Functional imaging before and after constraint-induced language therapy for aphasia using magnetoencephalography

Treatment-induced neural reorganization in aphasia is language-domain specific: Evidence from a large-scale fMRI study

Studies investigating the effects of language intervention on the re-organization of language networks in chronic aphasia have resulted in mixed findings, likely related to-among other factors-the language function targeted during treatment. The present study investigated the effects of the type of treatment provided on neural reorganization. Seventy individuals with chronic stroke-induced aphasia, recruited from three research laboratories and meeting criteria for agrammatism, anomia or dysgraphia were assigned to either treatment (N = 51) or control (N = 19) groups. Participants in the treatment group received 12-weeks of language intervention targeting sentence comprehension/production, naming, or spelling. At baseline and post-testing, all participants performed an fMRI story comprehension task, with blocks of auditorily-presented stories alternated with blocks of reversed speech. Participants in the treatment, but not control, group significantly improved in the treated language domain. FMRI region-of-interest (ROI) analyses, conducted within regions that were either active (or homologous to active) regions in a group of 22 healthy participants on the story comprehension task, revealed a significant increase in activation from pre-to post-treatment in right-hemisphere homologues of these regions for participants in the sentence and spelling, but not naming, treatment groups, not predicted by left-hemisphere lesion size. For the sentence (but not the spelling) treatment group, activation changes within right-hemisphere homologues of language regions were positively associated with changes in measures of verb and sentence comprehension. These findings support previous research pointing to recruitment of right hemisphere tissue as a viable route for language recovery and suggest that sentence-level treatment may promote greater neuroplasticity on naturalistic, language comprehension tasks, compared to word-level treatment.

The role of disrupted functional connectivity in aphasia

Language is one of the most complex and specialized higher cognitive processes. Brain damage to the distributed, primarily left-lateralized language network can result in aphasia, a neurologic disorder characterized by receptive and/or expressive deficits in spoken and/or written language. Most often, aphasia is the consequence of stroke-termed poststroke aphasia (PSA)-yet, aphasia can also manifest due to neurodegenerative disease, specifically, a disorder called primary progressive aphasia (PPA). In recent years, functional connectivity neuroimaging studies have provided emerging evidence supporting theories regarding the relationships between language impairments, structural brain damage, and functional network properties in these two disorders. This chapter reviews the current evidence for the "network phenotype of stroke injury" hypothesis (Siegel et al., 2016) as it pertains to PSA and the "network degeneration hypothesis" (Seeley et al., 2009) as it pertains to PPA. Methodologic considerations for functional connectivity studies, limitations of the current functional connectivity literature in aphasia, and future directions are also discussed.

Increased Recruitment of Domain-General Neural Networks in Language Processing Following Intensive Language-Action Therapy: fMRI Evidence From People With Chronic Aphasia

Purpose This study aimed to provide novel insights into the neural correlates of language improvement following intensive language-action therapy (ILAT; also known as constraint-induced aphasia therapy). Method Sixteen people with chronic aphasia underwent clinical aphasia assessment (Aachen Aphasia Test [AAT]), as well as functional magnetic resonance imaging (fMRI), both administered before (T1) and after ILAT (T2). The fMRI task included passive reading of single written words, with hashmark strings as visual baseline. Results Behavioral results indicated significant improvements of AAT scores across therapy, and fMRI results showed T2-T1 blood oxygenation-level-dependent (BOLD) signal change in the left precuneus to be modulated by the degree of AAT score increase. Subsequent region-of-interest analysis of this precuneus cluster confirmed a positive correlation of T2-T1 BOLD signal change and improvement on the clinical aphasia test. Similarly, the entire default mode network revealed a positive correlation between T2-T1 BOLD signal change and clinical language improvement. Conclusion These results are consistent with a more efficient recruitment of domain-general neural networks in language processing, including those involved in attentional control, following aphasia therapy with ILAT. Supplemental Material https://doi.org/10.23641/asha.12765755.

The influence of conversation parameters on gesture production in aphasia

Conversation is important in everyday life and this importance is not diminished in aphasia. Context parameters such as topic and partner are known to influence the linguistic content of conversations. With gesture being closely linked to language, these parameters may influence gestures used in conversations. This has not been investigated in previous studies. This study explored the spontaneous use of gestures in the conversations of participants with aphasia (PWA) and neurologically healthy participants (NHP). It aimed to examine the influence of conversation topic and partner on gesture production overall and on the production of semantically rich and empty gestures. Twenty PWA and 21 NHP were filmed during conversations with different topics (narrative & procedural) and different partners (familiar & unfamiliar). Analysis 1 investigated the influence of the conversation topic on gesture production overall and on the production of semantically rich and empty gestures. In Analysis 2, the influence of the conversation partner on gesture production was investigated. Both groups produced significantly more gestures in procedural than in narrative conversations. Moreover, PWA and NHP produced significantly more semantically rich gestures in procedural conversations. In terms of the conversation partner, both groups produced significantly more gestures in the conversations with the unfamiliar than in those with the familiar conversation partner. For all findings, there were no group differences and no interactions between group and context parameters. These findings shed light on factors that influence gesture production and suggest that both modalities should be viewed together as a communicative resource for PWA.

Neurocognitive Recovery of Sentence Processing in Aphasia

Purpose Reorganization of language networks in aphasia takes advantage of the facts that (a) the brain is an organ of plasticity, with neuronal changes occurring throughout the life span, including following brain damage; (b) plasticity is highly experience dependent; and (c) as with any learning system, language reorganization involves a synergistic interplay between organism-intrinsic (i.e., cognitive and brain) and organism-extrinsic (i.e., environmental) variables. A major goal for clinical treatment of aphasia is to be able to prescribe treatment and predict its outcome based on the neurocognitive deficit profiles of individual patients. This review article summarizes the results of research examining the neurocognitive effects of psycholinguistically based treatment (i.e., Treatment of Underlying Forms; Thompson & Shapiro, 2005) for sentence processing impairments in individuals with chronic agrammatic aphasia resulting from stroke and primary progressive aphasia and addresses both behavioral and brain variables related to successful treatment outcomes. The influences of lesion volume and location, perfusion (blood flow), and resting-state neural activity on language recovery are also discussed as related to recovery of agrammatism and other language impairments. Based on these and other data, principles for promoting neuroplasticity of language networks are presented. Conclusions Sentence processing treatment results in improved comprehension and production of complex syntactic structures in chronic agrammatism and generalization to less complex, linguistically related structures in chronic agrammatism. Patients also show treatment-induced shifts toward normal-like online sentence processing routines (based on eye movement data) and changes in neural recruitment patterns (based on functional neuroimaging), with posttreatment activation of regions overlapping with those within sentence processing and dorsal attention networks engaged by neurotypical adults performing the same task. These findings provide compelling evidence that treatment focused on principles of neuroplasticity promotes neurocognitive recovery in chronic agrammatic aphasia. Presentation Videohttps://doi.org/10.23641/asha.10257587.

Recovery of offline and online sentence processing in aphasia: Language and domain-general network neuroplasticity

This paper examined the effects of treatment on both offline and online sentence processing and associated neuroplasticity within sentence processing and dorsal attention networks in chronic stroke-induced agrammatic aphasia. Twenty-three neurotypical adults and 19 individuals with aphasia served as participants. Aphasic individuals were randomly assigned to receive a 12-week course of linguistically-based treatment of passive sentence production and comprehension (N = 14, treatment group) or to serve as control participants (N = 5, natural history group). Both aphasic groups performed two offline tasks at baseline and three months following (at post-testing) to assess production and comprehension of trained passive structures and untrained syntactically related and unrelated structures. The aphasic participants and a healthy age-matched group also performed an online eyetracking comprehension task and a picture-verification fMRI task, which were repeated at post-testing for the aphasic groups. Results showed that individuals in the treatment, but not in the natural history, group improved on production and comprehension of both trained structures and untrained syntactically related structures. Treatment also resulted in a shift toward more normal-like eye movements and a significant increase in neural activation from baseline to post-testing. Upregulation encompassed right hemisphere regions homologs of left hemisphere regions involved in both sentence processing and domain-general functions and was positively correlated with treatment gains, as measured by offline comprehension accuracy, and with changes in processing strategies during sentence comprehension, as measured by eyetracking. These findings provide compelling evidence in favor of the contribution of both networks within the right hemisphere to the restoration of normal-like sentence processing patterns in chronic aphasia.

A lesion and connectivity-based hierarchical model of chronic aphasia recovery dissociates patients and healthy controls

Traditional models of left hemisphere stroke recovery propose that reactivation of remaining ipsilesional tissue is optimal for language processing whereas reliance on contralesional right hemisphere homologues is less beneficial or possibly maladaptive in the chronic recovery stage. However, neuroimaging evidence for this proposal is mixed. This study aimed to elucidate patterns of effective connectivity in patients with chronic aphasia in light of healthy control connectivity patterns and in relation to damaged tissue within left hemisphere regions of interest and according to performance on a semantic decision task. Using fMRI and dynamic causal modeling, biologically-plausible models within four model families were created to correspond to potential neural recovery patterns, including Family A: Left-lateralized connectivity (i.e., no/minimal damage), Family B: Bilateral anterior-weighted connectivity (i.e., posterior damage), Family C: Bilateral posterior-weighted connectivity (i.e., anterior damage) and Family D: Right-lateralized connectivity (i.e., extensive damage). Controls exhibited a strong preference for left-lateralized network models (Family A) whereas patients demonstrated a split preference for Families A and C. At the level of connections, controls exhibited stronger left intrahemispheric task-modulated connections than did patients. Within the patient group, damage to left superior frontal structures resulted in greater right intrahemispheric connectivity whereas damage to left ventral structures resulted in heightened modulation of left frontal regions. Lesion metrics best predicted accuracy on the fMRI task and aphasia severity whereas left intrahemispheric connectivity predicted fMRI task reaction times. These results are discussed within the context of the hierarchical recovery model of chronic aphasia.

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The semantic network in neurologically-intact, healthy controls was characterized by left-lateralized connectivity.

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Patient connectivity was split between left-lateralized and bilateral, posterior-weighted (i.e., anterior damage) models.

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Controls solely recruited LITG-driven connections whereas patients recruited a distributed network of connections.

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Within the patient group, intra- and inter-hemispheric connections were related to lesion site and/or size. Lesion size predicted aphasia severity and fMRI task accuracy, and effective connectivity predicted task reaction times.

Benchmarks of Significant Change After Aphasia Rehabilitation

OBJECTIVE

To establish benchmarks of significant change for aphasia rehabilitation outcome measures (ie, Western Aphasia Battery-Aphasia Quotient [WAB-AQ], Communicative Effectiveness Index [CETI], Boston Naming Test [BNT]) and assess if those benchmarks significantly differ across subgroups (ie, time post onset, dose frequency, treatment type).

DATA SOURCES

A comprehensive literature search of 12 databases, reference lists of previous reviews, and evidence-based practice materials was conducted.

STUDY SELECTION

Randomized controlled trials, quasi-experimental studies, single-subject design, and case studies that used a standardized outcome measure to assess change were included. Titles and full-text articles were screened using a dual review process. Seventy-eight studies met criteria for inclusion.

DATA EXTRACTION

Data were extracted independently, and 25% of extractions were checked for reliability. All included studies were assigned quality indicator ratings and an evidence level.

DATA SYNTHESIS

Random-effects meta-analyses were conducted separately for each study design group (ie, within-/between-group comparisons). For within-group designs, the summary effect size after aphasia rehabilitation was 5.03 points (95% confidence interval, 3.95-6.10, P<.001) on the WAB-AQ, 10.37 points (6.08-14.66, P<.001) on the CETI, and 3.30 points (2.43-4.18, P<.001) on the BNT. For between-group designs, the summary effect size was 5.05 points (1.64-8.46, P=.004) on the WAB-AQ and 0.55 points (-1.33 to 2.43, P=.564) on the BNT, the latter of which was not significant. Subgroup analyses for the within-group designs showed no significant differences in the summary effect size as a function of dose frequency or treatment type.

CONCLUSIONS

This study established benchmarks of significant change on 3 standardized outcome measures used in aphasia rehabilitation.

Intensive Auditory Comprehension Treatment for Severe Aphasia: A Feasibility Study

BACKGROUND

Severe auditory comprehension impairments secondary to aphasia can adversely influence rehabilitative outcomes and quality of life. Studies examining intensive rehabilitative treatments for severe single-word auditory comprehension impairments are needed.

OBJECTIVES

Our purpose was to examine the feasibility and influence of a high-intensity word-picture verification treatment on high-frequency, word response accuracy. Research questions: (a) Can people with severe aphasia tolerate an intensive comprehension treatment? (b) Does an intensive intervention increase auditory comprehension response accuracy of spoken high-frequency words?

METHOD

This single-case ABA design study included 2 participants with chronic, severe auditory comprehension deficits secondary to stroke. A high-frequency, word-picture verification treatment was administered 2 hr/day, 5 days/week for 4 weeks and required participants to match the spoken word of the examiner to a picture representing an object.

RESULTS

Preliminary results suggest that some people with severe chronic aphasia can tolerate an intensive auditory comprehension treatment and demonstrate improvements in high-frequency, word-level response accuracy with large effect sizes suggesting generalization to untrained stimuli.

CONCLUSIONS

An intensive auditory comprehension treatment protocol can contribute to improvements in response accuracy for some people with severe aphasia. Larger sample size studies are needed to further examine the influence of intensity on improvements in auditory comprehension.

Treatment Response to a Double Administration of Constraint-Induced Language Therapy in Chronic Aphasia

Purpose

This study investigated changes in oral-verbal expressive language associated with improvements following 2 treatment periods of constraint-induced language therapy in 4 participants with stroke-induced chronic aphasia. Generalization of treatment to untrained materials and to discourse production was also analyzed, as was the durability of the treatment effect.

Method

Participants with aphasia were assessed using standardized measures and discourse tasks at 3 to 4 time points to document behavioral changes throughout each of two 30-hr treatment periods of constraint-induced language therapy. Daily probes of trained and untrained materials were also administered.

Results

Despite participant heterogeneity, behavioral results for each person with aphasia indicated a positive response to treatment following each treatment period indicated by performance on standardized tests, trained materials, or both. Treatment effects generalized to some degree to untrained stimuli and to discourse measures and were generally maintained at follow-up testing.

Conclusions

Data support the utility of a 2nd treatment period. Results are relevant to rehabilitation in chronic aphasia, confirming that significant language gains continue well past the point of spontaneous recovery and can occur in a relatively short time period. Importantly, changes are not confined to a single treatment period, suggesting that people with aphasia may benefit from multiple doses of high-intensity treatment.

Neuroimaging Correlates of Post-Stroke Aphasia Rehabilitation in a Pilot Randomized Trial of Constraint-Induced Aphasia Therapy

Background

Recovery from post-stroke aphasia is a long and complex process with an uncertain outcome. Various interventions have been proposed to augment the recovery, including constraint-induced aphasia therapy (CIAT). CIAT has been applied to patients suffering from post-stroke aphasia in several unblinded studies to show mild-to-moderate linguistic gains. The aim of the present study was to evaluate the neuroimaging correlates of CIAT in patients with chronic aphasia related to left middle cerebral artery stroke.

Material/Methods

Out of 24 patients recruited in a pilot randomized blinded trial of CIAT, 19 patients received fMRI of language. Eleven of them received CIAT (trained) and eight served as a control group (untrained). Each patient participated in three fMRI sessions (before training, after training, and 3 months later) that included semantic decision and verb generation fMRI tasks, and a battery of language tests. Matching healthy control participants were also included (N=38; matching based on age, handedness, and sex).

Results

Language testing showed significantly improved performance on Boston Naming Test (BNT; p<0.001) in both stroke groups over time and fMRI showed differences in the distribution of the areas involved in language production between groups that were not present at baseline. Further, regression analysis with BNT indicated changes in brain regions correlated with behavioral performance (temporal gyrus, postcentral gyrus, precentral gyrus, thalamus, left middle and superior frontal gyri).

Conclusions

Overall, our results suggest the possibility of language-related cortical plasticity following stroke-induced aphasia with no specific effect from CIAT training.

Right Hemisphere Grey Matter Volume and Language Functions in Stroke Aphasia

The role of the right hemisphere (RH) in recovery from aphasia is incompletely understood. The present study quantified RH grey matter (GM) volume in individuals with chronic stroke-induced aphasia and cognitively healthy people using voxel-based morphometry. We compared group differences in GM volume in the entire RH and in RH regions-of-interest. Given that lesion site is a critical source of heterogeneity associated with poststroke language ability, we used voxel-based lesion symptom mapping (VLSM) to examine the relation between lesion site and language performance in the aphasic participants. Finally, using results derived from the VLSM as a covariate, we evaluated the relation between GM volume in the RH and language ability across domains, including comprehension and production processes both at the word and sentence levels and across spoken and written modalities. Between-subject comparisons showed that GM volume in the RH SMA was reduced in the aphasic group compared to the healthy controls. We also found that, for the aphasic group, increased RH volume in the MTG and the SMA was associated with better language comprehension and production scores, respectively. These data suggest that the RH may support functions previously performed by LH regions and have important implications for understanding poststroke reorganization.

Intensive Language Action Therapy in Chronic Aphasia: A Randomized Clinical Trial Examining Guidance by Constraint

Purpose

Intensive language action therapy (ILAT) can be effective in overcoming learned nonuse in chronic aphasia. It is suggested that all three guiding principles (constraint, communication embedding, massed practice) are essential to ILAT's success. We examined whether one of these, guidance by constraint, is critical.

Method

Twenty-four participants with aphasia (PWAs) were assigned to ILAT or a modified version of promoting aphasic communicative effectiveness (PACE) in a randomized block, single-blind, parallel-group treatment study. Blocking was by severity (mild/moderate, moderate to severe, severe). Both groups received intensive treatment in the context of therapeutic language action games. Whereas the ILAT group was guided toward spoken responses, the PACE group could choose any response modality.

Results

All participants, whether assigned to ILAT or PACE groups, improved on the primary outcome measure, picture naming. There was a Severity × Treatment interaction, with the largest effects estimated for PWAs with mild/moderate and moderate to severe aphasia. Regardless of severity, the ILAT group outperformed the PACE group on untrained pictures, suggesting some benefit of ILAT to generalization. However, this difference was not statistically significant.

Conclusion

Although the groups differed in subtle ways, including better generalization to untrained pictures for ILAT, the study was inconclusive on the influence of guidance by constraint.

Ultra-rapid access to words in chronic aphasia: the effects of intensive language action therapy (ILAT)

Effects of intensive language action therapy (ILAT) on automatic language processing were assessed using Magnetoencephalography (MEG). Auditory magnetic mismatch negativity (MMNm) responses to words and pseudowords were recorded in twelve patients with chronic aphasia before and immediately after two weeks of ILAT. Following therapy, Patients showed significant clinical improvements of auditory comprehension as measured by the Token Test and in word retrieval and naming as measured by the Boston Naming Test. Neuromagnetic responses dissociated between meaningful words and meaningless word-like stimuli ultra-rapidly, approximately 50 ms after acoustic information first allowed for stimulus identification. Over treatment, there was a significant increase in the left-lateralisation of this early word-elicited activation, observed in perilesional fronto-temporal regions. No comparable change was seen for pseudowords. The results may reflect successful, therapy-induced, language restitution in the left hemisphere.

Changes of right-hemispheric activation after constraint-induced, intensive language action therapy in chronic aphasia: fMRI evidence from auditory semantic processing

The role of the two hemispheres in the neurorehabilitation of language is still under dispute. This study explored the changes in language-evoked brain activation over a 2-week treatment interval with intensive constraint induced aphasia therapy (CIAT), which is also called intensive language action therapy (ILAT). Functional magnetic resonance imaging (fMRI) was used to assess brain activation in perilesional left hemispheric and in homotopic right hemispheric areas during passive listening to high and low-ambiguity sentences and non-speech control stimuli in chronic non-fluent aphasia patients. All patients demonstrated significant clinical improvements of language functions after therapy. In an event-related fMRI experiment, a significant increase of BOLD signal was manifest in right inferior frontal and temporal areas. This activation increase was stronger for highly ambiguous sentences than for unambiguous ones. These results suggest that the known language improvements brought about by intensive constraint-induced language action therapy at least in part relies on circuits within the right-hemispheric homologs of left-perisylvian language areas, which are most strongly activated in the processing of semantically complex language.

Releasing the constraints on aphasia therapy: the positive impact of gesture and multimodality treatments

PURPOSE

There is a 40-year history of interest in the use of arm and hand gestures in treatments that target the reduction of aphasic linguistic impairment and compensatory methods of communication (Rose, 2006). Arguments for constraining aphasia treatment to the verbal modality have arisen from proponents of constraint-induced aphasia therapy (Pulvermüller et al., 2001). Confusion exists concerning the role of nonverbal treatments in treating people with aphasia. The central argument of this paper is that given the state of the empirical evidence and the strong theoretical accounts of modality interactions in human communication, gesture-based and multimodality aphasia treatments are at least as legitimate an option as constraint-based aphasia treatment.

METHOD

Theoretical accounts of modality interactions in human communication and the gesture production abilities of individuals with aphasia that are harnessed in treatments are reviewed. The negative effects on word retrieval of restricting gesture production are also reviewed, and an overview of the neurological architecture subserving language processing is provided as rationale for multimodality treatments. The evidence for constrained and unconstrained treatments is critically reviewed.

CONCLUSION

Together, these data suggest that constraint treatments and multimodality treatments are equally efficacious, and there is limited support for constraining client responses to the spoken modality.

Constrained versus unconstrained intensive language therapy in two individuals with chronic, moderate-to-severe aphasia and apraxia of speech: behavioral and fMRI outcomes

PURPOSE

This Phase I study investigated behavioral and functional MRI (fMRI) outcomes of 2 intensive treatment programs to improve naming in 2 participants with chronic moderate-to-severe aphasia with comorbid apraxia of speech (AOS). Constraint-induced aphasia therapy (CIAT; Pulvermüller et al., 2001) has demonstrated positive outcomes in some individuals with chronic aphasia. Whether constraint to the speech modality or treatment intensity is responsible for such gains is still under investigation. Moreover, it remains to be seen whether CIAT is effective in individuals with persistent severe nonfluent speech and/or AOS.

METHOD

A single-subject multiple-baseline approach was used. Both participants were treated simultaneously, first with Promoting Aphasics' Communicative Effectiveness (PACE; Davis & Wilcox, 1985) and then with CIAT. Pre-/posttreatment testing included an overt naming fMRI protocol. Treatment effect sizes were calculated for changes in probe accuracy from baseline to posttreatment phases and maintenance where available.

RESULTS

Both participants made more and faster gains in naming following CIAT. Treatment-induced changes in BOLD activation suggested that better naming was correlated with the recruitment of perilesional tissue.

CONCLUSION

Participants produced more target words accurately following CIAT than following PACE. Behavioral and fMRI results support the notion that the intense and repetitive nature of obligatory speech production in CIAT has a positive effect on word retrieval, even in participants with chronic moderate-to-severe aphasia with comorbid AOS.

First decade of research on constrained-induced treatment approaches for aphasia rehabilitation

Approaches for treating poststroke language impairments (aphasia) based on constraint-induced (CI) principles were first introduced in 2001. CI principles as previously applied to upper extremity and locomotor retraining in stroke survivors were derived from basic neuroscience. They comprise forced-use of the affected modality, a gradual rebuilding of targeted functions using a highly intensive treatment protocol, administered in a behaviorally relevant context. CI-based approaches have stimulated considerable neurorehabilitation research interest in the past decade. The original CI aphasia treatment protocol was tailored to improve functional communication in chronic aphasia (ie, 6-12mo after stroke) and more recently, it has been adapted to treat language impairments in acute stroke survivors as well. Moreover, CI therapy applied to aphasia has been used as a model to assess language network plasticity in response to treatment using functional imaging techniques. In the following article, we review the first 10 years of behavioral and functional brain imaging research on CI-based approaches for aphasia rehabilitation.

Behavioral and neurophysiologic response to therapy for chronic aphasia

Breier JI, Juranek J, Maher LM, Schmadeke S, Men D, Papanicolaou AC. Behavioral and neurophysiologic response to therapy for chronic aphasia.

OBJECTIVE

To characterize the relationship between neurophysiologic changes in the brain and behavioral response to constraint-induced language therapy (CILT) by using magnetoencephalography (MEG).

DESIGN

Case series.

SETTING

Medical school.

PARTICIPANTS

Patients (N=23) with chronic aphasia after first-time unilateral stroke in the left hemisphere.

INTERVENTIONS

Constraint-induced language therapy administered for 3 hours 4 times per week for 3 weeks. Language testing and functional imaging during a language comprehension task using MEG before, immediately after, and 3 months after CILT with a subgroup of patients undergoing additional MEG scanning and language testing 3 weeks before CILT.

MAIN OUTCOME MEASURES

The percent of correct information units and the number of late dipoles normalized to total activation.

RESULTS

Three patterns of behavioral and neurophysiologic response to CILT were identified. Patients with significant improvement in language immediately after CILT who lost these gains at follow-up had greater right hemisphere activation than other patients at all MEG scanning sessions. Patients with significant improvement in language immediately after CILT who maintained these gains at follow-up exhibited an increase in left temporal activation after CILT, whereas patients who did not exhibit significant improvement in language after CILT exhibited comparably greater activation in left parietal areas.

CONCLUSIONS

Results suggest that although the right hemisphere may support recovery of language function in response to therapy, this recovery may not be stable, and some participation of perilesional areas of the left hemisphere may be necessary for a stable behavioral response.

Changes in maps of language activity activation following melodic intonation therapy using magnetoencephalography: two case studies

Two patients with chronic expressive aphasia underwent two blocks of melodic intonation therapy (MIT) each. Maps of language-specific neurophysiological activity were obtained prior to and after each MIT block during a covert action naming task using magnetoencephalography. Both patients exhibited increased left hemisphere activation after MIT. The patient who responded positively to therapy exhibited decreasing activation within areas of the right hemisphere homotopic to left hemisphere language areas compared to baseline after both blocks of MIT. In contrast, the patient who did not show improvement after therapy exhibited increasing activation in these areas of the right hemisphere after therapy. Results are consistent with hypotheses that melodic intonation therapy acts through promotion of left hemisphere activation.

Changes in language-specific brain activation after therapy for aphasia using magnetoencephalography: a case study

A patient with chronic aphasia underwent functional imaging during a language comprehension task using magnetoencephalography (MEG) before and after constraint induced language therapy (CILT). In the pre- and immediate post-treatment (TX) scans MEG activity sources were observed within right hemisphere only, and were located in areas homotopic to left hemisphere language areas. There was a significant increase in activation in these areas between the two sessions. This change was not observed in an age-matched patient with chronic aphasia who underwent sequential language testing and MEG scanning across a similar time period without being administered therapy. In the 3-month post-TX scan bilateral activation was observed, including significant activation within the left temporal lobe. The changes in the spatial parameters of the maps of receptive language function after therapy were accompanied by improvement in language function. Results provide support, in the same individual, for a role for both hemispheres in recovery of language function after therapy for chronic aphasia.