Characterising error-awareness of attentional lapses and inhibitory control failures in patients with traumatic brain injury

The Breakfast and Dressing Conflict Task: Preliminary Evidence of Its Validity to Measure Online Self-Awareness After Acquired Brain Injury

IMPORTANCE

Impaired self-awareness (SA) of deficits after an acquired brain injury (ABI) severely affects patients' independence in activities of daily living (ADLs). However, any assessment tool permits an exhaustive evaluation of SA in the context of ADLs.

OBJECTIVE

To study the validity of the Breakfast and Dressing Conflict Task (BD Conflict Task) to assess online SA (awareness of performance in the context of a given task) in patients with ABI; to study its interactions with offline SA (general awareness); and to test the validity of a simplified measure of performance monitoring, the ADL Conflict-Monitoring Index.

DESIGN

Convergent validity and correlational study.

SETTING

Research laboratory, hospitals, and homes.

PARTICIPANTS

Thirty patients with ABI and 28 neurologically healthy controls.

OUTCOMES AND MEASURES

Using the BD Conflict Task, measures of emergent awareness, self-regulation, anticipatory awareness, and self-evaluation were assessed and their convergent validity and relationship with offline SA were analyzed. The ADL Conflict-Monitoring Index was calculated, and its convergent validity was tested.

RESULTS

The online SA variables of the BD Conflict Task showed convergent validity with traditional online SA measures. Offline SA correlated with emergent and anticipatory awareness in the Breakfast Task. The ADL Conflict-Monitoring Index proved to be a valid measure of patients' performance monitoring.

CONCLUSIONS AND RELEVANCE

These preliminary findings suggest that the BD Conflict Task is a valid tool to assess online SA in patients with ABI and provide further understanding of the online SA-offline SA interaction. Furthermore, the ADL Conflict-Monitoring Index may be a valid and easy-to-use monitoring measure in clinical settings. Plain-Language Summary: Patients with acquired brain injury (ABI) and reduced awareness of their cognitive deficits face problems performing activities of daily living (ADLs) and may show signs of unsafe behaviors. Being aware of one's own abilities involves anticipating problems before starting a task, detecting and correcting errors during the task, and evaluating performance afterward. This study provides preliminary validity for the Breakfast and Dressing Conflict Task, a new tool that assesses aspects of self-awareness simultaneously in the context of familiar and significant ADLs. Furthermore, the tool simplifies the assessment of detecting and correcting errors with an easy-to-use index, making it suitable for use in clinical settings.

Profiling self-awareness in brain injury rehabilitation: A mixed methods study

ABSTRACTImpaired self-awareness impacts outcomes for individuals with brain injury. Self-awareness is a complex construct, with little known about how its presentation differs across diagnostic groups, or how brain injury-related changes are expressed by individuals in the early phase post-brain injury. This study aims to identify differences and similarities in patterns of self-awareness between patients with different brain injury diagnoses, and provide a clinical account of how individuals with ABI describe changes to themselves arising from brain injury. This is a mixed methods retrospective cohort study involving an audit of medical files that included extraction of data from the Self-Awareness of Deficits Interview. Quantitative and qualitative techniques were used to analyse data from 173 participants. Individuals identified a range of brain injury-related impairments across domains, with greatest difficulty noted with linking impairments to functional implications and setting realistic goals. There were similarities and distinct differences in the expression of changes across diagnostic groups. Two main themes that aligned with self-awareness theory were identified from the data: 1/ Development of self-awareness; and 2/ Dimensions of self-awareness. These interrelated themes demonstrated the multifaceted nature of the clinical presentation of self-awareness, and highlight the need for an individualized approach to cognitive rehabilitation.

Self-caught methodologies for measuring mind wandering with meta-awareness: A systematic review

Mind wandering, also known as task-unrelated thought, refers to the drift of attention from a focal task or train of thought. Because self-caught measures of mind wandering require participants to spontaneously indicate when they notice their attention drift, self-caught methodologies provide a way to measure mind wandering with meta-awareness. Given the proposed role of meta-awareness in mental health and psychological interventions, an overview of existing self-caught methodologies would help clinicians and researchers make informed decisions when choosing or adapting a mind wandering or meta-awareness measure. This systematic review included 39 studies after 790 studies were assessed for eligibility. All studies operationalised mind wandering as instances of attention drift from a primary task. Three types of primary task were identified: (1) tasks adapted from computerised continuous performance tests (CPT) of sustained attention, (2) tasks involving focusing on the breath or a stream of aural beats, akin to in-vivo mindfulness meditation, (3) tasks involving an everyday life activity such as reading. Although data on mind wandering without meta-awareness (e.g., measured with probe-caught measures) was also obtained in many studies, such data was not always used in conjunction with self-caught mind wandering data to determine level of mind wandering meta-awareness. Few studies reported both reliability and validity of the measures used. This review shows that considerable methodological heterogeneity exists in the literature. Methodological variants of self-caught mind wandering methodologies are documented and examined, and suggestions for future research and clinical work are suggested.

The influence of working memory capacity and lapses of attention for variation in error monitoring

In two experiments, individual differences in working memory capacity (WMC), lapses of attention, and error monitoring were examined. Participants completed multiple WMC tasks along with a version of the Stroop task. During the Stroop, pupil diameter was continuously monitored. In both experiments, error phasic pupillary responses were larger than phasic pupillary responses associated with correct incongruent and correct congruent trials. WMC and indicators of lapses of attention were correlated with error pupillary response, suggesting that high WMC and low lapse individuals had enhanced error monitoring abilities compared with low WMC and high lapse individuals. Furthermore, in Experiment 2 error awareness abilities were associated with WMC, lapses of attention, and the error phasic pupillary responses. Importantly, individual differences in the susceptibility to lapses of attention largely accounted for the relationship between WMC and error monitoring in both experiments. Collectively, these results suggest that WMC is related to error monitoring abilities, but this association is largely due to individual differences in the ability to consistently maintain task engagement and avoid lapses of attention.

Momentary lapses of attention in multisensory environment

Momentary lapses in attention disrupt goal-directed behaviors, and have been associated with increased pre-stimulus activity in the default mode network (DMN). The human brain often encounters multisensory inputs. It remains unknown, however, whether the neural mechanisms underlying attentional lapses are supra-modal or modality-dependent. To answer this question in the present functional magnetic resonance imaging (fMRI) study, we asked participants to respond to either visual or auditory targets in a multisensory paradigm, and focused on the pre-stimulus neural signals underlying attentional lapses, which resulted in impaired task performance, in terms of both delayed RTs and behavioral errors, in different sensory modalities. Behaviorally, mean reaction times (RTs) were equivalent between the visual and auditory modality. At the neural level, increased pre-stimulus neural activity in the majority of the core DMN regions, including medial prefrontal cortex (mPFC), posterior cingulate cortex (PCC), and left angular gyrus (AG), predicted delayed RTs more effectively in the visual than auditory modality. Especially, increased pre-stimulus activity in the mPFC predicted not only delayed RTs but also errors, more effectively in the visual than auditory modality. On the other hand, increased pre-stimulus activity in the anterior precuneus predicted both prolonged RTs and errors more effectively in the auditory than visual modality. Moreover, a supra-modal mechanism was revealed in the left middle temporal gyrus (MTG), which belongs to the posterior DMN. Increased pre-stimulus neural activity in the left MTG predicted impaired task performance in both the visual and auditory modality. Taken together, the core DMN regions manifest vision-dependent mechanisms of attentional lapses while a novel region in the anterior precuneus shows audition-dependent mechanisms of attentional lapses. Moreover, left MTG in the posterior DMN manifests a supra-modal mechanism of attentional lapses, independent of the modality of sensory inputs.

Is a structured work task application for the assessment of work performance in a constructed environment, useful for patients with attention deficits?

BACKGROUND

The purpose of our study was to develop a Structured Work Task application for the Assessment of Work Performance for patients with attention deficits.

MATERIAL AND METHODS

We developed a computer-based registration task titled the Attention-demanding Registration Task. It had a structured administrative procedure with additional scoring regarding time and accuracy, also linked to the original scoring of the Assessment of Work Performance. We evaluated the Attention-demanding Registration Task for content validity. Furthermore, we investigated it concerning sensitivity and specificity in patients with attention deficits due to acquired brain injury (n = 65) against a comparison group of healthy people (n = 47).

RESULTS

Our investigation on content validity using the Assessment of Work Characteristics confirmed that the Attention-demanding Registration Task sets high demands on process skills, especially on energy, temporal organization, and adaptation. The Attention-demanding Registration Task showed high sensitivity and specificity in differing between patients with attention deficits and a healthy working group; nine out of ten participants were placed in the correct group.

CONCLUSIONS

To assess work performance, the use of a Structured Work Task application, the Attention-demanding Registration Task, linked with the Assessment of Work Performance, proved to be sensitive to attention deficits.Implications for rehabilitationA Structured Work Task application for the Assessment of Work Performance was developed for use in people with attention deficits and showing a high degree of sensitivity and specificity.Linking performance time and accuracy to the Assessment of Work Performance scoring and providing a guide for linking task performance to the Assessment of Work Performance skills in addition to the usual observations performed, may increase scoring accuracy.Reference data for a comparison group of healthy subjects are provided.The use of the Attention demanding Registration Task, while using the Assessment of Work Performance within clinical practice ensures a more accurate description of process skills in performance.

Early childhood head injury attenuates declines in impulsivity and aggression across adolescent development in twins

OBJECTIVE

Head injury during development has been associated with behavioral changes such as impulsivity and antisocial behavior. This study investigates the extent to which behavioral changes associated with childhood head injury are sustained through adolescence and emerging adulthood.

METHOD

Survey data was collected at 5 waves spanning 12 years (ages 9-20) from the University of Southern California Risk Factors for Antisocial Behavior twin study. Impulsivity was measured by errors of commission in a Go/NoGo behavioral task, and aggression was measured through youth self-report using the Reactive-Proactive Aggression Questionnaire. Head injury was assessed retrospectively using caregiver questionnaires at twin ages 14-15 years and self-reported at ages 19-20 years.

RESULTS

Participants with a head injury in early childhood showed significant delay in the normative developmental decline of impulsivity relative to the noninjured by mid-adolescence (ages 14-15.) Moreover, earlier age at injury was related to a slower decrease in impulsivity and greater increase in reactive aggression scores. Finally, among discordant monozygotic twin pairs, the twin with a head injury experienced significantly less decline in impulsivity by ages 19-20 than the noninjured co-twin.

CONCLUSIONS

These findings indicate early childhood head injury may play a significant role in blunting the decline in impulsivity across development, exposing an additional risk factor for antisocial behavior. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Postdecisional Processing Delays in Metacognitive Monitoring After Traumatic Brain Injury

OBJECTIVE

To document the process by which metacognitive judgments ("online" monitoring of one's own cognitive performance during task completion) are made after traumatic brain injury (TBI).

PARTICIPANTS

Sixteen community-dwelling adults with moderate to severe TBI and 16 matched healthy controls.

DESIGN

Prospective, cross-sectional design.

MEASURES

Metacognitive retrospective confidence judgments and reaction times were collected as participants performed a metamemory task.

RESULTS

Adults with TBI did not differ from healthy peers in metacognitive accuracy; however, they took significantly longer to make retrospective confidence judgments. Retrospective confidence judgment reaction times were not consistently correlated to measures of processing speed in either sample.

CONCLUSIONS

Adults with TBI engage in different postdecisional processes to make metacognitive judgments compared with healthy controls. Findings suggest that reaction times may be an important dimension of metacognition to assess clinically after TBI.

Trauma-related psychiatric and behavioral conditions are uniquely associated with sustained attention dysfunction

OBJECTIVE

It is increasingly recognized that trauma victims, particularly Veterans, have co-occurring psychological and physical conditions that impact cognition, especially the domains of sustained attention and executive functioning. Although previous work has generally attempted to isolate the unique cognitive effects of common combat-related comorbidities, less work has been done to examine how these conditions co-occur, and whether unique cognitive signatures accompany certain clinical combinations.

METHOD

To address this gap, we examined how several deployment-related conditions were associated with performance on a well-validated measure of sustained attention (i.e., gradual onset continuous performance task [gradCPT]) and a battery of standard neuropsychological measures in 123 Veterans from the Translational Research Center for TBI and Stress Disorders. Initially, a Principal component analysis was conducted to investigate how comorbid conditions grouped together.

RESULTS

Several sustained attention measures from the gradCPT were differentially associated with four unique combinations of trauma-related pathology. Specifically, a somatic component representing the combination of current pain, sleep disturbance, and mild traumatic brain injury was associated with a higher rate of failures of attentional engagement. On the other hand, a comorbid posttraumatic stress disorder (PTSD) and mood disorder component (moodPTSD), as well as a substance use disorder component, were associated with higher rates of inhibitory control failures. Increased attentional instability was associated with moodPTSD as well as an anxiety disorder component. In contrast, the cognitive effects of deployment-related trauma were not observed on standard neuropsychological measures.

CONCLUSION

These findings suggest that unique combinations of trauma-related pathology have dissociable effects on sustained attentional control. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

A Failure to Launch: Regulatory Modes and Boredom Proneness

Boredom is a ubiquitous human experience characterized as a state of wanting but failing to engage with the world. Individuals prone to the experience of boredom demonstrate lower levels of self-control which may be at the heart of their failures to engage in goal-directed, meaningful behaviors. Here we develop the hypothesis that distinct self-regulatory profiles, which in turn differentially influence modes of goal pursuit, are at the heart of boredom proneness. Two specific regulatory modes are addressed: Locomotion, the desire to 'just do it,' an action oriented mode of goal-pursuit, and Assessment, the desire to 'do the right thing,' an evaluative orientation toward goal pursuit. We present data from a series of seven large samples of undergraduates showing that boredom proneness is negatively correlated with Locomotion, as though getting on with things acts as a prophylactic against boredom. This 'failure to launch' that we suggest is prevalent in the highly boredom prone individual, could be due to an inability to appropriately discriminate value (i.e., everything is tarred with the same gray brush), an unwillingness to put in the required effort to engage, or simply a failure to get started. In contrast, boredom proneness was consistently positively correlated with the Assessment mode of self-regulation. We suggest that this association reflects a kind of rumination that hampers satisfying goal pursuit.

Lasting deficit in inhibitory control with mild traumatic brain injury

Being able to focus on a complex task and inhibit unwanted actions or interfering information (i.e., inhibitory control) are essential human cognitive abilities. However, it remains unknown the extent to which mild traumatic brain injury (mTBI) may impact these critical functions. In this study, seventeen patients and age-matched healthy controls (HC) performed a variant of the Stroop task and attention-demanding 4-choice response tasks (4CRT) with identical stimuli but two contexts: one required only routine responses and the other with occasional response conflicts. The results showed that mTBI patients performed equally well as the HC when the 4CRT required only routine responses. However, when the task conditions included occasional response conflicts, mTBI patients with even a single concussion showed a significant slow-down in all responses and higher error rates relative to the HC. Results from event-related functional magnetic resonance imaging (efMRI) revealed altered neural activity in the mTBI patients in the cerebellum-thalamo-cortical and the fronto-basal-ganglia networks regulating inhibitory control. These results suggest that even without apparent difficulties in performing complex attention-demanding but routine tasks, patients with mTBI may experience long-lasting deficits in regulating inhibitory control when situations call for rapid conflict resolutions.

Rehabilitation of emergent awareness of errors post traumatic brain injury: A pilot intervention

Impaired awareness of errors is common following traumatic brain injury (TBI) and can be a barrier to successful rehabilitation. The objective of this study was to develop and evaluate a computer-based intervention programme aimed at improving error awareness in individuals with TBI. A further aim was to explore its effects on metacognitive awareness and variability of performance. Participants were 11 individuals with TBI and impaired error awareness who performed a sustained attention task twice-weekly for four weeks. The intervention consisted of audio-visual feedback-on-errors during the sustained attention task. Six participants received audio-visual feedback-on-error, five did not receive feedback. Emergent and metacognitive awareness were measured pre- and post-intervention. Between-groups comparisons of emergent awareness from pre- to post-intervention showed that audio-visual feedback-on-error improved emergent awareness compared to no feedback-on-error. Some changes in metacognitive awareness of executive behaviours as a result of feedback were observed. Audio-visual feedback-on-error improved emergent awareness in individuals with TBI following a four-week/eight-session intervention. This improvement was not observed in the no-feedback group. This pilot intervention is not a stand-alone treatment but it has potential to be usefully incorporated into cognitive or clinical rehabilitation programmes to improve emergent awareness.

Social Disinhibition: Piloting a New Clinical Measure in Individuals with Traumatic Brain Injury

Social disinhibition difficulties are common following traumatic brain injury (TBI). However, clinically sensitive tools to objectively assess the difficulties are lacking. This study aimed to pilot a new clinical measure of social disinhibition, the social disinhibition task (SDT). Whether social disinhibition is dependent on the type of social information judgements required and whether disinhibited responses can be adjusted with additional guidance were also examined. Participants were 31 adults (25 Male) with moderate-to-severe TBI and 22 adult (17 Male) healthy control participants. Participants viewed scenes of complex social situations and were asked to describe a character in them (Part A), describe a character while inhibiting inappropriate or negative responses (Part B), and describe a character while not only inhibiting negative responses, but also providing positive responses (Part C). One-half of the items contained a faux pas requiring participants to make inferences about a character's mental state. TBI and control participants responded similarly to Part A, although control participants responded less positively than TBI participants in the faux pas items. TBI participants were significantly impaired on Part B indicating they experienced difficulties in inhibiting automatic responding. TBI participants were however able to adjust their responding in Part C so that they respond similarly to the control participants. Between group differences were not detected in reaction time. Overall, the SDT appears to be suitable to detect social inhibition difficulties in clinical settings and provides a new direction for remediation of the difficulties in individuals with TBI.

Evaluating the accuracy of self-report for the diagnosis of HIV-associated neurocognitive disorder (HAND): defining "symptomatic" versus "asymptomatic" HAND

The criteria for differentiating symptomatic from asymptomatic HIV-associated neurocognitive disorder require evaluation of (1) cognitive impairment, (2) daily functioning declines, and (3) whether the functional declines are attributable to cognitive versus physical problems. Many providers rely only on self-report to evaluate these latter criteria. However, the accuracy of patient-provided information may be limited. This study evaluated the validity of self-assessment for HIV-associated neurocognitive disorder (HAND) diagnoses by comparing objective findings with self-report of criteria 2 and 3 above. Self-reports were used to stratify 277 cognitively impaired HIV+ individuals into functionally dependent (n = 159) and independent (n = 118) groups, followed by group comparisons of objective functional problems. The dependent group was then divided into those who self-attributed their functional dependence to only cognitive (n = 80) versus only physical (n = 79) causes, for further comparisons on objective findings. The functionally dependent group was significantly worse than the independent group on all objective disability characteristics except severity of cognitive impairment, while those who attributed their dependence to physical (versus cognitive) factors were similar on all objective physical, cognitive, and functioning variables. Of note, 28 % of physical attributors showed no physical abnormalities on neuromedical examinations. Results suggest that patient report is consistently associated with objective measures of functional loss; in contrast, patient identification of physical versus cognitive causes is poorly associated with objective criteria. These findings caution against relying solely on patient self-report to determine whether functional disability in cognitively impaired HIV+ individuals can be attributed to strictly physical causes.

Exploring the relationship between boredom proneness and self-control in traumatic brain injury (TBI)

Characterized as an agitated state in which the individual is motivated to engage in their environment but all attempts to do so fail to satisfy, boredom represents a disengaged attentional state that is associated with negative affect and poor self-control. There have been anecdotal reports of increased levels of boredom post-traumatic brain injury (TBI). For the first time, we provide objective evidence that TBI patients do indeed experience higher levels of boredom proneness. Hierarchical regression analyses showed that the presence and severity of head injury were a significant positive predictor of levels of boredom proneness and a negative predictor of self-control. As with healthy controls, TBI patients showed a strong negative correlation between boredom proneness and self-control-those with lower levels of self-control exhibited higher levels of boredom proneness. This was despite the fact that our TBI patients reported higher overall levels of self-control (probably concomitant with their older mean age). The TBI patients also showed strong positive correlations between boredom proneness and measures of physical aggression and anger. Together, this suggests that patients with TBI may be more susceptible to increased levels of boredom proneness and other negative affective states that arise as a consequence of failures of self-control.

Connecting Self-Awareness and Error-Awareness in Patients with Traumatic Brain Injury

Impaired self-awareness after traumatic brain injury (TBI) is often seen in stark contrast to the observations of significant-others, who are acutely aware of the difficulties experienced by patients. Our objective was to investigate the relationship between metacognitive knowledge in daily life and emergent awareness of errors during laboratory tasks, since the breakdown of error detection mechanisms may impose limitations on the recovery of metacognitive knowledge after TBI. We also examined the extent to which these measures of awareness can predict dysexecutive behaviors. A sample of TBI patients (n=62) and their significant-others, provided reports of daily functioning post injury. In addition, patients underwent a neuropsychological assessment and were instructed to signal their errors during go/no-go tests. Interrelationships between metacognitive and emergent levels of awareness were examined, after controlling for the influence of secondary cognitive variables. Significant-other ratings correlated with errors made by the patients on neuropsychological tests but not with their premorbid function. Patients who under-reported daily life difficulties or over-reported their competency, compared to significant-other reports, were less likely to show awareness of laboratory errors. Emergent awareness was also identified as the sole predictor of performance on the modified six-element test, an ecologically valid test of multitasking. The online breakdown of error awareness after brain injury is related to difficulties with metacognitive awareness as reported in daily life, and is also predictive of dysexecutive behaviors. These findings are discussed in the context of multidimensional and neural models of awareness and error monitoring.

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.

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.

Definition of Impulsivity and Related Terms Following Traumatic Brain Injury: A Review of the Different Concepts and Measures Used to Assess Impulsivity, Disinhibition and other Related Concepts

Impulsivity is a common and debilitating sequela following traumatic brain injury (TBI), but there is no consensual definition or measure to assess this construct. The following review aims to elucidate the differences and resemblances between impulsivity, disinhibition and other related terms following brain injury and the instruments that are commonly used to measure these constructs. To do so, a search through different databases was conducted in order to find articles that mention and define impulsivity, disinhibition, impulse control, regulation deficits, dyscontrol and risky behavior. The concepts that stand out from the literature, the measures used, the similarities, the differences between these concepts are observed. The fit with the UPPS model of impulsivity, according to which impulsivity is a multidimensional concept composed of four distinct dimensions (urgency, perseverance, premeditation and sensation-seeking) is discussed.

Transcranial direct current stimulation over right dorsolateral prefrontal cortex enhances error awareness in older age

The ability to detect errors during cognitive performance is compromised in older age and in a range of clinical populations. This study was designed to assess the effects of transcranial direct current stimulation (tDCS) on error awareness in healthy older human adults. tDCS was applied over DLPFC while subjects performed a computerized test of error awareness. The influence of current polarity (anodal vs cathodal) and electrode location (left vs right hemisphere) was tested in a series of separate single-blind, Sham-controlled crossover trials, each including 24 healthy older adults (age 65-86 years). Anodal tDCS over right DLPFC was associated with a significant increase in the proportion of performance errors that were consciously detected, and this result was recapitulated in a separate replication experiment. No such improvements were observed when the homologous contralateral area was stimulated. The present study provides novel evidence for a causal role of right DLPFC regions in subserving error awareness and marks an important step toward developing tDCS as a tool for remediating the performance-monitoring deficits that afflict a broad range of populations.

Traumatic brain injury, boredom and depression

Traumatic brain injury (TBI) often presents with co-morbid depression and elevated levels of boredom. We explored the relationship between boredom and depression in a group of mild (n = 38), moderate-to-severe TBI patients (n = 14) and healthy controls (n = 88), who completed the Beck Depression Inventory and Boredom Proneness Scales as part of a larger study. Results showed that the relationship between boredom and depression was strongest in moderate-to-severe TBI patients. We explored two boredom proneness factors that index an individual's need for external or internal stimulation. Results indicated that the need for external stimulation was the critical driver in the relation between boredom and depression. Once again, this relationship was strongest in the moderate-to-severe TBI group. These results suggest that one common factor underlying boredom and depression is the need for stimulation from the external environment and, presumably, a failure to satisfy that need-a disconnection felt most strongly in moderate-to-severe TBI.

Subjective cognition and amyloid deposition imaging: a Pittsburgh Compound B positron emission tomography study in normal elderly individuals

OBJECTIVE

To study the relationship between subjective cognition and the neuropathological hallmark of Alzheimer disease (AD), amyloid-β (Aβ) deposition, using carbon 11-labeled Pittsburgh Compound B (PiB) positron emission tomography in normal elderly individuals.

DESIGN

Cross-sectional analysis.

SUBJECTS

Forty-eight cognitively normal elderly subjects (11 with high PiB uptake and 28 with low PiB uptake) were included. All underwent clinical and neuropsychological evaluations, magnetic resonance imaging, and positron emission tomography.

SETTING

Berkeley Aging Cohort Study.

MAIN OUTCOME MEASURE

Relationship between PiB uptake and subjective cognition measures.

RESULTS

Subjects with high PiB uptake showed significantly lower performance than those with low PiB uptake on an episodic memory measure and were less confident about their general memory abilities when required to evaluate themselves relative to other people of the same age. High and low PiB uptake groups did not differ on the accuracy of their cognitive self-reports compared with objective cognitive performance. General memory self-reports from the whole group were significantly correlated with regional PiB uptake in the right medial prefrontal cortex and anterior cingulate cortex and in the right precuneus and posterior cingulate cortex. Reduced confidence about memory abilities was associated with greater PiB uptake in these brain regions. All results were independent of demographic variables and depressive affects.

CONCLUSIONS

A decrease of self-confidence about memory abilities in cognitively normal elderly subjects may be related to the neuropathological hallmark of AD measured with PiB-positron emission tomography. Subjective cognitive impairment may represent a very early clinical manifestation of AD.

Factors contributing to impaired self-awareness of cognitive functioning in an HIV positive and at-risk population

PURPOSE

To examine the association between self-awareness of cognitive impairment and age, selected mood disorders, and type and severity of cognitive impairment in a sample of individuals with HIV/AIDS and at risk for HIV.

METHOD

75 subjects, 52 HIV+ and 23 at risk for HIV completed a psychosocial interview, the Patient's Assessment of Own Functioning (PAOF) questionnaire, and a battery of neuropsychological tests. Based upon the differences between their clinical impairment and self-reported impairment, subjects were classified as being "Underestimators", "Good Awareness", or "Impaired Awareness" with regard to self-awareness.

RESULTS

Those with more severe cognitive impairment were less aware than those with normal or borderline cognitive impairment. A one-way ANOVA suggested that the Impaired Awareness group differed significantly from the Underestimators on the Rey Figure Immediate and Delayed Recall tasks, and from both the Underestimators and Good Awarenesss groups on the Digit Symbol Substitution Task. There were significant differences among all awareness groups on the test of Simple Reaction Time. Furthermore there is some suggestion that age may contribute to impaired self-awareness. The role of HIV in self-awareness remains unclear, as both, individuals with HIV and at risk, demonstrated impaired self-awareness.

CONCLUSIONS

Overall, impaired awareness was associated with poorer test performance, suggesting a relationship between awareness and sustained complex attention and visual spatial processing. This research has implications for understanding factors contributing to poor awareness among individuals with cognitive impairment.

Deficits in analogical reasoning in adolescents with traumatic brain injury

Individuals with traumatic brain injury (TBI) exhibit deficits in executive control, which may impact their reasoning abilities. Analogical reasoning requires working memory and inhibitory abilities. In this study, we tested adolescents with moderate to severe TBI and typically developing (TD) controls on a set of picture analogy problems. Three factors were varied: complexity (number of relations in the problems), distraction (distractor item present or absent), and animacy (living or non-living items in the problems). We found that TD adolescents performed significantly better overall than TBI adolescents. There was also an age effect present in the TBI group where older participants performed better than younger ones. This age effect was not observed in the TD group. Performance was affected by complexity and distraction. Further, TBI participants exhibited lower performance with distractors present than TD participants. The reasoning deficits exhibited by the TBI participants were correlated with measures of executive function that required working memory updating, attention, and attentional screening. Using MRI-derived measures of cortical thickness, correlations were carried out between task accuracy and cortical thickness. The TD adolescents showed negative correlations between thickness and task accuracy in frontal and temporal regions consistent with cortical maturation in these regions. This study demonstrates that adolescent TBI results in impairments in analogical reasoning ability. Further, TBI youth have difficulty effectively screening out distraction, which may lead to failures in comprehension of the relations among items in visual scenes. Lastly, TBI youth fail to show robust cortical–behavior correlations as observed in TD individuals.

Awareness of deficits and error processing after traumatic brain injury

Severe traumatic brain injury is frequently associated with alterations in performance monitoring, including reduced awareness of physical and cognitive deficits. We examined the relationship between awareness of deficits and electrophysiological indices of performance monitoring, including the error-related negativity and posterror positivity (Pe) components of the scalp-recorded event-related potential, in 16 traumatic brain injury survivors who completed a Stroop color-naming task while event-related potential measurements were recorded. Awareness of deficits was measured as the discrepancy between patient and significant-other ratings on the Frontal Systems Behavior Scale. The amplitude of the Pe, but not error-related negativity, was reliably associated with decreased awareness of deficits. Results indicate that Pe amplitude may serve as an electrophysiological indicator of awareness of abilities and deficits.

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.

Long-term cognitive outcome in moderate to severe traumatic brain injury: a meta-analysis examining timed and untimed tests at 1 and 4.5 or more years after injury

OBJECTIVES

To examine long-term outcome of moderate to severe traumatic brain injury (TBI) on timed and untimed cognitive tests using meta-analysis.

DESIGN

Meta-analysis examining outcome at 2 epochs, 6 to 18 months postinjury (epoch 1) and 4.5 to 11 years postinjury (epoch 2).

SETTING

Data source was published articles (1966-2007) identified through electronic and manual search.

PARTICIPANTS

A total of 1380 subjects with moderate to severe TBI participated in the 16 studies meeting inclusion criteria.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Timed and untimed neuropsychologic tests with quantitative results (means, SDs, t, and df tests) from studies containing a healthy comparison group and a mean time since injury falling within 1 of the 2 epochs.

RESULTS

Patient versus control weighted effect sizes were medium to large at epoch 1 for both untimed tasks (r=-.46; confidence interval [CI], -.32 to -.65) and timed tasks (r=-.46; CI, -.35 to -.59). At epoch 2, effect sizes were slightly smaller for untimed tasks (r=-.38; CI, -.25 to -.60) and timed tasks (r=-.40; CI, -.32 to -.62).

CONCLUSIONS

Patients showed robust, persisting impairments on both timed and untimed tests at recovery plateau (ie, 6-18mo postinjury) and many years later. These findings converge with previous studies, though using an alternative approach that obviates some of the methodologic problems of longitudinal studies, such as selective attrition.

Functional neuroimaging evidence for high cognitive effort on the Word Memory Test in the absence of external incentives

PRIMARY OBJECTIVE

This study presents data from a functional neuroimaging experiment which brings into question whether poor performance on the Word Memory Test (WMT) can be construed as straightforward evidence for 'poor effort' in the context of cognitive assessment, as asserted in a recent report in this journal.

METHODS AND PROCEDURES

Functional magnetic resonance image (fMRI) data were acquired from four participants without brain injury who engaged in the delayed recognition (DR) portion of Green's WMT protocol.

OUTCOMES AND RESULTS

Compared to a simple perceptual identification control task, this study found a highly reliable activation pattern across all participants which was restricted almost exclusively to cortical areas most commonly associated with task difficulty, memory load, concentration and other forms of cognitive effort These areas include dorsolateral prefrontal cortex, anterior insula, superior parietal cortex and the dorsal anterior cingulate.

CONCLUSIONS

These findings demonstrate that the WMT activates numerous cortical regions that are critical for cognitive effort. Given the extensive neural network necessary to perform the WMT, this study raises important questions about what WMT 'failure' truly means in patients with traumatic brain injury, who have increased likelihood of disruption within this neural network of vision, language, attention, effort and working memory.

Neuropsychology and clinical neuroscience of persistent post-concussive syndrome

On the mild end of the acquired brain injury spectrum, the terms concussion and mild traumatic brain injury (mTBI) have been used interchangeably, where persistent post-concussive syndrome (PPCS) has been a label given when symptoms persist for more than three months post-concussion. Whereas a brief history of concussion research is overviewed, the focus of this review is on the current status of PPCS as a clinical entity from the perspective of recent advances in the biomechanical modeling of concussion in human and animal studies, particularly directed at a better understanding of the neuropathology associated with concussion. These studies implicate common regions of injury, including the upper brainstem, base of the frontal lobe, hypothalamic-pituitary axis, medial temporal lobe, fornix, and corpus callosum. Limitations of current neuropsychological techniques for the clinical assessment of memory and executive function are explored and recommendations for improved research designs offered, that may enhance the study of long-term neuropsychological sequelae of concussion.

Recent advances in structural and functional brain imaging studies of attention-deficit/hyperactivity disorder

The field of neuroimaging of attention-deficit/hyperactivity disorder (ADHD) is now 30 years old. This brief selective review highlights the increasing sophistication of recent structural and functional neuroimaging studies of ADHD. In volumetric studies, investigators are examining extra-frontal, as well as frontal-striatal circuits and beginning to differentiate the potential effects of medication exposure. Functional MRI studies are focusing on familial/genetic influences and enrolling medication naïve, as well as medicated children with ADHD. A promising trend is the application of resting state approaches to mapping functional connectivity, which provides unexpectedly detailed information about interregional relationships while bypassing potentially confounding issues related to task performance. These developments allow us to conclude that neuroimaging studies of ADHD will increasingly inform our understanding of the neuronal substrates of ADHD.

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.