Performance and ERP components in the equiprobable go/no‐go task: Inhibition in children

The equiprobable go/no‐go task lacks the dominant go imperative found in the usual go/no‐go task, and hence we previously regarded it as involving little inhibition. However, children have relative difficulty with this task, and demonstrate large frontal no‐go N2s. We investigated whether this child N2 plays an inhibitory role, using performance measures to illuminate the link between N2 and inhibition. Forty children aged 8 to 13 were presented with four stimulus blocks each containing 75 go and 75 no‐go tone stimuli in random order. A temporal PCA with unrestricted varimax rotation quantified the mean go and no‐go ERP component amplitudes. Most identified components were differentially enhanced to go or no‐go as in adults, supporting a previously proposed differential processing schema. Between subjects, larger frontocentral no‐go N2bs were associated with fewer commission errors. Hence, the no‐go N2b in this paradigm can be interpreted as an individual marker of inhibition in children.     

Caffeine affects children’s ERPs and performance in an equiprobable go/no‐go task: Testing a processing schema

Caffeine’s stimulant properties were used to test a proposed processing schema for children’s processing stages in the equiprobable auditory go/no‐go task. Active control‐related ERP components were hypothesized to be differentially enhanced by caffeine. Caffeine (80 mg) was administered in a counterbalanced, randomized, double‐blind, placebo‐controlled, cross‐over study of 24 children, aged 8–12 years. Four blocks of an equiprobable auditory go/no‐go task were completed on each of two occasions, while on or off caffeine. ERP data sets from each condition (caffeine/go, placebo/go, caffeine/no‐go, placebo/no‐go) were subjected to separate temporal PCAs with extraction and varimax rotation of all components. Caffeine significantly reduced reaction time and go omission errors, and enhanced go PN, N2c, and P3b, and no‐go N1‐1 and N2b. This selective enhancement of different go/no‐go components by caffeine matched the predicted amplification of biomarkers of children’s active control processing in this task. Some unexpected findings also support further refinements in the child processing schema.     

Sequential processing in the classic oddball task: ERP components,probability, and behavior

This study compared the ERP components and behavior associated with the auditory equiprobable and classic oddball tasks, to relate the cognitive processing stages in those paradigms and continue the development of the sequential processing schema. Target and nontarget ERP data were acquired from 66 healthy young adults (M_age = 20.1, SD = 2.4 years, 14 male) who completed both equiprobable (target p = 0.5) and oddball tasks (target p = 0.3). Separate temporal PCAs were used to decompose the ERP data in each task and condition, and the similarity of the components identified in each condition was examined between tasks. Probability effects on component amplitudes and behavior were also analyzed to identify task differences in cognitive demands. A highly similar series of components was identified in each task, closely matching the schema: targets elicited N1‐3, N1‐1, PN, N2c, P3b, SW1, SW2; whereas nontargets elicited N1‐3, N1‐1, PN, N2b, P3a, SW1, SW2. N1‐1 and PN amplitudes increased as stimulus probability decreased, irrespective of the condition. N2b, P3b, SW1, and SW2 amplitudes also varied between tasks, illustrating task‐specific demands on those processing stages. These findings complemented the behavioral outcomes, which demonstrated greater accuracy and control in the classic oddball task. Overall, this study demonstrated comparable processing in the auditory equiprobable and classic oddball tasks, extending the generalizability of the schema and enabling further integration of the ERP theory associated with these tasks. This study also clarifies stimulus probability effects on the schema, providing important insight into the functionality of common ERP components.     

Resting state intrinsic EEG impacts on go stimulus‐response processes

Neuropsychological research and practice rely on cognitive task performance measures as indicators of brain functioning. The neural activity underlying stimulus‐response processes can be assessed with ERPs, but the relations between these cognitive processes and the brain's intrinsic resting state EEG activity are less understood. This study focused on the neurocognitive functioning of 20 healthy young adults in an equiprobable go/no‐go task to map the ERP correlates of behavioral responses and examine contributions of the resting state intrinsic EEG to task‐related outcomes. Continuous EEG was recorded during pretask eyes‐closed (EC) and eyes‐open (EO) conditions, and in the subsequent task. Delta, theta, alpha, and beta band amplitudes were assessed for the EC state and also for the reactive change to EO. Go/no‐go ERPs were submitted to temporal principal components analysis, where the P2, N2, P3, and slow wave components of interest were extracted. The performance measure of reaction time (RT) variability was positively correlated with no‐go and go errors, and also with go P2 amplitude, linking these to stimulus discrimination efforts involved in appropriate response selection. An N2c‐P3b pairing was enhanced for shorter mean RTs, supporting their involvement in the decision to execute a response. A stepwise regression model identified EC midline delta as a predictor of P3b positivity, highlighting the relevance of delta in the neural mechanisms of attentional processes. These findings clarify the electrophysiology underlying decision‐making processes in executive function, and provide a platform for further research assessing performance outcomes in larger samples and in developmental/clinical contexts.     

Nontarget-to-nontarget interval determines the nontarget P300 in an auditory equiprobable Go/NoGo task

Increases in the target-to-target interval (TTI) systematically enhance the amplitude of the target P300 ERP component. Research examining changes in nontarget P300 related to nontarget-to-nontarget interval (NNI) or sequential probability manipulations has produced inconsistent results, with some studies reporting no enhancement in nontarget P300 and others finding response profiles analogous to TTI effects. Our aim was to clarify these differences. All participants completed a specially designed auditory equiprobable Go/NoGo task with manipulations of TTI and NNI while their EEG activity was recorded. P300 amplitudes were extracted using temporal PCA with Varimax rotation. P3b to targets and nontargets increased systematically as respective TTIs/NNIs increased, but this change did not differ between stimulus types. The Slow Wave did not show any effect of interval, but was more positive to targets than nontargets when interval was collapsed. P3b findings show that matching-stimulus interval effects are not restricted to targets, but discrepancies relative to previous research suggest that NNI effects in P3b may depend on additional processing of nontarget stimuli.     

Modulation of ERP components by task instructions in a cued go/no‐go task

The present study investigated how components of ERPs are modulated when participants optimize speed versus accuracy in a cued go/no‐go task. Using a crossover design, 35 participants received instructions to complete the task prioritizing response speed in half of the task, and accurate responding in the other half of the task. Analysis was performed on the contingent negative variation (CNV), P3go, and P3no‐go and the corresponding independent components (IC), as identified by group independent component analysis. After speed instructions, the IC CNV_late, P3go_anterior, P3no‐go_early, and P3no‐go_late all had larger amplitudes than after accuracy instructions. Furthermore, both the IC P3go_posterior and IC P3go_anterior had shorter latencies after speed than after accuracy instructions. The results demonstrate that components derived from the CNV and P3 components are facilitated when participants optimize response speed. These findings indicate that these ERP components reflect executive processes enabling adjustment of behavior to changing demands.     

Functional indexes of reactive cognitive control: ERPs in cued go/no‐go tasks

We aimed to determine the functional meaning of latent (hidden) components decomposed from ERPs, in the context of a go/no‐go paradigm. To accomplish this, we used a new group blind source separation method, based on joint diagonalization of covariance matrices of ERPs. Four variants of a frequently used go/no‐go paradigm were designed, in which operations of reactive cognitive control, such as conflict detection and action inhibition, were independently manipulated. The results showed that a latent component, generated in the anterior cingulate cortex, induced N2/P3 fluctuation only in conditions in which the prepotent model was violated, and thus can be associated with conflict detection operations. In contrast, the two latent components generated in the vicinity of the central sulcus induced P3‐like fluctuations in conditions in which the prepared action was suppressed, and thus can be associated with action inhibition operations. The advantages and limitations of the new blind source separation method in relation to ERP research are also discussed.     

Influence of acute stress on response inhibition in healthy men: An ERP study

The current study investigated the influence of acute stress and the resulting cortisol increase on response inhibition and its underlying cortical processes, using EEG. Before and after an acute stressor or a control condition, 39 healthy men performed a go/no‐go task while ERPs (N2, P3), reaction times, errors, and salivary cortisol were measured. Acute stress impaired neither accuracy nor reaction times, but differentially affected the neural correlates of response inhibition; namely, stress led to enhanced amplitudes of the N2 difference waves (N2d, no‐go minus go), indicating enhanced response inhibition and conflict monitoring. Moreover, participants responding to the stressor with an acute substantial rise in cortisol (high cortisol responders) showed reduced amplitudes of the P3 of the difference waves (P3d, no‐go minus go) after the stressor, indicating an impaired evaluation and finalization of the inhibitory process. Our findings indicate that stress leads to a reallocation of cognitive resources to the neural subprocesses of inhibitory control, strengthening premotor response inhibition and the detection of response conflict, while concurrently diminishing the subsequent finalization process within the stream of processing.     

Auditory hallucinations and the P3a: Attention-switching to speech in schizophrenia

Background

In line with emerging research strategies focusing on specific symptoms rather than global syndromes in psychiatric disorders, we examined the functional neural correlates of auditory verbal hallucinations (AHs) in schizophrenia. Recent neuroimaging and behavioural evidence suggest altered early cognitive processes may be seen in patients with AH as a result of limited processing resources.

Methods

The P3a subcomponent of the P300, an event-related potential (ERP) index of early attention switching, was assessed in 12 hallucinating patients (HP), 12 non-hallucinating patients (NP) and 12 healthy controls (HC) within a passive two-tone auditory oddball paradigm using vowel phonemes. P3a amplitudes and latencies were measured in response to across-phoneme changes. Following P3a acquisition, patients indicated the duration, intensity and clarity of their auditory hallucinations during recording.

Results

Hallucinating patients exhibited smaller P3a amplitudes than non-hallucinating patients and healthy controls. In HPs, P3a amplitude was negatively correlated with AH trait scores.

Significance

These findings suggest that AHs are associated with impaired processing of speech as evidenced by altered P3a amplitudes to vowel phonemes. This finding may be due to limited cognitive resources available for incoming external stimuli due to a usurping of finite resources by AHs. The P3a may be a useful non-invasive tool for probing relationships between hallucinatory and neural states within schizophrenia and the manner in which auditory processing is altered in these afflicted patients.     

Stimulus modality, perceptual overlap, and the go/no-go N2

Stimuli that elicit a prepotent but incorrect response are typically associated with an enhanced electrophysiological N2 that is thought to index the operation of a control process such as inhibition or conflict detection. However, recent studies reporting the absence of the N2 modulation in go/no-go tasks involving auditory stimuli challenge this view: It is not clear why inhibition or conflict detection should be sensitive to the modality of the stimulus. Here we present electrophysiological data from a go/no-go task suggesting that the relative size of the N2 modulation in visual and auditory tasks depends on the perceptual overlap between the go and no-go stimuli. Stimuli that looked similar but sounded different were associated with a typical visual N2 modulation and the absence of an auditory N2 modulation, consistent with previous findings. However, when we increased the perceptual overlap between the auditory stimuli, a large no-go N2 was observed. These findings are discussed in terms of existing hypotheses of the N2, and clarify why previous studies have not found an N2 modulation in auditory go/no-go tasks.     

Emotional content modulates response inhibition and perceptual processing

In this study, event‐related potentials were used to investigate the effect of emotion on response inhibition. Participants performed an emotional go/no‐go task that required responses to human faces associated with a “go” valence (i.e., emotional, neutral) and response inhibition to human faces associated with a “no‐go” valence. Emotional content impaired response inhibition, as evidenced by decreased response accuracy and N2 amplitudes in no‐go trials. More importantly, emotional expressions elicited larger N170 amplitudes than neutral expressions, and this effect was larger in no‐go than in go trials, indicating that the perceptual processing of emotional expression had priority in inhibitory trials. In no‐go trials, correlation analysis showed that increased N170 amplitudes were associated with decreased N2 amplitudes. Taken together, our findings suggest that emotional content impairs response inhibition due to the prioritization of emotional content processing.     

Preferential neural processing of attended stimuli in attention-deficit hyperactivity disorder and normal boys

Event-related auditory and visual potentials were recorded from 36 attention-deficit hyperactivity disorder (ADHD) and 35 normal 6-year-old subjects engaged in a two-choice discrimination task. When normal subjects attended to stimuli in a given modality, enhanced negative (N2) and positive (P3b) responses (as compared with responses to nonattended stimuli) were found for auditory and visual target stimuli. In contrast, when ADHD subjects attended, little or no enhanced negative responses were found in either modality, and enhanced positive P3b responses were found only in response to visual target stimuli. Auditory N1, N2, and P3b and visual N2 amplitudes to attended target stimuli were significantly reduced in ADHD subjects as compared with normal subjects. No between-group differences were found for responses to nonattended stimuli. Both amplitude and latency abnormalities indicate that ADHD boys suffer from deficient preferential processing of attended stimuli. P3b and N2 abnormalities found here suggest deficiencies in two independent cognitive processes thought to be crucial to what we perceive, learn, and remember.     

Developmental differences in behavioral and event-related brain responses associated with response preparation and inhibition in a go/nogo task

The present study investigated developmental trends in response inhibition and preparation by studying behavior and event-related brain activity in a cued go/nogo task, administered to nine-year-old children and young adults. Hits, false alarms, inattention, and impulsivity scores and ERP measures of inhibition (fronto-central nogo-N2 and P3), target selection (parietal go-nogo P3 difference), and response preparation (contingent negative variation; CNV) were collected. Higher false alarm and impulsivity scores and the absence of the fronto-central nogo P3 all suggest a developmental lag in response inhibition in children. A developmental lag in sustained attention processes was suggested by worse target detection and larger parietal target/nontarget P3 effects in children. Cue orientation and response preparation processes were respectively measured by early and late CNV activity. Children displayed smaller early CNV amplitudes at fronto-central locations, but mature late CNV. The smaller early CNV activity might indicate inefficient cue-orientation processes caused by incomplete frontal lobe development.     

Neural correlates of successful and partial inhibitions in children: An ERP study

This experiment used event‐related potentials (ERPs) to investigate the neural processes underlying the development of response inhibition in a modified version of the go/no‐go paradigm [Cragg and Nation [2008] Developmental Science 11(6): 819–827]. N2 and P3 ERP components on correct go trials and partial and successful inhibitions were compared in 7‐ and 9‐year‐old children. A larger N2 effect on successful inhibitions was found in 9‐year‐olds compared to 7‐year‐olds at fronto‐central electrodes. N2 amplitude was positively related to behavioral performance in the 7‐year‐olds suggesting it may reflect inhibitory processes; however, this relationship was not present in the 9‐year‐olds. Age differences were also apparent in the go P3, perhaps indicating differences in stimulus processing. The no‐go P3 component was larger on successful than partial inhibitions. In contrast, there was no difference in N2 amplitude between partial and successful inhibitions. A significant difference was found in N2 latency however. This suggests that inhibitory processes are similar in both cases but initiated earlier on successful inhibitions. N2 latency was also shorter in 9‐year‐olds than 7‐year‐olds supporting an increase in the efficiency of response inhibition with age. © 2009 Wiley Periodicals, Inc. Dev Psychobiol 51: 533–543, 2009.     

Electrocortical measures of performance monitoring from go/no-go and flanker tasks: Differential relations with trait dimensions of the triarchic model of psychopathy

This study examined associations of performance-monitoring event-related potentials (ERPs) from go/no-go and flanker tasks with one another, and with psychopathy-related traits of disinhibition, meanness, and boldness. A task-dependent relationship was evident between the error-related negativity (ERN) and trait disinhibition, with high-disinhibited participants showing reduced no-go ERN but not flanker ERN. Disinhibition was also inversely related to variants of the P3 and the error positivity (Pe) from these two tasks. A factor analysis of the ERPs revealed two distinct factors, one reflecting shared variance among the P3 and Pe measures from the two tasks, and the other covariance among the N2 and ERN measures. Scores on the P3/Pe factor, but not the N2/ERN factor, were inversely related to disinhibition, and accounted for associations of this trait with variants of the P3 and Pe across tasks. The implication is that high trait disinhibition relates mainly to reductions in brain responses associated with later elaborative stages in the processing of motivationally significant events across different tasks. Importantly, no-go ERN predicted disinhibition scores beyond N2/ERN factor scores, indicating that high disinhibition is not generally related to diminished early preresponse conflict and error processing, but rather to processing impairments in conditions calling for inhibition of prepotent response tendencies.     

Brain correlates of the orientation of auditory spatial attention onto speaker location in a “cocktail‐party” situation

Successful speech perception in complex auditory scenes with multiple competing speakers requires spatial segregation of auditory streams into perceptually distinct and coherent auditory objects and focusing of attention toward the speaker of interest. Here, we focused on the neural basis of this remarkable capacity of the human auditory system and investigated the spatiotemporal sequence of neural activity within the cortical network engaged in solving the “cocktail‐party” problem. Twenty‐eight subjects localized a target word in the presence of three competing sound sources. The analysis of the ERPs revealed an anterior contralateral subcomponent of the N2 (N2ac), computed as the difference waveform for targets to the left minus targets to the right. The N2ac peaked at about 500 ms after stimulus onset, and its amplitude was correlated with better localization performance. Cortical source localization for the contrast of left versus right targets at the time of the N2ac revealed a maximum in the region around left superior frontal sulcus and frontal eye field, both of which are known to be involved in processing of auditory spatial information. In addition, a posterior‐contralateral late positive subcomponent (LPCpc) occurred at a latency of about 700 ms. Both these subcomponents are potential correlates of allocation of spatial attention to the target under cocktail‐party conditions.     

Can working memory predict target-to-target interval effects in the P300?

It has been suggested that the P300 component of the ERP is an electrophysiological index of memory-updating processes associated with task-relevant stimuli. Component magnitude varies with the time separating target stimuli (target-to-target interval: TTI), with longer TTIs eliciting larger P300 amplitudes. According to the template-update perspective, TTI effects observable in the P300 reflect the updating of stimulus-templates in working memory (WM). The current study explored whether young adults' memory-task ability could predict TTI effects in P300. EEG activity was recorded from 50 university students (aged 18–25 years) while they completed an auditory equiprobable Go/NoGo task with manipulations of TTIs. Participants also completed a CogState® battery and were sorted according to their WM score. ERPs were analysed using a temporal PCA. Two P300 components, P3b and the Slow Wave, were found to linearly increase in amplitude to longer TTIs. This TTI effect differed between groups only for the P3b component: The high WM group showed a steeper increase in P3b amplitude with TTI than the low WM group. These results suggest that TTI effects in P300 are directly related to WM processes.     

Auditory stimulus- and response-locked ERP components and behavior

To clarify the functional significance of Go event-related potential (ERP) components, this study aimed to explore stimulus- and response-locked ERP averaging effects on the series of ERP components elicited during an auditory Go/NoGo task. Go stimulus- and response-locked ERP data from 126 healthy young adults (M_age = 20.3, SD = 2.8 years, 83 female) were decomposed using temporal principal components analysis (PCA). The extracted components were then identified as stimulus-specific, response-specific, or common to both stimulus- and response-locked data. MANOVAs were then used to test for stimulus- versus response-locked averaging effects on common component amplitudes to determine their primary functional significance (i.e., stimulus- or response-related). Go stimulus- and response-related component amplitudes were then entered into stepwise linear regressions predicting the reaction time (RT), RT variability, and omission errors. Nine ERP components were extracted from the stimulus- and response-locked data, including N1-1, processing negativity (PN), P2, response-related N2 (RN2), motor potential (MP), P3b, P420, and two slow wave components; SW1 and SW2. N1-1, PN, and P2 were stimulus-specific, whereas, RN2, MP, and P420 were response-specific; P3b, SW1, and SW2 were common to both data sets. P3b, SW1, and SW2 were significantly larger in the response-locked data, indicating that they were primarily response-related. RT, RT variability, and omission errors were predicted by various stimulus- and response-related components, providing further insight into ERP markers of auditory information processing and cognitive control. Further, the results of this study indicate the utility of quantifying some common components (i.e., Go P3b, SW1, and SW2) using the response-locked ERP.     

Using principal components analysis to examine resting state EEG in relation to task performance

Brain dynamics research has highlighted the significance of the ongoing EEG in ERP genesis and cognitive functioning. Few studies, however, have assessed the contributions of the intrinsic resting state EEG to these stimulus‐response processes and behavioral outcomes. Principal components analysis (PCA) has increasingly been used to obtain more objective, data‐driven estimates of the EEG and ERPs. PCA was used here to reassess resting state EEG and go/no‐go task ERP data from a previous study (Karamacoska et al., 2017) and the relationships between these measures. Twenty adults had EEG recorded with eyes closed (EC) and eyes open (EO), and as they completed an auditory go/no‐go task. Separate EEG and ERP PCAs were conducted on each resting condition and stimulus type. For each state, seven EEG components were identified within the delta‐beta frequency range, and six ERP components were obtained for go and no‐go stimuli. Within the task, mean reaction time (RT) correlated positively with go P2 amplitude and negatively with P3b positivity. Regressions revealed that greater EC delta‐1 amplitude predicted shorter mean RT, and larger alpha‐3 amplitude predicted go P3b enhancement. These findings demonstrate the immediate P2 and P3b involvement in decision making and response control and the intrinsic EC delta‐1 and alpha‐3 amplitudes that underpin these processes.     

Overcoming limitations of the ERP method with Residue Iteration Decomposition (RIDE): A demonstration in go/no‐go experiments

The usefulness of the event‐related potential (ERP) method can be compromised by violations of the underlying assumptions, for example, confounding variations of latency and amplitude of ERP components within and between conditions. Here we show how the ERP subtraction method might yield misleading information due to latency variability of ERP components. We propose a solution to this problem by correcting for latency variability using Residue Iteration Decomposition (RIDE), demonstrated with data from representative go/no‐go experiments. The overlap of N2 and P3 components in go/no‐go data gives rise to spurious topographical localization of the no‐go–N2 component. RIDE decomposes N2 and P3 based on their latency variability. The decomposition restored the N2 topography by removing the contamination from latency‐variable late components. The RIDE‐derived N2 and P3 give a clearer insight about their functional relevance in the go/no‐go paradigm.