Changes in functional connectivity related to direct training and generalization effects of a word finding treatment in chronic aphasia.
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SUBMITTER: Sandberg CW
PROVIDER: S-EPMC4663144 | biostudies-literature | 2015 Nov
REPOSITORIES: biostudies-literature
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Changes in functional connectivity related to direct training and generalization effects of a word finding treatment in chronic aphasia.
Sandberg Chaleece W CW Bohland Jason W JW Kiran Swathi S
Brain and language 20150920
The neural mechanisms that underlie generalization of treatment-induced improvements in word finding in persons with aphasia (PWA) are currently poorly understood. This study aimed to shed light on changes in functional network connectivity underlying generalization in aphasia. To this end, we used fMRI and graph theoretic analyses to examine changes in functional connectivity after a theoretically-based word-finding treatment in which abstract words were used as training items with the goal of ...[more]
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Project description:IntroductionAphasia is one of the most disabling sequelae after stroke, occurring in 25%-40% of stroke survivors. However, there remains a lack of good evidence for the efficacy or mechanisms of speech comprehension rehabilitation.Trial designThis within-subjects trial tested two concurrent interventions in 20 patients with chronic aphasia with speech comprehension impairment following left hemisphere stroke: (1) phonological training using 'Earobics' software and (2) a pharmacological intervention using donepezil, an acetylcholinesterase inhibitor. Donepezil was tested in a double-blind, placebo-controlled, cross-over design using block randomisation with bias minimisation.MethodsThe primary outcome measure was speech comprehension score on the comprehensive aphasia test. Magnetoencephalography (MEG) with an established index of auditory perception, the mismatch negativity response, tested whether the therapies altered effective connectivity at the lower (primary) or higher (secondary) level of the auditory network.ResultsPhonological training improved speech comprehension abilities and was particularly effective for patients with severe deficits. No major adverse effects of donepezil were observed, but it had an unpredicted negative effect on speech comprehension. The MEG analysis demonstrated that phonological training increased synaptic gain in the left superior temporal gyrus (STG). Patients with more severe speech comprehension impairments also showed strengthening of bidirectional connections between the left and right STG.ConclusionsPhonological training resulted in a small but significant improvement in speech comprehension, whereas donepezil had a negative effect. The connectivity results indicated that training reshaped higher order phonological representations in the left STG and (in more severe patients) induced stronger interhemispheric transfer of information between higher levels of auditory cortex.Clinical trial registrationThis trial was registered with EudraCT (2005-004215-30, https://eudract.ema.europa.eu/) and ISRCTN (68939136, http://www.isrctn.com/).
| S-EPMC5659142 | biostudies-literature
Project description:ObjectiveOf 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.MethodTo 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.ResultsAll 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.ConclusionsWhile 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.
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Project description:ObjectiveTo examine the cost-effectiveness of self-managed computerised word finding therapy as an add-on to usual care for people with aphasia post-stroke.DesignCost-effectiveness modelling over a life-time period, taking a UK National Health Service (NHS) and personal social service perspective.SettingBased on the Big CACTUS randomised controlled trial, conducted in 21 UK NHS speech and language therapy departments.ParticipantsBig CACTUS included 278 people with long-standing aphasia post-stroke.InterventionsComputerised word finding therapy plus usual care; usual care alone; usual care plus attention control.Main measuresIncremental cost-effectiveness ratios (ICER) were calculated, comparing the cost per quality adjusted life year (QALY) gained for each intervention. Credible intervals (CrI) for costs and QALYs, and probabilities of cost-effectiveness, were obtained using probabilistic sensitivity analysis. Subgroup and scenario analyses investigated cost-effectiveness in different subsets of the population, and the sensitivity of results to key model inputs.ResultsAdding computerised word finding therapy to usual care had an ICER of £42,686 per QALY gained compared with usual care alone (incremental QALY gain: 0.02 per patient (95% CrI: -0.05 to 0.10); incremental costs: £732.73 per patient (95% CrI: £674.23 to £798.05)). ICERs for subgroups with mild or moderate word finding difficulties were £22,371 and £21,262 per QALY gained respectively.ConclusionComputerised word finding therapy represents a low cost add-on to usual care, but QALY gains and estimates of cost-effectiveness are uncertain. Computerised therapy is more likely to be cost-effective for people with mild or moderate, as opposed to severe, word finding difficulties.
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Project description:Focal brain damage caused by stroke can result in aphasia and advances in cognitive neuroscience suggest that impairment may be associated with network-level disorder rather than just circumscribed cortical damage. Several studies have shown meaningful relationships between brain-behaviour using lesions; however, only a handful of studies have incorporated in vivo structural and functional connectivity. Patients with chronic post-stroke aphasia were assessed with structural (n = 68) and functional (n = 39) MRI to assess whether predicting performance can be improved with multiple modalities and if additional variance can be explained compared to lesion models alone. These neural measurements were used to construct models to predict four key language-cognitive factors: (i) phonology; (ii) semantics; (iii) executive function; and (iv) fluency. Our results showed that each factor (except executive ability) could be significantly related to each neural measurement alone; however, structural and functional connectivity models did not explain additional variance above the lesion models. We did find evidence that the structural and functional predictors may be linked to the core lesion sites. First, the predictive functional connectivity features were found to be located within functional resting-state networks identified in healthy controls, suggesting that the result might reflect functionally specific reorganization (damage to a node within a network can result in disruption to the entire network). Second, predictive structural connectivity features were located within core lesion sites, suggesting that multimodal information may be redundant in prediction modelling. In addition, we observed that the optimum sparsity within the regularized regression models differed for each behavioural component and across different imaging features, suggesting that future studies should consider optimizing hyperparameters related to sparsity per target. Together, the results indicate that the observed network-level disruption was predicted by the lesion alone and does not significantly improve model performance in predicting the profile of language impairment.
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Project description:People with aphasia often show partial impairments on a given task. This trial-to-trial variability offers a potential window into understanding how damaged language networks function. We test the hypothesis that successful word reading in participants with phonological system damage reflects semantic system recruitment. Residual semantic and phonological networks were defined with fMRI in 21 stroke participants with phonological damage using semantic- and rhyme-matching tasks. Participants performed an oral word reading task, and activation was compared between correct and incorrect trials within the semantic and phonological networks. The results showed a significant interaction between hemisphere, network activation, and reading success. Activation in the left hemisphere semantic network was higher when participants successfully read words. Residual phonological regions showed no difference in activation between correct and incorrect trials on the word reading task. The results provide evidence that semantic processing supports successful phonological retrieval in participants with phonological impairment.
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Project description:Primary progressive aphasia (PPA) is a clinical neurodegenerative syndrome with word finding problems as a core clinical symptom. Many aspects of word finding have been clarified in psycholinguistics using picture naming and a picture-word interference (PWI) paradigm, which emulates naming under contextual noise. However, little is known about how word finding depends on white-matter tract integrity, in particular, the atrophy of tracts located ventrally to the Sylvian fissure. To elucidate this question, we examined word finding in individuals with PPA and healthy controls employing PWI, tractography, and computer simulations using the WEAVER++ model of word finding. Twenty-three individuals with PPA and twenty healthy controls named pictures in two noise conditions. Mixed-effects modelling was performed on naming accuracy and reaction time (RT) and fixel-based tractography analyses were conducted to assess the relation between ventral white-matter integrity and naming performance. Naming RTs were longer for individuals with PPA compared to controls and, critically, individuals with PPA showed a larger noise effect compared to controls. Moreover, this difference in noise effect was differentially related to tract integrity. Whereas the noise effect did not depend much on tract integrity in controls, a lower tract integrity was related to a smaller noise effect in individuals with PPA. Computer simulations supported an explanation of this paradoxical finding in terms of reduced propagation of noise when tract integrity is low. By using multimodal analyses, our study indicates the significance of the ventral pathway for naming and the importance of RT measurement in the clinical assessment of PPA.
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Project description:BackgroundIncreasing life expectancy necessitates the better understanding of the neurophysiological underpinnings of age-related cognitive changes. The majority of research examining structural-cognitive relationships in aging focuses on the role of age-related changes to grey matter integrity. In the current study, we examined the relationship between age-related changes in white matter and language production. More specifically, we concentrated on word-finding failures, which increase with age.Methodology/principal findingsWe used Diffusion tensor MRI (a technique used to image, in vivo, the diffusion of water molecules in brain tissue) to relate white matter integrity to measures of successful and unsuccessful picture naming. Diffusion tensor images were used to calculate Fractional Anisotropy (FA) images. FA is considered to be a measure of white matter organization/integrity. FA images were related to measures of successful picture naming and to word finding failures using voxel-based linear regression analyses. Successful naming rates correlated positively with white matter integrity across a broad range of regions implicated in language production. However, word finding failure rates correlated negatively with a more restricted region in the posterior aspect of superior longitudinal fasciculus.Conclusions/significanceThe use of DTI-MRI provides evidence for the relationship between age-related white matter changes in specific language regions and word finding failures in old age.
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Project description:PurposeAnomia, or difficulty with naming and word finding, is a pervasive deficit among individuals with aphasia. There is an extensive literature on the mechanisms underlying anomia and on approaches to treatment, but very little is known about the subjective experience of anomia during day-to-day life.MethodAs part of a larger testing battery, 53 adults with poststroke aphasia took part in a novel, structured interview that included an open-ended question about the general experience of anomia: "Do you ever know what you want to say, but you can't say it out loud? Please describe that feeling." Video-recorded interview responses were transcribed and analyzed using thematic analysis, an iterative, data-driven process that categorizes interview data into common themes.ResultsFive main themes emerged among the data from 37 participants who produced adequate responses for use in thematic analysis: strategies to cope with or compensate for anomia, comments on awareness of the level of breakdown (e.g., "I have an idea, but can't get the right words"), negative emotions, impact on relationships, and changes in frequency over time.ConclusionsParticipants showed strong awareness of anomia and its implications, demonstrating an ability to describe their language breakdown, identify relevant strategies to compensate and/or cope, and acknowledge the impact of anomia on their emotions and social interactions. This patient perspective may serve as a valuable supplement to information typically gained via objective language assessments. Clinicians and researchers may wish to consider incorporating similar subjective measures during assessment and treatment planning. Supplemental Material https://doi.org/10.23641/asha.15032643.
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