Neural mechanisms involved in error processing: A comparison of errors made with and without awareness

Experience sampling during fMRI reveals default network and executive system contributions to mind wandering

Although mind wandering occupies a large proportion of our waking life, its neural basis and relation to ongoing behavior remain controversial. We report an fMRI study that used experience sampling to provide an online measure of mind wandering during a concurrent task. Analyses focused on the interval of time immediately preceding experience sampling probes demonstrate activation of default network regions during mind wandering, a finding consistent with theoretical accounts of default network functions. Activation in medial prefrontal default network regions was observed both in association with subjective self-reports of mind wandering and an independent behavioral measure (performance errors on the concurrent task). In addition to default network activation, mind wandering was associated with executive network recruitment, a finding predicted by behavioral theories of off-task thought and its relation to executive resources. Finally, neural recruitment in both default and executive network regions was strongest when subjects were unaware of their own mind wandering, suggesting that mind wandering is most pronounced when it lacks meta-awareness. The observed parallel recruitment of executive and default network regions--two brain systems that so far have been assumed to work in opposition--suggests that mind wandering may evoke a unique mental state that may allow otherwise opposing networks to work in cooperation. The ability of this study to reveal a number of crucial aspects of the neural recruitment associated with mind wandering underscores the value of combining subjective self-reports with online measures of brain function for advancing our understanding of the neurophenomenology of subjective experience.

On the positive side of error processing: error-awareness positivity revisited

Performance errors are indexed in the brain even if they are not consciously registered, as demonstrated by the error-related negativity (ERN or Ne) event-related potential. It has recently been shown that another response-locked potential, the error positivity (Pe), follows the Ne, but only in those trials in which the participants consciously detect making the error ('Aware Errors'). In the present study we generalize these findings to an auditory task and investigate possible caveats in the interpretation of the Pe as an index of error awareness. In an auditory Go/No-Go error-awareness task (auditory EAT) participants pressed an additional 'fix error' button after noticing that they had made an error. As in visual tasks, the Ne was similar for aware ('fixed') and unaware ('unfixed') errors, while the Pe was enhanced only for Aware Errors. Within subjects, the Ne and Pe behaved in similar fashions for auditory and visual errors. A control condition confirmed that the awareness effect was not due to the requirement to report error awareness. These results reinforce the evidence in favor of the Pe as a correlate of conscious error processing, and imply that this process is not modality-specific. Nevertheless, single-trial analysis suggested that the Pe may be a delayed P3b related to stimulus processing rather than to response monitoring.

Brain network dynamics during error commission

Previous studies suggest that the anterior cingulate and other prefrontal brain regions might form a functionally-integrated error detection network in the human brain. This study examined whole brain functional connectivity to both correct and incorrect button presses using independent component analysis (ICA) of functional magnetic resonance imaging (fMRI) data collected from 25 adolescent and 25 adult healthy participants (ages 11-37) performing a visual Go/No-Go task. Correct responses engaged a network comprising left lateral prefrontal cortex, left postcentral gyrus/inferior parietal lobule, striatum, and left cerebellum. In contrast, a similar network was uniquely engaged during errors, but this network was not integrated with activity in regions believed to be engaged for higher-order cognitive control over behavior. A medial/dorsolateral prefrontal-parietal neural network responded to all No-Go stimuli, but with significantly greater activity to errors. ICA analyses also identified a third error-related circuit comprised of anterior temporal lobe, limbic, and pregenual cingulate cortices, possibly representing an affective response to errors. There were developmental differences in error-processing activity within many of these neural circuits, typically reflecting greater hemodynamic activation in adults. These findings characterize the spatial structure of neural networks underlying error commission and identify neurobiological differences between adolescents and adults.

To P(E) or not to P(E): a P3-like ERP component reflecting the processing of response errors

ERP studies have highlighted several electrocortical components that can be observed when people make errors. We propose that the P(E) reflects processes functionally similar to those reflected in the P3 and that the P(E) and P3 should covary. We speculate that these processes refer to the motivational significance of rare target stimuli in case of the P3 and of salient performance errors in case of the P(E). Here we investigated whether P(E) amplitude after errors in a Simon task is correlated specifically to varying target-target intervals in a visual oddball task, a factor known to parametrically affect P3 amplitude. The amplitude of the P(E), but not the N(E), was observed to covary with the effect of target-target interval on P3 amplitude. The specificity of this novel finding supports the notion that the P(E) and P3 reflect similar neurocognitive processes as possibly involved in the conscious processing of motivationally significant events.

Anatomy of an error: a bidirectional state model of task engagement/disengagement and attention-related errors

We present arguments and evidence for a three-state attentional model of task engagement/disengagement. The model postulates three states of mind-wandering: occurrent task inattention, generic task inattention, and response disengagement. We hypothesize that all three states are both causes and consequences of task performance outcomes and apply across a variety of experimental and real-world tasks. We apply this model to the analysis of a widely used GO/NOGO task, the Sustained Attention to Response Task (SART). We identify three performance characteristics of the SART that map onto the three states of the model: RT variability, anticipations, and omissions. Predictions based on the model are tested, and largely corroborated, via regression and lag-sequential analyses of both successful and unsuccessful withholding on NOGO trials as well as self-reported mind-wandering and everyday cognitive errors. The results revealed theoretically consistent temporal associations among the state indicators and between these and SART errors as well as with self-report measures. Lag analysis was consistent with the hypotheses that temporal transitions among states are often extremely abrupt and that the association between mind-wandering and performance is bidirectional. The bidirectional effects suggest that errors constitute important occasions for reactive mind-wandering. The model also enables concrete phenomenological, behavioral, and physiological predictions for future research.

Dorsal medial prefrontal cortex plays a necessary role in rapid error prediction in humans

Activity in human dorsal anterior cingulate cortex (dACC) is correlated with errors, near-misses, and response conflict. Based on these observations, this region has been cast as playing a central role in models of error processing, conflict monitoring, and cognitive control. However, clear evidence that this region of the brain is necessary for these processes has been elusive. We studied the effects of damage to this region on four different error-related measures in five patients, and 19 healthy participants. Most error-related indices were not affected by such damage: patients had intact post-error slowing, and were able to report and to correct errors after they were made with accuracies comparable with the control group. However, all five patients were notably slow to correct errors, suggesting a deficit in on-line error prediction. This slowing was associated with impairment in the conscious prediction of error likelihood before a response. This finding constitutes important converging evidence for a critical role for human dACC in error monitoring, and sheds light on the selectivity and timing of the error-related process affected by dACC damage.

The Role of Awareness in Processing of Oculomotor Capture: Evidence from Event-related Potentials

Previous research has shown that task-irrelevant onsets trigger an eye movement in their direction. Such oculomotor capture is often impervious to conscious awareness. The present study used event-related brain potentials to examine how such oculomotor errors are detected, evaluated, and compensated for and whether awareness of an error played a role at any of these stages of processing. The results show that the early processes of error detection and correction (as represented by the error-related negativity and the parietal N1) are not directly affected by subjective awareness of making an error. Instead, they seem to be modulated by the degree of temporal overlap between the programming of the correct and erroneous saccade. We found that only a later component (the error-related positivity [Pe]) is modulated by awareness of making an erroneous eye movement. We propose that awareness of oculomotor capture primarily depends on this later process.

Acute effects of cocaine on the neurobiology of cognitive control

Compromised ability to exert control over drug urges and drug-seeking behaviour is a characteristic of addiction. One specific cognitive control function, impulse control, has been shown to be a risk factor for the development of substance problems and has been linked in animal models to increased drug administration and relapse. We present evidence of a direct effect of cocaine on the neurobiology underlying impulse control. In a laboratory test of motor response inhibition, an intravenous cocaine administration improved task performance in 13 cocaine users. This improvement was accompanied by increased activation in right dorsolateral and inferior frontal cortex, regions considered critical for this cognitive function. Similarly, for both inhibitory control and action monitoring processes, cocaine normalized activation levels in lateral and medial prefrontal regions previously reported to be hypoactive in users relative to drug-naive controls. The acute amelioration of neurocognitive dysfunction may reflect a chronic dysregulation of those brain regions and the cognitive processes they subserve. Furthermore, the effects of cocaine on midline function suggest a dopaminergically mediated intersection between cocaine's acute reinforcing effects and its effects on cognitive control.

Conflict-related activity in the caudal anterior cingulate cortex in the absence of awareness

The caudal anterior cingulate cortex (cACC) is thought to be involved in performance monitoring, as conflict and error-related activity frequently co-localize in this area. Recent results suggest that these effects may be differentially modulated by awareness. To clarify the role of awareness in performance monitoring by the cACC, we used rapid event-related fMRI to examine the cACC activity while subjects performed a dual task: a delayed recognition task and a serial response task (SRT) with an implicit probabilistic learning rule (i.e. the stimulus location followed a probabilistic sequence of which the subjects were unaware). Task performance confirmed that the location sequence was learned implicitly. Even though we found no evidence of awareness for the presence of the sequence, imaging data revealed increased cACC activity during correct trials which violated the sequence (high-conflict), relative to trials when stimuli followed the sequence (low conflict). Errors made with awareness also activated the same brain region. These results suggest that the performance monitoring function of the cACC extends beyond detection of errors made with or without awareness, and involves detection of multiple responses even when they are outside of awareness.

Neural mechanisms for illusory filling-in of degraded speech

The brain uses context and prior knowledge to repair degraded sensory inputs and improve perception. For example, listeners hear speech continuing uninterrupted through brief noises, even if the speech signal is artificially removed from the noisy epochs. In a functional MRI study, we show that this temporal filling-in process is based on two dissociable neural mechanisms: the subjective experience of illusory continuity, and the sensory repair mechanisms that support it. Areas mediating illusory continuity include the left posterior angular gyrus (AG) and superior temporal sulcus (STS) and the right STS. Unconscious sensory repair occurs in Broca's area, bilateral anterior insula, and pre-supplementary motor area. The left AG/STS and all the repair regions show evidence for word-level template matching and communicate more when fewer acoustic cues are available. These results support a two-path process where the brain creates coherent perceptual objects by applying prior knowledge and filling-in corrupted sensory information.

Decreased parahippocampal activity in associative priming: evidence from an event-related fMRI study

In recent years, there has been intense debate on the neural basis of associative priming, particularly on the role of the medial temporal lobe (MTL) in retrieving associative information without awareness. In this study, event-related fMRI was used while healthy subjects performed a perceptual identification task on briefly presented unrelated word pairs and an associative recognition memory task. Contamination of priming by explicit memory was successfully controlled, as associative priming and explicit memory were dissociated on the behavioral level. The fMRI results showed a functional dissociation within the MTL with respect to associative priming effects. The right parahippocampal cortex, but not the hippocampus, showed decreased activation for old vs. new pairs and old vs. recombined pairs (associative priming). The bilateral hippocampus and the right parahippocampal cortex were involved in explicit associative memory. These data provide evidence that subregions of the MTL participate in associative priming even when explicit involvement was controlled. Thus, different regions within the MTL play distinct roles in explicit and implicit associative memory.

Intention, choice, and the medial frontal cortex

The medial frontal cortex (MFC) has been identified with voluntary action selection. Recent evidence suggests that there are three principal ways in which the MFC is an essential part of the neural circuit for voluntary action selection. First, the MFC represents the reinforcement values of actions and is concerned with the updating of those action values. Because it is particularly concerned with the rate at which action values should be updated, it mediates the influence that the past reinforcement history has over the next choice that is made and it may determine the learning rate. The MFC's representation of action value does not just reflect the potential reward associations of an action but instead represents both the reward and effort costs that are intrinsic to the action. Second, the MFC is important when an exploratory action is generated in order to obtain more information about action values and the environment. Third, the MFC is critical when conflicting information in the immediate environment instructs more than one possible response. In such situations the MFC exerts an influence over how actions will be chosen by other motor regions of the brain.

Internal and external information in error processing

BACKGROUND

The use of self-generated and externally provided information in performance monitoring is reflected by the appearance of error-related and feedback-related negativities (ERN and FRN), respectively. Several authors proposed that ERN and FRN are supported by similar neural mechanisms residing in the anterior cingulate cortex (ACC) and the mesolimbic dopaminergic system. The present study is aimed to test the functional relationship between ERN and FRN. Using an Eriksen-Flanker task with a moving response deadline we tested 17 young healthy subjects. Subjects received feedback with respect to their response accuracy and response speed. To fulfill both requirements of the task, they had to press the correct button and had to respond in time to give a valid response.

RESULTS

When performance monitoring based on self-generated information was sufficient to detect a criterion violation an ERN was released, while the subsequent feedback became redundant and therefore failed to trigger an FRN. In contrast, an FRN was released if the feedback contained information which was not available before and action monitoring processes based on self-generated information failed to detect an error.

CONCLUSION

The described pattern of results indicates a functional interrelationship of response and feedback related negativities in performance monitoring.

Going AWOL in the Brain: Mind Wandering Reduces Cortical Analysis of External Events

Converging evidence from neuroscience suggests that our attention to the outside world waxes and wanes over time. We examined whether these periods of “mind wandering” are associated with reduced cortical analysis of the external environment. Participants performed a sustained attention to response task in which they responded to frequent “nontargets” (digits 0–9) and withheld responses for infrequent “targets” (the letter X). Mind wandering was defined both behaviorally, indicated by a failure to withhold a response to a target, and subjectively, via self-report at a thought probe. The P300 event-related potential component for nontargets was reduced prior to both the behavioral and subjective reports of mind wandering, relative to periods of being “on-task.” Regression analysis of P300 amplitude revealed significant common variance between behavioral and subjective markers of mind wandering, suggesting that both markers reflect a common underlying mental state. Finally, control analysis revealed that the effect of mind wandering on the P300 could not be ascribed to changes in motor activity nor was it associated with general arousal. Our data suggest that when trying to engage attention in a sustained manner, the mind will naturally ebb and flow in the depth of cognitive analysis it applies to events in the external environment.

Segmenting the stream of consciousness: The psychological correlates of temporal structures in the time series data of a continuous performance task

Using principal component analysis, we examined whether structural properties in the time series of response time would identify different mental states during a continuous performance task. We examined whether it was possible to identify regular patterns which were present in blocks classified as lacking controlled processing, either behaviourally (as a failure to withhold a response to a target) or subjectively (as an off task report at a thought probe). Principal component analysis identified three components present in response times accounting for 58.8% of the variance in the data. Of these components, the second largest factor showed two features that implied it was a marker for mind wandering. First, it was stronger under slow relative to fast stimulus presentation conditions, and so paralleled the distribution of mind wandering reports. Second, it was more powerful prior to behaviour markers of mind wandering (failures in response inhibition) and less powerful prior to reports of task focused thinking (on task reports). Taken together, the use of principal components analysis on response times seem a viable tool for differentiating different mental states and so could help identify the neural substrates which underpin mind wandering and other subjective states.

Self-awareness and self-monitoring of cognitive and behavioral deficits in behavioral variant frontotemporal dementia, primary progressive aphasia and probable Alzheimer's disease

Lack of insight is a core diagnostic criterion for behavioral variant frontotemporal dementia (bvFTD), and is believed to be intact in the early stages of primary progressive aphasia (PPA). In other neurological conditions, symptom-specific insight has been noted, with behavioral symptoms appearing especially vulnerable to reduced insight. Different components of insight, self-awareness and self-monitoring, are also often considered separate phenomena. The current study compared insight in patients with PPA, bvFTD, and probable Alzheimer's disease (PrAD) and a group of cognitively intact control subjects. Additionally, differences in insight for the domains primarily affected by the three types of dementia, namely, Behavior, Naming, and Memory, were assessed, and self-awareness and self-monitoring were compared. A total of 55 participants were enrolled. Participants were asked to complete self-estimate scales demonstrating their perceived ability immediately prior to, and immediately following a test in each domain of interest. Results indicated that PPA and normal control groups performed very similarly on control (Weight and Eyesight) and cognitive domains, whereas bvFTD and PrAD patients were unable to accurately assess Memory. All three diagnostic groups failed to accurately assess their behavioral symptoms, suggesting that this domain is vulnerable to loss of insight across diagnoses. Naming ability, in contrast, was either accurately assessed or underestimated in all groups. Finally, there were no notable differences between self-awareness and self-monitoring, potential explanations for this are examined.

Findings of preserved implicit attention in methamphetamine dependent subjects

Long-term methamphetamine (MA) abuse is associated with a wide range of deficits on explicit tasks of selective attention. Less is known however about the effects of MA abuse on implicit measures of attention. Accordingly, we used a computerized spatial priming task to assess implicit attentional processes in 54 MA dependent subjects (mean age=37.04+/-8.9 years) and 32 healthy controls without history of any form of substance abuse (mean age=33.63+/-7.05 years). The MA dependent subjects had been drug-abstinent a minimum of 3 weeks with a mean duration of MA use of 13.27+/-7.75 years. The MA dependent subjects did not differ significantly from controls on either inhibitory priming [p=.37] or facilitory priming) [p=.69]. This result comports with our earlier findings of intact object-based priming in MA dependent individuals and suggests that intact priming effects extend across spatial domains. Further, this pattern of sparing suggests that cortical brain systems typically supporting implicit attentional functioning are relatively intact in long-term MA dependent individuals whereas brain systems supporting explicit attentional processes are affected.

The influence of response conflict on error processing: evidence from event-related fMRI

The ability to detect errors is a crucial prerequisite for the appropriate adjustment of behavior to future situations. In the present event-related fMRI study, we provide evidence for the existence of different error-related networks within the human brain using a Simon task based on coherent motion perception. While errors related to incompatible trials were mainly associated with activation of the rostral anterior cingulate cortex (rACC) and the precuneus/posterior cingulate, errors related to trials without pre-response conflict showed specific activation in the right inferior parietal cortex. Despite this functional dissociation of brain networks, conjunction analysis revealed common clusters of activation in the medial wall (dorsal anterior cingulate cortex (dACC) and medial superior frontal cortex (msFC)), and bilateral inferior frontal gyrus/insula, consistent with earlier reports of error-related BOLD-signal increases. The present data support the view that despite of an overlapping core system of error processing, additional brain areas come into play depending on the existence or absence of cognitive conflict.

Discriminant validity and neuroanatomical correlates of rule monitoring in frontotemporal dementia and Alzheimer's disease

Despite the predominant frontal neuropathology of frontotemporal dementia (FTD), traditional measures of executive functioning do not reliably distinguish FTD from Alzheimer's disease (AD). Performance monitoring is an executive function that is associated with frontal lobe integrity and may be disrupted in FTD. The current study adopted a component process approach to evaluate the discriminant validity and neuroanatomical correlates of performance monitoring (i.e., rule monitoring) during an executive spatial planning task. Forty-four participants with FTD, 30 with AD, and 27 healthy comparison (HC) subjects completed the Delis-Kaplan Executive Function System (D-KEFS) Tower task. A subset of patients underwent structural magnetic resonance imaging to obtain regional measures of cortical volumes. FTD and AD groups demonstrated significantly poorer overall achievement scores on the Tower test relative to the HC sample, but did not differ from one another. In contrast, the FTD group committed significantly more rule violation errors than both HC and AD groups, indicating poorer performance monitoring. In addition, poorer overall achievement correlated with smaller brain volumes in several regions, including bilateral frontal and parietal regions, whereas an increased number of rule violations correlated specifically with decreased bilateral frontal volume. Both left and right frontal volumes remained significant predictors of rule violation errors after controlling for the contribution of overall achievement on the task and all other brain regions. Findings are consistent with literature implicating the frontal lobes in performance monitoring and highlight the importance of characterizing the component processes of performance failures in the cognitive assessment of FTD and AD.

ERP correlates of conscious error recognition: aware and unaware errors in an antisaccade task

Event-related potential (ERP) studies identified the error-related negativity (Ne/ERN) and the error positivity (Pe) to be associated with performance errors. However, the functional significance of these components is not yet resolved. With the present study we intended to further investigate to what extent these components are related to error awareness. ERPs were recorded during an antisaccade task, and error awareness was obtained from accuracy ratings on each trial. In accordance with earlier findings, aware and unaware errors did not differ in Ne/ERN amplitude. Whereas the late Pe (400-600 ms) shows an increased parietal positivity for aware compared with unaware errors, the early Pe (200-300 ms) shows no dissociation between aware and unaware errors. These data lend further support to the view that the Ne/ERN and the (late) Pe reflect different processes in performance monitoring. In fact the present results provide a clear replication of [S. Nieuwenhuis et al. (2001) Psychophysiology, 38, 752-760], showing that the Pe is associated with error awareness and remedial action. Furthermore, it has been shown that this is only true for the late Pe, whereas the early Pe like the Ne/ERN is not modulated by error awareness.

Post-error behavior in active cocaine users: poor awareness of errors in the presence of intact performance adjustments

Active cocaine abusers have a diminished neural response to errors, particularly in the anterior cingulate cortex thought critical to error processing. The inability to detect, or adjust performance following errors has been linked to clinical symptoms including the loss of insight and perseverative behavior. We investigated the cognitive implications of this diminished error-related activity, using response inhibition tasks that required error awareness and performance adaptation. Twenty-one active cocaine users (six female subjects, mean age=40.3) and 22 non-drug using adults (six female subjects, mean=39.9) participated. The results indicated that cocaine users consistently demonstrated poorer inhibitory control, a deficit accompanied by reduced awareness of errors. Adaptation of post-error reaction times did not differ between groups, although a different measure of adaptive behavior: exerting inhibitory control on the trial immediately after failing to inhibit, was significantly poorer in the cocaine using sample. In summary, cocaine users demonstrated a diminished capacity for monitoring their behavior, but were able to perform post-error adjustment to processes not already suffering an underlying deficit. These difficulties are consistent with previous reports of cocaine-related hypoactivity in the neural system underlying cognitive control, and highlight the potential for cognitive dysfunction to manifest as behavioral deficits that likely contribute to the maintenance of drug dependence.

Neural correlates of primary and reflective consciousness of spatial orienting

Using functional magnetic resonance imaging, we asked participants to perform a visual target detection task with peripheral cues. In the first part of the experiment, cues were not predictive of the side of occurrence of the incoming target. In the second part of the experiment, unbeknownst to the participants, cues became 80% predictive, thus inducing an endogenous orienting of spatial attention. Confirming previous results, in the second part response times (RTs) decreased for validly cued trials and increased for invalid trials. Half of the participants were subsequently able to correctly describe the cue-target relationships ('verbalizers'), thus demonstrating reflective consciousness of endogenous orienting. Also non-verbalizer participants showed a similar RT pattern, indicating the occurrence of endogenous orienting without reflective consciousness. Both groups of participants showed fronto-parietal activity typically observed in spatial attention tasks. Verbalizers, in addition, demonstrated stronger activity in the anterior cingulate cortex (ACC), consistent with the proposed role of this structure in purposeful behaviour and in the monitoring of its consequences. The extensive pattern of connectivity of the ACC is ideally suited to integrate the activity of the large neural assemblies necessary for reflective consciousness to emerge.

Absent minded but accurate: delaying responses increases accuracy but decreases error awareness

Previous work has suggested that conscious error awareness may fluctuate with levels of attention. Here, we explore this relationship by showing that error awareness can be impaired when exogenous support to attentional systems is reduced by decreasing task demands. Twenty participants performed a manual Go/No-Go response-inhibition task optimized to examine error awareness. In one condition (Immediate), participants were asked to respond as quickly and as accurately as possible to each Go stimulus, and in the other condition (Delayed) they were asked to time their responses to the offset of the stimulus, thereby decreasing task difficulty and imposing a more automated response set. As expected, speeding increased the error rate. However, contrary to the expectation (and to participants' subjective reports) that speeding would impair awareness of performance, we found the opposite to be true: errors were more likely to be unnoticed when the task was easier. We suggest that this tradeoff reflects two qualitatively different types of errors arising from the different cognitive demands of the Immediate and Delayed conditions. We propose that unaware errors reflect pure lapses of sustained attention and are therefore more susceptible to changes in task demands, while aware errors mostly reflect failures to inhibit responses, and are therefore most susceptible to increased response speed.

The role of cingulate cortex in the detection of errors with and without awareness: a high-density electrical mapping study

Error-processing research has demonstrated that the brain uses a specialized neural network to detect errors during task performance but the brain regions necessary for conscious awareness of an error are poorly understood. In the present study we show that two well-known error-related event-related potential (ERP) components, the error-related negativity (ERN) and error positivity (Pe) have a differential relationship with awareness during performance of a manual response inhibition task optimized to examine error awareness. While the ERN was unaffected by the participants' conscious experience of errors, the Pe was only seen when participants were aware of committing an error. Source localization of these components indicated that the ERN was generated by a caudal region of the anterior cingulate cortex (ACC) while the Pe was associated with contributions from a more anterior ACC region and the posterior cingulate-precuneus. Tonic EEG measures of cortical arousal were correlated with individual rates of error awareness and showed a specific relationship with the amplitude of the Pe. The latter finding is consistent with evidence that the Pe represents a P3-like facilitation of information processing modulated by subcortical arousal systems. Our data suggest that the ACC might participate in both preconscious and conscious error detection and that cortical arousal provides a necessary setting condition for error awareness. These findings may be particularly important in the context of clinical studies in which a proper understanding of self-monitoring deficits requires an explicit measurement of error awareness.

Loss of insight in frontotemporal dementia, corticobasal degeneration and progressive supranuclear palsy

Loss of insight is one of the core features of frontal/behavioural variant frontotemporal dementia (FTD). FTD shares many clinical and pathological features with corticobasal degeneration (CBD) and progressive supranuclear palsy (PSP). The aim of this study was to investigate awareness of cognitive deficits in FTD, CBD and PSP using a multidimensional approach to assessment, which examines metacognitive knowledge of the disorders, online monitoring of errors (emergent awareness) and ability to accurately predict performance on future tasks (anticipatory awareness). Thirty-five patients (14 FTD, 11 CBD and 10 PSP) and 20 controls were recruited. Results indicated that loss of insight was a feature of each of the three patient groups. FTD patients were most impaired on online monitoring of errors compared to the other two patient groups. Linear regression analysis demonstrated that different patterns of neuropsychological performance and behavioural rating scores predicted insight deficits across the three putative awareness categories. Furthermore, higher levels of depression were associated with poor anticipatory awareness, reduced empathy was related to impaired metacognitive awareness and impaired recognition of emotional expression in faces was associated with both metacognitive and anticipatory awareness deficits. The results are discussed in terms of neurocognitive models of awareness and different patterns of neurobiological decline in the separate patient groups.

Developmental changes in error monitoring: an event-related potential study

The aim of the study was to investigate the developmental trajectory of error monitoring. For this purpose, children (age 7-8), young adolescents (age 13-14) and adults (age 23-24) performed a Go/No-Go task and were compared on overt reaction time (RT) performance and on event-related potentials (ERPs), thought to reflect error detection (error-related negativity: ERN) and conscious evaluation (error positivity: Pe) of the error. RT on correct trials, variability of responding and percentage of errors decreased with age. The latencies of incorrect responses, compared to correct responses, were shorter in children and adolescents than in adults, indicative of developmental changes in impulsive response style. Groups did not differ in the ability to adjust response strategies after making an error (post-error slowing). The ERN amplitude increased with age, the Pe amplitude did not change with age. Possible explanations for the developmental changes in ERN are discussed.

Neural correlates of error awareness

Error processing results in a number of consequences on multiple levels. The posterior frontomedian cortex (pFMC) is involved in performance monitoring and signalling the need for adjustments, which can be observed as post-error speed-accuracy shifts at the behavioural level. Furthermore autonomic reactions to an error have been reported. The role of conscious error awareness for this processing cascade has received little attention of researchers so far. We examined the neural correlates of conscious error perception in a functional magnetic resonance imaging (fMRI) study. An antisaccade task known to yield sufficient numbers of aware and unaware errors was used. Results from a metaanalysis were used to guide a region of interest (ROI) analysis of the fMRI data. Consistent with previous reports, error-related activity in the rostral cingulate zone (RCZ), the pre-supplementary motor area (pre-SMA) and the insular cortex bilaterally was found. Whereas the RCZ activity did not differentiate between aware and unaware errors, activity in the left anterior inferior insular cortex was stronger for aware as compared to unaware errors. This could be due to increased awareness of the autonomic reaction to an error, or the increased autonomic reaction itself. Furthermore, post-error adjustments were only observed after aware errors and a correlation between post-error slowing and the hemodynamic activity in the RCZ was revealed. The data suggest that the RCZ activity alone is insufficient to drive error awareness. Its signal appears to be useful for post-error speed-accuracy adjustments only when the error is consciously perceived.

Automaticity and reestablishment of executive control-an fMRI study

The ability to exert control over automatic behavior is of particular importance as it allows us to interrupt our behavior when the automatic response is no longer adequate or even dangerous. However, despite the literature that exists on the effects of practice on brain activation, little is known about the neuroanatomy involved in reestablishing executive control over previously automatized behavior. We present a visual search task that enabled participants to automatize according to defined criteria within about 3 hr of practice and then required them to reassert control without changing the stimulus set. We found widespread cortical activation early in practice. Activation in all frontal areas and in the inferior parietal lobule decreased significantly with practice. Only selected prefrontal (Brodmann's areas [BAs] 9/46/8) and parietal areas (BAs 39/40) were specifically reactivated when executive control was required, underlining the crucial role of the dorsolateral prefrontal cortex in executive control to guide our behavior.

The neural basis of interindividual variability in inhibitory efficiency after sleep deprivation

Sleep deprivation results in the loss of our ability to suppress a prepotent response. The extent of decline in this executive function varies across individuals. Here, we used functional magnetic resonance imaging to study the neural correlates of sleep deprivation-induced differences in inhibitory efficiency. Participants performed a go/no-go task after normal sleep and after 24 h of total sleep deprivation. Regardless of the extent of change in inhibitory efficiency, sleep deprivation lowered go/no-go sustained, task-related activation of the ventral and anterior prefrontal (PFC) regions bilaterally. However, individuals better able to maintain inhibitory efficiency after sleep deprivation could be distinguished by lower stop-related, phasic activation of the right ventral PFC during rested wakefulness. These persons also showed a larger rise in such activation both here and in the right insula after sleep deprivation relative to those whose inhibitory efficiency declined.

Dissociable Components of Error Processing

Abstract: We conducted a literature review to examine the functional significance of the error positivity (Pe), an error-related electrophysiological brain potential often observed in combination with the error negativity (Ne). The review revealed many dissociations between documented effects on the Ne and Pe, suggesting that these components reflect different aspects of error processing. We found little support for the proposed hypotheses that the Pe is associated with the affective processing of errors or with posterror behavioral adaptation. Some support was found for the hypothesis that the Pe reflects conscious recognition of an error. Finally, we discuss the notion that the Pe may reflect a P3b associated with the motivational significance of the error. We conclude that more research is needed to test predictions of the various Pe hypotheses, and that more rigorous investigation of the neural generators of the Pe may contribute to a better understanding of the neurocognitive processes involved in error monitoring.