ERP Correlates of Proactive and Reactive Cognitive Control in Treatment-Naïve Adult ADHD

Noninvasive Brain Stimulation for Improving Cognitive Deficits and Clinical Symptoms in Attention-Deficit/Hyperactivity Disorder: A Systematic Review and Meta-Analysis

Objective: Noninvasive brain stimulation (NIBS) is a promising complementary treatment for attention-deficit/hyperactivity disorder (ADHD). However, its efficacy varies due to diverse participant profiles and methodologies. This meta-analysis, registered with PROSPERO (CRD42023457269), seeks to assess NIBS efficacy in improving cognitive deficits and clinical symptoms in individuals with ADHD. Methods: We systematically searched five databases (October 2024) for randomized controlled trials focusing on cognitive functions and clinical symptoms in individuals meeting the DSM/ICD criteria for ADHD. A meta-analytical synthesis was conducted using RevMan 5.4.1. Results: Meta-analyses found significant improvement in inhibitory control, working memory, and inattention in active transcranial direct current stimulation (tDCS) groups compared with sham groups. Conversely, repetitive transcranial magnetic stimulation (rTMS) did not demonstrate significant therapeutic benefits for ADHD symptoms. Additionally, four transcranial random noise stimulation (tRNS) and three transcranial alternating current stimulation (tACS) studies demonstrated promising improvements in executive functions and the alleviation of ADHD symptoms. Conclusions: The findings from this meta-analysis highlight NIBS as a promising adjunctive therapy for managing ADHD, advancing both theoretical knowledge and practical treatment options in this field.

Proactive and Reactive Inhibitory Control Strategies: Exploring the Impact of Interindividual Variables on an ERP Continuous Performance Task (AX-CPT)

According to the Dual Mechanisms of Control (DMC) framework, cognitive control can be divided into two strategies: proactive cognitive control, which relies mainly on the active maintenance of contextual information relevant to the ongoing task; and reactive cognitive control, which is a form of transient control triggered by an external cue. Although cognitive control has been studied extensively, little is known about the specificities of inhibition within the framework of the DMC model and the influence of interindividual variables on inhibitory control.Thanks to an inhibitory version of the continuous performance task (CPT), we studied behavioral performances and Event-Related Potentials (ERPs) related to proactive and reactive inhibition, and their links to psychological profile and cognitive performances. One hundred and five young adults underwent the task, along with a short clinical and cognitive evaluation.We were able to observe ERPs related to proactive (cue-N1, cue-N2, cue-P3, and the contingent negative variation) and reactive inhibitory control (target-N2 and target-P3). Our results showed that proactive strategies appeared to be linked with impulsivity, working memory abilities, dominant response inhibition, gender, and the consumption pattern of nicotine. Reactive strategies appeared to be linked with attentional and working memories abilities.Overall, the inhibitory AX-CPT allowed a specific investigation of cognitive control within the framework of the DMC based on behavioral and ERP variables. This provided us an opportunity to investigate the principal ERP components related to proactive and reactive inhibitory control strategies as well as to link them with specific clinical and cognitive variables.

Video game addiction is associated with early stage of inhibitory control problems: An event-related potential study using cued Go/NoGo task

Video game addiction (VGA) is associated with cognitive problems, particularly deficits in inhibitory control. The present study aimed to investigate behavioural responses and event-related potential associated with specific response inhibition using the cued Go/NoGo task to examine the effects of VGA on brain activity related to response inhibition. Twenty-five individuals addicted to video games (action video games) and 25 matched healthy controls participated in the study. The results showed that the VGA group had significantly more commission error in the NoGo trials and faster reaction time in the Go trials compared with the control group. The event-related potential analyses revealed significant reductions in amplitudes of N2 cue and N2 NoGo in the VGA group. While there was no significant difference between the N2 amplitudes of the Go and NoGo trials in the VGA group, the control group had a larger N2 amplitude in the NoGo trials. These results indicate that VGA subjects have difficulties in the early stages of response inhibition, as well as some level of impairment in proactive cognitive control.

Electrophysiological underpinnings of dysfunctional inhibitory control in adults with attention-deficit/hyperactivity disorder: evidence for reduced NoGo anteriorization

Our aim was to delineate the electrophysiological basis of dysfunctional inhibitory control of adult ADHD via investigating the anteriorization of the P3 component of the event-related brain response associated with the NoGo task condition (i.e., NoGo anteriorization, NGA). NGA is a neurophysiological measure of brain topography for cognitive response control, which indexes an overall shift of the brain's electrical activity in anterior direction towards the prefrontal areas. While the NoGo P3 received considerable attention in the adult ADHD literature, the brain topography of this component, which reflects the inhibitory process, remains largely unaddressed. EEG recordings were obtained during a Go/NoGo task from 51 subjects (n = 26 adult patients with ADHD, n = 25 healthy controls) using a high-density, 128-channel BioSemi ActiveTwo recording system. ADHD patients had significantly lower P3 NGA response compared to controls. The decrease in NGA was related to impulsivity scores as measured by the Conners' Adult ADHD Rating Scale: patients with higher impulsivity scores had significantly lower NGA. Treatment with stimulant medication, as compared to the lack of such treatment, was associated with a correction of the lower NGA response in ADHD patients. The current study revealed a lower NGA in adult ADHD, a finding which is consistent with the inhibitory control and frontal lobe dysfunctions described in the disorder. Our finding of the inverse relationship between NGA and impulsivity suggests that clinically more severe impulsivity is linked to a more pronounced frontal dysfunction in adult ADHD subjects.

Longitudinal investigation in children and adolescents with ADHD and healthy controls: A 2-year ERP study

Cross-sectional group comparisons have shown altered neurocognitive and neurophysiological profiles in individuals with attention-deficit/hyperactivity disorder (ADHD). We report a two-year longitudinal observational study of ADHD children and adolescents (N = 239) regarding ADHD symptoms, behavioral metrics, and event-related potentials (ERP) and compared them to healthy controls (N = 91). The participants were assessed up to five times with a cued Go/NoGo task while ERPs were recorded. We fitted the trajectories of our variables of interest with univariate and bivariate latent growth curve models. At baseline, the ADHD group had increased reaction time variability, higher number of omission and commission errors, and attenuated CNV and P3d amplitudes compared to controls. The task performance in terms of behavioral metrics improved in both groups over two years; however, with differential patterns: the decrease in reaction time and omission errors were stronger in the control group, and the reduction of commission errors was more substantial in the ADHD group. The cueP3, CNV, and N2d amplitudes changed slightly over two years, with negligible differences between both groups. Furthermore, the parent-rated symptom burden in the ADHD group decreased by 22 % (DSM-5-based questionnaire). We did not identify any associations between the changes in symptoms and the changes in the behavioral or neurophysiological metrics. The lack of association between the changes in symptoms and the behavioral or ERP metrics supports the trait liability hypothesis, which claims that the neurocognitive deficits are independent of symptom alleviation. Furthermore, the change in symptom burden was substantial, questioning the stability of the reported ADHD symptoms.

Impact of Early Childhood Malnutrition on Adult Brain Function: An Evoked-Related Potentials Study

More than 200 million children under the age of 5 years are affected by malnutrition worldwide according to the World Health Organization. The Barbados Nutrition Study (BNS) is a 55-year longitudinal study on a Barbadian cohort with histories of moderate to severe protein-energy malnutrition (PEM) limited to the first year of life and a healthy comparison group. Using quantitative electroencephalography (EEG), differences in brain function during childhood (lower alpha1 activity and higher theta, alpha2 and beta activity) have previously been highlighted between participants who suffered from early PEM and controls. In order to determine whether similar differences persisted into adulthood, our current study used recordings obtained during a Go-No-Go task in a subsample of the original BNS cohort [population size (N) = 53] at ages 45-51 years. We found that previously malnourished adults [sample size (n) = 24] had a higher rate of omission errors on the task relative to controls (n = 29). Evoked-Related Potentials (ERP) were significantly different in participants with histories of early PEM, who presented with lower N2 amplitudes. These findings are typically associated with impaired conflict monitoring and/or attention deficits and may therefore be linked to the attentional and executive function deficits that have been previously reported in this cohort in childhood and again in middle adulthood.

Can electroencephalography (EEG) identify ADHD subtypes? A systematic review

Attention Deficit/Hyperactivity Disorder (ADHD) has been associated with atypical patterns of neural activity measured by electroencephalography (EEG). However, the identification of EEG diagnostic biomarkers has been complicated by the disorder's heterogeneity. The objective of this review was to synthesize the literature investigating EEG variation in patients diagnosed with ADHD, addressing the following questions: 1) Are the diagnostic ADHD subtypes associated with different EEG characteristics? 2) Are EEG measures correlated with ADHD traits and/or symptom severity? and 3) Do classification techniques using EEG measures reveal different clinical presentations of ADHD? Outcomes highlight the potential for electrophysiological measures to provide meaningful insights into the heterogeneity of ADHD, although direct translation of EEG biomarkers for diagnostic purposes is not yet supported. Key measures that show promise for the discrimination of existing ADHD subtypes and symptomatology include: resting state and task-related modulation of alpha, beta and theta power, and the event-related N2 and P3 components. Prescriptions are discussed for future studies that may help to bridge the gap between research and clinical application.

Proactive and reactive inhibitory control are differently affected by video game addiction: An event-related potential study

INTRODUCTION

Video game addiction (VGA) is associated with physical and mental disorders, one of which is problem in executive function, particularly inhibitory control. The present study aimed to investigate reactive and proactive inhibitory controls by event-related potential (ERP).

METHODS

Thirty video game (action video games)-addicted subjects and 30 matched healthy controls participated in the study, who were tested by the selective stop-signal task.

RESULTS

The main results revealed that the VGA group had significantly more problems in preparatory processes and proactive stop trials, showing that VGA has a negative effect on proactive inhibition.

CONCLUSION

Finding the problem in proactive inhibitory control might be helpful in developing new treatments and rehabilitation methods in these fields.

Multimodal Virtual Reality-Based Assessment of Adult ADHD: A Feasibility Study in Healthy Subjects

Neuropsychological assessments are often surprisingly inaccurate in mapping clinically-reported attention-deficit hyperactivity disorder (ADHD) symptoms, presumably due to their low ecological validity. Virtual reality (VR) might offer a potential solution for this problem, given its capability to generate standardized and yet highly realistic virtual environments. As the first adaptation of existing virtual classroom scenarios to an adult population, we developed a Virtual Seminar Room (VSR) for multimodal characterization of ADHD symptoms. To test its feasibility, N = 35 healthy participants were immersed into the VSR via a head-mounted display and carried out a VR-embedded continuous performance task (CPT) under varying levels of distractions in two experimental blocks (24 min each). CPT performance, electroencephalography (EEG) measures, and head movements (actigraphy) were simultaneously recorded and analyzed offline. Although CPT performance remained constant throughout the task, head movements increased significantly from Block 1 to Block 2. In addition, EEG theta (4-7 Hz) and beta (13-30 Hz) power was higher during Block 1 than Block 2, and during distractor-present than distractor-absent phases. Moreover, P300 amplitudes were higher during Block 1 than Block 2, and P300 latencies were prolonged in distractor-absent compared with distractor-present phases. Although the paradigm awaits further improvements, this study confirms the general feasibility of the VSR and provides a first step toward a multimodal, ecologically valid, and reliable VR-based adult ADHD assessment.

Longitudinal Analysis of Self-Reported Symptoms, Behavioral Measures, and Event-Related Potential Components of a Cued Go/NoGo Task in Adults With Attention-Deficit/Hyperactivity Disorder and Controls

This study characterizes a large sample of adults with attention-deficit/hyperactivity disorder (ADHD) and healthy controls regarding their task performance and neurophysiology; cross-sectionally and longitudinally. Self-reported symptoms, behavioral measures, and event-related potentials from a classical cued Go/NoGo task were used to outline the symptom burden, executive function deficits and neurophysiological features, and the associations between these domains. The study participants (N = 210 ADHD, N = 158 controls, age: 18–62 years) were assessed five (ADHD) or three (controls) times over two years. We describe cross-sectional and longitudinal group differences, and associations between symptom burden, and behavioral and event-related potential (ERP) components variables by latent growth curve models, including random slopes and intercepts. The ADHD group showed increased reaction time variability, increased commission and omission errors, and attenuated cueP3, CNV, N2d, and P3d amplitudes. We observed a decrease in self-reported symptoms in the ADHD group over the two years. The behavioral measures (reaction time variability, number of omission, and commission errors) did not change over time, whereas the cueP3, P3d, and N2d amplitude attenuated in both groups. There was no evidence for a robust association between symptom burden and behavioral or ERP measures. The changes in the ERP components with stable task performance, potentially indicate more efficient neuronal processing over the two years. Whether the lack of association between symptom burden and behavioral or ERP measures might be due to the low reliability of the ADHD assessment criteria, or the inappropriateness of the objective measures cannot be inferred.

P300 Modulation via Transcranial Alternating Current Stimulation in Adult Attention-Deficit/Hyperactivity Disorder: A Crossover Study

OBJECTIVE

A repeated finding regarding event-related potentials (ERPs) is that patients with ADHD show a reduced P300 amplitude. This raises the question of whether the attention of ADHD patients can be increased by stabilizing the P300. Assuming that the P300 is generated by event-related oscillations (EROs) in the low frequency range (0-8 Hz), one approach to increase the P300 could be to stimulate the patient's P300 underlying ERO by means of transcranial alternating current stimulation (tACS). The aim of this follow-up study was to investigate this hypothesized mechanism of action in adult ADHD patients.

MATERIALS AND METHODS

Undergoing a crossover design, 20 adult ADHD patients (10 female) received an actual stimulation via tACS on one day and a sham stimulation on another day. Before and after each intervention, EEG characteristics (P300 amplitudes, low frequency power) and attention performances (d2 attention test, visual oddball task (VOT)) were recorded.

RESULTS

Electrophysiological analyses revealed no evidence for an enhanced P300 amplitude or low frequency power increase after actual stimulation compared to sham stimulation. Instead, a significant effect was found for a stronger N700 amplitude increase after actual stimulation compared to sham stimulation. Consistent with the P300 null results, none of the examined neuropsychological performance measures indicated a tACS-induced improvement in attentional ability.

CONCLUSION

Contrary to a previous study using tACS to modulate the P300 in adult ADHD patients, the current study yields no evidence that tACS can increase the P300 amplitude in adult ADHD patients and that such P300 enhancement can directly improve neuropsychological parameters of attention.

DelIrium VULnerability in GEriatrics (DIVULGE) study: a protocol for a prospective observational study of electroencephalogram associations with incident postoperative delirium

INTRODUCTION

Delirium is a neurocognitive disorder common in older adults in acute care settings. Those who develop delirium are at an increased risk of dementia, cognitive decline and death. Electroencephalography (EEG) during delirium in older adults is characterised by slowing and reduced functional connectivity, but markers of vulnerability are poorly described. We aim to identify EEG spectral power and event-related potential (ERP) markers of incident delirium in older adults to understand neural mechanisms of delirium vulnerability. Characterising delirium vulnerability will provide substantial theoretical advances and outcomes have the potential to be translated into delirium risk assessment tools.

METHODS AND ANALYSIS

We will record EEG in 90 participants over 65 years of age prior to elective coronary artery bypass grafting (CABG) or transcatheter aortic valve implantation (TAVI). We will record 4-minutes of resting state (eyes open and eyes closed) and a 5-minute frequency auditory oddball paradigm. Outcome measures will include frequency band power, 1/f offset and slope, and ERP amplitude measures. Participants will undergo cognitive and EEG testing before their elective procedures and daily postoperative delirium assessments. Group allocation will be done retrospectively by linking preoperative EEG data according to postoperative delirium status (presence, severity, duration and subtype).

ETHICS AND DISSEMINATION

This study is approved by the Human Research Ethics Committee of the Royal Adelaide Hospital, Central Adelaide Local Health Network and the University of South Australia Human Ethics Committee. Findings will be disseminated through peer-reviewed journal articles and presentations at national and international conferences.

TRIAL REGISTRATION NUMBER

ACTRN12618001114235 and ACTRN12618000799257.

Slower adaptation of control strategies in individuals with high impulsive tendencies

Flexible use of reactive and proactive control according to environmental demands is the key to adaptive behavior. In this study, forty-eight adults performed ten blocks of an AX-CPT task to reveal the strength of proactive control by the calculation of the proactive behavioral index (PBI). They also filled out the UPPS questionnaire to assess their impulsiveness. The median-split method based on the global UPPS score distribution was used to categorize participants as having high (HI) or low (LI) impulsiveness traits. The analyses revealed that the PBI was negatively correlated with the UPPS scores, suggesting that the higher is the impulsiveness, the weaker the dominance of proactive control processes. We showed, at an individual level, that the PBI increased across blocks and suggested that this effect was due to a smaller decrease in reactive control processes. Notably, the PBI increase was slower in the HI group than in the LI group. Moreover, participants who did not adapt to task demands were all characterized as high impulsive. Overall, the current study demonstrates that (1) impulsiveness is associated with less dominant proactive control due to (2) slower adaptation to task demands (3) driven by a stronger reliance on reactive processes. These findings are discussed in regards to pathological populations.

Behavioral and Neurophysiological Markers of ADHD in Children, Adolescents, and Adults: A Large-Scale Clinical Study

This study aimed to re-evaluate the possible differences between attention-deficit/hyperactivity disorder (ADHD) subjects and healthy controls in the context of a standard Go/NoGo task (visual continuous performance test [VCPT]), frequently used to measure executive functions. In contrast to many previous studies, our sample comprises children, adolescents, and adults. We analyzed data from 447 ADHD patients and 227 healthy controls. By applying multivariate linear regression analyses, we controlled the group differences between ADHD patients and controls for age and sex. As dependent variables we used behavioral (number of omission and commission errors, reaction time, and reaction time variability) and neurophysiological measures (event-related potentials [ERPs]). In summary, we successfully replicated the deviations of ADHD subjects from healthy controls. The differences are small to moderate when expressed as effect size measures (number of omission errors: d = 0.60, reaction time variability: d = 0.56, contingent negative variation (CNV) and P3 amplitudes: -0.35 < d < -0.47, ERP latencies: 0.21 < d < 0.29). Further analyses revealed no substantial differences between ADHD subtypes (combined, inattentive, and hyperactive/impulsive presentation), subgroups according to high- and low-symptomatic burden or methylphenidate intake for their daily routine. We successfully replicated known differences between ADHD subjects and controls for the behavioral and neurophysiological variables. However, the small-to-moderate effect sizes limit their utility as biomarkers in the diagnostic procedure. The incongruence of self-reported symptomatic burden and clinical diagnosis emphasizes the challenges of the present clinical diagnosis with low reliability, which partially accounts for the low degree of discrimination between ADHD subjects and controls.

Electrophysiological correlates of improved executive function following EEG neurofeedback in adult attention deficit hyperactivity disorder

OBJECTIVE

Event-related potentials (ERPs) are reported to be altered in relation to cognitive processing deficits in attention deficit hyperactivity disorder (ADHD). However, this evidence is mostly limited to cross-sectional data. The current study utilized neurofeedback (NFB) as a neuromodulatory tool to examine the ERP correlates of attentional and inhibitory processes in adult ADHD using a single-session, within-subject design.

METHODS

We recorded high-density EEG in 25 adult ADHD patients and 22 neurotypical controls during a Go/NoGo task, before and after a 30-minute NFB session designed to down-regulate the alpha (8-12 Hz) rhythm.

RESULTS

At baseline, ADHD patients demonstrated impaired Go/NoGo performance compared to controls, while Go-P3 amplitude inversely correlated with ADHD-associated symptomatology in childhood. Post NFB, task performance improved in both groups, significantly enhancing stimulus detectability (d-prime) and reducing reaction time variability, while increasing N1 and P3 ERP component amplitudes. Specifically for ADHD patients, the pre-to-post enhancement in Go-P3 amplitude correlated with measures of improved executive function, i.e., enhanced d-prime, reduced omission errors and reduced reaction time variability.

CONCLUSIONS

A single-session of alpha down-regulation NFB was able to reverse the abnormal neurocognitive signatures of adult ADHD during a Go/NoGo task.

SIGNIFICANCE

The study demonstrates for the first time the beneficial neurobehavioral effect of a single NFB session in adult ADHD, and reinforces the notion that ERPs could serve as useful diagnostic/prognostic markers of executive dysfunction.

An EZ-Diffusion Model Analysis of Attentional Ability in Patients With Retinal Pigmentosa

Retinitis pigmentosa (RP) is characterized by visual acuity decrease and visual field loss. However, the impact of visual field loss on the cognitive performance of RP patients remains unknown. In the present study, in order to understand whether and how RP affects spatial processing and attentional function, one spatial processing task and three attentional tasks were conducted on RP patients and healthy controls. In addition, an EZ-diffusion model was performed for further data analysis with four parameters, mean decision time, non-decision time, drift rate, and boundary separation. It was found that in the spatial processing task, compared with the control group, the RP group exhibited a slower response speed in large and medium visual eccentricities, and slower drift rate for the large stimulus, which is strongly verified by the significant linear correlation between the visual field eccentricity with both reaction time (p = 0.047) and non-decision time (p = 0.043) in RP patients. In the attentional orienting task and the attentional switching task, RP exerted a reduction of speed and an increase of non-decision time on every condition, with a decrease of drift rate in the orienting task and boundary separation in the switching task. In addition, the switching cost for large stimulus was observed in the control group but not in the RP group. The stop-signal task demonstrated similar inhibition function between the two groups. These findings implied that RP exerted the impairment of spatial cognition correlated with the visual field eccentricity, mainly in the peripheral visual field. Moreover, specific to the peripheral visual field, RP patients had deficits in the attentional orienting and flexibility but not in the attentional inhibition.

Potential targets for the treatment of ADHD using transcranial electrical current stimulation

Attention deficit hyperactivity disorder (ADHD) is a psychiatric disease with a prevalence of 2%-7.5% among the population. It is characterized by three core symptoms: hyperactivity, impulsivity, and inattention. Although the majority of ADHD patients respond to a combination of psychotherapy and standard pharmacotherapy with Methylphenidate, there is a significant minority of patients that do not respond to these substances. Additionally, the treatment with Methylphenidate can cause a variety of side effects like insomnia, headache, decreased appetite, and xerostomia. It would be favorable to have an alternative treatment-option that could circumnavigate the shortcomings of traditional pharmacological treatments. Recent results show that transcranial electrical stimulation (tES) might offer a promising approach. Since research has shown that ADHD is associated with various alterations in brain activity, brain stimulation methods targeting different facets of neuronal functions are currently under investigation. In this article, we briefly review different tES techniques like transcranial random noise stimulation (tRNS), transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS) and explain the modes of action of these brain stimulations. We will specifically focus on transcranial alternating current stimulation (tACS) as a potential method of treating ADHD.

Social exclusion modulates dual mechanisms of cognitive control: Evidence from ERPs

Many studies have investigated how social exclusion influences cognitive control but reported inconsistent findings. Based on the dual mechanisms of control framework, this study investigated how social exclusion influences proactive and reactive modes of control (Experiment 1) and the underlying mechanisms (Experiment 2). The Cyberball game was used to manipulate social exclusion. Eighty-six female participants (about 40 for each experiment) performed cognitive control tasks while event-related potentials were recorded. In Experiment 1, an AX Continuous Performance Task (AX-CPT) was adopted to differentiate between proactive and reactive control. Results showed that social exclusion weakened proactive control but enhanced reactive control, as reflected by the weaker proactive control indicators (i.e., P3b and CNV), but strengthened reactive control indicators (accuracy and N2) in excluded individuals. More importantly, in Experiment 2, through varying in whether task cues were available before or after target onset in a cued-flanker task, we further manipulated the possibility of engaging proactive control, and found the weakened proactive control could be attributed to both impaired cognitive ability and lowered motivation to engage proactive control in excluded individuals. Together, these results provide insight on how social exclusion influences cognitive control and suggest promising implications for designing effective interventions to relieve the negative impact of social exclusion.

Electrophysiological Evidence for Distinct Proactive Control Mechanisms in a Stop-Signal Task: An Individual Differences Approach

Proactive control reflects a sustained, top-down maintenance of a goal representation prior to task-related events, whereas reactive control reflects a transient, bottom-up goal reactivation in response to them. We designed a manual stop-signal task to isolate electrophysiological signals specifically involved in proactive control. Participants performed a simple choice reaction time task but had to withhold their response to an infrequent stop signal, resulting in go- and stop-signal trials. We manipulated the stop-signal probability (30% vs. 10%) over different blocks of trials so that different proactive control levels were sustained within each block. The behavioral results indicated that most participants proactively changed their behaviors. The reaction times in the go trials increased and the number of response errors in the stop-signal trials decreased. However, those two behavioral measures did not correlate: individuals with an increased delayed reaction did not necessarily manifest a higher decrease in response errors in the stop-signal trials. To isolate the proactive control signal, we obtained event-related potentials (ERPs) locked to an uninformative fixation onset and compared the signals between the two stop-signal probability conditions. We found that the ERPs at the left hemisphere were more negatively shifted with the increasing stop-signal probability. Moreover, ERP differences obtained from a set of electrodes in the left hemisphere accounted for the changes in response errors in the stop-signal trials but did not explain the changes in reaction times of the go trials. Together, the behavioral and electrophysiological results suggest that proactive control mechanisms reducing erroneous responses of the stop-signal trials are different from mechanisms slowing reaction times of the go trials.

Significance of Beta-Band Oscillations in Autism Spectrum Disorders During Motor Response Inhibition Tasks: A MEG Study

In Autism Spectrum Disorders (ASD), impaired response inhibition and lack of adaptation are hypothesized to underlie core ASD symptoms, such as social communication and repetitive, stereotyped behavior. Thus, the aim of the present study was to compare neural correlates of inhibition, post-error adaptation, and reaction time variability in ASD and neuro-typical control (NTC) participants by investigating possible differences in error-related changes of oscillatory MEG activity. Twelve male NTC (mean age 20.3 ± 3.7) and fourteen male patients with ASD (mean age 17.8 ± 2.9) were included in the analysis. Subjects with ASD showed increased error-related reaction time variability. MEG analysis revealed decreased beta power in the ASD group in comparison to the NTC group over the centro-parietal channels in both, the pre-stimulus and post-response interval. In the ASD group, mean centro-parietal beta power negatively correlated with dimensional autism symptoms. In both groups, false alarms were followed by an early increase in temporo-frontal theta to alpha power; and by a later decrease in alpha to beta power at central and posterior sensors. Single trial correlations were additionally studied in the ASD group, who showed a positive correlation of pre-stimulus beta power with post-response theta, alpha, and beta power, particularly after hit trials. On a broader scale, the results deliver important insights into top-down control deficits that may relate to core symptoms observed in ASD.

Transcranial Alternating Current Stimulation (tACS) as a Tool to Modulate P300 Amplitude in Attention Deficit Hyperactivity Disorder (ADHD): Preliminary Findings

Studies examining event-related potentials (ERP) in patients affected by attention deficit/hyperactivity disorder (ADHD) have found considerable evidence of reduced target P300 amplitude across different perceptual modalities. P300 amplitude has been related to attention-driven context comparison and resource allocation processes. Altered P300 amplitude in ADHD can be reasonably assumed to be related to ADHD typical cognitive performance deficits. Transcranial alternating current stimulation (tACS) can increase the amplitude of endogenous brain oscillations. Because ERP components can be viewed as event-related oscillations (EROs), with P300 translating into the delta (0–4 Hz) and theta (4–8 Hz) frequency range, an increase of delta and theta ERO amplitudes by tACS should result in an increase of P300 amplitudes in ADHD patients. In this pilot study, 18 adult ADHD patients (7 female) performed three consecutive blocks of a visual oddball task while the electroencephalogram (EEG) was recorded. Patients received either 20 min of tACS or sham stimulation at a stimulation intensity of 1 mA. Individual stimulation frequency was determined using a time–frequency decomposition of the P300. Our preliminary results demonstrate a significant increase in P300 amplitude in the stimulation group which was accompanied by a decrease in omission errors pre-to-post tACS. However, studies including larger sample sizes are advised.

Neural Processes of Proactive and Reactive Controls Modulated by Motor-Skill Experiences

This study investigated the experience of open and closed motor skills on modulating proactive and reactive control processes in task switching. Fifty-four participants who were open-skilled (n = 18) or closed-skilled athletes (n = 18) or non-athletic adults (n = 18) completed a cued task-switching paradigm task. This task tapped into proactive or reactive controls of executive functions under different validity conditions. Electroencephalograms of the participants were captured during the task. In the 100% validity condition, the open-skilled participants showed significantly lower switch cost of response time than the closed-skilled and control participants. Results showed that the open-skilled participants had less positive-going parietal cue-locked P3 in the switch than repeat trials. Participants in the control group showed more positive-going cue-locked P3 in the switch than repeat trials, whereas the closed-skilled participants had no significant differences between the two types of trials. In the 50% validity condition, the open- and closed-skilled participants had less switch cost of response time than the control participants. Participants in the open- and closed-skilled groups showed less positive-going parietal stimulus-locked P3 in the switch than repeat trials, which was not the case for those in the control group. Our findings confirm the dissociation between proactive and reactive controls in relation to their modulations by the different motor-skill experiences. Both proactive and reactive controls of executive functions could be strengthened by exposing individuals to anticipatory or non-anticipatory enriched environments, suggesting proactive and reactive controls involved in motor-skill development seem to be transferable to domain-general executive functions.

Electrophysiological evidence of an attentional bias towards appetitive and aversive words in adults with attention-deficit/hyperactivity disorder

OBJECTIVE

Emotional dysregulation has emerged as a core symptom domain in adults with Attention-Deficit/Hyperactivity Disorder (ADHD). However, the pathophysiological underpinnings remain poorly understood. This study investigated attentional biases to positive and negative emotional words as possible contributing mechanisms.

METHODS

Event-related potentials (ERPSs) and behavioral attention bias indices were recorded from 39 adult patients with ADHD and 41 healthy controls during a verbal dot-probe task with positive-neutral, negative-neutral, and neutral-neutral word pairs.

RESULTS

Cue-locked N2pc amplitudes indicated a significant attentional bias towards emotional words in patients with ADHD and healthy controls. In healthy controls, the bias was only significant in positive trials. In patients, the bias was associated with ADHD severity and self-reported poor emotion regulation skills. ADHD patients also exhibited reduced target-locked P1 amplitudes and inferior behavioral performance compared with healthy controls.

CONCLUSIONS

Our findings provide evidence of an attention bias to positive and negative emotional stimuli in adult patients with ADHD and adverse effects of emotional stimuli on task performance.

SIGNIFICANCE

An attentional bias to emotional stimuli might contribute to emotional reactivity and dysregulation in adult patients with ADHD.

Shared and Disorder-Specific Event-Related Brain Oscillatory Markers of Attentional Dysfunction in ADHD and Bipolar Disorder

Attention-deficit/hyperactivity disorder (ADHD) and bipolar disorder (BD) often present with overlapping symptoms and cognitive impairments, such as increased fluctuations in attentional performance measured by increased reaction-time variability (RTV). We previously provided initial evidence of shared and distinct event-related potential (ERP) impairments in ADHD and BD in a direct electrophysiological comparison, but no study to date has compared neural mechanisms underlying attentional impairments with finer-grained brain oscillatory markers. Here, we aimed to compare the neural underpinnings of impaired attentional processes in ADHD and BD, by examining event-related brain oscillations during a reaction-time task under slow-unrewarded baseline and fast-incentive conditions. We measured cognitive performance, ERPs and brain-oscillatory modulations of power and phase variability in 20 women with ADHD, 20 women with BD (currently euthymic) and 20 control women. Compared to controls, both ADHD and BD groups showed increased RTV in the baseline condition and increased RTV, theta phase variability and lower contingent negative variation in the fast-incentive condition. Unlike controls, neither clinical group showed an improvement from the slow-unrewarded baseline to the fast-incentive condition in attentional P3 amplitude or alpha power suppression. Most impairments did not differ between the disorders, as only an adjustment in beta suppression between conditions (lower in the ADHD group) distinguished between the clinical groups. These findings suggest shared impairments in women with ADHD and BD in cognitive and neural variability, preparatory activity and inability to adjust attention allocation and activation. These overlapping impairments may represent shared neurobiological mechanisms of attentional dysfunction in ADHD and BD, and potentially underlie common symptoms in both disorders.

Event-Related Potentials in a Cued Go-NoGo Task Associated with Executive Functions in Adolescents with Autism Spectrum Disorder; A Case-Control Study

Executive functions are often affected in autism spectrum disorders (ASD). The underlying biology is however not well known. In the DSM-5, ASD is characterized by difficulties in two domains: Social Interaction and Repetitive and Restricted Behavior, RRB. Insistence of Sameness is part of RRB and has been reported related to executive functions. We aimed to identify differences between ASD and typically developing (TD) adolescents in Event Related Potentials (ERPs) associated with response preparation, conflict monitoring and response inhibition using a cued Go-NoGo paradigm. We also studied the effect of age and emotional content of paradigm related to these ERPs. We investigated 49 individuals with ASD and 49 TD aged 12-21 years, split into two groups below (young) and above (old) 16 years of age. ASD characteristics were quantified by the Social Communication Questionnaire (SCQ) and executive functions were assessed with the Behavior Rating Inventory of Executive Function (BRIEF), both parent-rated. Behavioral performance and ERPs were recorded during a cued visual Go-NoGo task which included neutral pictures (VCPT) and pictures of emotional faces (ECPT). The amplitudes of ERPs associated with response preparation, conflict monitoring, and response inhibition were analyzed. The ASD group showed markedly higher scores than TD in both SCQ and BRIEF. Behavioral data showed no case-control differences in either the VCPT or ECPT in the whole group. While there were no significant case-control differences in ERPs from the combined VCPT and ECPT in the whole sample, the Contingent Negative Variation (CNV) was significantly enhanced in the old ASD group (p = 0.017). When excluding ASD with comorbid ADHD we found a significantly increased N2 NoGo (p = 0.016) and N2-effect (p = 0.023) for the whole group. We found no case-control differences in the P3-components. Our findings suggest increased response preparation in adolescents with ASD older than 16 years and enhanced conflict monitoring in ASD without comorbid ADHD during a Go-NoGo task. The current findings may be related to Insistence of Sameness in ASD. The pathophysiological underpinnings of executive dysfunction should be further investigated to learn more about how this phenomenon is related to core characteristics of ASD.