Inhibitory processing during the Go/NoGo task: an ERP analysis of children with attention-deficit/hyperactivity disorder

Inhibitory control deficits in patients with mesial temporal lobe epilepsy: an event-related potential analysis based on Go/NoGo task

Objective

Neuropsychiatric comorbidities are common among patients with mesial temporal lobe epilepsy (MTLE). One of these comorbidities, impulsivity, can significantly impact the quality of life and prognosis. However, there have been few studies of impulsivity in these patients, and the existing findings are inconsistent. The present study investigates impulsivity in MTLE patients from the perspective of inhibitory control and its underlying processes using event-related potentials (ERPs) initiated using a Go/NoGo task.

Methods

A total of 25 MTLE patients and 25 age-, gender-, and education-matched healthy controls (HCs) completed an unequal visual Go/NoGo task. Different waveforms as well as behavioral measures were analyzed between Go and NoGo conditions (N2d and P3d). Impulsivity was also assessed using self -rating scales, and clinical variables that may be related to ERPs were explored.

Results

Compared with HCs, MTLE patients exhibited significantly longer reaction time (RT) (p = 0.002) and lower P3d especially at the frontal electrode sites (p = 0.001). In the MTLE group, the seizure frequency (p = 0.045) and seizure types (p < 0.001) were correlated with the P3d amplitude. A self-rated impulsivity assessment revealed that MTLE patients had higher non-planning (p = 0.017) and total scores (p = 0.019) on the BIS-11 as well as higher DI (p = 0.010) and lower FI (p = 0.007) on the DII.

Conclusion

The findings demonstrate that the presence of inhibitory control deficits in patients with MTLE are characterized by deficits in the late stage of inhibition control, namely the motor inhibition stage. This study improves our understanding of impulsivity in MTLE patients and suggests that ERPs may constitute a sensitive means of detecting this trait.

High-frequency rTMS over the left DLPFC improves the response inhibition control of young healthy participants: an ERP combined 1H-MRS study

Introduction

Unlike the effect of repetitive transcranial magnetic stimulation (rTMS) in treating neuropsychiatric diseases, little is known about how personal factors might account for the disparity of results from studies of cognition and rTMS. In this study, we investigated the effects of high-frequency rTMS on response inhibition control and explored the time course changes in cognitive processing and brain metabolic mechanisms after rTMS using event-related potentials (ERPs) and magnetic resonance spectroscopy (¹H-MRS).

Methods

Participants were all right-handed and were naive to rTMS and the Go/NoGo task. Twenty-five healthy young participants underwent one 10 Hz rTMS session per day in which stimulation was applied over the left dorsolateral prefrontal cortex (DLPFC), and a homogeneous participant group of 25 individuals received a sham rTMS treatment for 1  week. A Go/NoGo task was performed, an electroencephalogram (EEG) was recorded, and ¹H-MRS was performed.

Results

The results revealed that there was a strong trend of decreasing commission errors of NoGo stimuli by high frequency rTMS over the left DLPFC, whereas there was no significant difference between before and after rTMS treatment with respect to these parameters in the sham rTMS group. High-frequency rTMS significantly increased the amplitude of NoGo-N2 but not Go-N2, Go-P3, or NoGo-P3. The myo-inositol /creatine complex (MI/Cr) ratio, indexing cerebral metabolism, in the left DLPFC was decreased in the rTMS treated group.

Discussion

This observation supports the view that high-frequency rTMS over the left DLPFC has the strong tendency of reducing commission errors behaviorally, increase the amplitude of NoGo-N2 and improve the response inhibition control of healthy young participants. The results are consistent with the excitatory properties of high frequency rTMS. We suggest that the increase in the NoGo-N2 amplitude may be related to the increased excitability of the DLPFC-anterior cingulate cortex (ACC) neural loop. Metabolic changes in the DLPFC may be a possible mechanism for the improvement of the response inhibition control of rTMS.

Sex differences in learning and performing the Go/NoGo tasks

BACKGROUND

The quality of learning and post-learning performances is critical for daily life. The behavioral flexibility is equally important for adapting the changing circumstances. The learning process requires repeated practices, which enhances prompt and proper behavioral responses, in turn, which promotes habits formation as well. Despite the well-documented sex differences in learning and performances, contradictory results were reported. A possible cause might be a systematic analysis due to specific research interests, regardless of the continuity of natural acquisition process. Here, we investigate the potential sex differences in learning, performances and adjustments of habited behaviors with regular and reversal Go/NoGo tasks.

METHODS

Both male and female Sprague-Dawley rats were used in this study. All rats were trained for a regular rodent Go/NoGo task and a subset of rats were trained for a reversal rodent Go/NoGo task, both with strict elimination criteria. The behavioral performance data were stored in PC for off-line analysis. Multiple behavioral indices were analyzed for both passed and retired rats.

RESULTS

The ability of learning the regular the reversal Go/NoGo tasks was similar for both male and female rats, however, the female rats took longer time to master the task principles in later stages for both tasks. In the regular Go/NoGo task, the female rats spent more time on completing the trial in performance optimization phases, which implied female rats were more cautious than male rats. Along with the progression of training, both male and female rats developed Go-preference strategies to perform the regular Go/NoGo task, which induced failure to meet the setting success criteria. The retired male rats exhibited shorter RTs and MTs than the retired female rats after developing Go-preference. Moreover, the time needed to complete the Go trials was significantly prolonged for male rats in the reversal Go/NoGo task.

CONCLUSIONS

Overall, we conclude that distinctive strategies were employed in performing Go/NoGo tasks for both male and female rats. Male rats required less time to stabilize the performance in behavioral optimization phase. In addition, male rats were more accurate in estimating time elapsing. In contrast, female rats took more cautious considerations in performing the task, through which minimal influences were manifested in the reversal version of task.

Sound localization and auditory selective attention in school-aged children with ADHD

This study aimed to identify the neurophysiologic bases of auditory attention deficits in children with attention-deficit/hyperactivity disorder (ADHD), focusing on the electroencephalography component of auditory spatial selective attention [the N2 anterior contralateral component (N2ac)]. EEG data were collected from 7- to 11-year-old children with ADHD (n = 54) and age-, sex-, and IQ-matched typically developing (TD) children (n = 61), while they performed an auditory spatial selective task. For behavior, the children with ADHD showed a shorter reaction time (RT) but a higher RT coefficient of variability (RT_CV) than TD children. For ERPs, the TD group showed a significant "adult-like" N2ac component; however, the N2ac component was absent in children with ADHD. More importantly, the smaller N2ac component could predict longer RT in both groups, as well as higher severity of inattentive symptoms in children with ADHD. Our results indicated that 7- to 11-year-old TD children have developed an "adult-like" ability to balance auditory target selection and distractor suppression; the absence of N2ac in children with ADHD provided novel evidence supporting their dysfunctional auditory spatial selective attention.

Sex differences in automatic emotion regulation in adolescents with autism spectrum disorder

Autism may be underdiagnosed in females because their social difficulties are often less noticeable. This study explored sex differences in automatic facial emotion processing in 45 adolescents with autism spectrum disorder (22 female, 23 male), age 10-16 years, performing active target detection task and Go/NoGo tasks where faces with positive and negative emotional expressions served as irrelevant distractors. The combined sample demonstrated more accurate performance on the target detection (response initiation) than the Go/NoGo task (response inhibition), replicating findings previously reported in typical participants. Females exhibited greater difficulty than males with response initiation in the target detection task, especially in the context of angry faces, while males found withholding a response in the Go/NoGo block with happy faces more challenging. Electrophysiological data revealed no sex differences or emotion discrimination effects during the early perceptual processing of faces indexed by the occipitotemporal N170. Autistic males demonstrated increased frontal N2 and parietal P3 amplitudes compared to females, suggesting greater neural resource allocation to automatic emotion regulation processes. The associations between standardized behavioral measures (autism severity, theory of mind skills) and brain responses also varied by sex: more adaptive social functioning was related to the speed of perceptual processing (N170 latency) in females and the extent of deliberate attention allocation (P3 amplitudes) in males. Together, these findings suggest that males and females with autism may rely on different strategies for social functioning and highlight the importance of considering sex differences in autism. LAY SUMMARY: Females with autism may exhibit less noticeable social difficulties than males. This study demonstrates that autistic females are more successful than males at inhibiting behavioral responses in emotional contexts, while males are more likely to initiate a response. At the neural level, social functioning in females is related to the speed of automatic perceptual processing of facial cues, and in males, to the extent of active attention allocation to the stimuli. These findings highlight the importance of considering sex differences in autism diagnosis and treatment selection.

The dynamics of theta-related pro-active control and response inhibition processes in AD(H)D

Impulsivity and deficits in response inhibition are hallmarks of attention-deficit(-hyperactivity) disorder (AD(H)D), can cause severe problems in daily functioning, and are thus of high clinical relevance. Traditionally, research to elucidate associated neural correlates has intensively, but also quite selectively examined mechanisms during response inhibition in various tasks. Doing so, in-between trial periods or periods prior to the response inhibition process, where no information relevant to inhibitory control is presented, have been neglected. Yet, these periods may nevertheless reveal relevant information. In the present study, using a case-control cross-sectional design, we take a more holistic approach, examining the inter-relation of pre-trial and within-trial periods in a Go/Nogo task with a focus on EEG theta band activity. Applying EEG beamforming methods, we show that the dynamics between pre-trial (pro-active) and within-trial (inhibition-related) control processes significantly differ between AD(H)D subtypes. We show that response inhibition, and differences between AD(H)D subtypes, exhibit distinct patterns of (at least) three factors: (i) strength of pre-trial (pro-active control) theta-band activity, (ii) the inter-relation of pro-active control and inhibition-relation theta band activity and (iii) the functional neuroanatomical region active during theta-related pro-active control processes. This multi-factorial pattern is captured by AD(H)D subtype clinical symptom clusters. The study provides a first hint that novel cognitive-neurophysiological facets of AD(H)D may be relevant to distinguish AD(H)D subtypes.

A Longitudinal Study on Bidirectional Relations between Executive Functions and English Word-Level Reading in Chinese American Children in Immigrant Families

This two-wave (1.5 years apart) longitudinal study examined the bidirectional relations between measures of executive function (EF; working memory, attention focusing, inhibitory control, and a comprehensive EF measure) and two types of English word-level reading (pseudoword reading and word reading) among 258 school-aged children (52.6% boys, age = 5.8-9.1 years, in 1st to 3rd grades at Wave 1) from Chinese American immigrant families. Cross-lagged panel analyses were conducted to test whether the four EF measures and English word-level reading proficiency predicted one another controlling for prior levels of EF or word reading, as well as demographic characteristics and children's English and Chinese language proficiency. We found a positive bidirectional association between the comprehensive EF measure and pseudoword reading. By contrast, although the comprehensive EF measure positively predicted word reading over time, word reading did not predict comprehensive EF. Additionally, both word reading and pseudoword reading positively predicted working memory over time. The results provided partial evidence that English word-level reading is bidirectionally related to EF among early elementary school-age dual language learners.

Neural generators involved in visual cue processing in children with attention-deficit/hyperactivity disorder (ADHD)

Event-related potentials (ERP) studies report alterations in the ongoing visuo-attentional processes in children with attention-deficit/hyperactivity disorder (ADHD). We hypothesized that the neural generators progressively recruited after a cue stimulus imply executive-related areas well before engagement in executive processing in children with ADHD compared to typically developed children (TDC). We computed source localization (swLORETA) of the ERP and ERSP evoked by the Cue stimulus during a visual Cue-Go/Nogo paradigm in 15 ADHD compared to 16 TDC. A significant difference in N200/P200 amplitude over the right centro-frontal regions was observed between ADHD and TDC, supported by a stronger contribution of the left visuo-motor coordination area, premotor cortex, and prefrontal cortex in ADHD. In addition, we recorded a greater beta power spectrum in ADHD during the 80-230 ms interval, which was explained by increased activity in occipito-parieto-central areas and lower activity in the left supramarginal gyrus and prefrontal areas in ADHD. Successive analysis of the ERP generators (0-500 ms with successive periods of 50 ms) revealed significant differences beginning at 50 ms, with higher activity in the ventral anterior cingulate cortex, premotor cortex, and fusiform gyrus, and ending at 400-500 ms with higher activity of the dorsolateral prefrontal cortex and lower activity of the posterior cingulate cortex in ADHD compared to TDC. The areas contributing to ERP in ADHD and TDC differ from the early steps of visuo-attentional processing and reveal an overinvestment of the executive networks interfering with the activity of the dorsal attention network in children with ADHD.

The Relationship Between Response-Inhibitory Event-Related Potentials and Symptoms of Attention-Deficit/Hyperactivity Disorder in Adult Patients with Major Depressive Disorder

OBJECTIVE

Attention-deficit and poor impulse control have frequently been observed in major depressive disorder (MDD) and attention-deficit and hyperactivity disorder (ADHD). Altered event-related potential (ERP) performance, such as GoNogo tasks, has been regarded as a neurocognitive process associated with attention and behavioral inhibition. The aim of this study was to investigate the association between Nogo ERP and adult ADHD in MDD.

METHODS

A total of 64 participants with MDD (32 comorbid with ADHD) and 32 healthy controls aged 19-45 years were recruited; they performed GoNogo paradigms during electroencephalogram measurement. Beck Depression Inventory (BDI), State-Trait Anxiety Inventory (STAI), and the Adult ADHD Self-Report Scale (ASRS) were evaluated. Clinical measures and GoNogo ERP were compared between three groups: depression with ADHD, depression without ADHD, and healthy controls.

RESULTS

MDD subjects with ADHD showed significantly decreased Nogo P3 amplitude at frontal electrode, compared with those without ADHD and healthy controls. MDD subjects with ADHD showed significantly longer Nogo N2 latency at frontal and frontocentral electrodes, compared with those without ADHD and healthy controls. In MDD subjects with ADHD, the Nogo P3 amplitude at the frontal electrode was negatively correlated with the ASRS score and inattention. The Nogo N2 latency at the frontal electrode was positively correlated with false alarm rate.

CONCLUSION

The decreased Nogo P3 amplitude in the frontal area might be a potential biological marker for inattention in depressed patients with ADHD.

Executive dysfunction in medication-naïve children with ADHD: A multi-modal fNIRS and EEG study

OBJECTIVE

Children with attention deficit hyperactivity disorder (ADHD) exhibit deficits in executive function. Since there are no clear biomarkers for the disorder, this study aimed to investigate the neurophysiological biomarkers for deficits in executive function in children with ADHD using functional near-infrared spectroscopy (fNIRS) and electroencephalography.

METHODS

Twenty patients diagnosed with ADHD and 19 typically developing children (TDC; 8-11 years old) were included. Event related potentials (ERPs) were recorded using an electroencephalogram (EEG) and oxygenated hemoglobin concentrations (Oxy-Hb) were recorded using fNIRS during a colored Go/NoGo task, simultaneously. Latencies and amplitudes of NoGo-N2 and NoGo/Go-P3 tasks were measured using EEG.

RESULTS

Children with ADHD showed significantly decreased Oxy-Hb in the right frontal cortex as well as longer NoGo-P3 latencies and a decreased NoGo/Go-P3 amplitude. There was a significant positive correlation between the Oxy-Hb and NoGo/Go-P3 amplitude.

CONCLUSIONS

These results suggest that children with ADHD experience executive dysfunction. Hemodynamic and electrophysiological findings during the Go/NoGo task might be useful as a biomarker of executive function.

SIGNIFICANCE

These findings have key implications for understanding the pathophysiology of deficits in executive function in ADHD.

Economical Assessment of Working Memory and Response Inhibition in ADHD Using a Combined n-back/Nogo Paradigm: An ERP Study

The development of cognitive interventions in attention-deficit/hyperactivity disorder (ADHD) often requires the assessment of multiple cognitive functions. However, experimental settings consisting of various tasks are particularly strenuous for patients and can thus result in poor data quality. For the economical assessment of working memory and response inhibition, this study aims to validate a combined n-back/nogo paradigm by comparing it to single task versions and to demonstrate its applicability for ADHD research. Twenty-five healthy individuals and 34 ADHD patients between 9 and 16 years participated in this event-related potential (ERP) study. Healthy controls underwent single task versions of a 2-back working memory task and a go/nogo response inhibition task as well as the introduced combined 2-back/nogo task. This combined task demonstrated a comparable ERP structure for working memory and response inhibition aspects as single task versions. Behaviorally, higher working memory performance during the combined paradigm indicated lower task difficulty, while high correlations between combined and single task versions still indicated valid working memory measures. For response inhibition performance, different task versions resulted in similar outcomes. The application of the combined n-back/nogo paradigm in ADHD patients revealed the expected working memory and response inhibition deficits, increased omission errors, reaction times, and standard deviation of reaction time, as well as diminished n-back P3 and nogo P3 amplitudes. We conclude that the combined n-back/nogo task is an effective paradigm for the economical assessment of working memory and response inhibition deficits in ADHD on a behavioral and neurophysiological level.

Age-Related Changes in Auditory Nogo-N200 Latency in Medication-Naïve Children and Adolescents with Attention-Deficit/Hyperactivity Disorder

OBJECTIVE

Event-related potential (ERP) changes with brain development in healthy children and adolescents. However, few studies have focused on age-related changes in the N200 and P300 components among individuals with attention-deficit/hyperactivity disorder (ADHD). Therefore, this study aimed to assess age-related differences in the auditory nogo-N200 components in individuals with ADHD.

METHODS

We enrolled 46 participants with auditory nogo-N200 and nogo-P300 components. We assessed ADHD symptoms using the Advanced Test of Attention (ATA) and Korean ADHD Rating Scale-IV (K-ARS-IV). Moreover, we assessed emotional and behavioral problems using the Korean Child Behavior Checklist (K-CBCL). Further, we measured auditory ERPs.

RESULTS

There were no differences with respect to sex or ATA, K-ARS-IV, and K-CBCL scores between the groups. With a 1-year increase in age, the nogo-N200 latency at Fz and Cz decreased by 6.08 ms and 4.88 ms, respectively; this result was statistically significant in multivariable linear regression adjusted by sex and dominant hand.

CONCLUSION

Our findings revealed age-related changes in nogo-N200 latency at the Fz and Cz electrodes in individuals with ADHD. Future studies should perform comparisons with healthy controls to determine whether auditory nogo-N200 can be used to evaluate the developmental level in individuals with ADHD.

Impaired early information processing in adult ADHD: a high-density ERP study

BACKGROUND

Children with attention-deficit/hyperactivity disorder (ADHD) often demonstrate sensory processing difficulties in the form of altered sensory modulation, which may contribute to their symptomatology. Our objective was to investigate the neurophysiological correlates of sensory processing deficits and the electrophysiological characteristics of early information processing in adult ADHD, measured by the P1 event-related potential (ERP).

METHODS

We obtained ERPs during a Go/NoGo task from 26 adult patients with ADHD and 25 matched controls using a high-density 128-channel BioSemi ActiveTwo recording system.

RESULTS

ADHD patients had a significantly reduced P1 component at occipital and inferotemporal scalp areas compared to controls. The reduction was associated with inattention and hyperactivity symptom severity, as measured by the Conners' Adult ADHD Rating Scale. ADHD patients with higher inattention scores had significantly smaller P1 amplitudes at posterior scalp sites, while higher hyperactivity scores were associated with higher P1 amplitudes.

CONCLUSIONS

Deficits in early sensory processing, as measured by the P1 ERP component, are present in adult ADHD patients and are associated with symptom severity. These findings are suggestive of bottom-up cognitive deficits in ADHD driven by impairments in early visual processing, and provide evidence that sensory processing problems are present at the neurophysiological level in this population.

A controlled clinical crossover trial of exercise training to improve cognition and neural communication in pediatric brain tumor survivors

OBJECTIVE

To assess the efficacy of aerobic exercise training to improve controlled attention, information processing speed and neural communication during increasing task load and rest in pediatric brain tumor survivors (PBTS) treated with cranial radiation.

METHODS

Participants completed visual-motor Go and Go/No-Go tasks during magnetoencephalography recording prior to and following the completion of 12-weeks of exercise training. Exercise-related changes in response accuracy and visual-motor latency were evaluated with Linear Mixed models. The Phase Lag Index (PLI) was used to estimate functional connectivity during task performance and rest. Changes in PLI values after exercise training were assessed using Partial Least Squares analysis.

RESULTS

Exercise training predicted sustained (12-weeks) improvement in response accuracy (p<0.05) during No-Go trials. Altered functional connectivity was detected in theta (4-7Hz) alpha (8-12Hz) and high gamma (60-100Hz) frequency bands (p<0.001) during Go and Go/No-Go trials. Significant changes in response latency and resting state connectivity were not detected.

CONCLUSION

These findings support the efficacy of aerobic exercise to improve controlled attention and enhance functional mechanisms under increasing task load in participants.

SIGNIFICANCE

It may be possible to harness the beneficial effects of exercise as therapy to promote cognitive recovery and enhance brain function in PBTS.

Behavioral and Electrophysiological Correlates of Performance Monitoring and Development in Children and Adolescents with Attention-Deficit/Hyperactivity Disorder

The pathophysiology of attention-deficit/hyperactivity disorder (ADHD) involves deficits in performance monitoring and adaptive adjustments. Yet, the developmental trajectory and underlying neural correlates of performance monitoring deficits in youth with ADHD remain poorly understood. To address the gap, this study recruited 77 children and adolescents with ADHD and 77 age- and gender-matched healthy controls (HC), ages 8–18 years, who performed an arrow flanker task during electroencephalogram recording. Compared to HC, participants with ADHD responded more slowly and showed larger reaction time variability (RTV) and reduced post-error slowing; they also exhibited reduced error-related negativity (ERN) and error positivity effects, and reduced N2 and P3 congruency effects. Age effects were observed across groups: with increasing age, participants responded faster, with less variability, and with increased post-error slowing. They also exhibited increased ERN effects and increased N2 and P3 congruency effects. Increased RTV and reduced P3 amplitude in incongruent trials were associated with increased ADHD Problems Scale scores on the Child Behavior Checklist across groups. The altered behavioral and ERP responses in ADHD are consistent with the pattern associated with younger age across groups. Further research with a longitudinal design may determine specific aspects of developmental alteration and deficits in ADHD during performance monitoring.

Eye Movement Performance on the Stroop Test in Adults With ADHD

Objective: To compare the eye movement patterns of adults with ADHD with those of controls as they perform the Stroop test. Method: Thirty individuals with ADHD (ages 18-31), and 30 controls participated in this study. The hypothesis was that under the incongruent condition, the group with ADHD would focus longer on the distracter than the controls. Results: Participants with ADHD showed a more pronounced Stroop effect than the controls. Eye movements indicated that more time was spent fixating on the target than on the distracter. The most significant differences between the groups were the overall time spent on the target and the number of fixations on the target, rather than on the distracter. Furthermore, the group with ADHD made more transitions between the target and distracter stimuli. Conclusion: These results were interpreted to indicate an inefficient strategy used by the group with ADHD in their attempt to ignore the distracter stimuli.

Conducting Event-Related Potential (ERP) Research with Young Children: A Review of Components, Special Considerations and Recommendations for Research on Cognition and Emotion

There has been an unprecedented increase in the number of research studies employing event-related potential (ERP) techniques to examine dynamic and rapidly-occurring neural processes with children during the preschool and early childhood years. Despite this, there has been little discussion of the methodological and procedural differences that exist for studies of young children versus older children and adults. That is, reviewers, editors, and consumers of this work often expect developmental studies to simply apply adult techniques and procedures to younger samples. Procedurally, this creates unrealistic expectations for research paradigms, data collection, and data reduction and analyses. Scientifically, this leads to inappropriate measures and methods that hinder drawing conclusions and advancing theory. Based on ERP work with preschoolers and young children from 10 laboratories across North America, we present a summary of the most common ERP components under study in the area of emotion and cognition in young children along with 13 realistic expectations for data collection and loss, laboratory procedures and paradigms, data processing, ERP averaging, and typical challenges for conducting this type of work. This work is intended to supplement previous guidelines for work with adults and offer insights to aid researchers, reviewers, and editors in the design and evaluation of developmental research using ERPs. Here we make recommendations for researchers who plan to conduct or who are conducting ERP studies in children between ages 2 and 12, focusing on studies of toddlers and preschoolers. Recommendations are based on both data and our cumulative experience and include guidelines for laboratory setup, equipment and recording settings, task design, and data processing.

Effects of methylphenidate on the ERP amplitude in youth with ADHD: A double-blind placebo-controlled cross-over EEG study

Methylphenidate (MPH) is a first line drug for attention-deficit/hyperactivity disorder (ADHD), yet the neuronal mechanisms underlying the condition and the treatment are still not fully understood. Previous EEG studies on the effect of MPH in ADHD found changes in evoked response potential (ERP) components that were inconsistent between studies. These inconsistencies highlight the need for a well-designed study which includes multiple baseline sessions and controls for possible fatigue, learning effects and between-days variability. To this end, we employ a double-blind placebo-controlled cross-over study and explore the effect of MPH on the ERP response of subjects with ADHD during a Go/No-Go cognitive task. Our ERP analysis revealed significant differences in ADHD subjects between the placebo and MPH conditions in the frontal-parietal region at 250ms-400ms post stimulus (P3). Additionally, a decrease in the late 650ms-800ms ERP component (LC) is observed in frontal electrodes of ADHD subjects compared to controls. The standard deviation of response time of ADHD subjects was significantly smaller in the MPH condition compared to placebo and correlated with the increased P3 ERP response in the frontoparietal electrodes. We suggest that mental fatigue plays a role in the decrease of the P3 response in the placebo condition compared to pre-placebo, a phenomenon that is significant in ADHD subjects but not in controls, and which is interestingly rectified by MPH.

The neural correlates of temperamental inhibitory control in toddlers

The current study examined the association between effortful control and a well-studied neural index of self-regulation, the N2 event-related potential (ERP) component, in toddlers. Participants included 107 toddlers (44 girls) assessed at 30, 36 and 42 months of age. Participants completed a Go/NoGo task while electroencephalography data were recorded. The study focused on the N2 ERP component. Parent-reported effortful control was examined in association with the NoGo N2 ERP component. Findings suggest a positive association between the NoGo N2 component and the inhibitory control subscale of the wider effortful control dimension, suggesting that the N2 component may index processes associated with temperamental effortful control.This article is part of the theme issue 'Diverse perspectives on diversity: multi-disciplinary approaches to taxonomies of individual differences'.

Longitudinal associations between conflict monitoring and emergent academic skills: An event-related potentials study

Identifying the links between specific cognitive functions and emergent academic skills can help determine pathways to support both early academic performance and later academic achievement. Here, we investigated the longitudinal associations between a key aspect of cognitive control, conflict monitoring, and emergent academic skills from preschool through first grade, in a large sample of socioeconomically diverse children (N = 261). We recorded event-related potentials (ERPs) during a Go/No-Go task. The neural index of conflict monitoring, ΔN2, was defined as larger N2 mean amplitudes for No-Go versus Go trials. ΔN2 was observed over the right hemisphere across time points and showed developmental stability. Cross-lagged panel models revealed prospective links from ΔN2 to later math performance, but not reading performance. Specifically, larger ΔN2 at preschool predicted higher kindergarten math performance, and larger ΔN2 at kindergarten predicted higher first-grade math performance, above and beyond the behavioral performance in the Go/No-Go task. Early academic skills did not predict later ΔN2. These findings provided electrophysiological evidence for the contribution of conflict monitoring abilities to emergent math skills. In addition, our findings suggested that neural indices of cognitive control can provide additional information in predicting emergent math skills, above and beyond behavioral task performance.

Effects of multisensory stimuli on inhibitory control in adolescent ADHD: It is the content of information that matters

Even though deficits in inhibitory control and conflict monitoring are well-known in ADHD, factors that further modulate these functions remain to be elucidated. One factor that may be of considerable importance is how inhibitory control is modulated by multisensory information processing. We examined the influence of concurrent auditory conflicting or redundant information on visually triggered response inhibition processes in adolescent ADHD patients and healthy controls. We combined high-density event-related potential (ERP) recordings with source localization to delineate the functional neuroanatomical basis of the involved neurophysiological processes. In comparison to controls, response inhibition (RI) processes in ADHD were compromised in conflicting conditions, but showed no differences to controls when redundant or no concurrent auditory information was presented. These effects were reflected by modulations at the response selection stage (P3 ERP) in the medial frontal gyrus (BA32), but not at the attentional selection (P1, N1 ERPs) or resource allocation level (P2 ERP). Conflicting information during RI exerts its influences in adolescent ADHD via response selection mechanisms, but not via attentional selection. It is not the mere presence of concurrent information, but the presence of conflicting information during RI that may destabilize goal shielding processes in medial frontal cortical regions, by means of increasing the automaticity of response tendencies. The occurring RI deficits might relate to the increased impulsivity in adolescent ADHD and a corresponding vulnerability to react to an increased automaticity of pre-potent response tendencies. ADHD patients show a bias to a specific content of information which can modulate inhibitory control.

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Response inhibition (RI) performance in ADHD is modulated by multisensory information.

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Only incongruent/conflicting concurrent information modulates RI performance.

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RI deficits occur if this conflicting information braces the automaticity of response tendencies.

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These deficits relate to a predisposition of ADHD to engage in impulsive behavior.

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This may be due to deficient goal-shielding processes located in the MFG.

Children's neural processing of moral scenarios provides insight into the formation and reduction of in-group biases

Survival is dependent on sociality within groups which ensure sustenance and protection. From an early age, children show a natural tendency to sort people into groups and discriminate among them. The computations guiding evaluation of third-party behaviors are complex, requiring integration of intent, consequences, and knowledge of group affiliation. This study examined how perceiving third-party morally laden behavior influences children's likelihood to exhibit or reduce group bias. Following a minimal group paradigm assignment, young children (4-7 years) performed a moral evaluation task where group affiliations and moral actions were systematically juxtaposed, so that they were exposed to disproportionately antisocial in-group and prosocial out-group scenarios. Electroencephalography was recorded, and group preference was assessed with a resource allocation game before and after the EEG session. Across all children, evaluations of others' moral actions arose from early and automatic processing (~150 ms), followed by later interactive processing of affiliation and moral valence (~500 ms). Importantly, individual differences in bias manifestation and attitude change were predicted by children's neural responses. Children with high baseline bias selectively exhibited a rapid detection (~200 ms) of scenarios inconsistent with their bias (in-group harm and out-group help). Changes in bias corresponded to distinct patterns in longer latency neural processing. These new developmental neuroscience findings elucidate the multifaceted processing involved in moral evaluation of others' actions, their group affiliations, the nature of the integration of both into full judgments, and the relation of individual differences in neural responses to social decision-making in childhood.

Differences in response inhibition processes between adolescents and adults are modulated by sensory processes

Response inhibition processes undergo strong developmental changes. The same is true for sensory processes, and recent evidence shows that there also within-modality differences in the efficacy to trigger motor response inhibition. Yet, modulatory effects of within-modality differences during age-related changes in response inhibition between adolescence and adulthood are still indeterminate. We investigated this question in a system neurophysiological approach combining analysis of event-related potentials (ERPs) with temporal EEG signal decomposition and source localization processes. We used the somatosensory system to examine possible within-modality differences. The study shows that differences in response inhibition processes between adolescents and adults are modulated by sensory processes. Adolescents show deficient response inhibition when stimuli triggering these mechanisms are processed via SI somatosensory areas, compared to SII somatosensory areas. Opposed to this, no differences between adolescents and adults are evident, when response inhibition processes are triggered via SII cortical regions. The EEG data suggests that specific neurophysiological subprocesses are associated with this. Adolescents seem to encounter problems assigning processing resources to integrate motor with tactile information in posterior parietal areas when this information is processed via SI. Thus, basic perceptual and age-related processes interactively modulate response inhibition as an important instance of cognitive control.

EEG Dynamics of a Go/Nogo Task in Children with ADHD

Background: Studies investigating event-related potential (ERP) evoked in a Cue-Go/NoGo paradigm have shown lower frontal N1, N2 and central P3 in children with attention-deficit/hyperactivity disorder (ADHD) compared to typically developing children (TDC). However, the electroencephalographic (EEG) dynamics underlying these ERPs remain largely unexplored in ADHD. Methods: We investigate the event-related spectral perturbation and inter-trial coherence linked to the ERP triggered by visual Cue-Go/NoGo stimuli, in 14 children (7 ADHD and 7 TDC) aged 8 to 12 years. Results: Compared to TDC, the EEG dynamics of children with ADHD showed a lower theta-alpha ITC concomitant to lower occipito-parietal P1-N2 and frontal N1-P2 potentials in response to Cue, Go and Nogo stimuli; an upper alpha power preceding lower central Go-P3; a lower theta-alpha power and ITC were coupled to a lower frontal Nogo-N3; a lower low-gamma power overall scalp at 300 ms after Go and Nogo stimuli. Conclusion: These findings suggest impaired ability in children with ADHD to conserve the brain oscillations phase associated with stimulus processing. This physiological trait might serve as a target for therapeutic intervention or be used as monitoring of their effects.

Neurophysiological variability masks differences in functional neuroanatomical networks and their effectiveness to modulate response inhibition between children and adults

Executive functions are well-known to undergo developmental changes from childhood to adulthood. Considerable efforts have been made to elucidate the affected system neurophysiological mechanisms. But while it is well-known that developmental changes affect intra-individual variability, this potential bias has largely been neglected when investigating the neurophysiology underlying developmental differences between children and adults. We hypothesize that due to differences in intra-individual variability of neural processes between children and adults, reliable group differences will only be evident after accounting for intra-individual variability in neurophysiological processes. We, therefore, investigate response-inhibition processes as an important instance of executive control in children (between 10 and 14 years) and adults (between 20 and 29 years) and decompose EEG data on the basis of the latency and temporal variability. This was combined with source localization. Children showed more impulsive behavior than adults. Importantly, a reliable match between the neurophysiological and behavioral data could only be found when accounting for intra-individual variability in the EEG data. These decomposed data showed that children and adults use similar neurophysiological mechanisms at the response selection level to accomplish inhibitory control, but seem to engage different neuroanatomical structures to do so according to source localization results: In adults, these processes were related to the medial frontal cortex. In children, the same processes were reflected in a shift of the scalp topography and related to the superior parietal cortex. These shifts in neural networks were associated with lower effectiveness in exerting inhibitory control. However, these differences in the functional neuroanatomical architecture can only be seen when intra-individual variability is taken into account.

The 5 choice continuous performance test (5C-CPT): A novel tool to assess cognitive control across species

BACKGROUND

Neurodevelopmental disorders including Tourette's syndrome (TS) and attention deficit hyperactivity disorder (ADHD) are characterized by significant impairment in attention and cognitive control. These cognitive deficits persist throughout development, contribute significantly to socio-occupational impairment, and are relatively impervious to available treatment. A critical challenge in pro-cognitive drug discovery is translatability of findings across species, underscoring the need for developing valid and reliable cross-species cognitive tasks.

NEW METHOD

Here we describe a cross-species 5 choice continuous performance task that was developed to measure cognitive control processes of attention, vigilance, and response inhibition, enabling the translation of findings for pro-cognitive drug discovery across species and delineate neural mechanisms underlying cognitive control construct.

RESULTS

Construct validity of 5C-CPT has been verified by multiple cross-species studies. Several lines of evidence report consistent findings across species including, deficits resulting from 36-h sleep deprivation studies, engagement of parietal cortex in human brain imaging and rodent lesion studies, and vigilance decrements over time.

COMPARISON WITH EXISTING METHOD

Unlike the widely used rodent 5 choice serial reaction time task (5CSRTT) and the sustained attention task (SAT), the rodent 5C-CPT includes both target and non-target stimuli that allow measuring of cognitive control elements including response inhibition, an ability to inhibit pre-potent response during non-target trials, detect vigilance decrement and calculate signal detection parameters in rodents analogous to human CPT.

CONCLUSION

The cross-species 5C-CPT is a robust translational tool to characterize the neurobiological substrates underlying cognitive control deficits in clinical population including, ADHD and TS and develop targeted pro-cognitive therapeutics.

Diagnostic utility of brain activity flow patterns analysis in attention deficit hyperactivity disorder

BACKGROUND

A previous small study suggested that Brain Network Activation (BNA), a novel ERP-based brain network analysis, may have diagnostic utility in attention deficit hyperactivity disorder (ADHD). In this study we examined the diagnostic capability of a new advanced version of the BNA methodology on a larger population of adults with and without ADHD.

METHOD

Subjects were unmedicated right-handed 18- to 55-year-old adults of both sexes with and without a DSM-IV diagnosis of ADHD. We collected EEG while the subjects were performing a response inhibition task (Go/NoGo) and then applied a spatio-temporal Brain Network Activation (BNA) analysis of the EEG data. This analysis produced a display of qualitative measures of brain states (BNA scores) providing information on cortical connectivity. This complex set of scores was then fed into a machine learning algorithm.

RESULTS

The BNA analysis of the EEG data recorded during the Go/NoGo task demonstrated a high discriminative capacity between ADHD patients and controls (AUC = 0.92, specificity = 0.95, sensitivity = 0.86 for the Go condition; AUC = 0.84, specificity = 0.91, sensitivity = 0.76 for the NoGo condition).

CONCLUSIONS

BNA methodology can help differentiate between ADHD and healthy controls based on functional brain connectivity. The data support the utility of the tool to augment clinical examinations by objective evaluation of electrophysiological changes associated with ADHD. Results also support a network-based approach to the study of ADHD.

Disinhibition in children with attention-deficit/hyperactivity disorder: Changes in [oxy-Hb] on near-infrared spectroscopy during "rock, paper, scissors" task

OBJECTIVE

Attention-deficit/hyperactivity disorder (AD/HD) is a common developmental disorder. Many reports have suggested that symptoms of AD/HD are related to frontal lobe dysfunctions, particularly disinhibition. However, measuring neurological findings with biomarkers during frontal functional tasks has sometimes been difficult in children with AD/HD. This study aimed to investigate frontal inhibitory function objectively in children with AD/HD during "rock, paper, scissors" (RPS) tasks, as a familiar game for Japanese children, using near-infrared spectroscopy (NIRS).

SUBJECTS AND METHODS

Eighteen children with AD/HD were compared with 27 typically developing children (TDC). Children from each group were divided into two age groups: younger, 6-10years; and older, 11-16years. Changes in oxygenated hemoglobin [oxy-Hb] were measured in the prefrontal region using NIRS during a 'to lose' RPS task, in which subjects were asked to present the RPS signal that would lose in response to one of the three signals displayed randomly on a computer screen every 2.0s.

RESULTS

The rate of correct performance with both TDC and AD/HD increased with age. Only in the older group, the rate of correct performance was significantly higher with TDC than with AD/HD. However, children with AD/HD in both age groups showed significantly lower [oxy-Hb] activity in the prefrontal region during the 'to lose' RPS task, particularly in the dorsolateral area.

CONCLUSIONS

Our results suggest that prefrontal region activation during the 'to lose' RPS task could offer a biomarker for diagnosing AD/HD, and may help in the early treatment of AD/HD.

Hot executive control and response to a stimulant in a double-blind randomized trial in children with ADHD

Attention deficit hyperactivity disorder (ADHD) is thought to involve an executive inhibitory control (IC) deficit, yet it is not clear if this is a general deficit affecting both cold and hot EC, and if methylphenidate (MPH) affects both systems in treated children. We explored this by using a Stroop-like task in children with ADHD as compared to controls, containing different types of emotional stimuli (six levels), and we investigated the role of intervention with MPH on IC as compared to placebo. Children with ADHD and controls (N = 40; 7-13 years old) were tested with a hot and cold Stroop-like task. This was followed by a double-blind placebo-controlled crossover trial of the effect of MPH on these skills. Children with ADHD showed a specific difficulty inhibiting their responses, particularly to hot, angry and frustration-inducing stimuli. Further, treatment with MPH was effective in reducing errors toward frustration-inducing stimuli as compared to placebo (p < .05, η ² = .347), particularly with repeated exposure to the stimuli. Results indicate that children with ADHD experience executive control difficulties, particularly in hot negative emotional contexts. These emotion regulation difficulties are amenable to stimulant intervention.

What they bring: baseline psychological distress differentially predicts neural response in social exclusion by children's friends and strangers in best friend dyads

Friendships play a major role in cognitive, emotional and social development in middle childhood. We employed the online Cyberball social exclusion paradigm to understand the neural correlates of dyadic social exclusion among best friends assessed simultaneously. Each child played with their friend and an unfamiliar player. Event-related potentials (ERPs) were assessed via electroencephalogram during exclusion by friend and unfamiliar peer. Data were analyzed with hierarchical linear modeling to account for nesting of children within friendship dyads. Results showed that stranger rejection was associated with larger P2 and positive slow wave ERP responses compared to exclusion by a friend. Psychological distress differentially moderated the effects of friend and stranger exclusion such that children with greater psychological distress were observed to have larger neural responses (larger P2 and slow wave) to exclusion by a stranger compared to exclusion by a friend. Conversely, children with lower levels of psychological distress had larger neural responses for exclusion by a friend than by a stranger. Psychological distress within the dyad differentially predicted the P2 and slow wave response. Findings highlight the prominent, but differential role of individual and dyadic psychological distress levels in moderating responses to social exclusion in middle childhood.

Increased Event-Related Potentials and Alpha-, Beta-, and Gamma-Activity Associated with Intentional Actions

Objective: Internally guided actions are defined as being purposeful, self-generated and offering choices between alternatives. Intentional actions are essential to reach individual goals. In previous empirical studies, internally guided actions were predominantly related to functional responses in frontal and parietal areas. The aim of the present study was to distinguish event-related potentials and oscillatory responses of intentional actions and externally guided actions. In addition, we compared neurobiological findings of the decision which action to perform with those referring to the decision whether or not to perform an action.

Methods: Twenty-eight subjects participated in adapted go/nogo paradigms, including a voluntary selection condition allowing participants to (1) freely decide whether to press the response button or (2) to decide whether they wanted to press the response button with the right index finger or the left index finger.

Results: The reaction times were increased when participants freely decided whether and how they wanted to respond compared to the go condition. Intentional processes were associated with a fronto-centrally located N2 and P3 potential. N2 and P3 amplitudes were increased during intentional actions compared to instructed responses (go). In addition, increased activity in the alpha-, beta- and gamma-frequency range was shown during voluntary behavior rather than during externally guided responses.

Conclusion: These results may indicate that an additional cognitive process is needed for intentional actions compared to instructed behavior. However, the neural responses were comparatively independent of the kind of decision that was made (1) decision which action to perform; (2) decision whether or not to perform an action).

Significance: The study demonstrates the importance of fronto-central alpha-, beta-, and gamma oscillations for voluntary behavior.

Differences in the performance of NK1R-/- ('knockout') and wildtype mice in the 5‑Choice Continuous Performance Test

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We compared the behaviour of NK1R−/− mice and wildtypes in the 5-Choice Continuous Performance Test.

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NK1R−/− mice did not express excess impulsivity (premature response or false alarms) in this test.

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NK1R−/− mice expressed excessive perseveration, which is common in ADHD.

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The findings point to a behavioural phenotype for ADHD patients with polymorphism of the TACR1 gene.

Mice lacking functional NK1 (substance P-preferring) receptors typically display excessive inattentiveness (omission errors) and impulsivity (premature responses) when compared with wildtypes in the 5-Choice Serial Reaction-Time Test (5-CSRTT). These abnormal behaviours are analogous to those seen in humans suffering from Attention Deficit Hyperactivity Disorder (ADHD). Here we used the 5-Choice Continuous‑Performance Test (5C-CPT) to ascertain whether NK1R−/− mice also display excessive false alarms (an inappropriate response to a ‘no-go’ signal), which is another form of impulsive behaviour. NK1R−/− mice completed more trials than wildtypes, confirming their ability to learn and carry out the task. At the start of Stage 1 of training, but not subsequently, they also scored more premature responses than wildtypes. When the mice were tested for the first time, neither false alarms nor premature responses was higher in NK1R−/− mice than wildtypes but, as in the 5-CSRTT, the latter behaviour was strongly dependent on time of day. NK1R−/− mice expressed excessive perseveration during all stages of the 5C-CPT. This behaviour is thought to reflect compulsive checking, which is common in ADHD patients. These findings point to differences in the 5-CSRTT and 5C-CPT protocols that could be important for distinguishing why the cognitive performance and response control of NK1R−/− mice differs from their wildtypes. The results further lead to the prediction that ADHD patients with polymorphism of the TACR1 gene (the human equivalent of Nk1r) would express more perseveration, but not false alarms, in Continuous Performance Tests when compared with other groups of subjects.

Impaired response inhibition in juvenile delinquents with antisocial personality characteristics: A preliminary ERP study in a Go/Nogo task

The present study explored the time course of response inhibition function in juvenile delinquents with antisocial personality characteristics (JDAP) by recording the event-related potentials in a Go/Nogo task. Compared to healthy participants, JDAP participants showed similar performance to controls for the Go trails, but worse performance for the Nogo trails. Both N2nogo and P3nogo components showed reduction of the amplitudes in JDAP participants, reflecting the early stage of associated with conflict monitoring and the late stage of inhibition processing, respectively. These data suggest that JDAP participants exhibited impaired response inhibition function.

Emotional response inhibition in children with attention-deficit/hyperactivity disorder: neural and behavioural data

BACKGROUND

Although both emotion and response inhibition are thought to be important in attention-deficit/hyperactivity disorder (ADHD), little is known about the neural mechanisms that underlie the interaction between these two processes in patients with this disorder. This study aimed at examining how emotional contexts affect inhibitory control in children with ADHD.

METHOD

A total of 24 ADHD children and 24 healthy comparison subjects performed a modified go/no-go task during three different emotionally laden contexts: negative, neutral and positive. To explore the timing and the underlying neural substrates of emotion-modulated response inhibition, event-related potentials were measured and further analysed both at the scalp and at the voxel level.

RESULTS

Patients with ADHD showed greater activation of inhibition-related neural mechanisms (i.e. no-go P3 amplitudes and orbitofrontal cortex activity) to maintain a similar level of performance as healthy comparison subjects, especially during the emotionally arousing contexts (negative and positive).

CONCLUSIONS

This study provides plausible neural mechanisms for the difficulty that ADHD children have in controlling their behaviour in highly emotional situations. Such emotional contexts might increase the need for top-down inhibitory control and put ADHD children at greater risk for impulsive behaviours and emotional dysregulation.

Comprehensive analysis suggests simple processes underlying EEG/ERP - demonstration with the go/no-go paradigm in ADHD

BACKGROUND

Current basic or more advanced methods for analysis of averaged EEG/ERP are based on assumptions on the underlying processes, which are not necessarily precise.

NEW METHOD

In this work we present the findings of a method which obviates such assumptions and aims at a comprehensive analysis of the averaged EEG/ERP signal.

RESULTS

For the sake of demonstration we chose the established go/no-go paradigm in the context of ADHD. Our analysis method characterized two spatiotemporally distinct neurophysiologic processes which underlie the sampled signal: one which may be related to attention and the other which may be more related to perception.

COMPARISON WITH EXISTING METHOD(S)

We show how these processes accord with and provide insight on the waveforms reported in the literature.

CONCLUSIONS

Finally we suggest that application of our method on averaged EEG/ERP data sampled from other paradigms may point at a similarly parsimonious set of underlying neurophysiologic processes which underlie the signal.

Kin rejection: social signals, neural response and perceived distress during social exclusion

Across species, kin bond together to promote survival. We sought to understand the dyadic effect of exclusion by kin (as opposed to non-kin strangers) on brain activity of the mother and her child and their subjective distress. To this end, we probed mother-child relationships with a computerized ball-toss game Cyberball. When excluded by one another, rather than by a stranger, both mothers and children exhibited a significantly pronounced frontal P2. Moreover, upon kin rejection versus stranger rejection, both mothers and children showed incremented left frontal positive slow waves for rejection events. Children reported more distress upon exclusion than their own mothers. Similar to past work, relatively augmented negative frontal slow wave activity predicted greater self-reported ostracism distress. This effect, generalized to the P2, was limited to mother- or child-rejection by kin, with comparable magnitude of effect across kin identity (mothers vs. children). For both mothers and children, the frontal P2 peak was significantly pronounced for kin rejection versus stranger rejection. Taken together, our results document the rapid categorization of social signals as kin relevant and the specificity of early and late neural markers for predicting felt ostracism.

The effects of methylphenidate on cerebral activations to salient stimuli in healthy adults

Detection of a salient stimulus is critical to cognitive functioning. A stimulus is salient when it appears infrequently, carries high motivational value, and/or when it dictates changes in behavior. Individuals with neurological conditions that implicate altered catecholaminergic signaling, such as those with attention deficit hyperactivity disorder, are impaired in detecting salient stimuli, a deficit that can be remediated by catecholaminergic medications. However, the effects of these catecholaminergic agents on cerebral activities during saliency processing within the context of the stop-signal task are not clear. Here, we examined the effects of a single oral dose (45 mg) of methylphenidate in 24 healthy adults performing the stop-signal task during functional MRI (fMRI). Compared to 92 demographically matched adults who did not receive any medications, the methylphenidate group showed higher activations in bilateral caudate head, primary motor cortex, and the right inferior parietal cortex during stop as compared to go trials (p < .05, corrected for family-wise error of multiple comparisons). These results show that methylphenidate enhances saliency processing by promoting specific cerebral regional activities. These findings may suggest a neural basis for catecholaminergic treatment of attention disorders.

A phenotypic structure and neural correlates of compulsive behaviors in adolescents

BACKGROUND

A compulsivity spectrum has been hypothesized to exist across Obsessive-Compulsive disorder (OCD), Eating Disorders (ED), substance abuse (SA) and binge-drinking (BD). The objective was to examine the validity of this compulsivity spectrum, and differentiate it from an externalizing behaviors dimension, but also to look at hypothesized personality and neural correlates.

METHOD

A community-sample of adolescents (N=1938; mean age 14.5 years), and their parents were recruited via high-schools in 8 European study sites. Data on adolescents' psychiatric symptoms, DSM diagnoses (DAWBA) and substance use behaviors (AUDIT and ESPAD) were collected through adolescent- and parent-reported questionnaires and interviews. The phenotypic structure of compulsive behaviors was then tested using structural equation modeling. The model was validated using personality variables (NEO-FFI and TCI), and Voxel-Based Morphometry (VBM) analysis.

RESULTS

Compulsivity symptoms best fit a higher-order two factor model, with ED and OCD loading onto a compulsivity factor, and BD and SA loading onto an externalizing factor, composed also of ADHD and conduct disorder symptoms. The compulsivity construct correlated with neuroticism (r=0.638; p ≤ 0.001), conscientiousness (r=0.171; p ≤ 0.001), and brain gray matter volume in left and right orbitofrontal cortex, right ventral striatum and right dorsolateral prefrontal cortex. The externalizing factor correlated with extraversion (r=0.201; p ≤ 0.001), novelty-seeking (r=0.451; p ≤ 0.001), and negatively with gray matter volume in the left inferior and middle frontal gyri.

CONCLUSIONS

Results suggest that a compulsivity spectrum exists in an adolescent, preclinical sample and accounts for variance in both OCD and ED, but not substance-related behaviors, and can be differentiated from an externalizing spectrum.

Maturational delay in ADHD: evidence from CPT

While data from behavioral, neuropsychological, and brain studies suggested that Attention-Deficit/Hyperactivity Disorder (ADHD) is related to a developmental lag that reduces with age, other studies have proposed that ADHD represents a deviant brain function. The present study used a cross-sectional approach to examine whether ADHD children show a developmental delay in cognitive performance measured by continuous performance test (CPT). We thus, compared six age groups of ADHD children (N = 559) and their unaffected peers (N = 365), aged 6–11, in four parameters of MOXO-CPT performance: Attention, Timing, Hyperactivity and Impulsivity. Results have shown that despite improvement in CPT performance with age, ADHD children continued to demonstrate impaired performance as compared to controls. In most parameters, CPT performance of ADHD children matched that of 1–3 years younger normal controls, with a delay most prominent in older children. However, in the Hyperactivity parameter, ADHD children's performance resembled that of much younger healthy children, with almost no evidence for a developmental catch up. This study suggests that while some cognitive functions develop slower but normally, other functions (e.g., inhibitory control) show a different trajectory.

A comparison of phenylketonuria with attention deficit hyperactivity disorder: do markedly different aetiologies deliver common phenotypes?

Phenylketonuria (PKU) is a well-defined metabolic disorder arising from a mutation that disrupts phenylalanine metabolism and so produces a variety of neural changes indirectly. Severe cognitive impairment can be prevented by dietary treatment; however, residual symptoms may be reported. These residual symptoms appear to overlap a more prevalent childhood disorder: Attention Deficit/Hyperactivity Disorder (ADHD). However, the aetiology of ADHD is a vast contrast to PKU: it seems to arise from a complex combination of genes; and it has a substantial environmental component. We ask whether these two disorders result from two vastly different genotypes that converge on a specific core phenotype that includes similar dysfunctions of Gray's (Gray, 1982) Behavioural Inhibition System (BIS), coupled with other disorder-specific dysfunctions. If so, we believe comparison of the commonalities will allow greater understanding of the neuropsychology of both disorders. We review in detail the aetiology, treatment, neural pathology, cognitive deficits and electrophysiological abnormalities of PKU; and compare this with selected directly matching aspects of ADHD. The biochemical and neural pathologies of PKU and ADHD are quite distinct in their causes and detail; but they result in the disorder in the brain of large amino acid levels, dopamine and white matter that are very similar and could explain the overlap of symptoms within and between the PKU and ADHD spectra. The common deficits affect visual function, motor function, attention, working memory, planning, and inhibition. For each of PKU and ADHD separately, a subset of deficits has been attributed to a primary dysfunction of behavioural inhibition. In the case of ADHD (excluding the inattentive subtype) this has been proposed to involve a specific failure of the BIS; and we suggest that this is also true of PKU. This accounts for a substantial proportion of the parallels in the superficial symptoms of both disorders and we see this as linked to prefrontal, rather than more general, dysfunction of the BIS.