Evaluating circumlocution in naming as a predictor of communicative informativeness and efficiency in discourse.

Background: Discourse analyses yield quantitative measures of functional communication in aphasia. However, they are historically underutilized in clinical settings. Confrontation naming assessments are used widely clinically and have been used to estimate discourse-level production. Such work shows that naming accuracy explains moderately high proportions of variance in measures of discourse, but proportions of variance remain unexplained. We propose that the inclusion of circumlocution productions into predictive models will account for a significant amount more of the variance. Circumlocution productions at the naming-level, while they may not contain the target word, are similar to the content that contributes to discourse informativeness and efficiency. Thus, additionally measuring circumlocution may improve our ability to estimate discourse performance and functional communication. Aim: This study aimed to test whether, after controlling for naming accuracy, the addition of a measure of circumlocution into predictive models of discourse-level informativeness and efficiency would account for a significant amount more of the variance in these discourse-level outcomes. Methods & Procedures: Naming and discourse data from 43 people with poststroke aphasia were analyzed. Naming data were collected using 120 pictured items and discourse data were collected using two picture description prompts. Data scoring and coding yielded measures of naming accuracy, incorrect response type, communicative informativeness, and efficiency. We used robust hierarchical regression to evaluate study predictions. Outcomes & Results: After controlling for naming accuracy, the inclusion of circumlocution into predictive models accounted for a significant amount more of the variance in both informativeness and efficiency. The subsequent inclusion of other response types, such as real word and nonword errors, did not account for a significant amount more of the variance in either outcome. Conclusions: In addition to naming accuracy, the production of circumlocution during naming assessments may correspond with measures of informativeness and efficiency at the discourse-level. Reducing the burden of estimating patients' functional communication will increase our ability to estimate functional communication using tools that are easy to administer and interpret.

Listening to Yourself and Watching Your Tongue: Distinct Abilities and Brain Regions for Monitoring Semantic and Phonological Speech Errors.

Despite the many mistakes we make while speaking, people can effectively communicate because we monitor our speech errors. However, the cognitive abilities and brain structures that support speech error monitoring are unclear. There may be different abilities and brain regions that support monitoring phonological speech errors versus monitoring semantic speech errors. We investigated speech, language, and cognitive control abilities that relate to detecting phonological and semantic speech errors in 41 individuals with aphasia who underwent detailed cognitive testing. Then, we used support vector regression lesion symptom mapping to identify brain regions supporting detection of phonological versus semantic errors in a group of 76 individuals with aphasia. The results revealed that motor speech deficits as well as lesions to the ventral motor cortex were related to reduced detection of phonological errors relative to semantic errors. Detection of semantic errors selectively related to auditory word comprehension deficits. Across all error types, poor cognitive control related to reduced detection. We conclude that monitoring of phonological and semantic errors relies on distinct cognitive abilities and brain regions. Furthermore, we identified cognitive control as a shared cognitive basis for monitoring all types of speech errors. These findings refine and expand our understanding of the neurocognitive basis of speech error monitoring.

Aphasia severity is modulated by race and lesion size in chronic survivors: A retrospective study.

INTRODUCTION: In stroke survivors with aphasia (SWA), differences in behavioral language performance have been observed between Black and White Americans. These racial differences in aphasia outcomes may reflect biological stroke severity, disparities in access to care, potential assessment bias, or interactions between these factors and race. Understanding the origin of disparities in aphasia outcomes is critical to any efforts to promote health equity among SWA. In this study, we explore aphasia outcomes by examining the relationship between race, socioeconomic status, and neurological factors in SWA. METHOD: Eighty-five chronic left-hemisphere SWA (31 Black, 54 White) participated in the study. The primary aphasia outcome measure was the Western Aphasia Battery-Revised (WAB-R). Lesion size was measured based on manual lesion segmentations. FLAIR and T2 images were scored for severity of white matter disease. Independent sample t-tests were used to determine differences by race in education, age, income, aphasia severity, white matter disease, and lesion size. A linear regression model was used to explore factors that predicted aphasia severity on the WAB-R. RESULT: Level of education and estimated income differed by race in our sample. For predictors of aphasia severity, the regression model revealed a significant effect of lesion size on WAB Aphasia Quotient and an interaction of race x lesion size, such that Black and White participants with small lesions had similar WAB scores, but in individuals with larger lesions, Black participants had lower WAB scores than White participants. CONCLUSION: We suggest two explanations for the difference between Black and White SWA in the relationship between lesion size and aphasia severity. First, the impact of disparities in access to rehabilitation after stroke may be more evident when a stroke is larger and causes significant aphasia. Additionally, an assessment bias in aphasia outcome measures may be more evident with increasing severity of aphasia. Future studies should further discern the drivers of observed disparities in aphasia outcomes in order to identify opportunities to improve equity in aphasia care.

The organization of individually mapped structural and functional semantic networks in aging adults.

Language function in the brain, once thought to be highly localized, is now appreciated as relying on a connected but distributed network. The semantic system is of particular interest in the language domain because of its hypothesized integration of information across multiple cortical regions. Previous work in healthy individuals has focused on group-level functional connectivity (FC) analyses of the semantic system, which may obscure interindividual differences driving variance in performance. These studies also overlook the contributions of white matter networks to semantic function. Here, we identified semantic network nodes at the individual level with a semantic decision fMRI task in 53 typically aging adults, characterized network organization using structural connectivity (SC), and quantified the segregation and integration of the network using FC. Hub regions were identified in left inferior frontal gyrus. The individualized semantic network was composed of three interacting modules: (1) default-mode module characterized by bilateral medial prefrontal and posterior cingulate regions and also including right-hemisphere homotopes of language regions; (2) left frontal module extending dorsally from inferior frontal gyrus to pre-motor area; and (3) left temporoparietal module extending from temporal pole to inferior parietal lobule. FC within Module3 and integration of the entire network related to a semantic verbal fluency task, but not a matched phonological task. These results support and extend the tri-network semantic model (Xu in Front Psychol 8: 1538 1538, 2017) and the controlled semantic cognition model (Chiou in Cortex 103: 100 116, 2018) of semantic function.

Distinguishing semantic control and phonological control and their role in aphasic deficits: A task switching investigation.

People use cognitive control across many contexts in daily life, yet it remains unclear how cognitive control is used in contexts involving language. Distinguishing language-specific cognitive control components may be critical to understanding aphasia, which can co-occur with cognitive control deficits. For example, deficits in control of semantic representations (i.e., semantic control), are thought to contribute to semantic deficits in aphasia. Conversely, little is known about control of phonological representations (i.e., phonological control) in aphasia. We developed a switching task to investigate semantic and phonological control in 32 left hemisphere stroke survivors with aphasia and 37 matched controls. We found that phonological and semantic control were related, but dissociate in the presence of switching demands. People with aphasia exhibited group-wise impairment at phonological control, although individual impairments were subtle except in one case. Several individuals with aphasia exhibited frank semantic control impairments, and these individuals had relative deficits on other semantic tasks. The present findings distinguish semantic control from phonological control, and confirm that semantic control impairments contribute to semantic deficits in aphasia.

Absence of Perilesional Neuroplastic Recruitment in Chronic Poststroke Aphasia.

BACKGROUND AND OBJECTIVES: A prominent theory proposes that neuroplastic recruitment of perilesional tissue supports aphasia recovery, especially when language-capable cortex is spared by smaller lesions. This theory has rarely been tested directly and findings have been inconclusive. We tested the perilesional plasticity hypothesis using 2 fMRI tasks in 2 groups of patients with previous aphasia diagnosis. METHODS: Two cohorts totaling 82 patients with chronic left-hemisphere stroke with previous aphasia diagnosis and 82 control participants underwent fMRI using either a naming task or a reliable semantic decision task. Individualized perilesional tissue was defined by dilating anatomical lesions and language regions were defined using meta-analyses. Mixed modeling examined differences in activity between groups. Relationships with lesion size and aphasia severity were examined. RESULTS: Patients exhibited reduced activity in perilesional language tissue relative to controls in both tasks. Although a few cortical regions exhibited greater activity irrespective of distance from the lesion, or only when distant from the lesion, no regions exhibited increased activity only when near the lesion. Larger lesions were associated with reduced language activity irrespective of distance from the lesion. Using the reliable fMRI task, reduced language activity was related to aphasia severity independent of lesion size. DISCUSSION: We found no evidence for neuroplastic recruitment of perilesional tissue in aphasia beyond its typical role in language. Rather, our findings are consistent with alternative hypotheses that changes in left-hemisphere activation during recovery relate to normalization of language network dysfunction and possibly recruitment of alternate cortical processors. These findings clarify left-hemisphere neuroplastic mechanisms supporting language recovery after stroke.

Two types of phonological reading impairment in stroke aphasia.

Alexia is common in the context of aphasia. It is widely agreed that damage to phonological and semantic systems not specific to reading causes co-morbid alexia and aphasia. Studies of alexia to date have only examined phonology and semantics as singular processes or axes of impairment, typically in the context of stereotyped alexia syndromes. However, phonology, in particular, is known to rely on subprocesses, including sensory-phonological processing, motor-phonological processing, and sensory-motor integration. Moreover, many people with stroke aphasia demonstrate mild or mixed patterns of reading impairment that do not fit neatly with one syndrome. This cross-sectional study tested whether the hallmark symptom of phonological reading impairment, the lexicality effect, emerges from damage to a specific subprocess of phonology in stroke patients not selected for alexia syndromes. Participants were 30 subjects with left-hemispheric stroke and 37 age- and education-matched controls. A logistic mixed-effects model tested whether post-stroke impairments in sensory phonology, motor phonology, or sensory-motor integration modulated the effect of item lexicality on patient accuracy in reading aloud. Support vector regression voxel-based lesion-symptom mapping localized brain regions necessary for reading and non-orthographic phonological processing. Additionally, a novel support vector regression structural connectome-symptom mapping method identified the contribution of both lesioned and spared but disconnected, brain regions to reading accuracy and non-orthographic phonological processing. Specifically, we derived whole-brain structural connectomes using constrained spherical deconvolution-based probabilistic tractography and identified lesioned connections based on comparisons between patients and controls. Logistic mixed-effects regression revealed that only greater motor-phonological impairment related to lower accuracy reading aloud pseudowords versus words. Impaired sensory-motor integration was related to lower overall accuracy in reading aloud. No relationship was identified between sensory-phonological impairment and reading accuracy. Voxel-based and structural connectome lesion-symptom mapping revealed that lesioned and disconnected left ventral precentral gyrus related to both greater motor-phonological impairment and lower sublexical reading accuracy. In contrast, lesioned and disconnected left temporoparietal cortex is related to both impaired sensory-motor integration and reduced overall reading accuracy. These results clarify that at least two dissociable phonological processes contribute to the pattern of reading impairment in aphasia. First, impaired sensory-motor integration, caused by lesions disrupting the left temporoparietal cortex and its structural connections, non-selectively reduces accuracy in reading aloud. Second, impaired motor-phonological processing, caused at least partially by lesions disrupting left ventral premotor cortex and structural connections, selectively reduces sublexical reading accuracy. These results motivate a revised cognitive model of reading aloud that incorporates a sensory-motor phonological circuit.

Intellectual awareness of naming abilities in people with chronic post-stroke aphasia.

Anosognosia, or lack of self-awareness, is often present following neurological injury and can result in poor functional outcomes. The specific phenomenon of intellectual awareness, the knowledge that a function is impaired in oneself, has not been widely studied in post-stroke aphasia. We aim to identify behavioral and neural correlates of intellectual awareness by comparing stroke survivors' self-reports of anomia to objective naming performance and examining lesion sites. Fifty-three participants with chronic aphasia without severe comprehension deficits rated their naming ability and completed a battery of behavioral tests. We calculated the reliability and accuracy of participant self-ratings, then examined the relationship of poor intellectual awareness to speech, language, and cognitive measures. We used support vector regression lesion-symptom mapping (SVR-LSM) to determine lesion locations associated with impaired and preserved intellectual awareness. Reliability and accuracy of self-ratings varied across the participants. Poor intellectual awareness was associated with reduced performance on tasks that rely on semantics. Our SVR-LSM results demonstrated that anterior inferior frontal lesions were associated with poor awareness, while mid-superior temporal lesions were associated with preserved awareness. An anterior-posterior gradient was evident in the unthresholded lesion-symptom maps. While many people with chronic aphasia and relatively intact comprehension can accurately and reliably report the severity of their anomia, others overestimate, underestimate, or inconsistently estimate their naming abilities. Clinicians should consider this when administering self-rating scales, particularly when semantic deficits or anterior inferior frontal lesions are present. Administering self-ratings on multiple days may be useful to check the reliability of patient perceptions.

Providing Effective Speech-Language Pathology Group Treatment in the Comprehensive Inpatient Rehabilitation Setting.

Group treatment is an integral part of speech-language pathology (SLP) practice. The majority of SLP literature concerns group treatment provided in outpatient settings. This article describes the goals, procedures, and benefits of providing quality SLP group therapy in the comprehensive inpatient rehabilitation (CIR) setting. Effective CIR groups must be designed with attention to type and severity of communication impairment, as well physical stamina of group members. Group leaders need to target individualized patient goals while creating a challenging, complex, and dynamic group context that supports participation by all group members. Direct patient-to-patient interaction is fostered as much as possible. Peer feedback supports goal acquisition by fellow group members. The rich, complex group context fosters improved insight, initiation, social connectedness, and generalization of communication skills. Group treatment provides a unique type of treatment not easily replicated with individual treatment. SLP group treatment in a CIR is an essential component of an intensive, high-quality program. Continued advocacy for group therapy provision and research into its efficacy and effectiveness are warranted.