Awareness of deficits and error processing after traumatic brain injury

Doing it Wrong: A Systematic Review on Electrocortical and Behavioral Correlates of Error Monitoring in Patients with Neurological Disorders

Detecting errors in one's own and other's actions is a crucial ability for learning and adapting behavior to everchanging, highly volatile environments. Studies in healthy people demonstrate that monitoring errors in one's own and others' actions are underpinned by specific neural systems that are dysfunctional in a variety of neurological disorders. In this review, we first briefly discuss the main findings concerning error detection and error awareness in healthy subjects, the current theoretical models, and the tasks usually applied to investigate these processes. Then, we report a systematic search for evidence of dysfunctional error monitoring among neurological populations (basal ganglia, neurodegenerative, white-matter diseases and acquired brain injury). In particular, we examine electrophysiological and behavioral evidence for specific alterations of error processing in neurological disorders. Error-related negativity (ERN) amplitude were reduced in most (although not all) neurological patient groups, whereas Positivity Error (Pe) amplitude appeared not to be affected in most patient groups. Also theta activity was reduced in some neurological groups, but consistent evidence on the oscillatory activity has not been provided thus far. Behaviorally, we did not observe relevant patterns of pronounced dysfunctional (post-) error processing. Finally, we discuss limitations of the existing literature, conclusive points, open questions and new possible methodological approaches for clinical studies.

The Association Between Experimentally Induced Stress, Performance Monitoring, and Response Inhibition: An Event-Related Potential (ERP) Analysis

Psychological stress is increasingly associated with alterations in performance and affect. Yet, the relationship between experimentally induced psychological stress and neural indices of performance monitoring and error processing, as well as response inhibition, are unclear. Using scalp-recorded event-related potentials (ERPs), we tested the relationship between experimental stress, using the Trier Social Stress Test (TSST), and the error-related negativity (ERN), error positivity (Pe), and N2 ERP components. A final sample of 71 undergraduate students were randomly assigned to go through the TSST (n = 36; 18 female) or a brief mindfulness relaxation exercise (n = 35; 16 female) immediately followed by a go/no-go task while electroencephalogram (EEG) data were collected. Salivary cortisol, heart rate, and blood pressure confirmed increased physiological stress in the TSST group relative to control. Reaction times, accuracy, and post-error slowing did not differ by stress group. Two-group (TSST, control) by 2-trial type (correct, incorrect for ERN/Pe; go correct, no-go correct for N2) repeated measures ANOVAs for the ERN, Pe, and N2 showed the expected main effects of trial type; neither the ERN nor the N2 ERP components showed interactions with the stress manipulation. In contrast, the Pe component showed a significant Group by Trial interaction, with reduced Pe amplitude following the stress condition relative to control. Pe amplitude did not, however, correlate with cortisol reactivity. Findings suggest a reduction in Pe amplitude following experimental stress that may be associated with reduced error awareness or attention to errors following the TSST. Given the variability in the extant literature on the relationship between experimentally induced stress and neurophysiological reflections of performance monitoring, we provide another point of data and conclude that better understanding of moderating variables is needed followed by high-powered replication studies to get at the nuance that is not yet understood in the relationship between induced stress and performance monitoring/response inhibition processes.

Post-error Brain Activity Correlates With Incidental Memory for Negative Words

The present study had three main objectives. First, we aimed to evaluate whether short-duration affective states induced by negative and positive words can lead to increased error-monitoring activity relative to a neutral task condition. Second, we intended to determine whether such an enhancement is limited to words of specific valence or is a general response to arousing material. Third, we wanted to assess whether post-error brain activity is associated with incidental memory for negative and/or positive words. Participants performed an emotional stop-signal task that required response inhibition to negative, positive or neutral nouns while EEG was recorded. Immediately after the completion of the task, they were instructed to recall as many of the presented words as they could in an unexpected free recall test. We observed significantly greater brain activity in the error-positivity (Pe) time window in both negative and positive trials. The error-related negativity amplitudes were comparable in both the neutral and emotional arousing trials, regardless of their valence. Regarding behavior, increased processing of emotional words was reflected in better incidental recall. Importantly, the memory performance for negative words was positively correlated with the Pe amplitude, particularly in the negative condition. The source localization analysis revealed that the subsequent memory recall for negative words was associated with widespread bilateral brain activity in the dorsal anterior cingulate cortex and in the medial frontal gyrus, which was registered in the Pe time window during negative trials. The present study has several important conclusions. First, it indicates that the emotional enhancement of error monitoring, as reflected by the Pe amplitude, may be induced by stimuli with symbolic, ontogenetically learned emotional significance. Second, it indicates that the emotion-related enhancement of the Pe occurs across both negative and positive conditions, thus it is preferentially driven by the arousal content of an affective stimuli. Third, our findings suggest that enhanced error monitoring and facilitated recall of negative words may both reflect responsivity to negative events. More speculatively, they can also indicate that post-error activity of the medial prefrontal cortex may selectively support encoding for negative stimuli and contribute to their privileged access to memory.

Cognitive control of conscious error awareness: error awareness and error positivity (Pe) amplitude in moderate-to-severe traumatic brain injury (TBI)

Poor awareness has been linked to worse recovery and rehabilitation outcomes following moderate-to-severe traumatic brain injury (M/S TBI). The error positivity (Pe) component of the event-related potential (ERP) is linked to error awareness and cognitive control. Participants included 37 neurologically healthy controls and 24 individuals with M/S TBI who completed a brief neuropsychological battery and the error awareness task (EAT), a modified Stroop go/no-go task that elicits aware and unaware errors. Analyses compared between-group no-go accuracy (including accuracy between the first and second halves of the task to measure attention and fatigue), error awareness performance, and Pe amplitude by level of awareness. The M/S TBI group decreased in accuracy and maintained error awareness over time; control participants improved both accuracy and error awareness during the course of the task. Pe amplitude was larger for aware than unaware errors for both groups; however, consistent with previous research on the Pe and TBI, there were no significant between-group differences for Pe amplitudes. Findings suggest possible attention difficulties and low improvement of performance over time may influence specific aspects of error awareness in M/S TBI.

Deficits in error-monitoring by college students with schizotypal traits: an event-related potential study

The present study used event-related potentials (ERPs) to investigate deficits in error-monitoring by college students with schizotypal traits. Scores on the Schizotypal Personality Questionnaire (SPQ) were used to categorize the participants into schizotypal-trait (n = 17) and normal control (n = 20) groups. The error-monitoring abilities of the participants were evaluated using the Simon task, which consists of congruent (locations of stimulus and response are the same) and incongruent (locations of stimulus and response are different) conditions. The schizotypal-trait group committed more errors on the Simon task and exhibited smaller error-related negativity (ERN) amplitudes than did the control group. Additionally, ERN amplitude measured at FCz was negatively correlated with the error rate on the Simon task in the schizotypal-trait group but not in the control group. The two groups did not differ in terms of correct-related potentials (CRN), error positivity (Pe) and correct-related positivity (Pc) amplitudes. The present results indicate that individuals with schizotypal traits have deficits in error-monitoring and that reduced ERN amplitudes may represent a biological marker of schizophrenia.

Connecting clinical and experimental investigations of awareness in traumatic brain injury

Questionnaire-based demonstrations of impaired self-awareness (SA) after traumatic brain injury (TBI) are not always supported by experimental studies of in-the-moment or online awareness. This chapter begins by describing the clinical phenomenon of impaired SA, how it is measured, and why its interdependency with mechanisms of online awareness may provide the scaffolding from which appraisals of cognitive functioning can be accurately revised following a brain injury. We review research that has measured unawareness of errors in routine action in TBI patients and propose more rigorous methodological approaches to studying the emergent properties of awareness with greater clarity in the laboratory. We discuss how neuropsychological and electrophysiologic studies are beginning to inform our understanding of impaired error processing in TBI patients and we highlight recent theory proposing that online metacognitive processes accumulate evidence of erroneous responses in a graded fashion. Neural signals with amplitudes that scale with the strength of accruing evidence and peak latencies that mark the threshold at which awareness emerges represent important neural mechanisms to examine the breakdown of error awareness after brain injury. We also discuss how errors can be investigated in relation to different sources of evidence that contribute to aware experiences after brain injury. Finally, we explore conditions beyond error signaling, and how different "objects of insight" that require retrospective and prospective judgments of confidence need to be examined in relation to the clinical phenomenon of impaired SA.

The impact of a brief mindfulness meditation intervention on cognitive control and error-related performance monitoring

Meditation is associated with positive health behaviors and improved cognitive control. One mechanism for the relationship between meditation and cognitive control is changes in activity of the anterior cingulate cortex-mediated neural pathways. The error-related negativity (ERN) and error positivity (Pe) components of the scalp-recorded event-related potential (ERP) represent cingulate-mediated functions of performance monitoring that may be modulated by mindfulness meditation. We utilized a flanker task, an experimental design, and a brief mindfulness intervention in a sample of 55 healthy non-meditators (n = 28 randomly assigned to the mindfulness group and n = 27 randomly assigned to the control group) to examine autonomic nervous system functions as measured by blood pressure and indices of cognitive control as measured by response times, error rates, post-error slowing, and the ERN and Pe components of the ERP. Systolic blood pressure significantly differentiated groups following the mindfulness intervention and following the flanker task. There were non-significant differences between the mindfulness and control groups for response times, post-error slowing, and error rates on the flanker task. Amplitude and latency of the ERN did not differ between groups; however, amplitude of the Pe was significantly smaller in individuals in the mindfulness group than in the control group. Findings suggest that a brief mindfulness intervention is associated with reduced autonomic arousal and decreased amplitude of the Pe, an ERP associated with error awareness, attention, and motivational salience, but does not alter amplitude of the ERN or behavioral performance. Implications for brief mindfulness interventions and state vs. trait affect theories of the ERN are discussed. Future research examining graded levels of mindfulness and tracking error awareness will clarify relationship between mindfulness and performance monitoring.

What are the influences of orthogonally-manipulated valence and arousal on performance monitoring processes? The effects of affective state

Studies of the influence of affective state on the cognitive control process of performance monitoring are mixed and few studies have orthogonally manipulated affective valence and arousal. Performance monitoring can be measured using behaviors (e.g., response times and error rates) and components of the event-related potentials (ERPs), such as the error-related negativity (ERN), correct-related negativity (CRN), and post-error positivity (Pe). We used a pre/post design and standard mood induction paradigm in 121 healthy participants randomly assigned to orthogonal valence (positive or negative) and arousal (high or low) conditions (i.e., happy, calm, anxious, or sad mood states). Following mood induction, valence and arousal ratings differed between groups. Behavioral findings showed decreased accuracy in participants with high arousal and negative valence (i.e., anxious condition), but no additional response time (RT), post-error slowing, or accuracy effects. Amplitude of the CRN differentiated high and low valence, but was not related to arousal. Positive valence was associated with decreased CRN amplitude even when baseline affect and demographic variables were controlled. Valence and arousal did not significantly differentiate the amplitude of the ERN, although the ERN minus CRN difference was related to arousal but not valence ratings in multiple regression analyses. Affect-related differences were not shown for the Pe. Findings provide a context to understand how dimensional aspects of emotional valence and arousal influence performance-monitoring processes and suggest a need for further research on the functional role of the CRN and its relation to affective valence.

Is any awareness necessary for an Ne?

The Error-Related Negativity (Ne or ERN) is a reliable electrophysiological index of error processing, which has been found to be independent of whether a subject is aware of an error or not. A large Ne was equally seen after errors that were consciously detected (Aware errors) and those that were not (Unaware errors), compared to a small negativity for correct responses (CRN). This suggests a dissociation between an automatic, preconscious error processing mechanism and subjective evaluation. A common concern regarding this finding is that subjects could have been somewhat aware of their errors, but did not report them due to lack of confidence. Here we tested this possibility directly using a betting paradigm which allowed us to separate occasions in which the subjects were confident of their response and trials in which they were unsure. In a choice reaction time task, subjects directly judged the accuracy of each response (correct or error) and then bet on this judgment using a high, medium, or low amount of money. The bets were used to determine the level of confidence the subjects had of their response. The average across all subjects regardless of confidence (betting) measure replicated the reported finding of an equal Ne for Aware and Unaware errors which was larger than the CRN. However, when Ne measurement was confined to high confidence (high bet) trials in confident subjects, a prominent Ne was seen only for Aware errors, while confident Unaware errors (i.e., error trials on which subjects made high bets that they were correct) elicited a response that did not differ from the CRN elicited by truly correct answers. In contrast, for low confidence trials in unconfident subjects, an intermediate and equal Ne/CRN was elicited by Correct responses, Aware and Unaware errors. These results provide direct evidence that the Ne is related to error awareness, and suggest the amplitude of the Ne/CRN depends on individual differences in error reporting and confidence.

An electrophysiological signal that precisely tracks the emergence of error awareness

Recent electrophysiological research has sought to elucidate the neural mechanisms necessary for the conscious awareness of action errors. Much of this work has focused on the error positivity (Pe), a neural signal that is specifically elicited by errors that have been consciously perceived. While awareness appears to be an essential prerequisite for eliciting the Pe, the precise functional role of this component has not been identified. Twenty-nine participants performed a novel variant of the Go/No-go Error Awareness Task (EAT) in which awareness of commission errors was indicated via a separate speeded manual response. Independent component analysis (ICA) was used to isolate the Pe from other stimulus- and response-evoked signals. Single-trial analysis revealed that Pe peak latency was highly correlated with the latency at which awareness was indicated. Furthermore, the Pe was more closely related to the timing of awareness than it was to the initial erroneous response. This finding was confirmed in a separate study which derived IC weights from a control condition in which no indication of awareness was required, thus ruling out motor confounds. A receiver-operating-characteristic (ROC) curve analysis showed that the Pe could reliably predict whether an error would be consciously perceived up to 400 ms before the average awareness response. Finally, Pe latency and amplitude were found to be significantly correlated with overall error awareness levels between subjects. Our data show for the first time that the temporal dynamics of the Pe trace the emergence of error awareness. These findings have important implications for interpreting the results of clinical EEG studies of error processing.

Performance monitoring and cognitive control in individuals with mild traumatic brain injury

Literature suggests that individuals with mild traumatic brain injury (mTBI) show subtle abnormalities in the cognitive control process of performance monitoring. The neural bases of performance monitoring can be measured using the error-related negaitivity (ERN) and post-error positivity (Pe) components of the scalp-recorded event-related potential (ERP). Thirty-six individuals with mTBI and 46 demographically similar controls completed a modified color-naming Stroop task while ERPs were recorded. Separate repeated-measures analyses of variance were used to examine the behavioral (response times [RT] and error rates) and ERP (ERN and Pe amplitudes) indices of performance monitoring. Both groups showed slower RTs and increased error rates on incongruent trials relative to congruent trials. Likewise, both groups showed more negative ERN and more positive Pe amplitude to error trials relative to correct trials. Notably, there were no significant main effects or interactions of group for behavioral and ERP measures. Subgroup and correlational analyses with post-concussive symptoms and indices of injury severity were also not significant. Findings suggest comparable performance to non-injured individuals in some aspects of cognitive control in this sample. Neuropsychological implications and comparison with other cognitive control component processes in individuals with TBI are provided.

Error-related processing following severe traumatic brain injury: an event-related functional magnetic resonance imaging (fMRI) study

Continuous monitoring of one's performance is invaluable for guiding behavior towards successful goal attainment by identifying deficits and strategically adjusting responses when performance is inadequate. In the present study, we exploited the advantages of event-related functional magnetic resonance imaging (fMRI) to examine brain activity associated with error-related processing after severe traumatic brain injury (sTBI). fMRI and behavioral data were acquired while 10 sTBI participants and 12 neurologically-healthy controls performed a task-switching cued-Stroop task. fMRI data were analyzed using a random-effects whole-brain voxel-wise general linear model and planned linear contrasts. Behaviorally, sTBI patients showed greater error-rate interference than neurologically-normal controls. fMRI data revealed that, compared to controls, sTBI patients showed greater magnitude error-related activation in the anterior cingulate cortex (ACC) and an increase in the overall spatial extent of error-related activation across cortical and subcortical regions. Implications for future research and potential limitations in conducting fMRI research in neurologically-impaired populations are discussed, as well as some potential benefits of employing multimodal imaging (e.g., fMRI and event-related potentials) of cognitive control processes in TBI.

The effects of induced state negative affect on performance monitoring processes

Previous research suggests that performance-monitoring processes are related to personality traits; relationships with affective states, however, remain unclear. The purpose of this study was to replicate and extend previous findings that induced state negative affect alters electrophysiological reflections of performance monitoring. High-density event-related potentials (ERPs) were obtained from 69 healthy individuals (41 female, 28 male) who completed an Eriksen flanker task and received either encouraging or derogatory feedback based on mean reaction times (RTs) for 30-trial sub-blocks. Affective state, behavioral measures (i.e. error rates, RTs) and ERP measures [i.e. error-related negativity (ERN), post-error positivity (Pe) and N2] were assessed. Reaction times did not differ between feedback groups. Participants who received derogatory feedback committed more errors over time. Despite changes in affect, no significant group differences were demonstrated for behavioral or ERP measures of performance monitoring. Increases in vigilance were associated with more negative N2 amplitudes; no other changes in affective state were associated with changes in ERP measures. Results are consistent with findings suggesting performance-monitoring processes are only slightly affected by changes in affective state and fail to replicate previous studies suggesting the ERN is related to state changes in affect-supporting the possibility of the ERN as an endophenotype.

Predictors of performance monitoring abilities following traumatic brain injury: the influence of negative affect and cognitive sequelae

Performance monitoring is a cognitive control process modulated by both cognitive and affective variables. This study examined the relative contributions of negative affect (NA) and cognitive sequelae to performance monitoring dysfunction following severe traumatic brain injury (TBI). We used the error-related negativity (ERN) and post-error positivity (Pe) components of the event-related potential (ERP) to test the hypothesis that NA and cognitive sequelae would predict performance monitoring dysfunction beyond time since injury, and injury severity. Nineteen survivors of severe TBI completed neuropsychological tests, measures of NA, and a computerized Stroop task. Scores on NA and neuropsychological measures were standardized to form magnitude of cognitive sequelae and negative affect composite scores. Separate hierarchical regression analyses with ERN and Pe amplitudes as dependent variables and injury severity, time since injury, magnitude of cognitive sequelae, and NA as independent variables indicated that NA and cognitive sequelae significantly predicted ERN amplitude, with a larger relative contribution of NA than cognitive sequelae. Increased levels of NA were associated with decreased amplitude ERN. Cognitive sequelae, but not NA, predicted Pe amplitude. Injury severity and time since injury were not significant predictors. Results suggest that both NA and cognitive sequelae play critical roles in performance monitoring decrements following TBI and indicate a possible dissociation between the ERN and Pe, with the ERN more related to affective processes and the Pe to cognitive processes.

The relationship between performance monitoring, satisfaction with life, and positive personality traits

Neural reflections of performance monitoring, including the error-related negativity (ERN) component of the event-related potential (ERP), are modulated by personality and affective constructs. Little is known, however, about the relationship between positive personality traits and neural indices of performance monitoring. We investigated the relationship between measures of positive personality traits, including satisfaction with life, dispositional optimism, and positive affect, and indices of performance monitoring in a sample of 45 neurologically-healthy individuals. Increased satisfaction with life was associated with decreased (i.e., less negative) ERN amplitude. Dispositional optimism and positive affect were not related to ERN amplitude. Results remained consistent when negative affect and measures of positive personality were accounted for using multiple regression. There were no relationships between measures of positive personality and the post-error positivity (Pe) or behavioral indices. Findings are consistent with an affective salience interpretation of the ERN, with errors potentially being less meaningful for individuals with higher satisfaction with life.