Speech entrainment compensates for Broca's area damage

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.

The Effect of Prosodic Timing Structure on Unison Production in People With Aphasia

PURPOSE

Unison production is a common aphasia treatment technique in which the clinician and the person with aphasia (PWA) produce phrases aloud together. It can be implemented using a typical "conversational," syntax-influenced prosodic timing structure, or with a "metrical," beat-based timing structure, but to date no study has directly compared these two approaches. This study compared the effects of metrical versus conversational prosodic timing during unison production on the (a) accuracy of participants' spoken output and (b) timing alignment of participants' productions with the stimuli.

METHOD

PWAs and controls listened to conversationally timed and metrically timed sentences and repeated them in unison with audio recordings. Productions were transcribed and scored in two ways: (a) Accuracy was calculated as the percentage of correctly produced syllables, and (b) timing alignment was determined by extracting the voice onset moment of identical target syllables in the unison stimuli and participant productions in both conditions and comparing the corresponding time points.

RESULTS

Metrical timing yielded a greater number of accurate syllables in both groups, with larger effect in PWAs than in controls. Both groups exhibited more anticipatory, less variable timing when speaking along with metrical stimuli, though evidence of such prediction was also present in the conversational condition.

CONCLUSIONS

Results suggest that unison production works via entrainment-a process that utilizes prediction to guide synchronous production of spoken output. Metrically regular stimuli may facilitate this process as they are more rhythmically predictable. Future work will examine key behavioral variables that predict benefit from unison production and metrical timing.

Examining cortical tracking of the speech envelope in post-stroke aphasia

Introduction

People with aphasia have been shown to benefit from rhythmic elements for language production during aphasia rehabilitation. However, it is unknown whether rhythmic processing is associated with such benefits. Cortical tracking of the speech envelope (CTenv) may provide a measure of encoding of speech rhythmic properties and serve as a predictor of candidacy for rhythm-based aphasia interventions.

Methods

Electroencephalography was used to capture electrophysiological responses while Spanish speakers with aphasia (n = 9) listened to a continuous speech narrative (audiobook). The Temporal Response Function was used to estimate CTenv in the delta (associated with word- and phrase-level properties), theta (syllable-level properties), and alpha bands (attention-related properties). CTenv estimates were used to predict aphasia severity, performance in rhythmic perception and production tasks, and treatment response in a sentence-level rhythm-based intervention.

Results

CTenv in delta and theta, but not alpha, predicted aphasia severity. Neither CTenv in delta, alpha, or theta bands predicted performance in rhythmic perception or production tasks. Some evidence supported that CTenv in theta could predict sentence-level learning in aphasia, but alpha and delta did not.

Conclusion

CTenv of the syllable-level properties was relatively preserved in individuals with less language impairment. In contrast, higher encoding of word- and phrase-level properties was relatively impaired and was predictive of more severe language impairments. CTenv and treatment response to sentence-level rhythm-based interventions need to be further investigated.

Methodologies for task-fMRI based prognostic biomarkers in response to aphasia treatment

With the diversity in aphasia coupled with diminished gains at the chronic phase, it is imperative to deliver effective rehabilitation plans. Treatment outcomes have therefore been predicted using lesion-to-symptom mapping, but this method lacks holistic functional information about the language-network. This study, therefore, aims to develop whole-brain task-fMRI multivariate analysis to neurobiologically inspect lesion impacts on the language-network and predict behavioral outcomes in persons with aphasia (PWA) undergoing language therapy. In 14 chronic PWA, semantic fluency task-fMRI and behavioral measures were collected to develop prediction methodologies for post-treatment outcomes. Then, a recently developed imaging-based multivariate method to predict behavior (i.e., LESYMAP) was optimized to intake whole-brain task-fMRI data, and systematically tested for reliability with mass univariate methods. We also accounted for lesion size in both methods. Results showed that both mass univariate and multivariate methods identified unique biomarkers for semantic fluency improvements from baseline to 2-weeks post-treatment. Additionally, both methods demonstrated reliable spatial overlap in task-specific areas including the right middle frontal gyrus when identifying biomarkers of language discourse. Thus whole-brain task-fMRI multivariate analysis has the potential to identify functionally meaningful prognostic biomarkers even for relatively small sample sizes. In sum, our task-fMRI based multivariate approach holistically estimates post-treatment response for both word and sentence production and may serve as a complementary tool to mass univariate analysis in developing brain-behavior relationships for improved personalization of aphasia rehabilitation regimens.

Recursive Self-feedback Improved Speech Fluency in Two Patients with Chronic Nonfluent Aphasia

Background

Previous studies have demonstrated that people with nonfluent aphasia (PWNA) improve their language production after repeating personalized scripts, modeled by speech-language pathologists (SLPs). If PWNA could improve by using their own self-feedback, relying less on external feedback, barriers to aphasia treatment, such as a dearth of clinicians and mobility issues, can be overcome. Here we examine whether PWNA improve their language production through an automated procedure that exposes them to playbacks of their own speech, which are updated recursively, without any feedback from SLPs.

Method

We tested if recursive self-feedback could improve speech fluency in two persons with chronic nonfluent aphasia. We compared two treatments: script production with recursive self-feedback (a new technique) and a non-self-feedback training. We administered the treatments remotely to the participants through their smartphones using two versions of a mobile app we developed. Each participant engaged in each treatment for about three weeks. We estimated clinical improvements of script production through a quantitative trend analysis and nonoverlap of all pairs.

Results

Recursive self-feedback improved speaking rate and speech initiation latency of trained and untrained scripts in both participants. The control (non-self-feedback) training was also effective, but it induced a somewhat weaker improvement in speaking rate, and improved speech initiation latency in only one participant.

Conclusion

Our findings provide preliminary evidence that PWNA can improve their speaking rate and speech initiation latency during production of scripts via fully automated recursive self-feedback. The beneficial effects of recursive self-feedback training suggest that speech unison and repeated exposures to written scripts may be optional ingredients of script-based treatments for aphasia.

The role of the basal ganglia and cerebellum in adaptation to others' speech rate and rhythm: A study of patients with Parkinson's disease and cerebellar degeneration

BACKGROUND

Spoken language is constantly undergoing change: Speakers within and across social and regional groups influence each other's speech, leading to the emergence and drifts of accents in a language. These processes are driven by mutual unintentional imitation of the phonetic details of others' speech in conversational interactions, suggesting that continuous auditory-motor adaptation takes place in interactive language use and plasticity of auditory-motor representations of speech persists across the lifespan. The brain mechanisms underlying this large-scale social-linguistic behavior are still poorly understood.

RESEARCH AIM

To investigate the role of cerebellar and basal ganglia dysfunctions in unintended adaptation to the speech rhythm and articulation rate of a second speaker.

METHODS

Twelve patients with spinocerebellar ataxia type 6 (SCA6), 15 patients with Parkinson's disease (PD), and 27 neurologically healthy controls (CTRL) participated in two interactive speech tasks, i.e., sentence repetition and "turn-taking" (i.e., dyadic interaction with sentences produced by a model speaker). Production of scripted sentences was used as a control task. Two types of sentence rhythm were distinguished, i.e., regular and irregular, and model speech rate was manipulated in 12 steps between 2.9 and 4.0 syllables per second. Acoustic analyses of the participants' utterances were performed to determine the extent to which participants adapted their speech rate and rhythm to the model.

RESULTS

Neurologically healthy speakers showed significant adaptation of rate in all conditions, and of rhythm in the repetition task and partly also the turn-taking task. Patients with PD showed a stronger propensity to adapt than the controls. In contrast, the patients with cerebellar degeneration were largely insensitive to the model speaker's rate and rhythm. Contrary to expectations, sentences with an irregular speech rhythm exerted a stronger adaptive attraction than regular sentences in the two patient groups.

CONCLUSIONS

Cerebellar degeneration inhibits the propensity to covertly adapt to others' speech. Striatal dysfunction in Parkinson's disease spares or even promotes the tendency to accommodate to other speakers' speech rate and rhythm.

Effects of a new speech support application on intensive speech therapy and changes in functional brain connectivity in patients with post-stroke aphasia

Aphasia is a language disorder that occurs after a stroke and impairs listening, speaking, reading, writing, and calculation skills. Patients with post-stroke aphasia in Japan are increasing due to population aging and the advancement of medical treatment. Opportunities for adequate speech therapy in chronic stroke are limited due to time constraints. Recent studies have reported that intensive speech therapy for a short period of time or continuous speech therapy using high-tech equipment, including speech applications (apps, can improve aphasia even in the chronic stage. However, its underlying mechanism for improving language function and its effect on other cognitive functions remains unclear. In the present study, we investigated whether intensive speech therapy using a newly developed speech support app could improve aphasia and other cognitive functions in patients with chronic stroke. Furthermore, we examined whether it can alter the brain network related to language and other cortical areas. Thus, we conducted a prospective, single-comparison study to examine the effects of a new speech support app on language and cognitive functions and used resting state functional MRI (rs-fMRI) regions of interest (ROI) to ROI analysis to determine changes in the related brain network. Two patients with chronic stroke participated in this study. They used the independent speech therapy system to perform eight sets of 20 randomly presented words/time (taking approximately 20 min), for 8 consecutive weeks. Their language, higher cognitive functions including attention function, and rs-fMRI, were evaluated before and after the rehabilitation intervention using the speech support app. Both patients had improved pronunciation, daily conversational situations, and attention. The rs-fMRI analysis showed increased functional connectivity of brain regions associated with language and attention related areas. Our results show that intensive speech therapy using this speech support app can improve language and attention functions even in the chronic stage of stroke, and may be a useful tool for patients with aphasia. In the future, we will conduct longitudinal studies with larger numbers of patients, which we hope will continue the trends seen in the current study, and provide even stronger evidence for the usefulness of this new speech support app.

Predictors of Therapy Response in Chronic Aphasia: Building a Foundation for Personalized Aphasia Therapy

Chronic aphasia, a devastating impairment of language, affects up to a third of stroke survivors. Speech and language therapy has consistently been shown to improve language function in prior clinical trials, but few clinicially applicable predictors of individual therapy response have been identified to date. Consequently, clinicians struggle substantially with prognostication in the clinical management of aphasia. A rising prevalence of aphasia, in particular in younger populations, has emphasized the increasing demand for a personalized approach to aphasia therapy, that is, therapy aimed at maximizing language recovery of each individual with reference to evidence-based clinical recommendations. In this narrative review, we discuss the current state of the literature with respect to commonly studied predictors of therapy response in aphasia. In particular, we focus our discussion on biographical, neuropsychological, and neurobiological predictors, and emphasize limitations of the literature, summarize consistent findings, and consider how the research field can better support the development of personalized aphasia therapy. In conclusion, a review of the literature indicates that future research efforts should aim to recruit larger samples of people with aphasia, including by establishing multisite aphasia research centers.

Get in Sync: Active Ingredients and Patient Profiles in Scripted-Sentence Learning in Spanish Speakers With Aphasia

PURPOSE

Script training is a well-established treatment for aphasia, but its evidence comes almost exclusively from monolingual English speakers with aphasia. Furthermore, its active ingredients and profiles of people with aphasia (PWA) that respond to this treatment remain understudied. This study aimed to adapt a scripted-sentence learning protocol to Colombian Spanish speakers with aphasia, investigate speech entrainment (i.e., unison production of sentences) as an active ingredient for scripted-sentence learning, and identify patient profiles associated with better scripted-sentence learning.

METHOD

Fourteen monolingual Spanish speakers with aphasia learned a set of 30 sentences. To examine speech entrainment as an active ingredient for scripted-sentence learning, we investigated whether sentences containing externally added rhythmic cues (involving stress-aligned vs. metronomic rhythmic cues) would result in better scripted-sentence learning compared with control sentences. Learning was measured via postsession probes and analyzed using mixed-effects logistic regression models. The relationship between scripted-sentence learning and baseline language and rhythmic processing measures was also examined.

RESULTS

Significant scripted-sentence learning over time indicated a successful adaptation of a script-training protocol to Spanish. PWA learned significantly more scripted sentences in the rhythmically enhanced conditions compared with the control condition. There were no differences between rhythmically enhanced conditions (stress-aligned vs. metronomic). In terms of patient profiles, it was found that PWA with more severe aphasia demonstrated larger learning gains, but rhythmic processing showed little association with learning estimates.

CONCLUSIONS

To our knowledge, this study provides the first adaptation of a scripted-sentence learning protocol for monolingual Spanish speakers with aphasia, demonstrating cross-linguistic benefits of script training interventions. Highlighting rhythmic features during speech entrainment facilitated scripted-sentence learning in Spanish speakers with aphasia, suggesting that speech entrainment may be an active ingredient for scripted-sentence learning. More severe aphasia was associated with better scripted-sentence learning, suggesting that more severely impaired individuals are likely to benefit most from this treatment.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.19241847.

Complexity and feedback during script training in aphasia: A feasibility study

OBJECTIVE

To explore the impact of complexity and feedback on script training outcomes in aphasia DESIGN: Randomized balanced single-blind 2 × 2 factorial design SETTING: Freestanding urban rehabilitation hospital.

PARTICIPANTS

Adults with fluent and nonfluent aphasia (at least six months post-onset).

INTERVENTIONS

Experimental treatment was AphasiaScripts®, a computer-based script training program. Scripts were 10-turns long and developed at different complexity levels to allow for comparison of high versus low complexity. The program was modified to contrast high versus low feedback conditions during sentence practice. Participants were instructed to practice three 30-minute sessions per day, six days a week for three weeks.

MAIN MEASURES

Gains achieved from baseline in accuracy and rate of production of trained and untrained script sentences at post-treatment and at 3-, 6- and 12-weeks after the end of treatment.

RESULTS

Sixteen participants completed the intervention. On the trained script, gains were statistically significant for both accuracy and words per minute, at post-treatment and 3-, 6- and 12-week maintenance. Gains on the untrained script were smaller than on the trained script; they were statistically significant only for accuracy at post-treatment and 3-week maintenance. Complexity had an influence on accuracy at post-treatment (F(1) = 4.8391, p = 0.0501) and at maintenance (F(1) = 5.3391, p = 0.04125). Practicing scripts with high complexity increased accuracy by 11.33% at post-treatment and by 9.90% at maintenance compared to scripts with low complexity. Participants with nonfluent aphasia made greater gains than those with fluent aphasia. There was no significant effect of feedback.

CONCLUSION

This study reinforces script training as a treatment option for aphasia. Results highlight the use of more complex scripts to better promote acquisition and maintenance of script production skills. There is a need for further investigation of these variables with larger samples and with other types of aphasia treatments.

CLINICALTRIALS

gov identifier: NCT01597037.

Modified script training for nonfluent/agrammatic primary progressive aphasia with significant hearing loss: A single-case experimental design

Speech-language pathology caseloads often include individuals with hearing loss and a coexisting neurogenic communication disorder. However, specific treatment techniques and modifications designed to accommodate this population are understudied. Using a single-case experimental design, the current study investigated the utility of modified Video Implemented Script Training for Aphasia (VISTA) for an individual with nonfluent/agrammatic variant primary progressive aphasia and severe-to-profound, bilateral hearing loss. We analyzed the impact of this intervention, which incorporates orthographic input and rehearsal, on script production accuracy, speech intelligibility, grammatical complexity, mean length of utterance, and speech rate. Treatment resulted in comparable positive outcomes relative to a previous study evaluating script training in nonfluent/agrammatic primary progressive aphasia patients with functional hearing. Follow-up data obtained at three months, six months, and one year post-treatment confirmed maintenance of treatment effects for trained scripts. To our knowledge, this is the first study to investigate a modified speech-language intervention tailored to the needs of an individual with PPA and hearing loss, with findings confirming that simple treatment modifications may serve to broaden the range of treatment options available to those with concomitant sensory and communication impairments.

Behavioral interventions for primary progressive aphasia

Primary progressive aphasia (PPA) is a neurodegenerative syndrome characterized by a gradual loss of communication ability. Due to the centrality of communication deficits, speech-language pathologists play a prominent role in the provision of care for individuals with PPA. In this chapter, we outline a person-centered approach to the management of PPA that aims to preserve independence for as long as possible while anticipating future decline in communication and other domains. A growing evidence base supports the utility of speech-language treatment approaches in PPA, including restitutive, compensatory, and communication partner-focused techniques. Restitutive interventions aim to rebuild lost communication skills, such as naming or fluent speech production. Compensatory approaches include training with high- and low-tech augmentative and alternative communication systems that provide complementary means of communication beyond speech. Communication partner interventions focus on education and strategy training in order to equip conversation partners as skilled communication facilitators. Throughout intervention, clinicians should aim to provide treatment that impacts functional communication and promotes social engagement. Given the documented benefits of speech-language intervention in PPA, we are optimistic that such treatment will become the standard of care and that additional research will continue to improve the quality and accessibility of behavioral interventions.

Neuroanatomical correlates of speech and singing production in chronic post-stroke aphasia

A classical observation in neurology is that aphasic stroke patients with impairments in speech production can nonetheless sing the same utterances. This preserved ability suggests a distinctive neural architecture for singing that could contribute to speech recovery. However, to date, these structural correlates remain unknown. Here, we combined a multivariate lesion-symptom mapping and voxel-based morphometry approach to analyse the relationship between lesion patterns and grey matter volume and production rate in speech and singing tasks. Lesion patterns for spontaneous speech and cued repetition extended into frontal, temporal and parietal areas typically reported within the speech production network. Impairment in spontaneous singing was associated with damage to left anterior-posterior superior and middle temporal gyri. Preservation of grey matter volume in the same regions where damage led to poor speech and singing production supported better performance in these tasks. When dividing the patients into fluent and dysfluent singers based on singing performance from demographically matched controls, we found that preservation of left middle temporal gyrus was related to better spontaneous singing. These findings provide insights into the structural correlates of singing in chronic aphasia and may serve as biomarkers to predict treatment response in clinical trials using singing-based interventions for speech rehabilitation.

Functional Connectivity and Speech Entrainment Speech Entrainment Improves Connectivity Between Anterior and Posterior Cortical Speech Areas in Non-fluent Aphasia

BACKGROUND

Speech entrainment (SE), the online mimicking of an audio-visual speech model, has been shown to increase speech fluency in individuals with non-fluent aphasia. One theory that may explain why SE improves speech output is that it synchronizes functional connectivity between anterior and posterior language regions to be more similar to that of neurotypical speakers.

OBJECTIVES

The present study tested this by measuring functional connectivity between 2 regions shown to be necessary for speech production, and their right hemisphere homologues, in 24 persons with aphasia compared to 20 controls during both free (spontaneous) speech and SE.

METHODS

Regional functional connectivity in participants with aphasia were normalized to the control data. Two analyses were then carried out: (1) normalized functional connectivity was compared between persons with aphasia and controls during free speech and SE and (2) stepwise linear models with leave-one-out cross-validation including normed functional connectivity during both tasks and proportion damage to the left hemisphere as independent variables were created for each language score.

RESULTS

Left anterior-posterior functional connectivity and left posterior to right anterior functional connectivity were significantly more similar to connectivity of the control group during SE compared to free speech. Additionally, connectivity during free speech was more associated with language measures than connectivity during SE.

CONCLUSIONS

Overall, these results suggest that SE promotes normalization of functional connectivity (i.e., return to patterns observed in neurotypical controls), which may explain why individuals with non-fluent aphasia produce more fluent speech during SE compared to spontaneous speech.

Speech rehabilitation in post-stroke aphasia using visual illustration of speech articulators: A case report study

Recent studies on the remediation of speech disorders suggest that providing visual information of speech articulators may contribute to improve speech production. In this study, we evaluate the effectiveness of an illustration-based rehabilitation method on speech recovery of a patient with non-fluent chronic aphasia. The Ultraspeech-player software allowed visualization by the patient of reference tongue and lip movements recorded using ultrasound and video imaging. This method can improve the patient's awareness of their own lingual and labial movements, which can increase the ability to coordinate and combine articulatory gestures. The effects of this method were assessed by analyzing performance during speech tasks, the phonological processes identified in the errors made during the phoneme repetition task and the acoustic parameters derived from the speech signal. We also evaluated cognitive performance before and after rehabilitation. The integrity of visuospatial ability, short-term and working memory and some executive functions supports the effectiveness of the rehabilitation method. Our results showed that illustration-based rehabilitation technique had a beneficial effect on the patient's speech production, especially for stop and fricative consonants which are targeted (high visibility of speech articulator configurations) by the software, but also on reading abilities. Acoustic parameters indicated an improvement in the distinction between consonant categories: voiced and voiceless stops or alveolar, post-alveolar and labiodental fricatives. However, the patient showed little improvement for vowels. These results confirmed the advantage of using illustration-based rehabilitation technique and the necessity of detailed subjective and objective intra-speaker evaluation in speech production to fully evaluate speech abilities.

Speech timing changes accompany speech entrainment in aphasia

BACKGROUND

Prior speech entrainment studies, where individuals with non-fluent aphasia mimic an audio-visual model, suggest speech entrainment improves speech fluency, as indexed by various linguistic measures (e.g., the total number of different words produced per minute). Here, more precise speech timing adjustments accompanying entrained speech were studied and compared to spontaneous speech to determine how these temporal variables relate to the fluency inducing effects of speech entrainment in aphasia.

METHODS

Thirty-one left hemisphere stroke survivors classified with fluent or non-fluent speech were audio-video recorded as they described a picture and during speech entrainment. Speech fluency was documented using the Western Aphasia Battery-Revised. Acoustic measures of speech timing included total number of syllables, speech rate, articulatory rate, silent pause frequency and duration. Standard descriptive statistics and a two-factor mixed model analysis of variance were used to investigate group, task, and 'group x task' interaction effects.

FINDINGS

All acoustic measures of speech timing differentiated the fluent and nonfluent groups except for silent pause frequency. Differences between speech entrainment and spontaneous speech were found for most acoustic measures of speech timing and speaker groups, yet the direction of the effect varied. Stroke survivors classified with non-fluent aphasia improved speech fluency such that speech entrainment elicited pause adjustments facilitating more typical speech timing in comparison to spontaneous speech.

CONCLUSION

Overall, findings provide further evidence of the impact of speech entrainment on measures of speech timing to help individuals with non-fluent aphasia to practice speaking more fluently. Practicing speaking more fluently may ultimately impact perceptual judgments of speech naturalness and social acceptance for persons with aphasia.

Neural structures supporting spontaneous and assisted (entrained) speech fluency

Non-fluent speech is one of the most common impairments in post-stroke aphasia. The rehabilitation of non-fluent speech in aphasia is particularly challenging as patients are rarely able to produce and practice fluent speech production. Speech entrainment is a behavioural technique that enables patients with non-fluent aphasia to speak fluently. However, its mechanisms are not well understood and the level of improved fluency with speech entrainment varies among individuals with non-fluent aphasia. In this study, we evaluated the behavioural and neuroanatomical factors associated with better speech fluency with the aid of speech entrainment during the training phase of speech entrainment. We used a lesion-symptom mapping approach to define the relationship between chronic stroke location on MRI and the number of different words per second produced during speech entrainment versus picture description spontaneous speech. The behavioural variable of interest was the speech entrainment/picture description ratio, which, if ≥1, indicated an increase in speech output during speech entrainment compared to picture description. We used machine learning (shallow neural network) to assess the statistical significance and out-of-sample predictive accuracy of the neuroanatomical model, and its regional contributors. We observed that better assisted speech (higher speech entrainment/picture description ratio) was achieved by individuals who had preservation of the posterior middle temporal gyrus, inferior fronto-occipital fasciculus and uncinate fasciculus, while exhibiting lesions in areas typically associated with non-fluent aphasia, such as the superior longitudinal fasciculus, precentral, inferior frontal, supramarginal and insular cortices. Our findings suggest that individuals with dorsal stream damage but preservation of ventral stream structures are more likely to achieve more fluent speech with the aid of speech entrainment compared to spontaneous speech. This observation provides insight into the mechanisms of non-fluent speech in aphasia and has potential implications for future research using speech entrainment for rehabilitation of non-fluent aphasia.

Neuroplasticity and aphasia treatments: new approaches for an old problem

Given the profound impact of language impairment after stroke (aphasia), neuroplasticity research is garnering considerable attention as means for eventually improving aphasia treatments and how they are delivered. Functional and structural neuroimaging studies indicate that aphasia treatments can recruit both residual and new neural mechanisms to improve language function and that neuroimaging modalities may hold promise in predicting treatment outcome. In relatively small clinical trials, both non-invasive brain stimulation and behavioural manipulations targeting activation or suppression of specific cortices can improve aphasia treatment outcomes. Recent language interventions that employ principles consistent with inducing neuroplasticity also are showing improved performance for both trained and novel items and contexts. While knowledge is rapidly accumulating, larger trials emphasising how to select optimal paradigms for individualised aphasia treatment are needed. Finally, a model of how to incorporate the growing knowledge into clinical practice could help to focus future research.

Logoclonia might be a Characteristic of Logopenic Variant Primary Progressive Aphasia at an Advanced Stage: Potential Mechanisms Underlying Logoclonia

Logoclonia, which is the meaningless repetition of a syllable, particularly an end syllable of a word, has been described in patients with dementia for a century. The mechanisms behind logoclonia, however, have yet to be clarified. Among 914 patients with aphasia, five patients presented with logoclonia, all of whom were categorized as having logopenic variant PPA (lvPPA) during the initial stage of their illness and met the clinical criteria for diagnosis of probable Alzheimer’s disease. Cognitively, they were all severely impaired when they presented with logoclonia. During the progression from lvPPA to logoclonia in these patients, their naming abilities and phonological output function deteriorated despite their retained speech fluency. Logoclonia might be a characteristic sign of advanced-stage lvPPA. Although logoclonia might be associated with perseveration, deterioration in naming abilities and phonological output function along with retained speech fluency might form the basis for the development of logoclonia.

Video-Implemented Script Training in a Bilingual Spanish-English Speaker With Aphasia

Purpose This study examines the utility of Video-Implemented Script Training for Aphasia (VISTA) for improving speech production and fluency in a Spanish-English bilingual speaker with aphasia. Method In this single-subject, multiple-baseline intervention study, VISTA was utilized to facilitate fluent and intelligible speech through training with an audiovisual speech model. Scripts were developed from personalized topics of interest, and training stimuli were tailored for speech rate and linguistic complexity. One trained script per language contained a high proportion of cognates in order to examine the potential for enhancing cross-linguistic transfer. Primary and secondary outcome measures for trained and untrained scripts were percent correct and intelligible scripted words, grammatical errors, speech rate, and total percent intelligibility. Results R. C. showed significant improvement in accuracy, intelligibility, and grammaticality of trained scripts. Results revealed cross-linguistic transfer for both languages of treatment. A significantly greater magnitude of cross-language transfer was observed for scripts that were not cognate dense. Conclusions VISTA is a viable treatment method for bilingual individuals with aphasia. Cross-linguistic transfer was diminished when incorporating scripts with a high proportion of cognates; however, this may not be true for all bilingual individuals with aphasia and should be explored with additional participants.

Retraining speech production and fluency in non-fluent/agrammatic primary progressive aphasia

The non-fluent/agrammatic variant of primary progressive aphasia (nfvPPA) presents with a gradual decline in grammar and motor speech resulting from selective degeneration of speech-language regions in the brain. There has been considerable progress in identifying treatment approaches to remediate language deficits in other primary progressive aphasia variants; however, interventions for the core deficits in nfvPPA have yet to be systematically investigated. Further, the neural mechanisms that support behavioural restitution in the context of neurodegeneration are not well understood. We examined the immediate and long-term benefits of video implemented script training for aphasia (VISTA) in 10 individuals with nfvPPA. The treatment approach involved repeated rehearsal of individualized scripts via structured treatment with a clinician as well as intensive home practice with an audiovisual model using 'speech entrainment'. We evaluated accuracy of script production as well as overall intelligibility and grammaticality for trained and untrained scripts. These measures and standardized test scores were collected at post-treatment and 3-, 6-, and 12-month follow-up visits. Treatment resulted in significant improvement in production of correct, intelligible scripted words for trained topics, a reduction in grammatical errors for trained topics, and an overall increase in intelligibility for trained as well as untrained topics at post-treatment. Follow-up testing revealed maintenance of gains for trained scripts up to 1 year post-treatment on the primary outcome measure. Performance on untrained scripts and standardized tests remained relatively stable during the follow-up period, indicating that treatment helped to stabilize speech and language despite disease progression. To identify neural predictors of responsiveness to intervention, we examined treatment effect sizes relative to grey matter volumes in regions of interest derived from a previously identified speech production network. Regions of significant atrophy within this network included bilateral inferior frontal cortices and supplementary motor area as well as left striatum. Volumes in a left middle/inferior temporal region of interest were significantly correlated with the magnitude of treatment effects. This region, which was relatively spared anatomically in nfvPPA patients, has been implicated in syntactic production as well as visuo-motor facilitation of speech. This is the first group study to document the benefits of behavioural intervention that targets both linguistic and motoric deficits in nfvPPA. Findings indicate that behavioural intervention may result in lasting and generalized improvement of communicative function in individuals with neurodegenerative disease and that the integrity of spared regions within the speech-language network may be an important predictor of treatment response.

Dual-Task Effects on Story Retell for Participants With Moderate, Mild, or No Aphasia: Quantitative and Qualitative Findings

Purpose The aims of the study were to determine dual-task effects on content accuracy, delivery speed, and perceived effort during narrative discourse in people with moderate, mild, or no aphasia and to explore subjective reactions to retelling a story with a concurrent task. Method Two studies (1 quantitative and 1 qualitative) were conducted. In Study 1, participants with mild or moderate aphasia and neurotypical controls retold short stories in isolation and while simultaneously distinguishing between high and low tones. Story retell accuracy (speech productivity and efficiency), speed (speech rate, repetitions, and pauses), and perceived effort were measured and compared. In Study 2, participants completed semistructured interviews about their story retell experience. These interviews were recorded, transcribed orthographically, and coded qualitatively using thematic analysis. Results The dual task interfered more with spoken language of people with aphasia than controls, but different speed-accuracy trade-off patterns were noted. Participants in the moderate aphasia group reduced accuracy with little alteration to speed, whereas participants in the mild aphasia group maintained accuracy and reduced their speed. Participants in both groups also reported more negative emotional and behavioral reactions to the dual-task condition than their neurotypical peers. Intentional strategies for coping with the cognitive demands of the dual-task condition were only reported by participants with mild aphasia. Conclusion The findings suggest that, although communicating with a competing task is more difficult for people with aphasia than neurotypical controls, participants with mild aphasia may be better able to cope with cognitively demanding communication situations than participants with moderate aphasia. Supplemental Material https://doi.org/10.23641/asha.8233391.

Progression of Aphasia Severity in the Chronic Stages of Stroke

Background and Purpose The severity of aphasic impairment in chronic stroke survivors is typically thought to be stable by 6 months postonset. However, a recent study showed that stroke survivors with aphasia experience language improvement or decline in the chronic phase, years beyond onset. Little is known about why some individuals improve whereas others remain stable or decline. Additionally, no study has tracked changes in aphasia from assessments completed at multiple time points across many years. The current study offers a comprehensive analysis of potential predictive demographic and health information to determine which factors predict dynamic changes in aphasia severity in chronic stroke. Methods Individuals in the chronic stage of a single-event, left-hemisphere ischemic stroke were identified from an archival database and included for study ( N = 39). Participants were included if they had undergone 2 or more standardized language assessments acquired at time points at least 6 months apart, with the 1st assessment at least 6 months postinjury. A linear mixed-effects model was used to determine the impact of treatment and a variety of demographic and health factors on language change. Results Over time, half of the participants improved (51%), whereas approximately a quarter (26%) decreased, and a quarter (23%) remained stable. A greater number of aphasia treatment hours significantly predicted language improvement ( p = .03), whereas older stroke age was associated with long-term decline ( p = .04). Two interactions were found to be significant in predicting improvement in individuals with diabetes: Increased exercise and younger age at stroke were significant in predicting outcomes ( p < .05). Conclusions Factors that significantly influence language recovery in chronic aphasia include stroke age and receiving aphasia treatment. For those with diabetes, increased exercise was shown to improve outcomes. Results from this study offer clinicians greater insight into the influence of patient factors on long-term recovery from stroke aphasia while suggesting a potential adjunct to language therapy: exercise. Supplemental Material https://doi.org/10.23641/asha.7849304.

Come together: human-avatar on-line interactions boost joint-action performance in apraxic patients

Limb apraxia (LA) is a high-order motor disorder linked to left-hemisphere damage. It is characterized by defective execution of purposeful actions upon delayed imitation, or verbal command when the actions are performed in isolated, non-naturalistic, conditions. Whether interpersonal interactions provide social affordances that activate neural resources different from those requested by individual action execution, which may improve LA performance, is unknown. To fill this gap, we measured interaction performance, behavioral and kinematic indexes of left-brain damaged patients with/without LA in a social reach-to-grasp task involving two different degrees of spatio-temporal interactivity with an avatar. We found that LA patients' impairment in coordinating with the virtual partner was abolished in highly interactive conditions (where patients selected their actions on-line based on the behavior of the virtual partner) with respect to low interactive conditions (where actions were selected beforehand based on abstract instructions). Voxel-based-Lesion-Symptom-Mapping indicated that impairments in low-interactive conditions were underpinned by lesions of premotor, motor and insular areas, and of the basal ganglia. Our approach expands current understanding of the behavioral and neural correlates of interactive motor performance by highlighting the important role of social affordances, and provides novel, potentially important, views on rehabilitation of higher-order motor cognition disorders.

Neuroimaging of stroke recovery from aphasia - Insights into plasticity of the human language network

The role of left and right hemisphere brain regions in language recovery after stroke-induced aphasia remains controversial. Here, we summarize how neuroimaging studies increase the current understanding of functional interactions, reorganization and plasticity in the language network. We first discuss the temporal dynamics across the time course of language recovery, with a main focus on longitudinal studies from the acute to the chronic phase after stroke. These studies show that the functional contribution of perilesional and spared left hemisphere as well as contralesional right hemisphere regions to language recovery changes over time. The second section introduces critical variables and recent advances on early prediction of subsequent outcome. In the third section, we outline how multi-method approaches that combine neuroimaging techniques with non-invasive brain stimulation elucidate mechanisms of plasticity and reorganization in the language network. These approaches provide novel insights into general mechanisms of plasticity in the language network and might ultimately support recovery processes during speech and language therapy. Finally, the neurobiological correlates of therapy-induced plasticity are discussed. We argue that future studies should integrate individualized approaches that might vary the combination of language therapy with specific non-invasive brain stimulation protocols across the time course of recovery. The way forward will include the combination of such approaches with large data sets obtained from multicentre studies.

Non-fluent speech following stroke is caused by impaired efference copy

Efference copy is a cognitive mechanism argued to be critical for initiating and monitoring speech: however, the extent to which breakdown of efference copy mechanisms impact speech production is unclear. This study examined the best mechanistic predictors of non-fluent speech among 88 stroke survivors. Objective speech fluency measures were subjected to a principal component analysis (PCA). The primary PCA factor was then entered into a multiple stepwise linear regression analysis as the dependent variable, with a set of independent mechanistic variables. Participants' ability to mimic audio-visual speech ("speech entrainment response") was the best independent predictor of non-fluent speech. We suggest that this "speech entrainment" factor reflects integrity of internal monitoring (i.e., efference copy) of speech production, which affects speech initiation and maintenance. Results support models of normal speech production and suggest that therapy focused on speech initiation and maintenance may improve speech fluency for individuals with chronic non-fluent aphasia post stroke.

Advances in neurocognitive rehabilitation research from 1992 to 2017: The ascension of neural plasticity

OBJECTIVE

The last 25 years have seen profound changes in neurocognitive rehabilitation that continue to motivate its evolution. Although the concept of nervous system plasticity was discussed by William James (1890), the foundation for experience-based plasticity had not reached the critical empirical mass to seriously impact rehabilitation research until after 1992. The objective of this review is to describe how the emergence of neural plasticity has changed neurocognitive rehabilitation research.

METHOD

The important developments included (a) introduction of a widely available tool that could measure brain plasticity (i.e., functional MRI); (b) development of new structural imaging techniques that could define limits of and opportunities for neural plasticity; (c) deployment of noninvasive brain stimulation to leverage neural plasticity for rehabilitation; (d) growth of a literature indicating that exercise has positively impacts neural plasticity, especially for older persons; and (e) enhancement of neural plasticity by creating interventions that generalize beyond the boundaries of treatment activities. Given the massive literature, each of these areas is developed by example.

RESULTS

The expanding influence of neural plasticity has provided new models and tools for neurocognitive rehabilitation in neural injuries and disorders, as well as methods for measuring neural plasticity and predicting its limits and opportunities. Early clinical trials have provided very encouraging results.

CONCLUSION

Now that neural plasticity has gained a firm foothold, it will continue to influence the evolution of neurocognitive rehabilitation research for the next 25 years and advance rehabilitation for neural injuries and disease. (PsycINFO Database Record

Revealing the dual streams of speech processing

Several dual route models of human speech processing have been proposed suggesting a large-scale anatomical division between cortical regions that support motor-phonological aspects vs. lexical-semantic aspects of speech processing. However, to date, there is no complete agreement on what areas subserve each route or the nature of interactions across these routes that enables human speech processing. Relying on an extensive behavioral and neuroimaging assessment of a large sample of stroke survivors, we used a data-driven approach using principal components analysis of lesion-symptom mapping to identify brain regions crucial for performance on clusters of behavioral tasks without a priori separation into task types. Distinct anatomical boundaries were revealed between a dorsal frontoparietal stream and a ventral temporal-frontal stream associated with separate components. Collapsing over the tasks primarily supported by these streams, we characterize the dorsal stream as a form-to-articulation pathway and the ventral stream as a form-to-meaning pathway. This characterization of the division in the data reflects both the overlap between tasks supported by the two streams as well as the observation that there is a bias for phonological production tasks supported by the dorsal stream and lexical-semantic comprehension tasks supported by the ventral stream. As such, our findings show a division between two processing routes that underlie human speech processing and provide an empirical foundation for studying potential computational differences that distinguish between the two routes.

Investigating structure and function in the healthy human brain: validity of acute versus chronic lesion-symptom mapping

Modern voxel-based lesion-symptom mapping (VLSM) analyses techniques provide powerful tools to examine the relationship between structure and function of the healthy human brain. However, there is still uncertainty on the type of and the appropriate time point of imaging and of behavioral testing for such analyses. Here we tested the validity of the three most common combinations of structural imaging data and behavioral scores used in VLSM analyses. Given the established knowledge about the neural substrate of the primary motor system in humans, we asked the mundane question of where the motor system is represented in the normal human brain, analyzing individual arm motor function of 60 unselected stroke patients. Only the combination of acute behavioral scores and acute structural imaging precisely identified the principal brain area for the emergence of hemiparesis after stroke, i.e., the corticospinal tract (CST). In contrast, VLSM analyses based on chronic behavior-in combination with either chronic or acute imaging-required the exclusion of patients who had recovered from an initial paresis to reveal valid anatomical results. Thus, if the primary research aim of a VLSM lesion analysis is to uncover the neural substrates of a certain function in the healthy human brain and if no longitudinal designs with repeated evaluations are planned, the combination of acute imaging and behavior represents the ideal dataset.

Preservation of structural brain network hubs is associated with less severe post-stroke aphasia

PURPOSE

Post-stroke aphasia is typically associated with ischemic damage to cortical areas or with loss of connectivity among spared brain regions. It remains unclear whether the participation of spared brain regions as networks hubs affects the severity of aphasia.

METHODS

We evaluated language performance and magnetic resonance imaging from 44 participants with chronic aphasia post-stroke. The individual structural brain connectomes were constructed from diffusion tensor. Hub regions were defined in accordance with the rich club classification and studied in relation with language performance.

RESULTS

Number of remaining left hemisphere rich club nodes was associated with aphasia, including comprehension, repetition and naming sub-scores. Importantly, among participants with relative preservation of regions of interest for language, aphasia severity was lessened if the region was not only spared, but also participated in the remaining network as a rich club node: Brodmann area (BA) 44/45 - repetition (p = 0.009), BA 39 - repetition (p = 0.045) and naming (p <  0.01), BA 37 - fluency (p <  0.001), comprehension (p = 0.025), repetition (p <  0.001) and naming (p <  0.001).

CONCLUSIONS

Disruption of language network structural hubs is directly associated with aphasia severity after stroke.