Awareness of deficits in traumatic brain injury: a multidimensional approach to assessing metacognitive knowledge and online-awareness.

Recent models of impaired awareness in brain injury draw a distinction between metacognitive knowledge of difficulties and online awareness of errors (emergent and anticipatory). We examined performance of 31 Traumatic Brain Injury (TBI) participants and 31 healthy controls using a three-strand approach to assessing awareness. Metacognitive knowledge was assessed with an awareness interview and discrepancy scores on three questionnaires--Patient Competency Rating Scale, Frontal Systems Behavioral Scale and the Cognitive Failures Questionnaire. Online Emergent Awareness was assessed using an online error-monitoring task while participants performed tasks of sustained attention. Online anticipatory awareness was examined using prediction performance on two cognitive tasks. Results indicated that the TBI Low Self-Awareness (SA) group and High SA group did not differ in terms of severity, chronicity or standard neuropsychological tasks but those with Low SA were more likely to exhibit disinhibition, interpersonal problems and more difficulties in total competency. Sustained attention abilities were associated with both types of online awareness (emergent and anticipatory). There was a strong relationship between online emergent and online anticipatory awareness. Metacognitive knowledge did not correlate with the other two measures. This study highlights the necessity in adopting a multidimensional approach to assessing the multifaceted phenomenon of awareness of deficits.

Capture by misleading information and its false acceptance in patients with traumatic brain injury.

Exposure to misleading information, presented after a critical episode, can alter or impair memory reports about that episode. Here, we examine vulnerability to misleading information in patients with traumatic brain injury (TBI). The ability to initiate an effective retrieval strategy and inhibit irrelevant or interfering information requires participation from the prefrontal cortices, which are susceptible to damage following brain injury. We report that TBI patients are more prone to interference effects produced by misleading information during a cued-recall task and are more likely to accept this information as the product of 'remembering' compared with healthy controls. The results are consistent with a model proposing that patients are captured by highly accessible responses eliminating their opportunity to engage in recollection. Correlations between the cued-recall interference task and other executive measures helped elucidate the processes underlying 'capture'. In TBI patients, reduced recollection produced by a misleading prime was associated with impaired prospective remembering when engaged in a background task. A common functional deficit that may underlie poor performance on both tasks is the failure to inhibit previously relevant but currently irrelevant information. Subjective reports pertaining to the subject's cued-recall response were indexed by electrodermal activity. In control subjects, larger skin conductance responses (SCRs) were associated with a greater frequency of guess reports, suggesting that SCRs provide a marker for uncertainty regarding the candidacy of a selected response. TBI patients did not show this relationship, suggesting that impairments of post-retrieval evaluation might also underlie greater false acceptance of misinformation. Discussion focuses on the role of the prefrontal cortex and cognitive processes that mediate the selection and evaluation of memories.

Sustained attention in traumatic brain injury (TBI) and healthy controls: enhanced sensitivity with dual-task load.

Poor sustained attention or alertness is a common consequence of traumatic brain injury (TBI) and has a considerable impact on the recovery and adjustment of TBI patients. Here, we describe the development of a sensitive laboratory task in healthy subjects (Experiment 1) and its enhanced sensitivity to sustained attention errors in TBI patients (Experiment 2). The task involves withholding a key press to an infrequent no-go target embedded within a predictable sequence of numbers (primary goal) and detecting grey-coloured targets within the sequence (secondary goal). In Experiment 1, we report that neurologically healthy subjects are more likely to experience a lapse of attention and neglect the primary task goal, despite ceiling performance on the secondary task. Further, attentional lapses on the task correlated with everyday attentional failures and variability of response time. In Experiment 2, the task discriminates between TBI patients and controls with a large effect size. The dual-task yields more errors in both groups than a simple task involving only the primary goal that is commonly used to detect sustained attention deficits in neurologically impaired groups. TBI patients' errors also correlated with everyday cognitive failures and variability of response time. This was not the case in the simple version of the task. We conclude that the dual-task demand associated with this task enhances its sensitivity as a measure of sustained attention in TBI patients and neurologically healthy controls that relates to everyday slips of attention.