Activation shifts after treatment-induced recovery of sentence processing and production in agrammatism

This presentation video is from the Research Symposium at the 2018 annual convention of the American Speech-Language-Hearing Association held in Boston, MA.The abstract for the accompanying article is below. This article is part of the JSLHR Forum: Advances in Neuroplasticity Research on Language Recovery 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.Thompson, C. K. (2019). Neurocognitive recovery of sentence processing in aphasia. Journal of Speech, Language, and Hearing Research, 62(11), 3947–3972. https://doi.org/10.1044/2019_JSLHR-L-RSNP-19-0219

Syntactic priming and the lexical boost effect during sentence production and sentence comprehension: An fMRI study

ABSTRACTExploring generalisation following treatment of language deficits in aphasia can provide insights into the functional relation of the cognitive processing systems involved. In the present study, we first review treatment outcomes of interventions targeting sentence processing deficits and, second report a treatment study examining the occurrence of practice effects and generalisation in sentence comprehension and production. In order to explore the potential linkage between processing systems involved in comprehending and producing sentences, we investigated whether improvements generalise within (i.e., uni-modal generalisation in comprehension or in production) and/or across modalities (i.e., cross-modal generalisation from comprehension to production or vice versa). Two individuals with aphasia displaying co-occurring deficits in sentence comprehension and production were trained on complex, non-canonical sentences in both modalities. Two evidence-based treatment protocols were applied in a crossover intervention study with sequence of treatment phases being randomly allocated. Both participants benefited significantly from treatment, leading to uni-modal generalisation in both comprehension and production. However, cross-modal generalisation did not occur. The magnitude of uni-modal generalisation in sentence production was related to participants’ sentence comprehension performance prior to treatment. These findings support the assumption of modality-specific sub-systems for sentence comprehension and production, being linked uni-directionally from comprehension to production.

Comprehending and producing sentences is a complex endeavor requiring the coordinated activity of multiple brain regions. We examined three issues related to the brain networks underlying sentence comprehension and production in healthy individuals: First, which regions are recruited for sentence comprehension and sentence production? Second, are there differences for auditory sentence comprehension vs. visual sentence comprehension? Third, which regions are specifically recruited for the comprehension of syntactically complex sentences? Results from activation likelihood estimation (ALE) analyses (from 45 studies) implicated a sentence comprehension network occupying bilateral frontal and temporal lobe regions. Regions implicated in production (from 15 studies) overlapped with the set of regions associated with sentence comprehension in the left hemisphere, but did not include inferior frontal cortex, and did not extend to the right hemisphere. Modality differences between auditory and visual sentence comprehension were found principally in the temporal lobes. Results from the analysis of complex syntax (from 37 studies) showed engagement of left inferior frontal and posterior temporal regions, as well as the right insula. The involvement of the right hemisphere in the comprehension of these structures has potentially important implications for language treatment and recovery in individuals with agrammatic aphasia following left hemisphere brain damage.

The cross-modal generalization effects of training complex sentence comprehension and complex sentence production were examined in 4 individuals with agrammatic Broca's aphasia who showed difficulty comprehending and producing complex, noncanonical sentences. Object-cleft and passive sentences were selected for treatment because the two are linguistically distinct, relying on wh-and NP movement, respectively (Chomsky, 1986). Two participants received comprehension training, and 2 received production training using linguistic specific treatment (LST). LST takes participants through a series of steps that emphasize the verb and verb argument structure, as well as the linguistic movement required to derive target sentences. A single-subject multiple-baseline design across behaviors was used to measure acquisition and generalization within and across sentence types, as well as cross-modal generalization (i.e., from comprehension to production and vice versa) and generalization to discourse. Results indicated that both treatment methods were effective for training comprehension and production of target sentences and that comprehension treatment resulted in generalization to spoken and written sentence production. Sentence production treatment generalized to written sentence production only; generalization to comprehension did not occur. Across sentence types generalization also did not occur, as predicted, and the effects of treatment on discourse were inconsistent across participants. These data are discussed with regard to models of normal sentence comprehension and production.

Background: Verb difficulties in aphasia often co-occur with difficulties specifying argument structure of the sentence. Recent exploration of verb and argument structure deficits has shown dissociations between lexical semantic information, argument structure information, and production of the argument structure. There is currently limited evidence regarding the implications of these dissociations for treatment.Aims: This paper explores the patterns of generalisation following intervention to increase access to verb argument structure for a 62-year-old woman (YR) with chronic agrammatic aphasia. YR had good access to nouns and verbs in picture naming alongside severe sentence production difficulties characterised by difficulty specifying argument structure.Methods & Procedures: Detailed pre-therapy language assessment investigated single word and sentence comprehension and production, with a specific focus on whether YR could produce argument structure. Intervention targeted verb retrieval, awareness of argument structure information, cueing of arguments, and production of argument and syntactic structure involving transitive verbs. A single-subject multiple baseline design was used to monitor the effectiveness of treatment. The primary outcome measure was accuracy of two-argument structures in sentence production to picture and sentence generation to written word tasks, with effects on treated and untreated verbs considered. Other measures of sentence comprehension and production were also obtained to determine any further generalisation.Outcomes & Results: Following the first phase of therapy, YR showed a significant improvement in the production of two-argument structures across both treated and untreated verbs in sentence production to pictures, with a corresponding significant reduction in incomplete argument structures. No change was seen in two-argument structures in sentence generation to written words. After the second phase of therapy, significant gains were seen in two-argument structures with both treated and untreated verbs in the sentence generation task while sentence production to picture performance maintained. Gains in sentence generation were more vulnerable following the cessation of therapy. Other tasks of sentence production also improved with no change seen on a control task.Conclusions: Argument structure can be selectively impaired in aphasia, in the presence of good verb and noun access at the single word level, and targeted in therapy to improve sentence production. The study highlights the complexity of the relationship between verbs and argument structure and that argument structure difficulties are not always a consequence of a semantic verb deficit. Generalised improvement in argument structure production provides evidence that therapy targeted general processes rather than lexically specified argument structure information.

Psych verb production and comprehension in agrammatic Broca's aphasia

Common and distinct neural substrates of sentence production and comprehension

What belongs together goes together: the speaker-hearer perspective. A commentary on MacDonald's PDC account

Background: Over recent years there have been a number of studies investigating the effects of therapy for verb and sentence processing difficulties in people with aphasia. A variety of therapies have been described, with apparently different foci and different methods. Despite this, similarities in the outcomes reported would suggest that the therapy techniques are in fact targeting similar processes. Aims: The paper describes two periods of speech and language therapy intervention with a person with non‐fluent aphasia, MV. The contrasting effects of the two therapy periods are discussed and the mechanisms underpinning the improvements seen following the second period involving “verb and noun association therapy” are considered. Methods & Procedures: A case study approach is used to evaluate the effects of two periods of intervention. The client, MV, was diagnosed with a semantic impairment resulting in a noun and verb retrieval deficit, as well as difficulties with argument structure and mapping. In the first intervention period, therapy consisted of verb‐centred mapping therapy and tasks promoting divergent noun and verb retrieval. In the second intervention period, “verb and noun association” therapy was used. Therapy was preceded and followed by detailed assessment of single word and sentence comprehension and production. Outcomes & Results: The initial period of therapy resulted in no linguistic improvement. In contrast, the verb and noun association therapy resulted in item‐specific improvement in verb naming and a parallel improvement in verb comprehension. Significant gains in sentence production were also seen; MV was able to produce more nouns within a sentence context and produce more thematically complete and grammatically accurate sentences. These gains were not related to her ability to produce the nouns targeted within the therapy. Conclusions: It is proposed that the gains in sentence production following the verb and noun association therapy were a consequence of the improved specification of the argument structure around verbs. It is not clear whether this resulted from improved access to lexically specified argument structure information or more generalised gains in argument structure production. The study suggests that gains in sentence production can be achieved for some clients without explicit identification or cueing of arguments and that this approach may be more beneficial for people who struggle with the demands of a more “meta‐linguistic” approach.

ABSTRACTBackground & Aims: Impaired message-structure mapping results in deficits in both sentence production and comprehension in aphasia. Structural priming has been shown to facilitate syntactic production for persons with aphasia (PWA). However, it remains unknown if structural priming is also effective in sentence comprehension. We examined if PWA show preserved and lasting structural priming effects during interpretation of syntactically ambiguous sentences and if the priming effects occur independently of or in conjunction with lexical (verb) information.Methods & Procedures: Eighteen PWA and 20 healthy older adults (HOA) completed a written sentence-picture matching task involving the interpretation of prepositional phrases (PP; the chef is poking the solider with an umbrella) that were ambiguous between high (verb modifier) and low attachment (object noun modifier). Only one interpretation was possible for prime sentences, while both interpretations were possible for target sentences. In Experiment 1, the target was presented immediately after the prime (0-lag). In Experiment 2, two filler items intervened between the prime and the target (2-lag). Within each experiment, the verb was repeated for half of the prime-target pairs, while different verbs were used for the other half. Participants’ off-line picture matching choices and response times were measured.Results: After reading a prime sentence with a particular interpretation, HOA and PWA tended to interpret an ambiguous PP in a target sentence in the same way and with faster response times. Importantly, both groups continued to show this priming effect over a lag (Experiment 2), although the effect was not as reliable in response times. However, neither group showed lexical (verb-specific) boost on priming, deviating from robust lexical boost seen in the young adults of prior studies.Conclusions: PWA demonstrate abstract (lexically-independent) structural priming in the absence of a lexically-specific boost. priming is preserved in aphasia, effectively facilitating not only immediate but also longer-lasting structure-message mapping during sentence comprehension.

Processing Argument Structure and Syntactic Complexity in People with Schizophrenia Spectrum Disorders

The purpose of the study was to evaluate Verb Network Strengthening Treatment (VNeST) paired with the transcranial direct current stimulation (tDCS) of the left inferior frontal gyrus, which was compared to VNeST paired with a sham stimulation in primary progressive aphasia (PPA). A double-blind, within-subject, sham-controlled crossover design was used. Eight participants with PPA were enrolled. Participants were enrolled in two treatment phases, one with VNeST plus real tDCS and one with VNeST plus sham. Participants received fifteen 1-hr sessions of VNeST in each phase. Linear mixed-effects models were used to compare changes between baseline and two follow-up time points (1 week and 8 weeks posttreatment) in naming trained verbs, untrained verbs, and untrained nouns; sentence production and comprehension; and producing content units and complete utterances in discourse. VNeST was effective for significantly improving naming trained verbs and producing more complete utterances in discourse at 1 week posttreatment in both tDCS and sham conditions. A significant tDCS advantage yielded generalization of treatment effects to untrained verbs (at 1 week and 8 weeks posttreatment), sentence production (at 1 week posttreatment), and sentence comprehension (at 8 weeks posttreatment). Untrained verb naming and sentence comprehension declined when VNeST was not augmented with tDCS. Our findings provide emerging evidence that VNeST paired with tDCS can improve word finding, and other language abilities, in people with PPA. VNeST without neuromodulation can improve trained verb naming, but untrained verbs will likely decline faster when VNeST is not augmented with tDCS. Future research is required with a larger sample size to continue investigating the potential of treating word finding with VNeST and tDCS in PPA. https://doi.org/10.23641/asha.27914325.

The disruption of sentence production: Some dissociations

Sentence production and comprehension both draw on linguistic knowledge, but current research is unclear on whether these fundamental language tasks involve similar or distinct competitive processes. Previous studies suggest that production and comprehension may involve similar conflict resolution processes, but that production may additionally recruit motor-related conflict not necessarily present in comprehension. To examine these possibilities, we combined an experimental animacy-driven manipulation eliciting difficulty in separate production and comprehension tasks with an examination of how this manipulation interacted with individual variability in motor-related and lexicosemantic conflict resolution performance beyond vocabulary measures. We reasoned that a different pattern of interactions for production and comprehension would point to distinct processes across these tasks, whereas interactions with the same individual performance task would indicate similar conflict-related processes. We found that beyond a significant role of vocabulary, only a measure of context-dependent lexical ambiguity resolution interacted with the animacy manipulation in the production and the comprehension task. These findings suggest a role for linguistic knowledge and similar lexically driven competitive processes in both sentence production and comprehension. Alongside current computational models, these results raise the possibility that despite different task demands, some production and comprehension competitive processes are not entirely distinct from one another nor separable from lexical knowledge. Implications for current views on the relationship between sentence production and comprehension are discussed. (PsycInfo Database Record (c) 2022 APA, all rights reserved).