Assessment of linguistic and verbal short-term memory components of language abilities in aphasia

Right Hemisphere Language Network Plasticity in Aphasia

The role of the right hemisphere in aphasia recovery has been controversial since the 19th century. Imaging studies have sometimes found increased activation in right hemisphere regions homotopic to canonical left hemisphere language regions, but these results have been questioned due to small sample sizes, unreliable imaging tasks, and task performance confounds that affect right hemisphere activation levels even in neurologically healthy adults. Several principles of right hemisphere language recruitment in aphasia have been proposed based on these studies: that the right hemisphere is recruited primarily by individuals with severe left hemisphere damage, that transcallosal disinhibition results in recruitment of right hemisphere nodes homotopic to the lesion, and that increased right hemisphere activation diminishes to baseline levels over time. It is debated whether engagement of language homotopes reflects upregulation of weakly active right hemisphere nodes in a bihemispheric language network, versus recruitment of new nodes into the network. Here, we address these issues in 76 chronic left hemisphere stroke survivors and 69 neurologically healthy older adults using a semantic decision fMRI paradigm that elicits reliable and strongly left-lateralized individual-participant language activation and adapts to require effortful performance irrespective of participant ability levels. Right hemisphere activation was greater in stroke survivors than controls, and related to younger age, left-handedness, and higher education. Right hemisphere activation magnitude was modest compared to left hemisphere activation. In contrast to prior proposals, right hemisphere activation was unrelated to lesion size and greater with longer time-since-stroke. Right ventral inferior frontal and mid-anterior temporal nodes were weakly engaged in language processing in controls and co-activated with their homotopic left hemisphere counterparts. Lesions to those left hemisphere counterparts resulted in increased homotopic activation that contributed to naming and word reading outcomes. In contrast, the right dorsal inferior frontal cortex was not engaged during language processing in controls and did not coactivate with its left hemisphere counterpart. After stroke, it exhibited the largest increase in group-level activation due to complex lesion-activation interactions, but the activation was unrelated to aphasia outcomes. In sum, right hemisphere language homotopes are recruited in the chronic phase of aphasia recovery, consistent with both upregulation of weakly active nodes in a bihemispheric language network and recruitment of the dorsal inferior frontal gyrus as a new node. These findings clarify the mechanisms of, and constraints on, right hemisphere language network plasticity in adults and may guide selection of candidates likely to benefit from neuromodulatory aphasia treatments.

Executive Functions Training Improves Language Abilities in Aphasia Rehabilitation: A Systematic Review

Background/Objectives: In recent years, the popularity of non-verbal cognitive training for aphasia has increased. Building on evidence that language abilities engage brain areas involved in executive functions (EFs) processing, this review aims to analyze the utility of EFs training alone or combined with traditional rehabilitation approaches to improve language abilities in aphasia. Methods: Systematic searches were performed in four databases evaluating studies focusing on the effects of EFs training in language rehabilitation, yielding 185 studies. After reading the full text of the selected studies and applying predefined inclusion criteria, nine studies were included based on pertinence and relevance to the topic. This systematic review has been registered in the Prospective Register of Systematic Reviews (PROSPERO 2024) with the number CRD42024519087. Results: The results of the analyzed studies indicate that various EFs training methods, such as computer-assisted executive control training, Cognitive Flexibility in Aphasia Therapy (CFAT), and the Dr. Neuronowski® program, as well as the combination of transcranial direct current stimulation (tDCS) with EFs training, can lead to improvements in language abilities in people with aphasia. Additionally, EFs training often results in specific effects on treated functions like working memory (near transfer effects) and untreated ones such as spoken sentence comprehension (far transfer effects). Conclusions: Despite the heterogeneity of the treatments and the small simple size of the studies analyzed, preliminary results are promising. Future research should further explore the effectiveness and specific contribution of EFs training to improving language functions in aphasia.

A shared serial order system for verbal working memory and language production: evidence from aphasia

Many aspects of human performance require producing sequences of items in serial order. The current study takes a multiple-case approach to investigate whether the system responsible for serial order is shared across cognitive domains, focusing on working memory (WM) and word production. Serial order performance in three individuals with post-stroke language and verbal WM disorders (hereafter persons with aphasia, PWAs) were assessed using recognition and recall tasks for verbal and visuospatial WM, as well as error analyses in spoken and written production tasks to assess whether there was a tendency to produce the correct phonemes/letters in the wrong order. One PWA exhibited domain-specific serial order deficits in verbal and visuospatial WM. The PWA with verbal serial order WM deficit made more serial order errors than expected by chance in both repetition and writing-to-dictation tasks, whereas the other two PWAs showed no serial order deficits in verbal WM and production tasks. These findings suggest separable serial order systems for verbal and visuospatial WM and a shared system for serial order processing in verbal WM and word production. Implications for the domain-generality of WM, its connection to language production, and serial order processing across cognitive functionssc are discussed.

Self-Improved Language Production in Nonfluent Aphasia Through Automated Recursive Self-Feedback

BACKGROUND

Persons with nonfluent aphasia (PWNA) use feedback from external agents (e.g., speech-language pathologists) and self-feedback to improve their language production. The extent to which PWNA can improve their language production using their self-feedback alone is underexplored. In a proof-of-concept study, we developed an automated recursive self-feedback procedure to demonstrate the extent to which two PWNA who used self-feedback alone improved their production of sentences from trained and untrained scripts. In the current study, we use the Rehabilitation Response Specification System as a framework to replicate our initial findings.

METHOD

We tested the effects of two treatments: script production with recursive self-feedback and script production with external feedback in four persons with chronic nonfluent aphasia. We compared the effects of treatment by measuring percent script produced, speaking rate, and speech initiation latency of trained and untrained scripts. The participants received the treatments remotely through mini tablets using two versions of a mobile app we developed. All the participants received each treatment intensively for 14 sessions across 2-3 weeks. We estimated clinical improvements of production of sentences from trained and untrained scripts through nonoverlap of all pairs analysis of performance pretreatment and posttreatment.

RESULTS

Both treatments improved PWNA's language production. Recursive self-feedback improved speaking rate and speech initiation latency, which generalized to untrained scripts in all participants. External feedback treatment did not generalize to improvement in speaking rate in two participants.

CONCLUSIONS

Our findings confirm our initial evidence that PWNA can self-improve their sentence production from scripts through recursive self-feedback. This novel procedure enables PWNA to autonomously enhance their language production over time. Given the evidence and the mechanics of the procedure, we propose that its utility is not constrained by linguistic idiosyncrasies across cultures. Consequently, it has the potential to bypass linguistic barriers to aphasia care.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.27007060.

Verbal working memory and syntactic comprehension segregate into the dorsal and ventral streams, respectively

Syntactic processing and verbal working memory are both essential components to sentence comprehension. Nonetheless, the separability of these systems in the brain remains unclear. To address this issue, we performed causal-inference analyses based on lesion and connectome network mapping using MRI and behavioural testing in two groups of individuals with chronic post-stroke aphasia. We employed a rhyme judgement task with heavy working memory load without articulatory confounds, controlling for the overall ability to match auditory words to pictures and to perform a metalinguistic rhyme judgement, isolating the effect of working memory load (103 individuals). We assessed non-canonical sentence comprehension, isolating syntactic processing by incorporating residual rhyme judgement performance as a covariate for working memory load (78 individuals). Voxel-based lesion analyses and structural connectome-based lesion symptom mapping controlling for total lesion volume were performed, with permutation testing to correct for multiple comparisons (4000 permutations). We observed that effects of working memory load localized to dorsal stream damage: posterior temporal-parietal lesions and frontal-parietal white matter disconnections. These effects were differentiated from syntactic comprehension deficits, which were primarily associated with ventral stream damage: lesions to temporal lobe and temporal-parietal white matter disconnections, particularly when incorporating the residual measure of working memory load as a covariate. Our results support the conclusion that working memory and syntactic processing are associated with distinct brain networks, largely loading onto dorsal and ventral streams, respectively.

Language impairments in Alzheimer´s disease: What changes can be found between mild and moderate stages of the disease?

OBJECTIVE

To investigate how language deteriorates over the Alzheimer's Disease course.

METHODS

A cross-sectional, observational study was carried out. 35 patients diagnosed with dementia due to AD using the NINCDS-ARDRA criteria and undergoing treatment for AD with a therapeutic dose of acetylcholinesterase inhibitors were assessed by the Boston Diagnostic Aphasia Examination (BDAE). The sample comprised 15 patients with mild AD (MMSE > 23, CDR = 0 or 0.5‒1.0) and 20 patients with moderate AD (MMSE = 13‒23, CDR = 2). The results for the 2 groups on all language tasks were compared.

RESULTS

A statistically significant difference was found between the mild and moderate AD groups for total score on the BDAE (95% CI 47.10‒114.08, t = 5.0, DF = 21, p = 0.000*), as well as on several tasks involving oral and writing comprehension, language oral expression and writing.

CONCLUSION

The study results showed major changes in the moderate stage. Also, the decline in language performance correlated with the worsening of dementia syndrome, independently of sociodemographic variables.

Verbal working memory and syntactic comprehension segregate into the dorsal and ventral streams

Syntactic processing and verbal working memory are both essential components to sentence comprehension. Nonetheless, the separability of these systems in the brain remains unclear. To address this issue, we performed causal-inference analyses based on lesion and connectome network mapping using MRI and behavioral testing in 103 individuals with chronic post-stroke aphasia. We employed a rhyme judgment task with heavy working memory load without articulatory confounds, controlling for the overall ability to match auditory words to pictures and to perform a metalinguistic rhyme judgment, isolating the effect of working memory load. We assessed noncanonical sentence comprehension, isolating syntactic processing by incorporating residual rhyme judgment performance as a covariate for working memory load. Voxel-based lesion analyses and structural connectome-based lesion symptom mapping controlling for total lesion volume were performed, with permutation testing to correct for multiple comparisons (4,000 permutations). We observed that effects of working memory load localized to dorsal stream damage: posterior temporal-parietal lesions and frontal-parietal white matter disconnections. These effects were differentiated from syntactic comprehension deficits, which were primarily associated with ventral stream damage: lesions to temporal lobe and temporal-parietal white matter disconnections, particularly when incorporating the residual measure of working memory load as a covariate. Our results support the conclusion that working memory and syntactic processing are associated with distinct brain networks, largely loading onto dorsal and ventral streams, respectively.

Home-Based Transcranial Direct Current Stimulation in Primary Progressive Aphasia: A Pilot Study

BACKGROUND

This study aims to determine (a) if home-based anodal transcranial direct current stimulation (a-tDCS) delivered to the left supramarginal gyrus (SMG) coupled with verbal short-term memory/working memory (vSTM/WM) treatment ("RAM", short for "Repeat After Me") is more effective than sham-tDCS in improving vSTM/WM in patients with primary progressive aphasia (PPA), and (b) whether tDCS effects generalize to other language and cognitive abilities.

METHODS

Seven PPA participants received home-based a-tDCS and sham-tDCS coupled with RAM treatment in separate conditions in a double-blind design. The treatment task required participants to repeat word spans comprising semantically and phonologically unrelated words in the same and reverse order. The evaluation of treatment effects was carried out using the same tasks as in the treatment but with different items (near-transfer effects) and tasks that were not directly related to the treatment (far-transfer effects).

RESULTS

A-tDCS showed (a) a significant effect in improving vSTM abilities, measured by word span backward, and (b) a generalization of this effect to other language abilities, namely, spelling (both real words and pseudowords) and learning (retention and delayed recall).

CONCLUSIONS

These preliminary results indicate that vSTM/WM intervention can improve performance in trained vSTM/WM tasks in patients with PPA, especially when augmented with home-based tDCS over the left SMG.

Revealing Linguistic and Verbal Short-Term and Working Memory Abilities in People with Severe Aphasia

Background

The assessment of aphasia in people with severe deficits is hampered by a paucity of tests that are appropriate for this population and that are sensitive to their underlying linguistic and short-term and working memory (STM/WM) strengths and weaknesses. The Temple Assessment of Language and Short-Term Memory in Aphasia (TALSA) provides a means of assessing people with severe aphasia (PWSA).

Aims

The aim of this paper is to demonstrate the sensitivity of the TALSA to the underlying linguistic and STM/WM strengths and weaknesses in PWSA. We assessed eight PWSA on selected subtests of the TALSA and found that 1) the TALSA is sensitive to the underlying linguistic and verbal STM/WM abilities of PWSA, 2) the TALSA reveals a wide variety of linguistic and verbal STM/WM profiles in PWSA and, 3) the TALSA can potentially demonstrate common patterns of performance in PWSA.

Main contributions

The TALSA allows researchers to include more PWSA in the study of aphasia and enables clinicians to establish more accurate prognoses, create precisely targeted treatment plans and document incremental progress in therapy.

Conclusions

The TALSA is an important addition to the assessment of severe aphasia. It provides an in-depth evaluation of underlying linguistic and verbal STM/WM strengths and weaknesses of PWSA.

An electrophysiological and behavioral investigation of feedback-based learning in aphasia

Introduction

Feedback is a fundamental aspect of aphasia treatments. However, learning from feedback is a cognitively demanding process. At the most basic level, individuals must detect feedback and extract outcome-related information (i.e., feedback processing). Neuroanatomical and neuropsychological differences associated with post-stroke aphasia may influence feedback processing and potentially how people with aphasia (PWA) respond to feedback-based treatments. To better understand how post-stroke aphasia affects feedback-based learning, the current study leverages event-related potentials (ERPs) to (1) characterize the relationship between feedback processing and learning, (2) identify cognitive skills that are associated with feedback processing, and (3) identify behavioural correlates of feedback-based learning in PWA.

Methods

Seventeen PWA completed a feedback-based novel word learning task. Feedback processing was measured using the feedback-related negativity (FRN), an ERP hypothesized to reflect the detection and evaluation of outcomes communicated via feedback. Individuals also completed neuropsychological assessments of language (phonological processing, verbal short-term memory) and executive functioning.

Results

PWA elicited an FRN that was sensitive to feedback valence. The magnitude of the FRN was not associated with novel word learning but was strongly correlated with performance on another feedback-based task, the Berg Card Sort. Cognitive variables (information updating, selective attention) but not language variables were associated with novel word learning.

Discussion & Conclusion

For PWA, feedback processing may be associated with learning in some but not all feedback-based contexts. These findings may inform future research in determining which variables moderate the relationship between feedback processing and learning with the long-term goal of identifying how feedback can be modified to support successful learning during aphasia rehabilitation.

Telepractice in speech-language pathology: Assessing remote speech discrimination

PURPOSE

To evaluate adult remote performance in speech discrimination on the Temple Assessment of Language and Short-term Memory in Aphasia (TALSA), and to compare to remote performance in NU-6 word repetition and participant ratings of self-perceived hearing ability obtained via remote session.

METHOD

Sixty older adults completed TALSA speech discrimination of concrete, low frequency words and of non-words via telephone. Remote repetition of words controlled for sound frequency was assessed using the Northwestern University (NU-6) word lists administered in live voice and recorded voice conditions. Forty-six of the participants completed questionnaires about their hearing via Zoom videoconference.

RESULTS

Mean performance in TALSA speech discrimination for words was similar to performance in NU-6 word repetition. Word repetition of NU-6 lists did not differ significantly for live voice versus recorded voice conditions. TALSA non-word speech discrimination was significantly worse than TALSA speech discrimination for words and was associated with age and self-reported hearing ability.

CONCLUSIONS

TALSA speech discrimination can be administered remotely to evaluate potential perceptual influences on auditory comprehension. In remote assessment, participants demonstrated the expected pattern of more accurate speech discrimination for word stimuli than for non-words. The non-word TALSA condition may be particularly useful for detecting speech perception impairment, both in face-to-face and telepractice sessions. Similar performance of participants in both live voice and recorded conditions of the NU-6 word lists suggests that recordings used in SLP receptive language or memory assessment, including the TALSA, need not be abandoned in favor of live voice to support audition during telepractice.

Expressive recall and recognition as complementary measures to assess novel word learning ability in aphasia

Novel word learning ability has been associated with language treatment outcomes in people with aphasia (PWA), and its assessment could inform prognosis and rehabilitation. We used a brief experimental task to examine novel word learning in PWA, determine the value of phonological cueing in assessing learning outcomes, and identify factors that modulate learning ability. Twelve PWA and nineteen healthy controls completed the task, and recall and recognition tests of learning ability. Most PWA showed comparable learning outcomes to those of the healthy controls. Learning assessed via expressive recall was more clearly evidenced with phonological cues. Better single word processing abilities and phonological short-term memory and higher integrity of the left inferior frontal gyrus were related to better learning performance. Brief learning tasks like this one are clinically feasible and hold promise as screening tools of verbal learning in PWA once validated and evaluated for their capacity to predict treatment outcomes.

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.

The right uncinate fasciculus supports verbal short-term memory in aphasia

Verbal short-term memory (STM) deficits are associated with language processing impairments in people with aphasia. Importantly, the integrity of STM can predict word learning ability and anomia therapy gains in aphasia. While the recruitment of perilesional and contralesional homologous brain regions has been proposed as a possible mechanism for aphasia recovery, little is known about the white-matter pathways that support verbal STM in post-stroke aphasia. Here, we investigated the relationships between the language-related white matter tracts and verbal STM ability in aphasia. Nineteen participants with post-stroke chronic aphasia completed a subset of verbal STM subtests of the TALSA battery including nonword repetition (phonological STM), pointing span (lexical-semantic STM without language output) and repetition span tasks (lexical-semantic STM with language output). Using a manual deterministic tractography approach, we investigated the micro- and macrostructural properties of the structural language network. Next, we assessed the relationships between individually extracted tract values and verbal STM scores. We found significant correlations between volume measures of the right Uncinate Fasciculus and all three verbal STM scores, with the association between the right UF volume and nonword repetition being the strongest one. These findings suggest that the integrity of the right UF is associated with phonological and lexical-semantic verbal STM ability in aphasia and highlight the potential compensatory role of right-sided ventral white matter language tracts in supporting verbal STM after aphasia-inducing left hemisphere insult.

Effects of task types and time interval conditions on age-related decline in verbal working memory

Age-related differences in working memory (WM) components were investigated by manipulating the time interval and interference effects between phonological and semantic judgment tasks to identify tasks to best discriminate between younger and older groups. The 96 participants (young = 48; old = 48) prospectively performed two task types of WM, with phonological and semantic judgment tasks, which were administered while varying the three interval conditions: 1-s unfilled (UF), 5-s UF, and 5-s filled (F). The main effect for age was significant in the semantic judgment task but not in the phonological judgment task. The main effect for the interval conditions were significant in both tasks. A 5-s UF condition applied to a semantic judgment task could significantly differentiate the older group from the younger group. Differential effects of time interval manipulation in semantic and phonological processing are involved in WM resources. The older group could be differentiated by varying the task types and interval conditions, indicating that the semantic-related WM burdens may contribute to a superior differential diagnosis of aging-related WM decline.

Targeted neurorehabilitation strategies in post-stroke aphasia

BACKGROUND

Aphasia is a debilitating language impairment, affecting millions of people worldwide. About 40% of stroke survivors develop chronic aphasia, resulting in life-long disability.

OBJECTIVE

This review examines extrinsic and intrinsic neuromodulation techniques, aimed at enhancing the effects of speech and language therapies in stroke survivors with aphasia.

METHODS

We discuss the available evidence supporting the use of transcranial direct current stimulation (tDCS), repetitive transcranial magnetic stimulation, and functional MRI (fMRI) real-time neurofeedback in aphasia rehabilitation.

RESULTS

This review systematically evaluates studies focusing on efficacy and implementation of specialized methods for post-treatment outcome optimization and transfer to functional skills. It considers stimulation target determination and various targeting approaches. The translation of neuromodulation interventions to clinical practice is explored, emphasizing generalization and functional communication. The review also covers real-time fMRI neurofeedback, discussing current evidence for efficacy and essential implementation parameters. Finally, we address future directions for neuromodulation research in aphasia.

CONCLUSIONS

This comprehensive review aims to serve as a resource for a broad audience of researchers and clinicians interested in incorporating neuromodulation for advancing aphasia care.

Language learning in aphasia: A narrative review and critical analysis of the literature with implications for language therapy

People with aphasia (PWA) present with language deficits including word retrieval difficulties after brain damage. Language learning is an essential life-long human capacity that may support treatment-induced language recovery after brain insult. This prospect has motivated a growing interest in the study of language learning in PWA during the last few decades. Here, we critically review the current literature on language learning ability in aphasia. The existing studies in this area indicate that (i) language learning can remain functional in some PWA, (ii) inter-individual variability in learning performance is large in PWA, (iii) language processing, short-term memory and lesion site are associated with learning ability, (iv) preliminary evidence suggests a relationship between learning ability and treatment outcomes in this population. Based on the reviewed evidence, we propose a potential account for the interplay between language and memory/learning systems to explain spared/impaired language learning and its relationship to language therapy in PWA. Finally, we indicate potential avenues for future research that may promote more cross-talk between cognitive neuroscience and aphasia rehabilitation.

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.

Integrity of input verbal short-term memory ability predicts naming accuracy in aphasia

Background

Contemporary models of aphasia predominantly attribute lexical retrieval deficits to impaired access and/or maintenance of semantic, lexical, and phonological representations of words. A central hypothesis of language-emergent models of verbal short-term memory (STM) is that temporary storage and maintenance of verbal information arises from activation of linguistic representations in long-term memory. This close relationship between short-term retention and linguistic representations has prompted accounts of aphasia that include impairments to both these components.

Aims

We investigated associations between measures of input semantic and phonological verbal STM and corresponding output processing measures. We hypothesised that both input and output functions of verbal STM rely on a common substrate (i.e., temporary activation and maintenance of long-term linguistic representations).

Methods & Procedure

Twenty adults with aphasia completed a series of semantic and phonological probe spans. Results were compared with naming performance in immediate and delayed conditions. The data were analysed using correlations, principal components analysis and linear regressions.

Results & Discussion

Input semantic and phonological verbal STM abilities were predictive of naming accuracy. Greater input semantic and phonological STM spans were associated with fewer semantic and phonological naming errors. Latent factors identified by principal components analysis of probe span data were consistent with a two-step interactive model of word retrieval. Probe spans measuring access to semantic and initial consonant-vowel representations aligned with lexical-semantic abilities (lexical-semantic factor). Probe spans assessing access to the rhyme component of a word measured lexical-phonological abilities (lexical-phonological factor). The principal components analysis indicated that stronger lexical-semantic abilities were associated with fewer semantic and nonword errors, and stronger lexical phonological abilities were associated with fewer formal and unrelated errors. In addition, our results were consistent with models that postulate serial access to phonology, proceeding from initial to final phonemes. The span measuring access to initial consonant-vowel was associated with lexical selection, while the span measuring access to rhyme information was associated with phonological selection.

Conclusion

Performance on input semantic and phonological tasks predicts accuracy of picture naming performance and types of errors made by people with aphasia. These results indicate overlap in input and output semantic and phonological processing, which must be accounted for in models of lexical processing. These findings also have implications for approaches to diagnosis and treatments for lexical comprehension and production that capitalise on the overlap of input and output processing.

Treatment of the Linguistic and Temporal Components of Lexical Activation to Improve Word Retrieval in Aphasia

Current approaches to treatments for word processing impairments in aphasia emphasize two components to target, the linguistic content, semantic or phonological representations of words, and the processing component, access to and retrieval of those representations. In this study, we explore these two components of a treatment to improve lexical activation that supports access and retrieval of word representations. Five people with aphasia participated. The treatment task was repetition of concrete word pairs after a 5-s response delay which was intended to provide practice in maintaining activation of the words for that 5-s period before reproducing them. Two of the five participants demonstrated a difficulty in maintaining activation of single words in repetition, with accuracy decreasing significantly after the 5-s interval. The treatment was applied to all participants, however, to determine if its benefit was specific to those with the activation maintenance impairment. Results confirmed that the activation maintenance treatment in the context of this repetition task led to more treatment gains for the two participants who demonstrated this specific impairment. They made gains on four of the nine measures compared to improvements on one to two measures for the other participants. A second question addressed in this study was the relative importance of the item component (linguistic content) of the treatment and the processing component, maintenance of activation. To that end, there were two conditions of treatment probes, (1) repeated content for all treatment, immediate post-treatment and 3-month maintenance probes and (2) novel content for probes in these three phases of treatment. Only one participant showed significant improvement in treatment when items were novel for all probes. We discuss the possibility that this outcome reflects a more specific deficit in the temporal processing component of lexical activation compared to the two other participants who showed better performance on probes with repeated items in treatment and post-treatment phases. Clinical implications of this study and directions of future research are discussed.

Effect of Working Memory Load and Typicality on Semantic Processing in Aphasia

PURPOSE

This study evaluated the effects of a linguistic characteristic, typicality, and a processing variable, working memory on the abilities of people with aphasia (PWA) and neurologically intact adults to process semantic representations. This was accomplished using a newly developed assessment task, the Category Typicality Test, which was created for the Temple Assessment of Language and Short-Term Memory in Aphasia.

METHOD

A post hoc quasi-experimental design was used. Participants included 27 PWA and 14 neurologically intact adults who completed the picture and word versions of the Category Typicality Test, which required them to determine if two items are in the same category. Memory load was altered by increasing the number of items to be compared, and the typicality of items was altered to increase linguistic complexity.

RESULTS

A four-way mixed analysis of covariance was conducted. There was a significant interaction between working memory load and category typicality with performance accuracy decreasing as working memory load increased and category typicality decreased. There was also a significant interaction for typicality and stimuli with better performance in the picture condition and a significant interaction for working memory and group with lower performance accuracy for PWA. Post hoc pairwise comparisons revealed differences between memory load, typicality, stimuli conditions, and group. PWA also showed greater magnitude of change than neurologically intact adults when comparing high and low working memory load conditions, but not typicality conditions.

DISCUSSION

Increasing working memory load had the most substantial impact on the accuracy of category judgments in PWA, but the interaction between increased working memory load and decreased category typicality of items to be compared resulted in reduced accuracy in both groups. These findings suggest that manipulation of processing and linguistic variables in assessment will provide insight into the nature of linguistic breakdown in aphasia. Supplemental Material https://doi.org/10.23641/asha.14781996.

Exploring the Complexity of Aphasia With Network Analysis

Purpose Aphasia is a complex, neurogenic language disorder, with different aphasia syndromes hallmarked by impairment in fluency, auditory comprehension, naming, and/or repetition. Broad, standardized assessments of language domains and specific language and cognitive assessments provide a holistic impairment profile of a person with aphasia. While many recognize the correlations between assessments, there remains a need to continue understanding the complexity of relationships between assessments for the purpose of better characterization of language impairment profiles of persons with aphasia. We explored the use of network analysis to identify the complex relationships between a variety of language assessments. Method We computed a regularized partial correlation network and a directed acyclic graph network to estimate the relations between different aphasia assessments in 128 persons with aphasia. Results Western Aphasia Battery-Revised Comprehension subtest was the most central assessment in the aphasia symptom network, whereas the Philadelphia Naming Test had the most putative causal influence on other assessments. Additionally, the language assessments segregated into three empirically derived communities denoting phonology, semantics, and syntax. Furthermore, several assessments, including the Philadelphia Naming Test, belonged to multiple communities, suggesting that certain assessments may capture multiple language impairments. Conclusion We discuss the implications of using a network analysis approach for clinical intervention and driving forward novel questions in the field of clinical aphasiology. Supplemental Material https://doi.org/10.23641/asha.16620229.

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.

Individualized response to semantic versus phonological aphasia therapies in stroke

Attempts to personalize aphasia treatment to the extent where it is possible to reliably predict individual response to a particular treatment have yielded inconclusive results. The current study aimed to (i) compare the effects of phonologically versus semantically focussed naming treatment and (ii) examine biographical and neuropsychological baseline factors predictive of response to each treatment. One hundred and four individuals with chronic post-stroke aphasia underwent 3 weeks of phonologically focussed treatment and 3 weeks of semantically focussed treatment in an unblinded cross-over design. A linear mixed-effects model was used to compare the effects of treatment type on proportional change in correct naming across groups. Correlational analysis and stepwise regression models were used to examine biographical and neuropsychological predictors of response to phonological and semantic treatment across all participants. Last, chi-square tests were used to explore the association between treatment response and phonological and semantic deficit profiles. Semantically focussed treatment was found to be more effective at the group-level, independently of treatment order (P = 0.041). Overall, milder speech and language impairment predicted good response to semantic treatment (r range: 0.256-0.373) across neuropsychological tasks. The Western Aphasia Battery-Revised Spontaneous Speech score emerged as the strongest predictor of semantic treatment response (R 2 = 0.188). Severity of stroke symptoms emerged as the strongest predictor of phonological treatment response (R 2 = 0.103). Participants who showed a good response to semantic treatment were more likely to present with fluent speech compared to poor responders (P = 0.005), whereas participants who showed a good response to phonological treatment were more likely to present with apraxia of speech (P = 0.020). These results suggest that semantic treatment may be more beneficial to the improvement of naming performance in aphasia than phonological treatment, at the group-level. In terms of personalized predictors, participants with relatively mild impairments and fluent speech responded better to semantic treatment, while phonological treatment benefitted participants with more severe impairments and apraxia of speech.

Treatment of verbal short-term memory abilities to improve language function in aphasia: A case series treatment study

Recent approaches to interventions for aphasia have incorporated verbal short-term memory (STM) and working memory (WM) components. We investigated whether a treatment involving repetition of word sequences after a response delay would improve tolerance of increased verbal STM load in repetition and, consequently, improve performance on repetition and other language tasks. Eight individuals with aphasia participated. We used a single subject design with outcome measures on near-transfer tasks closely related to the treatment task and far-transfer tasks more distantly related to the treatment task. We minimized repeated presentation of stimuli in all phases of treatment to control for confounding effects of repeated exposure of treated items. Four participants demonstrated modest acquisition effects. On outcome measures, we observed improvements by some participants on near-transfer tasks, (repetition of concrete and abstract word strings and verbal spans) and far-transfer tasks (naming and discourse). Some participants demonstrated a significant decline in word repetition accuracy after a response delay before treatment, indicating difficulty in maintaining activation of linguistic representations. It was these participants who showed the most improvement on outcome measures. More studies are needed to determine who will respond to this treatment and what factors might influence the effectiveness of this treatment approach.

Understanding Speed-Accuracy Processing Dynamics in Aphasia Using Response Time Modeling

People with aphasia demonstrate language impairments evident in both performance accuracy and processing speed, but the direct relationship between accuracy and speed requires further consideration. This article describes two recent attempts to make quantitative progress in this domain using response time modeling: the diffusion model (Ratcliff, 1978) applied to two-choice tasks and a multinomial ex-Gaussian model applied to picture naming. The diffusion model may be used to characterize core linguistic processing efficiency and speed-accuracy tradeoffs independently, and research suggests that maladaptive speed-accuracy tradeoffs lead to performance impairments in at least some people with aphasia. The multinomial ex-Gaussian response time model of picture naming provides a simple and straightforward way to estimate the optimal response time cutoffs for individual people with aphasia (i.e., the cutoff where additional time is unlikely to lead to a correct response). While response time modeling applied to aphasia research is at an early stage of development, both the diffusion model and multinomial ex-Gaussian response time model of picture naming show promise and should be further developed in future work. This article also provides preliminary recommendations for clinicians regarding how to conceptualize, identify, and potentially address maladaptive speed-accuracy tradeoffs for people with aphasia.

Moving Toward Accurate Assessment of Working Memory in Adults With Neurogenically Based Communication Disorders

Purpose This article presents a viewpoint highlighting concerns regarding currently available assessments of working memory in adults with neurogenic communication disorders. Additionally, we provide recommendations for improving working memory assessment in this population. Method This viewpoint includes a critique of clinical and experimental working memory tests relevant to speech-language pathologists. We consider the terminology used to describe memory, as well as discuss language demands and test construction. Results Clinical and experimental testing of working memory in adults with neurogenic communication disorders is challenged due to theoretical, methodological, and practical limitations. The major limitations are characterized as linguistic and task demands, presentation and response modality effects, test administration, and scoring parameters. Taking these limitations into consideration, several modifications to working memory testing and their relevance to neurogenic populations are discussed. Conclusions The recommendations provided in this article can better guide clinicians and researchers to advocate for improved tests of working memory in adults with neurogenic communication disorders. Future research should continue to address these concerns and consider our recommendations.

Predicting language recovery in post-stroke aphasia using behavior and functional MRI

Language outcomes after speech and language therapy in post-stroke aphasia are challenging to predict. This study examines behavioral language measures and resting state fMRI (rsfMRI) as predictors of treatment outcome. Fifty-seven patients with chronic aphasia were recruited and treated for one of three aphasia impairments: anomia, agrammatism, or dysgraphia. Treatment effect was measured by performance on a treatment-specific language measure, assessed before and after three months of language therapy. Each patient also underwent an additional 27 language assessments and a rsfMRI scan at baseline. Patient scans were decomposed into 20 components by group independent component analysis, and the fractional amplitude of low-frequency fluctuations (fALFF) was calculated for each component time series. Post-treatment performance was modelled with elastic net regression, using pre-treatment performance and either behavioral language measures or fALFF imaging predictors. Analysis showed strong performance for behavioral measures in anomia (R² = 0.948, n = 28) and for fALFF predictors in agrammatism (R² = 0.876, n = 11) and dysgraphia (R² = 0.822, n = 18). Models of language outcomes after treatment trained using rsfMRI features may outperform models trained using behavioral language measures in some patient populations. This suggests that rsfMRI may have prognostic value for aphasia therapy outcomes.

Lesions that do or do not impair digit span: a study of 816 stroke survivors

Prior studies have reported inconsistency in the lesion sites associated with verbal short-term memory impairments. Here we asked: How many different lesion sites can account for selective impairments in verbal short-term memory that persist over time, and how consistently do these lesion sites impair verbal short-term memory? We assessed verbal short-term memory impairments using a forward digit span task from the Comprehensive Aphasia Test. First, we identified the incidence of digit span impairments in a sample of 816 stroke survivors (541 males/275 females; age at stroke onset 56 ± 13 years; time post-stroke 4.4 ± 5.2 years). Second, we studied the lesion sites in a subgroup of these patients (n = 39) with left hemisphere damage and selective digit span impairment-defined as impaired digit span with unimpaired spoken picture naming and spoken word comprehension (tests of speech production and speech perception, respectively). Third, we examined how often these lesion sites were observed in patients who either had no digit span impairments or digit span impairments that co-occurred with difficulties in speech perception and/or production tasks. Digit span impairments were observed in 222/816 patients. Almost all (199/222 = 90%) had left hemisphere damage to five small regions in basal ganglia and/or temporo-parietal areas. Even complete damage to one or more of these five regions was not consistently associated with persistent digit span impairment. However, when the same regions were spared, only 5% (23/455) presented with digit span impairments. These data suggest that verbal short-term memory impairments are most consistently associated with damage to left temporo-parietal and basal ganglia structures. Sparing of these regions very rarely results in persistently poor verbal short-term memory. These findings have clinical implications for predicting recovery of verbal short-term memory after stroke.

Adaption and preliminary validation of the Addenbrooke's Cognitive Examination-III as a screening test for mild cognitive impairment and dementia in hearing-impaired individuals

BACKGROUND

A large proportion of older adults assessed for cognitive impairment likely have hearing loss, potentially affecting accuracy of cognitive performance estimations. This study aimed to develop a hearing-impaired version of the Addenbrooke's Cognitive Examination-III (HI-ACE-III) and to assess whether the HI-ACE-III can accurately distinguish people with mild cognitive impairment (MCI) and dementia from cognitively intact controls.

METHODS

The HI-ACE-III was developed by converting verbal instructions into a visual, timed PowerPoint presentation. Seventy-four participants over the age of 60 years were classified into three groups: 29 had MCI, 15 had mild to moderate dementia and 30 were cognitively intact controls. Receiver operating characteristic (ROC) curves were graphed to test screening accuracy. Concurrent validity was examined through correlations between HI-ACE-III domain scores and relevant, visually presented standardized neuropsychological measures.

RESULTS

ROC analysis for dementia revealed an area under the curve (AUC) of 0.99, achieving excellent sensitivity (100%) and good specificity (93.3%) at an optimum cut-off of <87. The AUC for MCI was 0.86, achieving reasonable sensitivity (75.9%) and good specificity (86.7%) at an optimum cut-off of <92. HI-ACE-III subtests shared anticipated and statistically significant correlations with established measures of cognitive functioning. Internal consistency of the HI-ACE-III was excellent as verified with Cronbach's alpha (α = 0.904).

CONCLUSIONS

Preliminarily, the HI-ACE-III showed good reliability, validity and screening utility for MCI and dementia in older adults in a hearing-impairment context. The adapted HI-ACE-III may offer accurate and reliable indication of cognitive performance, supporting timely diagnosis and research examining links between hearing loss and cognitive decline.

Identifying Verbal Short-Term Memory and Working Memory Impairments in Individuals With Latent Aphasia

Purpose This study was undertaken to explore whether measures of verbal short-term memory and working memory are sensitive to impairments in people with latent aphasia, who score within normal limits on typical aphasia test batteries. Method Seven individuals with latent aphasia and 24 neurotypical control participants completed 40 tasks from the Temple Assessment of Language and Short-term Memory in Aphasia (TALSA) that assess various aspects of verbal short-term memory, working memory, and language processing. Subtests were identified that differentiated between the two groups of participants. Results Twenty-one TALSA tasks were identified on which the participants with latent aphasia had significantly different performance than the typical control participants. All of these subtests engaged verbal short-term memory, and some involved working memory as well. Furthermore, the TALSA detected individual differences in linguistic profiles among participants with latent aphasia. Conclusions People with latent aphasia may be identified by tests that tap verbal short-term memory and working memory. In addition, the TALSA was found to be sensitive to the heterogeneity of this population. Further development of these measures will improve identification and treatment of this challenging population.

Saying thirteen instead of forty-two but saying lale instead of tale: is number production special?

Stimulus Type Effect on Phonological and Semantic errors (STEPS) occurs when a person, following brain damage, produces phonemic errors with non-number words (e.g., lale for tale), but produces semantic errors with number words (e.g., thirteen for forty-two). Despite the relative frequency of this phenomenon, it has received little scholarly attention thus far. To explain STEPS, the Building Blocks hypothesis has been proposed (Cohen, Verstichel, & Dehaene, 1997; Dotan & Friedmann, 2015): the phonological output buffer includes single phonemes as the units of speech production for words, whereas entire number words are the building blocks of multi-digit production. Impairment in the phonological output buffer results in the incorrect selection of these units, leading to phonemic errors when producing non-number words, but semantic errors when producing numbers. In the present study we consider two patients, one with a deficit in the phonological output buffer, and one with a deficit in the phonological input buffer but with a preserved phonological output buffer. Number word and non-number word repetition, naming, and reading abilities were assessed. As expected, STEPS was found in the patient with deficits in the phonological output buffer in the three tasks; more notably, evidence of STEPS was also found for the patient with deficits in the phonological input buffer in the repetition task. Since our results cannot be fully explained by the Building Blocks hypothesis in its present form, we discuss the suitability of this hypothesis for the current data, and consider alternative accounts of STEPS.

Evaluating the Contribution of Executive Functions to Language Tasks in Cognitively Demanding Contexts

Purpose The purpose of this study was to determine the degree to which the executive functions of attention switching and inhibition predicted performance on language subtests from the Temple Assessment of Language and (Verbal) Short-Term Memory in Aphasia (TALSA; N. Martin, Minkina, Kohen, &Kalinyak-Fliszar, 2018) across 3 interval conditions (no delay, 5-s delay, and 5-s filled delay), which was designed to add a memory and executive load to language tasks. Method This study was a post hoc experimental design. Participants included 27 people with aphasia who were administered 5 subtests from the TALSA (Naming, Word Repetition, Nonword Repetition, Category Judgment, and Rhyming Judgment), which were selected to evaluate input and output levels of processing in the 3 interval conditions listed above. Three executive tasks were administered to evaluate inhibition (Simon and Flanker tasks) and attention switching (number-letter shifting). Results Independent variables were proportion correct on each TALSA task in 3 separate time conditions, and predictor variables were efficiency on the Simon task and number-letter shifting task. Linear regression modeling was completed, which revealed that inhibition was a significant predictor of proportion correct for Word Repetition and Category Judgment in the 5-s filled interval condition. Conclusions Our findings indicate that inhibition plays a role in completing tasks that require lexical and/or semantic processing in cognitively demanding conditions. Attention switching was not a significant predictor for any task. These results are an important step toward creating methods to evaluate executive skills in the context of language production. Supplemental Material https://doi.org/10.23641/asha.9765107.

Clinician Perspectives on the Assessment of Short-Term Memory in Aphasia

BACKGROUND

Verbal short-term memory (STM) and the related ability, working memory (WM), are widely understood to be integral components of language production and comprehension. However, assessment of these abilities in people with aphasia is hampered by a lack of valid, standardized measures that are clinically appropriate. Focusing primarily on verbal STM, we held a series of five focus groups with speech-language pathologists (SLPs) to understand better their current clinical practices and their beliefs and attitudes regarding assessment of verbal STM in aphasia.

AIMS

The purpose of this study was to explore the attitudes, beliefs and preferences of clinical SLPs to determine: (1) current practices related to verbal STM assessment; (2) the extent to which practices reflect current theories of aphasia and the role of verbal STM in language processing; and (3) practical considerations regarding aphasia assessment in clinical practice.

METHODS & PROCEDURES

Five focus groups were conducted using a semi-structured interview protocol with a total of 44 SLPs. Grounded theory methodology was used to collect, code and analyse the data. Codes were reviewed to identify emerging themes. Themes were compared to explore meta-themes, connections and potential theoretical frameworks.

OUTCOMES & RESULTS

Five main themes were identified: (1) The theoretical understanding that clinical SLPs have regarding the role of verbal STM in aphasia is not always consistent with clinical practice; (2) Clinical SLPs highly value functionally relevant assessments; (3) The intense time constraints in clinical practice affect all aspects of assessment; (4) Clinical SLPs feel that there is a lack of appropriate tests for assessment of STM in aphasia; and (5) Clinical SLPs prefer tests that are comprehensive, easy to administer and psychometrically sound.

CONCLUSIONS

Clinical SLPs report a lack of standardized measures to assess STM in individuals with aphasia. Researchers are met with several challenges in the development of these tests including effective communication with clinicians regarding the benefit of verbal STM assessments, especially as it relates to functional skills, and the creation of a test that is comprehensive yet simple, quick and easy to administer.

WORD LEARNING IN APHASIA: TREATMENT IMPLICATIONS AND STRUCTURAL CONNECTIVITY ANALYSES

OBJECTIVE

Of current interest in aphasia research is the relevance of what we can learn from studying word learning ability in aphasia. In a preliminary study, we addressed two issues related to the novel word learning ability of individuals with aphasia. First, as word learning engages large-scale cognitive-linguistic systems (language skills, verbal short-term memory (STM), other memory and executive functions), we probed whether novel word learning practice in three people with aphasia could stimulate these language-related systems. Second, as lesion correlates affecting word learning in aphasia remain unclear, we examined whether the structural integrity of the left arcuate fasciculus (AF) in the same three individuals is related to outcomes of novel word learning practice.

METHOD

To stimulate word learning systems, our three participants practiced for 4 weeks with an explicit novel word - novel referent word learning task, adopted from the Ancient Farming Equipment learning paradigm (Laine & Salmelin, 2010). The participants' progress on receptive and expressive novel word learning was followed up, and their language and verbal STM abilities as well as single-session novel word learning (Learning to Name Aliens by Gupta, Martin, Abbs, Schwartz & Lipinski, 2006) were tested before and after the practice period. To address the second question, we analyzed the participants' structural MRI scans with respect to the integrity of the left AF and its overlap with the lesion areas.

RESULTS

All participants showed some receptive word learning in the trained task, as well as improvements in verbal STM span at posttest. Two of the three participants also showed improved performance on some of the language outcome measures. One participant with partially spared left AF, especially temporo-parietal connections, exhibited better word learning performance than the other two who had larger damage and disconnection of the AF.

CONCLUSIONS

While the present results are preliminary, they open the possibility that novel word learning practice in aphasia may stimulate remaining word learning mechanisms in aphasia, and thereby influence language and verbal STM abilities. These results also suggest that preservation of novel word learning ability in aphasia in part depends on the integrity of the left arcuate track.

Maintenance Versus Transmission Deficits: The Effect of Delay on Naming Performance in Aphasia

We propose that deficits in lexical retrieval can involve difficulty in transmission of activation between processing levels, or difficulty in maintaining activation. In support, we present an investigation of picture naming by persons with aphasia in which the naming response is generated after a 1 s (sec) cue to respond in one condition or a 5 s cue to respond in another. Some individuals did better after 5 s, some did worse after 5 s, and some were not impacted by the delay. It is suggested that better performance after 5 s indicates a transmission deficit and that worse performance after 5 s indicates a maintenance deficit. To support this hypothesis, we adapted the two-step semantic-phonological model of lexical retrieval (Schwartz et al., 2006) so that it can simulate the passage of time and can simulate lesions in transmission (its semantic and phonological connection strength parameters) and/or maintenance (its decay parameter). The naming error patterns after 1 and 5 s for each participant were successfully fit to the model. Persons who did better after 5 s were found to have low connection strength parameters, persons who did worse after 5 s were simulated with an increased decay rate, and persons whose performance did not differ with delay were found to have lesions of both types. Some potential theoretical and clinical implications are discussed.

The Link Between Verbal Short-Term Memory and Anomia Treatment Gains

Purpose A significant relationship between verbal short-term memory (STM) and language performance in people with aphasia has been found across studies. However, very few studies have examined the predictive value of verbal STM in treatment outcomes. This study aims to determine if verbal STM can be used as a predictor of treatment success. Method Retrospective data from 25 people with aphasia in a larger randomized controlled trial of phonomotor treatment were analyzed. Digit and word spans from immediately pretreatment were run in multiple linear regression models to determine whether they predict magnitude of change from pre- to posttreatment and follow-up naming accuracy. Pretreatment, immediately posttreatment, and 3 months posttreatment digit and word span scores were compared to determine if they changed following a novel treatment approach. Results Verbal STM, as measured by digit and word spans, did not predict magnitude of change in naming accuracy from pre- to posttreatment nor from pretreatment to 3 months posttreatment. Furthermore, digit and word spans did not change from pre- to posttreatment or from pretreatment to 3 months posttreatment in the overall analysis. A post hoc analysis revealed that only the less impaired group showed significant changes in word span scores from pretreatment to 3 months posttreatment. Discussion The results suggest that digit and word spans do not predict treatment gains. In a less severe subsample of participants, digit and word span scores can change following phonomotor treatment; however, the overall results suggest that span scores may not change significantly. The implications of these findings are discussed within the broader purview of theoretical and empirical associations between aphasic language and verbal STM processing.

Nonlinguistic Cognitive Factors Predict Treatment-Induced Recovery in Chronic Poststroke Aphasia

OBJECTIVE

To determine if pretreatment nonlinguistic cognition predicted language treatment outcomes and if so, which specific nonlinguistic cognitive subskills predicted naming therapy outcomes.

DESIGN

Retrospective.

SETTING

Research clinic.

PARTICIPANTS

Study 1 included data from 67 persons with aphasia who underwent language treatment and a pretreatment cognitive-linguistic assessment battery (N=67). Study 2 included data from 27 study 1 participants who completed additional pretreatment nonlinguistic cognitive assessments.

INTERVENTIONS

120-minute sessions of sentence comprehension (n=26) or naming treatment (n=41) 2 times per week for up to 10-12 weeks.

MAIN OUTCOME MEASURES

Proportion of potential maximal gain (PMG) (assessed immediately after treatment [10-12wk]; formula=mean posttreatment score-mean pretreatment score/total number of trained items-mean pretreatment score) and proportion of potential maximal gain maintained (PMGM) (assessed 12wk after posttreatment [22-24wk]; formula=mean maintenance score-mean pretreatment score/total number of trained items-mean pretreatment score) as outcome variables; and pretreatment assessment scores as predictor variables.

RESULTS

In study 1, 37% of participants demonstrated nonlinguistic cognitive deficits. Principal component analyses reduced assessment data to 2 components: linguistic and nonlinguistic cognition. Backward elimination regression revealed that higher linguistic and nonlinguistic cognitive function significantly predicted higher PMG after language therapy. In study 2, principal component analysis of only the nonlinguistic cognitive measures identified 3 components: executive function, verbal short-term memory, and visual short-term memory. Controlling for pretreatment apraxia of speech and auditory comprehension deficits, regression analyses revealed that higher executive function and visual short-term memory significantly predicted higher PMG and PMGM after naming therapy.

CONCLUSIONS

Pretreatment nonlinguistic cognitive function significantly influenced language treatment outcomes and maintenance of therapy gains.

The Methodological Quality of Short-Term/Working Memory Treatments in Poststroke Aphasia: A Systematic Review

Purpose The aims of this systematic review are to provide a critical overview of short-term memory (STM) and working memory (WM) treatments in stroke aphasia and to systematically evaluate the internal and external validity of STM/WM treatments. Method A systematic search was conducted in February 2014 and then updated in December 2016 using 13 electronic databases. We provided descriptive characteristics of the included studies and assessed their methodological quality using the Risk of Bias in N-of-1 Trials quantitative scale ( Tate et al., 2015 ), which was completed by 2 independent raters. Results The systematic search and inclusion/exclusion procedure yielded 17 single-case or case-series studies with 37 participants for inclusion. Nine studies targeted auditory STM consisting of repetition and/or recognition tasks, whereas 8 targeted attention and WM, such as attention process training including n-back tasks with shapes and clock faces as well as mental math tasks. In terms of their methodological quality, quality scores on the Risk of Bias in N-of-1 Trials scale ranged from 4 to 17 ( M = 9.5) on a 0-30 scale, indicating a high risk of bias in the reviewed studies. Effects of treatment were most frequently assessed on STM, WM, and spoken language comprehension. Transfer effects on communication and memory in activities of daily living were tested in only 5 studies. Conclusions Methodological limitations of the reviewed studies make it difficult, at present, to draw firm conclusions about the effects of STM/WM treatments in poststroke aphasia. Further studies with more rigorous methodology and stronger experimental control are needed to determine the beneficial effects of this type of intervention. To understand the underlying mechanisms of STM/WM treatment effects and how they relate to language functioning, a careful choice of outcome measures and specific hypotheses about potential improvements on these measures are required. Future studies need to include outcome measures of memory functioning in everyday life and psychosocial functioning more generally to demonstrate the ecological validity of STM and WM treatments.

Effects of Verb Overlap on Structural Priming in Dialogue: Implications for Syntactic Learning in Aphasia

Purpose Although there is increasing interest in using structural priming as a means to ameliorate grammatical encoding deficits in persons with aphasia (PWAs), little is known about the precise mechanisms of structural priming that are associated with robust and enduring effects in PWAs. Two dialogue-like comprehension-to-production priming experiments investigated whether lexically independent (abstract structural) priming and/or lexically (verb) specific priming yields immediate and longer, lasting facilitation of syntactic production in PWAs. Method Seventeen PWAs and 20 healthy older adults participated in a collaborative picture-matching task where participant and experimenter took turns describing picture cards using transitive and dative sentences. In Experiment 1, a target was elicited immediately following a prime. In Experiment 2, 2 unrelated utterances intervened between a prime and target, thereby allowing us to examine lasting priming effects. In both experiments, the verb was repeated for half of the prime-target pairs to examine the lexical (verb) boost on priming. Results Healthy older adults demonstrated abstract priming in both transitives and datives not only in the immediate (Experiment 1) but also in the lasting (Experiment 2) priming condition. They also showed significantly enhanced priming by verb overlap (lexical boost) in transitives during immediate priming. PWAs demonstrated abstract priming in transitives in both immediate and lasting priming conditions. However, the magnitude of priming was not enhanced by verb overlap. Conclusions Abstract structural priming, but not lexically specific priming, is associated with reliable and lasting facilitation of message-structure mapping in aphasia. The findings also suggest that implicit syntactic learning via a dialogue-like comprehension-to-production task remains preserved in aphasia.

The Subjective Experience of Inner Speech in Aphasia Is a Meaningful Reflection of Lexical Retrieval

Purpose Individuals with aphasia often report that they feel able to say words in their heads, regardless of speech output ability. Here, we examine whether these subjective reports of successful "inner speech" (IS) are meaningful and test the hypothesis that they reflect lexical retrieval. Method Participants were 53 individuals with chronic aphasia. During silent picture naming, participants reported whether or not they could say the name of each item inside their heads. Using the same items, they also completed 3 picture-based tasks that required phonological retrieval and 3 matched auditory tasks that did not. We compared participants' performance on these tasks for items they reported being able to say internally versus those they reported being unable to say internally. Then, we examined the relationship of psycholinguistic word features to self-reported IS and spoken naming accuracy. Results Twenty-six participants reported successful IS on nearly all items, so they could not be included in the item-level analyses. These individuals performed correspondingly better than the remaining participants on tasks requiring phonological retrieval, but not on most other language measures. In the remaining group ( n = 27), IS reports related item-wise to performance on tasks requiring phonological retrieval, but not to matched control tasks. Additionally, IS reports were related to 3 word characteristics associated with lexical retrieval, but not to articulatory complexity; spoken naming accuracy related to all 4 word characteristics. Six participants demonstrated evidence of unreliable IS reporting; compared with the group, they also detected fewer errors in their spoken responses and showed more severe language impairments overall. Conclusions Self-reported IS is meaningful in many individuals with aphasia and reflects lexical phonological retrieval. These findings have potential implications for treatment planning in aphasia and for our understanding of IS in the general population.

Short-term memory span in aphasia: Insights from speech-timing measures

Auditory-verbal short-term memory impairments are part and parcel of aphasia and interfere with linguistic processing. To date, the science about short-term memory impairments in aphasia has been generated and dominated by studying measures of accuracy, that is, span length. Because accuracy is expressed through speech, examining the speech-timing characteristics of persons with aphasia as they engage in spoken recall could reveal insights about the manner in which accuracy is achieved. Six speech-timing measures (e.g., response durations, pause durations) were elicited from the speech waveform of word span tasks from twelve people with aphasia. Speech-timing measures were compared to neuro-typical control participants. Speech-timing performance between erroneous and correct responses in the aphasia group was also examined. Across all measures, people with aphasia produced considerably longer speech-timing patterns in comparison to control participants. Memory load affected some measures in people with aphasia and control participants. Speech-timing in correct response trials was shorter than responses in erroneous trials. Memory span correlated only with one measure, namely, speech time (defined as the sum of each individual word duration in a response). Speech time also correlated with the following measures: Aphasia severity (Aphasia Quotient of the Western Aphasia Battery), spontaneous speech, and language comprehension (also measured by the Western Aphasia Battery). Some protracted speech-timing patterns in the aphasia group may be explained by a deregulation of activation-decay patterns. However, in the absence of further evidence from people with aphasia, possible issues around the sensitivity of some speech-timing measures limit firmer conclusions. Speech-timing measures are response-time measures, which have not been systematically studied in studies of short-term or working memory in aphasia and as such, can push the current boundaries of knowledge of short-term and working memory impairments in aphasia, not only in stroke related aphasia but also other neurological conditions.