Retest reliability of medial frontal negativities during performance monitoring

The error‐related negativity (ERN) and feedback‐related negativity (FRN) have been used as electrophysiological indices of performance monitoring produced in response to internally generated (errors) and externally generated (feedback) activations of the anterior cingulate cortex (ACC). No studies to date have systematically examined the measurement reliability of these components. In this article, we present the retest reliability of the ERN and FRN during response tasks designed to elicit errors or feedback responses on two occasions. Data from four experiments are presented in which participants performed tasks over various periods of time. Results indicate good retest reliability of the ERN and FRN amplitudes and source generation of these components. The present article provides important validation of the ERN and FRN as stable and trait‐like electrophysiological reflections of performance monitoring and ACC functional integrity.     

Differentiation of neuronal operations in latent components of event‐related potentials in delayed match‐to‐sample tasks

The goal of this study was to decompose ERPs into latent components associated with hypothetical processes of category discrimination, comparison to working memory and action‐related operations. In five variants of the delayed match‐to‐sample s1‐s2 task, instructions were varied for manipulation of the processes. The blind source separation was applied to the collection of ERPs. The category discrimination operation is attributed to three latent components with peak latencies of 130 to 170 ms, which are generated in different parts of the prestriate cortex. The comparison to working memory operation is attributed to a latent component that is generated in the temporal cortex and manifested in a positive deflection with a peak latency of 250 ms after s2. The category discrimination and comparison to working memory effects were dissociated spatially and temporally from attention and action selection effects.     

Reliability of event‐related EEG functional connectivity during visual entrainment: Magnitude squared coherence and phase synchrony estimates

There is an increasing trend towards using noninvasive electroencephalography (EEG) to quantify functional brain connectivity. However, little is known about the psychometrics of commonly used functional connectivity indices. We examined the internal consistency of two different connectivity metrics: magnitude squared coherence and phase synchrony. EEG was recorded during visual entrainment to elicit a strong oscillatory component of known frequency. We found acceptable to good split‐half reliability for the connectivity metrics when computing all possible pairwise interactions and after selecting an a priori seed reference. We also compared reliability estimates when using average referenced sensor versus reference independent current source density EEG data. Additional considerations were given to determining how reliability was influenced by factors including trial number, signal‐to‐noise ratio, and frequency content.     

Linking internal and external signals for performance monitoring: An event‐related potential study

The present study explored the relevance of internal signals for the dynamics of personal and nonpersonal feedback processing. To this end, pairs of participants performed concurrently a choice‐response task and received external signals in four feedback contexts. In two contexts, feedback was informative about the personal performance (personal/private and personal/public); in the other two contexts, instructions suggested that feedback was informative about the other participant's performance (nonpersonal/other) or that it was random (nonpersonal/random). Since personal feedback was contingent on performance, the two contexts with personal feedback allowed a reference between internal and external signals. This reference significantly affected personal feedback processing. On the one hand, in the processing of personal feedback, the feedback‐related negativities (FRNs) evoked by feedback associated with distinctively fast or slow responses were less negative than the FRN elicited by feedback related to responses made with average speed. On the other hand, feedback signals evoked FRNs with similar amplitudes in the two contexts with nonpersonal feedback. Furthermore, personal and nonpersonal feedback elicited ERPs with different strength. Starting with the P2 potential, personal feedback evoked a more positive electrophysiological response than nonpersonal feedback. Based on these results, we conclude that a link between internal and external signals, as for personal feedback, is a key factor influencing the dynamics of feedback processing.     

Cortical processing of simultaneous hand and foot movements: Evidence from event‐related potentials

The motor processes involved in generating simultaneous hand and foot movements were studied by recording event‐related potentials (ERPs) during reaction time tasks in which participants made hand and foot movements either alone or in combination with one another. In particular, we assessed whether the motor potentials generated during combined movements were simply superpositions of the potentials generated during the individual movements in isolation. ERPs generated during single‐limb movements replicated previously observed motor potentials, and those generated during both the execution (Experiment 1) and preparation (Experiment 2) of combined movements showed some deviations from the predictions of the superposition hypothesis, suggesting the presence of neural interactions between the hand and foot movement systems during preparation and execution of these actions.     

Psychometric properties of conflict monitoring and conflict adaptation indices: Response time and conflict N2 event‐related potentials

We assessed the psychometric properties, including internal consistency, test‐retest reliability, and number of trials needed for stability, for response time (RT) and conflict N2 amplitude measures of conflict adaptation (i.e., sequential trial or Gratton effects). Event‐related potentials (ERPs) were obtained from 79 healthy individuals (44 female) during completion of a modified Eriksen flanker task. RTs and N2 amplitude showed reliable conflict adaptation (i.e., previous‐trial congruency influenced current‐trial measures). Conflict adaptation indices were stable as indicated by reliable internal consistency and 2‐week test‐retest stability. The number of trials needed for conservative, reliable RT and N2 amplitude measurements was 29 and 30, respectively. This investigation empirically establishes that these conflict adaptation indices represent robust, dependable measures.     

Error‐related electromyographic activity over the corrugator supercilii is associated with neural performance monitoring

Emerging research in social and affective neuroscience has implicated a role for affect and motivation in performance monitoring and cognitive control. No study, however, has investigated whether facial electromyography (EMG) over the corrugator supercilii—a measure associated with negative affect and the exertion of effort—is related to neural performance monitoring. Here, we explored these potential relationships by simultaneously measuring the error‐related negativity, error positivity (Pe), and facial EMG over the corrugator supercilii muscle during a punished, inhibitory control task. We found evidence for increased facial EMG activity over the corrugator immediately following error responses, and this activity was related to the Pe for both between‐ and within‐subject analyses. These results are consistent with the idea that early, avoidance‐motivated processes are associated with performance monitoring, and that such processes may also be related to orienting toward errors, the emergence of error awareness, or both.     

In silico GABA+ MEGA‐PRESS: Effects of signal‐to‐noise ratio and linewidth on modeling the 3 ppm GABA+ resonance

To investigate the GABA+ modeling accuracy of MEGA‐PRESS GABA+‐edited MRS data with various spectral quality scenarios, the influence of varying signal‐to‐noise ratio (SNR) and linewidth on the model estimates was quantified. MEGA‐PRESS data from 46 volunteers were averaged to generate a template MEGA‐PRESS spectrum, which was modeled and quantified to generate a GABA+ level ground truth. This spectrum was then manipulated by adding 427 combinations of varying artificial noise levels and line broadening, mimicking variations in GABA+ SNR and B₀ homogeneity. GABA+ modeling and quantification was performed with 100 simulated spectra per condition using automated routines in both Gannet 3.0 and Tarquin. The GABA+ estimation error was calculated as the relative deviation to the quantified GABA+ ground truth levels to assess the accuracy of GABA+ modeling. Finally, the accordance between the simulations and different in vivo scenarios was assessed. The GABA+ estimation error was smaller than 5% for all GABA+ SNR values with creatine linewidths lower than 9.7 Hz in Gannet 3.0 or unequal 10.6 Hz in Tarquin. The standard deviation of the GABA+ amplitude over 100 spectra per condition varied between 3.1 and 17% (Gannet 3.0) and between 1 and 11% (Tarquin) over the in vivo relevant GABA+ SNR range between 2.6 and 3.5. GABA+ edited studies might be realized for voxels with low GABA+ SNR at the cost of higher group‐level variance. The accuracy of GABA+ modeling had no relation to commonly used quality metrics. The Tarquin algorithm was found to be more robust against linewidth changes than the fitting algorithm in Gannet.     

DTI of human skeletal muscle: the effects of diffusion encoding parameters,signal‐to‐noise ratio and T2 on tensor indices and fiber tracts

In this study, we have performed simulations to address the effects of diffusion encoding parameters, signal‐to‐noise ratio (SNR) and T₂ on skeletal muscle diffusion tensor indices and fiber tracts. Where appropriate, simulations were corroborated and validated by in vivo diffusion tensor imaging (DTI) of human skeletal muscle. Specifically, we have addressed: (i) the accuracy and precision of the diffusion parameters and eigenvectors at different SNR levels; (ii) the effects of the diffusion gradient direction encoding scheme; (iii) the optimal b value for diffusion tensor estimation; (iv) the effects of changes in skeletal muscle T₂; and, finally, the influence of SNR on fiber tractography and derived (v) fiber lengths, (vi) pennation angles and (vii) fiber curvatures. We conclude that accurate DTI of skeletal muscle requires an SNR of at least 25, a b value of between 400 and 500 s/mm², and data acquired with at least 12 diffusion gradient directions homogeneously distributed on half a sphere. Furthermore, for DTI studies focusing on skeletal muscle injury or pathology, apparent changes in the diffusion parameters need to be interpreted with great care in view of the confounding effects of T₂, particularly for moderate to low SNR values. Copyright © 2013 John Wiley & Sons, Ltd.     

Goal relevance influences performance monitoring at the level of the FRN and P3 components

The feedback‐related negativity (FRN) provides a reliable ERP marker of performance monitoring (PM). It is usually larger for negative compared to positive feedback, and for unexpected relative to expected feedback. In two experiments, we assessed whether these effects could be modulated by goal relevance, defined as feedback informativeness (reliability) and/or impact on a person's goals. EEG (64‐channel) was recorded while 30 participants (in each experiment) performed a speeded go/no‐go task across blocks in which the feedback on task performance was deemed either relevant or not. At the ERP level, the FRN component was larger for (frequent) negative compared to (deviant) positive feedback exclusively when the feedback was relevant (Experiment 1). When the probability of positive and negative feedback was balanced (Experiment 2), this valence‐driven FRN effect was absent. However, across these two experiments, the FRN was always larger for irrelevant than relevant feedback. Moreover, the subsequent P300 component was larger for feedback in the relevant than the irrelevant blocks. This effect was valence unspecific in Experiment 1, while in Experiment 2 larger P3 amplitudes were recorded for negative than positive (relevant) feedback. Across the two experiments, a larger correct‐related negativity in the irrelevant than relevant context was also observed, suggesting that PM is flexible. These ERP findings indicate that goal relevance influences feedback (and response) processing during PM, with two nonoverlapping neurophysiological effects: It gates reward prediction error brain mechanisms (FRN effect), before enhancing subsequent motivational processes (P300 effect).     

The effects of response sharing and stimulus presentation frequency on event‐related potentials in an auditory oddball paradigm

An experimental model for investigating the processes involved in reacting to unpredictable events is the oddball paradigm. We investigated how the commonality or independence of response options (i.e., many‐to‐one vs. one‐to‐one stimulus‐response mappings) influences processing in an auditory oddball paradigm. Participants performed a discrimination task with two one‐to‐one and one two‐to‐one mappings. The pattern of conflict‐ and oddball‐related N2 event‐related potentials suggest that information that would allow correct responding is represented at the latency of the N2. Integration of this information takes place only by the latency of P3b, and longer reaction times to rare stimuli are probably due to processes preventing the utilization of this information. We also suggest that, in the given task context, conflict‐related N2 may reflect the number of alternative stimuli leading to alternative response options.     

An event‐related source localization study of response monitoring and social impairments in autism spectrum disorder

A number of studies suggest anterior cingulate cortex (ACC) abnormalities in autism spectrum disorder (ASD), which might underlie response monitoring and social impairments exhibited by children and adolescents with ASD. The goal of the present study was to extend this work by examining error and correct response monitoring using event‐related potentials (ERN, Pe, CRN) and LORETA source localization in high functioning adults with ASD and controls. Adults with ASD showed reduced ERN and Pe amplitudes and reduced rostral ACC activation compared with controls. Adults with ASD also showed less differentiation between error and correct ERP components. Social impairments and higher overall autism symptoms were related to reduced rostral ACC activity at the time of the ERN, particularly in adults with ASD. These findings suggest that reduced ACC activity may reflect a putative brain mechanism involved in the origins and maintenance of social impairments and raise the possibility of the presence of stable brain‐behavior relation impairment across development in some individuals with ASD.     

Task relevance and recognition of concealed information have different influences on electrodermal activity and event‐related brain potentials

This study aimed at differentiating between memory‐ and task‐related processes and their correlates on the electrodermal and electrocortical level during information concealment. Variations of the Guilty Knowledge Test were implemented in two experiments while we measured skin conductance responses (SCRs) and event‐related brain potentials. P300 amplitudes were specifically enhanced for items requiring a deviant behavioral response but they were not sensitive to concealed knowledge. In contrast, N200 amplitudes differed between memorized and irrelevant items in both experiments. SCR measures reflected a combined influence of task relevance and probe recognition, and they provided incremental validity above N200 amplitudes. These results suggest that the P300 mainly reflects task relevance in the given experimental setting whereas the N200 amplitude is sensitive to previously encoded information and potentially linked to response monitoring processes.     

One‐year developmental stability and covariance among oddball,novelty, go/no‐go,and flanker event‐related potentials in adolescence: A monozygotic twin study

ERP measures may index genetic risk for psychopathology before disorder onset in adolescence, but little is known about their developmental rank‐order stability during this period of significant brain maturation. We studied ERP stability in 48 pairs of identical twins (age 14–16 years) tested 1 year apart. Trial‐averaged voltage waveforms were extracted from electroencephalographic recordings from oddball/novelty, go/no‐go, and flanker tasks, and 16 amplitude measures were examined. Members of twin pairs were highly similar, whether based on ERP amplitude measures (intraclass correlation [ICC] median = .64, range = .44–.86) or three factor scores (all ICCs ≥ .69) derived from them. Stability was high overall, with 69% of the 16 individual measures generating stability coefficients exceeding .70 and all factor scores showing stability above .75. Measures from 10 difference waveforms calculated from paired conditions within tasks were also examined, and were associated with lower twin similarity (ICC median = .52, .38–.64) and developmental stability (only 30% exceeding .70). In a supplemental analysis, we found significant developmental stability for error‐related negativity (range = .45–.55) and positivity (.56–.70) measures when average waveforms were based on one or more trials, and that these values were equivalent to those derived from averages using the current field recommendation, which requires six or more trials. Overall, we conclude that the studied brain measures are largely stable over 1 year of mid‐ to late adolescence, likely reflecting familial etiologic influences on brain functions pertaining to cognitive control and salience recognition.     

Event‐related potentials of attentional bias toward faces in the dot‐probe task: A systematic review

The dot‐probe task is a common task to assess attentional bias toward different stimuli and how groups differ (e.g., attentional bias in anxiety disorders). However, measuring reaction time has been suggested to be unreliable. Neuroimaging methods such as fMRI were shown to be more reliable in assessing attentional bias, but fMRI has poor temporal resolution and therefore cannot assess timing of attention. ERPs have been used to examine the time course of attentional bias. Although ERP research may be more reliable than reaction time, there have been inconsistencies in the literature. This review systematically searched for articles that used the dot‐probe task with facial expressions and measured neural correlates with ERP. We found that some of the inconsistencies might be the cause of methodological differences (e.g., timing of stimuli), differences in emotional expression, and/or sample differences (e.g., sex, age, etc.). Suggestions on how future research could address the issues presented in this review were discussed.     

Defensive motivation and attention in anticipation of different types of predictable and unpredictable threat: A startle and event‐related potential investigation

Predictability is an important characteristic of threat that impacts defensive motivation and attentional engagement. Supporting research has primarily focused on actual threat (e.g., shocks), and it is unclear whether the predictability of less intense threat (e.g., unpleasant pictures) similarly affects motivation and attention. The present study utilized a within‐subject design and examined defensive motivation (startle reflex and self‐reported anxiety) and attention (probe N100 and P300) in anticipation of shocks and unpleasant pictures during a no, predictable, and unpredictable threat task. This study also examined the impact of predictability on the P300 to shocks and late positive potential (LPP) to unpleasant pictures. The startle reflex and self‐reported anxiety were increased in anticipation of both types of threat relative to no threat. Furthermore, startle potentiation in anticipation of unpredictable threat was greater for shocks compared to unpleasant pictures, but there was no difference for predictable threat. The probe N100 was enhanced in anticipation of unpredictable threat relative to predictable threat and no threat, and the probe P300 was suppressed in anticipation of predictable and unpredictable threat relative to no threat. These effects did not differ between the shock and unpleasant picture trials. Finally, the P300 and early LPP component were increased in response to unpredictable relative to predictable shocks and unpleasant pictures, respectively. The present study suggests that the unpredictability of unpleasant pictures increases defensive motivation, but to a lesser degree relative to actual threat. Moreover, unpredictability enhances attentional engagement in anticipation of, and in reaction to, both types of threat.     

Teasing apart the anticipatory and consummatory processing of monetary incentives: An event‐related potential study of reward dynamics

The monetary incentive delay (MID) task has been widely used in fMRI studies to investigate the neural networks involved in anticipatory and consummatory reward processing. Previous efforts to adapt the MID task for use with ERPs, however, have had limited success. Here, we sought to further decompose reward dynamics using a comprehensive set of anticipatory (cue‐N2, cue‐P3, contingent negative variation [CNV]) and consummatory ERPs (feedback negativity [FN], feedback P3 [fb‐P3]). ERP data was recorded during adapted versions of the MID task across two experiments. Unlike previous studies, monetary incentive cues modulated the cue‐N2, cue‐P3, and CNV; however, cue‐related ERPs and the CNV were uncorrelated with one another, indicating distinct anticipatory subprocesses. With regard to consummatory processing, FN amplitude primarily tracked outcome valence (reward vs. nonreward), whereas fb‐P3 amplitude primarily tracked outcome salience (uncertain vs. certain). Independent modulation of the cue‐P3 and fb‐P3 was observed, indicating that these two P3 responses may uniquely capture the allocation of attention during anticipatory and consummatory reward processing, respectively. Overall, across two samples, consistent evidence of both anticipatory and consummatory ERP activity was observed on an adapted version of the MID paradigm, demonstrating for the first time how these ERP components may be integrated with one another to more fully characterize the time course of reward processing. This ERP‐MID paradigm is well suited to parsing reward dynamics, and can be applied to both healthy and clinical populations.     

Phasic brain activity related to the onset of rapid eye movements during rapid eye movement sleep: study of event‐related potentials and standardized low‐resolution brain electromagnetic tomography

The function of rapid eye movements (REMs) during REM sleep is still a matter that is open to debate. In a previous study, we found positive brain potential (P200r) time‐locked to the onset of REMs. This potential was not observed during saccades of wakefulness. In this study, we estimated the electrical generation of this potential to investigate the phasic brain activity related to REMs. Data were collected in a sleep laboratory from nine healthy university students. REMs during REM sleep were recorded during natural nocturnal sleep. Event‐related potential time‐locked to the onset of REMs were averaged. Standardized low‐resolution brain electromagnetic tomography (sLORETA) was used to identify the current sources of P200r. The results showed that P200r have neuronal generators in the left premotor area, left primary motor and sensory cortices, left inferior parietal lobule and bilateral occipital areas (precuneus, cuneus and lingual gyrus). All these areas are known to contribute to visuomotor processing. These phasic brain activities might play a key role in explaining the function of REMs during REM sleep.     

Event‐related potentials reveal the effects of aging on meaning selection and revision

ERPs were recorded as older adults decided if a target word was related to a lateralized ambiguous or unambiguous prime; prime‐target pairs were preceded by a related or unrelated context word. In an unrelated context, N400 facilitation effects differed from those seen in young adults, with older adults showing priming for the dominant meaning (e.g., BOOM‐BANK‐DEPOSIT) on right visual field/left hemisphere (RVF/LH) trials and priming for the subordinate meaning (e.g., BOOM‐BANK‐RIVER) on LVF/RH trials. Higher‐functioning older adults, especially those with better inhibition, were more likely to show bilateral activation of the dominant meaning and unilateral activation of the subordinate meaning, suggesting a retention of young‐like activation. In a biasing context (e.g., RIVER‐BANK‐DEPOSIT), older adults selected the contextually‐consistent meaning, but were less likely than young adults to revise their selection.     

Methodological reporting behavior,sample sizes,and statistical power in studies of event‐related potentials: Barriers to reproducibility and replicability

Methodological reporting guidelines for studies of ERPs were updated in Psychophysiology in 2014. These guidelines facilitate the communication of key methodological parameters (e.g., preprocessing steps). Failing to report key parameters represents a barrier to replication efforts, and difficulty with replicability increases in the presence of small sample sizes and low statistical power. We assessed whether guidelines are followed and estimated the average sample size and power in recent research. Reporting behavior, sample sizes, and statistical designs were coded for 150 randomly sampled articles from five high‐impact journals that frequently published ERP research from 2011 to 2017. An average of 63% of guidelines were reported, and reporting behavior was similar across journals, suggesting that gaps in reporting is a shortcoming of the field rather than any specific journal. Publication of the guidelines article had no impact on reporting behavior, suggesting that editors and peer reviewers are not enforcing these recommendations. The average sample size per group was 21. Statistical power was conservatively estimated as .72?.98 for a large effect size, .35?.73 for a medium effect, and .10?.18 for a small effect. These findings indicate that failing to report key guidelines is ubiquitous and that ERP studies are primarily powered to detect large effects. Such low power and insufficient following of reporting guidelines represent substantial barriers to replication efforts. The methodological transparency and replicability of studies can be improved by the open sharing of processing code and experimental tasks and by a priori sample size calculations to ensure adequately powered studies.