses, our results showed that individuals engaging in frequent binge drinking showed no impairments of cognitive flexibility or inhibition, as compared to non-frequent binge drinkers. These observations suggest that frequent binge drinking alone is not associated with the cognitive control deficits commonly observed in AUD. Importantly, the investigated executive functions are known to be altered both during binge drinking and in individuals with AUD. It could hence be speculated that their intermittent consumption pattern prevents non-AUD frequent binge drinkers from the homeostatic counter-regulations of alcohol- and control-associated neurotransmitter systems that may be observed in AUD patients. Yet, this hypothesis still needs to be tested in future research, including studies that combine MR and molecular imaging.

Detrimental effects of a high-dose alcohol intoxication on sequential cognitive flexibility are attenuated by practice

It is well-known that alcohol impairs behavioral control and motor response inhibition, but it has remained rather unclear whether it also impairs cognitive inhibition. As automatized behavior is less vulnerable towards the detrimental effects of alcohol than cognitive control processes, potential cognitive inhibition deficits might however improve with training. We investigated the effect of an acute, binge-like alcohol intoxication in a balanced within-subjects design, asking n=32 healthy young males to perform a backward inhibition paradigm once sober and once while intoxicated (~1.1 ‰). To identify the underlying neurophysiological mechanisms, we analyzed stimulus- and response selection-related processes in neurophysiological data after Residue Iteration Decomposition (RIDE). Alcohol generally impaired behavioral task performance (accuracy and response times) during task switching. This was associated with impaired attentional processing of the task-relevant cue (reflected by reduced P1 and N1 amplitudes), which likely resulted in a larger need for reactive control at the later stage of response selection and control (reflected by increased fronto-central theta power). Without prior practice (~30 minutes), the intoxicated participants further struggled to overcome the cognitive inhibition of a previously relevant task set (reflected by a larger backward inhibition effect). This was linked to reduced posterior theta power, which reflects alcohol-induced impairments in working memory capacity and task set-relevant memory retrieval. As individuals with ~30 min task practice did not show the same alcohol-related deficit, it may be deduced that (partial) task set automatization via stimulus-response associations may help to reduce the detrimental effects of alcohol on cognitive inhibition during task switching.

Effects of high-dose ethanol intoxication and hangover on cognitive flexibility

The effects of high-dose ethanol intoxication on cognitive flexibility processes are not well understood, and processes related to hangover after intoxication have remained even more elusive. Similarly, it is unknown in how far the complexity of cognitive flexibility processes is affected by intoxication and hangover effects. We performed a neurophysiological study applying high density electroencephalography (EEG) recording to analyze event-related potentials (ERPs) and perform source localization in a task switching paradigm which varied the complexity of task switching by means of memory demands. The results show that high-dose ethanol intoxication only affects task switching (i.e. cognitive flexibility processes) when memory processes are required to control task switching mechanisms, suggesting that even high doses of ethanol compromise cognitive processes when they are highly demanding. The EEG and source localization data show that these effects unfold by modulating response selection processes in the anterior cingulate cortex. Perceptual and attentional selection processes as well as working memory processes were only unspecifically modulated. In all subprocesses examined, there were no differences between the sober and hangover states, thus suggesting a fast recovery of cognitive flexibility after high-dose ethanol intoxication. We assume that the gamma-aminobutyric acid (GABAergic) system accounts for the observed effects, while they can hardly be explained by the dopaminergic system.

Effects of binge drinking and hangover on response selection sub-processes-a study using EEG and drift diffusion modeling

Effects of binge drinking on cognitive control and response selection are increasingly recognized in research on alcohol (ethanol) effects. Yet, little is known about how those processes are modulated by hangover effects. Given that acute intoxication and hangover seem to be characterized by partly divergent effects and mechanisms, further research on this topic is needed. In the current study, we hence investigated this with a special focus on potentially differential effects of alcohol intoxication and subsequent hangover on sub-processes involved in the decision to select a response. We do so combining drift diffusion modeling of behavioral data with neurophysiological (EEG) data. Opposed to common sense, the results do not show an impairment of all assessed measures. Instead, they show specific effects of high dose alcohol intoxication and hangover on selective drift diffusion model and EEG parameters (as compared to a sober state). While the acute intoxication induced by binge-drinking decreased the drift rate, it was increased by the subsequent hangover, indicating more efficient information accumulation during hangover. Further, the non-decisional processes of information encoding decreased with intoxication, but not during hangover. These effects were reflected in modulations of the N2, P1 and N1 event-related potentials, which reflect conflict monitoring, perceptual gating and attentional selection processes, respectively. As regards the functional neuroanatomical architecture, the anterior cingulate cortex (ACC) as well as occipital networks seem to be modulated. Even though alcohol is known to have broad neurobiological effects, its effects on cognitive processes are rather specific.

High vagally mediated resting-state heart rate variability is associated with superior action cascading

The neurovisceral integration model suggests that individual differences in heart rate variability (HRV), an index of vagal tone, may relate to prefrontal cortical activity and predict performance on cognitive control tasks. The aim of this study was to further verify this model by investigating the relationship between vagally-mediated resting-state HRV and action cascading, a crucial cognitive control function which refers to the ability to cope with multiple response options when confronted with various task goals. Resting-state HRV and performance on the stop-change paradigm, which provides a relatively well-established diagnostic measure of action cascading and response inhibition, was assessed in 88 healthy volunteers (age range 18-33). Compared to individuals with low resting-state HRV, participants with high resting-state HRV showed enhanced action cascading performance, both when a disruption (stopping) and change towards an alternative response were required simultaneously, and when requirements were cascaded (i.e. when the stopping process had already finished at the time the change was required). Our findings represent an important step towards extending our understanding of the neurovisceral integration model in cognitive control.

The effects of ethanol on diverse components of choice in the rat: reward discrimination, preference and relative valuation

Alcohol consumption impairs judgment and choice. How alcohol alters these crucial processes is primarily unknown. Choice can be fractionated into different components including reward discrimination, preference and relative valuation that can function together or in isolation depending upon diverse factors including choice context. We examined the diverse components and contextual effects by analyzing the effects of alcohol drinking on choice behavior in a task with a reduced level of temporal and spatial constraints. Rats were trained to drink 10% ethanol during 6 weeks of behavior testing using a combined sucrose-fade and two-bottle free-choice procedure. Two different sucrose pellet outcomes (e.g., constant vs. variable) were presented each week to examine the impact of voluntary drinking on reward-based decision-making. Behavioral contexts of single option, free choice and extinction were examined for each outcome set. Comparisons were made between alcohol and control groups and within the alcohol group over time to inspect choice profiles. Between-group results showed alcohol drinking animals expressed altered place preference and modified sucrose reward approach latencies. The within-group profile showed that alcohol drinking animals can express adequate reward discrimination, preference and incentive contrast during free choice. All of these components were significantly reduced during the context of extinction. Control animals were also impacted by extinction but not as severely. The findings point to a need for a greater focus on the context and the diverse components of choice when examining external and internal factors influencing decision-making during alcohol or other substance of abuse exposure.

Reversal of alcohol-induced effects on response control due to changes in proprioceptive information processing

Recent research has drawn interest to the effects of binge drinking on response selection. However, choosing an appropriate response is a complex endeavor that usually requires us to process and integrate several streams of information. One of them is proprioceptive information about the position of limbs. As to now, it has however remained elusive how binge drinking affects the processing of proprioceptive information during response selection and control in healthy individuals. We investigated this question using neurophysiological (EEG) techniques in a response selection task, where we manipulated proprioceptive information. The results show a reversal of alcohol-induced effects on response control due to changes in proprioceptive information processing. The most likely explanation for this finding is that proprioceptive information does not seem to be properly integrated in response selection processes during acute alcohol intoxication as found in binge drinking. The neurophysiological data suggest that processes related to the preparation and execution of the motor response, but not upstream processes related to conflict monitoring and spatial attentional orienting, underlie these binge drinking-dependent modulations. Taken together, the results show that even high doses of alcohol have very specific effects within the cascade of neurophysiological processes underlying response control and the integration of proprioceptive information during this process.

High-dose alcohol intoxication differentially modulates cognitive subprocesses involved in response inhibition

Aside from well-known physiological effects, high-dose alcohol intoxication (a.k.a. binge drinking) can lead to aversive social and legal consequences because response inhibition is usually compromised under the influence of alcohol. Although the behavioral aspects of this phenomenon were reported on extensively, the underlying neurophysiological mechanisms mediating this disinhibition are unclear. To close this gap, we used both behavioral and neurophysiological measures (event-related potentials, ERPs) to investigate which subprocesses of response inhibition are altered under the influence of high-dose alcohol intoxication. Using a within-subject design, we asked young healthy participants (n = 27) to complete a GO/NOGO task once sober and once intoxicated (approximately 1.2‰). During intoxication, high-dose alcohol effects were highest in a condition where the participants could not rely on automated stimulus-response mapping processes during response inhibition. In this context, the NOGO-P3 (ERP), that likely depends on dopaminergic signaling within mesocorticolimbic pathways and is thought to reflect motor inhibition and/or the evaluation of inhibitory processes, was altered in the intoxicated state. In contrast to this, the N2 component, which largely depends on nigrostriatal dopamine pathways and is thought to reflect inhibition on a pre-motor level, was not altered. Based on these results, we demonstrate that alcohol-induced changes of dopaminergic neurotransmission do not exert a global effect on response inhibition. Instead, changes are highly subprocess-specific and seem to mainly target mesocorticolimbic pathways that contribute to motor inhibition and the evaluation of such.

Action Video Gaming and Cognitive Control: Playing First Person Shooter Games Is Associated with Improved Action Cascading but Not Inhibition

There is a constantly growing interest in developing efficient methods to enhance cognitive functioning and/or to ameliorate cognitive deficits. One particular line of research focuses on the possibly cognitive enhancing effects that action video game (AVG) playing may have on game players. Interestingly, AVGs, especially first person shooter games, require gamers to develop different action control strategies to rapidly react to fast moving visual and auditory stimuli, and to flexibly adapt their behaviour to the ever-changing context. This study investigated whether and to what extent experience with such videogames is associated with enhanced performance on cognitive control tasks that require similar abilities. Experienced action videogame-players (AVGPs) and individuals with little to no videogame experience (NVGPs) performed a stop-change paradigm that provides a relatively well-established diagnostic measure of action cascading and response inhibition. Replicating previous findings, AVGPs showed higher efficiency in response execution, but not improved response inhibition (i.e. inhibitory control), as compared to NVGPs. More importantly, compared to NVGPs, AVGPs showed enhanced action cascading processes when an interruption (stop) and a change towards an alternative response were required simultaneously, as well as when such a change had to occur after the completion of the stop process. Our findings suggest that playing AVGs is associated with enhanced action cascading and multi-component behaviour without affecting inhibitory control.

Complex sensorimotor transformation processes required for response selection are facilitated by the striatum

Both fronto-parietal networks and the basal ganglia play an important role in action cascading. It is well-known that cortical structures mediate sensorimotor transformation for this purpose. The striatum receives extensive input from those cortical structures and has been shown to be modulated by the predictability of cortical input. Until today, it has however remained unclear whether the processing of spatial codes or even sensorimotor transformation processes for the purpose of action cascading involve the striatum. We therefore examined this question by means of fMRI using a stop-change task that varied the predictability as well as the complexity of sensorimotor transformations required for correct responding in the context of action cascading. On the behavioral level, we found that the complexity of sensorimotor transformation processes only prolonged reaction times when the requirement for this transformation was predictable. fMRI results matched this effect showing enhanced activity of the caudate in case a complex sensorimotor transformation could be anticipated. Irrespective of the complexity of the required transformations, the putamen was furthermore involved in the prediction of imminent action cascading demands. Taken together, our findings give rise to a conceptual advance regarding basal ganglia function by showing that the anticipation and, more importantly, processing of complex sensorimotor transformation processes involves the striatum.

γ-Aminobutyric acid (GABA) administration improves action selection processes: a randomised controlled trial

In order to accomplish a task goal, real-life environments require us to develop different action control strategies in order to rapidly react to fast-moving visual and auditory stimuli. When engaging in complex scenarios, it is essential to prioritise and cascade different actions. Recent studies have pointed to an important role of the gamma-aminobutyric acid (GABA)-ergic system in the neuromodulation of action cascading. In this study we assessed the specific causal role of the GABA-ergic system in modulating the efficiency of action cascading by administering 800 mg of synthetic GABA or 800 mg oral of microcrystalline cellulose (placebo). In a double-blind, randomised, between-group design, 30 healthy adults performed a stop-change paradigm. Results showed that the administration of GABA, compared to placebo, increased action selection when an interruption (stop) and a change towards an alternative response were required simultaneously, and when such a change had to occur after the completion of the stop process. These findings, involving the systemic administration of synthetic GABA, provide the first evidence for a possible causal role of the GABA-ergic system in modulating performance in action cascading.

RETRACTED: Transcutaneous vagus nerve stimulation (tVNS) enhances response selection during action cascading processes

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This retraction comes after a thorough and time-consuming analysis of the published article and the data it reports, following an investigation from the University of Leiden. On date 15th November 2021 European Neuropsychopharmacology received advice from University of Leiden, containing allegations of misconduct concerning the data reported in this article. Due to the nature of the concerns raised about this paper, the Editor-in-Chief examined all documents provided, all aspects of the peer review and editorial process and requested the view of each of the authors. The Editor-in-Chief wishes to acknowledge the co-operation of all parties. The Editor-in-Chief considers that there is a legitimate cause for concern regarding deletion of participants from datasets. The Editor-in-Chief commends the authors for their willingness in participating in this dialogue. However, given the concerns raised, the suggestion of the University of Leiden, and the view expressed by some of the authors, Retraction of this paper is inevitable. The Editor-in-Chief and the entire editorial board will use this case as a reminder to be as diligent as possible in the peer review process and to support transparency and openness in data sharing.

Different strategies, but indifferent strategy adaptation during action cascading

Every day, we need to apply different action control strategies to successfully interact with ever-changing environments. In situations requiring several responses, we often have to cascade different actions. The strategies used to accomplish this have been subject to extensive research in cognitive psychology and neuroscience but it has remained rather unclear if and to what degree such strategies are adapted while performing a task. Furthermore, we do not know if such adaptations are subject to differential effects depending on an individual’s preferred initial strategy to cope with multiple-demand situations. Using Bayesian analyses, we were able to show that even though the applied strategy is subject to slight modulations over the course of an action cascading task, this shift is equally strong for subjects who differ their general action cascading strategy. The action cascading strategy subjects apply to cope with multiple-demand situations is adapted independent of the preferred, inter-individually varying strategy that is initially used. Future research needs to test if the task goal activation strategy applied during action cascading reflects a ‘cognitive trait’ and is stable across different situations.

Neurofeedback and its possible relevance for the treatment of Tourette syndrome

Neurofeedback is an increasingly recognized therapeutic option in various neuropsychiatric disorders to treat dysfunctions in cognitive control as well as disorder-specific symptoms. In this review we propose that neurofeedback may also reflect a valuable therapeutic option to treat executive control functions in Gilles-de-la-Tourette syndrome (GTS). Deficits in executive control functions when ADHD symptoms appear in GTS likely reflect pathophysiological processes in cortico-thalamic-striatal circuits and may also underlie the motor symptoms in GTS. Such executive control deficits evident in comorbid GTS/ADHD depend on neurophysiological processes well-known to be modifiable by neurofeedback. However, so far efforts to use neurofeedback to treat cognitive dysfunctions are scarce. We outline why neurofeedback should be considered a promising treatment option, what forms of neurofeedback may prove to be most effective and how neurofeedback may be implemented in existing intervention strategies to treat comorbid GTS/ADHD and associated dysfunctions in cognitive control. As cognitive control deficits in GTS mostly appear in comorbid GTS/ADHD, neurofeedback may be most useful in this frequent combination of disorders.

Modulatory effects of proinflammatory cytokines for action cascading processes - evidence from neurosarcoidosis

Neurosarcoidosis is a rare central nervous system manifestation of sarcoidosis. T cell, T-helper cell and macrophage activation via the major histocompatibility complex (MHC) II-mediated pathway causes this disease. Little is known about the possible cognitive disturbances in this disease as most reported instances are case studies. Here, we provide the first in-depth analysis of psychomotor functions in a sample of 30 neurosarcoidosis patients. We investigated action control processes using a paradigm that is able to examine how different tasks are cascaded to achieve the task goal. We integrated electrophysiological (EEG) data with behavioural and neuroimmunological data. Our results show that there was no general cognitive decline in patients with neurosarcoidosis. Patients only presented deficits when two response options have to be prioritized. Patients apply an inefficient processing strategy where they try to processes different response options in parallel. The electrophysiological data show that the deficits are due to dysfunctions at the response selection stage. Behavioural and neurophysiological changes are predictable on the basis of soluble interleukin 2 receptor serum concentrations. The results show that neurosarcoidosis is not associated with nonspecific changes in cognitive functions but does lead to specific alterations in cognitive control that are strongly dependent on immunological parameters.

DRD1 and DRD2 genotypes modulate processing modes of goal activation processes during action cascading

Dopamine plays an important role in action selection, but little is known about the influence of different dopamine receptor systems on the subprocesses occurring during the cascading of actions. Because action selection and cascading can be accomplished in a serial manner or a parallel manner, we investigated the potential effects of DRD1 (rs4531) and DRD2 (rs6277) receptor polymorphisms on this dimension. We gathered behavioral and neurophysiological data from healthy human subjects (n = 162) and applied mathematical constraints to quantify their action selection strategy on a serial-parallel continuum. The behavioral results show a more serial and more effective action cascading strategy in homozygous DRD1 G allele carriers, who are assumed to have a higher D1 receptor efficiency than carriers of the A allele. In the group of homozygous DRD2 T-allele carriers, who have a higher striatal density of D2 receptors than C-allele carriers, we found a less effective and more parallel action cascading strategy. These findings suggest that, within the same sample, a higher D1 efficiency seems to shift the action cascading strategy toward a more serial processing mode, whereas the D2 receptors seem to promote a shift in the opposite direction by inducing a more parallel processing mode. Furthermore, the neurophysiological analysis shows that the observed differences are not based on attentional differences or basic inhibition. Instead, processes linking stimulus processing and response execution seem to differentiate between more serial and more parallel processing groups.

Feeling safe in the plane: neural mechanisms underlying superior action control in airplane pilot trainees--a combined EEG/MRS study

In day-to-day life, we need to apply strategies to cascade different actions for efficient unfolding of behavior. While deficits in action cascading are examined extensively, almost nothing is known about the neuronal mechanisms mediating superior performance above the normal level. To examine this question, we investigate action control in airplane pilot trainees. We use a stop-change paradigm that is able to estimate the efficiency of action cascading on the basis of mathematical constraints. Behavioral and EEG data is analyzed along these constraints and integrated with neurochemical data obtained using Magnetic Resonance Spectroscopy (MRS) from the striatal gamma-aminobutyric acid (GABA) -ergic system. We show that high performance in action cascading, as exemplified in airplane pilot trainees, can be driven by intensified attentional processes, circumventing response selection processes. The results indicate that the efficiency of action cascading and hence the speed of responding as well as attentional gating functions are modulated by striatal GABA and Glutamate + Glutamine concentrations. In superior performance in action cascading similar increases in the concentrations of GABA and Glutamate + Glutamine lead to stronger neurophysiological and behavioral effects as compared to subjects with normal performance in action cascading.