Karen Lê

Discourse production following injury to the dorsolateral prefrontal cortex.

Individuals with damage to the prefrontal cortex, and the dorsolateral prefrontal cortex (DLPFC) in particular, often demonstrate difficulties with the formulation of complex language not attributable to aphasia. The present study employed a discourse analysis procedure to characterize the language of individuals with left (L) or right (R) DLPFC lesions. All participants were 30-35 years post-onset of injury and presented with persistent discourse impairments. The discourse performance of the R DLPFC group was not significantly different from either the L DLPFC group or the non-injured comparison group. Individuals from the L DLPFC group demonstrated specific difficulties with narrative coherence and inclusion of critical story components. Both measures were significantly different from the comparison group. The discourse ability of the DLPFC groups was significantly correlated with measures of working memory. Findings support the use of discourse analysis for examining language impairments in individuals with PFC lesions.

The relationship of story grammar and executive function following TBI

Background: Story grammar is a super-structural measure of discourse performance that has shown to be sensitive to the deficits seen following traumatic brain injury (TBI). Narrative organisation and identification of logical relationships between events and characters are key components of story grammar. Reports of significant correlations for measures of story grammar and scores from various tests of executive functioning for individuals with TBI are thought to reflect executive control of cognitive and linguistic organisational processes. Aims: The purpose of the present study was to re-examine the relationship between story grammar and executive functions (EF) in a large group of participants with severe TBI secondary to diverse penetrating head wounds. It was hypothesised that participants with TBI would have significantly lower story grammar scores than a comparison group without TBI, and that story grammar performance of the group with TBI would be significantly correlated with their EF scores. Methods & Procedures: A total of 167 participants with TBI and a comparison group of 46 adults without TBI were asked to retell a 16-frame story. Transcripts of each story retelling were broken into T-units and were analysed for story grammar. Outcomes & Results: Results of MANOVA showed significant effect of group on the discourse measures. Univariate tests showed significant differences between the group with TBI and the comparison group for each of the story grammar measures. Story grammar measures were significantly correlated with executive function (EF) scores. Conclusions: Results indicated that the participants with TBI demonstrated significantly poorer performance on measures of story grammar abilities, lending support to earlier reports of story grammar impairments resulting from closed head injury (CHI). The present study also found significant correlations for measures of story grammar and the Sorting Test. Cognitive skills such as mental flexibility, required for successful performance on this card sorting task are likely the same as those required for episode generation. These findings have clinical implications for the management of cognitive-communication disorders in individuals with TBI. First, story grammar warrants inclusion in analyses of discourse. Second, discourse deficits following brain injury do not resolve spontaneously and persist as social barriers.

Measuring goodness of story narratives: Implications for traumatic brain injury

Background: This study examined the utility of story “goodness”, a measure of organisation and completeness, in quantifying narrative discourse deficits following traumatic brain injury (TBI). In an initial study, the story goodness measure demonstrated sensitivity and reliability in distinguishing individuals who had TBI from those who were non-brain-injured. Aims: The purpose of the current study was to validate previous findings of the story goodness index, specifically in discriminating performance between groups and identifying performance subgroups, in a larger sample of participants with TBI. Methods & Procedures: A total of 46 non-brain-injured adults and 171 adults with TBI participated. Story retellings were analysed for story grammar and story completeness. The two discourse scores were then plotted as coordinates, which allowed for quantification of story goodness. Statistical analyses included a multivariate analysis of variance and calculation of Pearson correlation coefficients for the discourse measures. Outcomes & Results: Results indicated that participants’ scores clustered differentially across quadrants between groups and discriminated groups into four distinct categories of story “goodness”. Conclusions: Findings paralleled those found in the initial study, suggesting that story goodness is a sensitive measure for examining the discourse of individuals with TBI. The story goodness has potential clinical utility and may have implications for investigation of discourse impairments in other clinical populations and treatment of discourse deficits.

Measuring communicative functioning in community‐dwelling stroke survivors: Conceptual foundation and item development

Background: Studies employing item response theory methods to evaluate communicative functioning assessment items have found that a broad range of communication tasks and activities may fit a unidimensional measurement model, but that additional item content is needed to extend the range of ability effectively measured by the small subset of items that have been evaluated. Aims: To describe the item identification, evaluation, and development process used to substantiate the content relevance and representativeness of a set of communicative functioning assessment items targeting community‐dwelling stroke survivors. Methods & Procedures: Electronic and secondary references were searched to identify assessment tools with item content designed to measure communicative functioning in adults with neurogenic communication disorders. Candidate items were evaluated using face‐to‐face interviewer‐assisted survey groups conducted independently with communicatively impaired stroke survivors (n = 59) and their communicative partners (n = 61). Web‐based surveys were employed to evaluate candidate items from the perspective of practising speech‐language pathologists (n = 114). Outcomes & Results: A total of 673 items were identified from 33 instruments. A total of 426 met the specified concept definition; 211 were determined to be non‐redundant; 166 were identified by key stakeholders as unambiguous, relevant, and moderately to very important to daily functioning. Conclusions: The item pool developed samples a representative range of communication behaviours, activities, and life situations that are relevant to community‐dwelling stroke survivors. Further research using item response theory methods is required to substantiate the construct dimensionality and range of ability effectively measured by the item pool, and to evaluate dynamic assessment algorithms designed to minimise response burden.

Does Brain Volume Loss Predict Cognitive and Narrative Discourse Performance Following Traumatic Brain Injury

PURPOSE In this study, the authors investigated the relationship between brain volume loss and performance on cognitive measures, including working memory, immediate memory, executive functions, and intelligence, and a narrative discourse production task. An underlying goal was to examine the prognostic potential of a brain lesion metric for discourse outcomes. It was hypothesized that brain volume loss would correlate with and predict cognitive and narrative discourse measures and have prognostic value for discourse outcomes. METHOD One hundred sixty-seven individuals with penetrating head injury participated. Correlational and regression analyses were performed for the percentages of total brain and hemispheric volume loss and scores on 4 cognitive measures (WMS-III Working Memory and Immediate Memory primary indexes, D-KEFS Sorting Test, and WAIS-III Full Scale IQ) and 7 narrative discourse measures (T-units, grammatical complexity, cohesion, local and global coherence, story completeness, and story grammar). RESULTS The volumetric measures had significant small-to-moderate correlations with all cognitive measures but only one significant correlation with the discourse measures. Findings from regression analyses were analogous but revealed several models that approached significance. CONCLUSION Findings suggest that an overall measure of brain damage may be more predictive of general cognitive status than of narrative discourse ability. Atrophy measures in specific brain regions may be more informative.