Training verb argument structure production in agrammatic aphasia: Behavioral and neural recovery patterns

Abstract

Introduction-Neuroimaging and lesion studies indicate a left hemisphere network for verb and verb argument structure processing, involving both frontal and temporoparietal brain regions. Although their verb comprehension is generally unimpaired, it is well known that individuals with agrammatic aphasia often present with verb production deficits, characterized by an argument structure complexity hierarchy, indicating faulty access to argument structure representations for production and integration into syntactic contexts. Recovery of verb processing in agrammatism, however, has received little attention and no studies have examined the neural mechanisms associated with improved verb and argument structure processing. In the present study we trained agrammatic individuals on verbs with complex argument structure in sentence contexts and examined generalization to verbs with less complex argument structure. The neural substrates of improved verb production were examined using functional magnetic resonance imaging (fMRI).Methods-Eight individuals with chronic agrammatic aphasia participated in the study (four experimental and four control participants). Production of three-argument verbs in active sentences was trained using a sentence generation task emphasizing the verb's argument structure and the thematic roles of sentential noun phrases. Before and after training, production of trained and untrained verbs was tested in naming and sentence production and fMRI scans were obtained, using an action naming task.Results-Significant pre-to post-training improvement in trained and untrained (one-and twoargument) verbs was found for treated, but not control, participants, with between-group differences found for verb naming, production of verbs in sentences, and production of argument structure. fMRI activation derived from post-treatment compared to pre-treatment scans revealed upregulation in cortical regions implicated for verb and argument structure processing in healthy controls. Conclusions-Training verb deficits emphasizing argument structure and thematic role mapping is effective for improving verb and sentence production and results in recruitment of neural networks engaged for verb and argument structure processing in healthy individuals.

Grammatical Planning Units During Real-Time Sentence Production in Speakers With Agrammatic Aphasia and Healthy Speakers

“…For targeting lexicalization and linear ordering of words, a treatment regimen utilizing a smaller planning unit of information, such as a single word or phrase, may lead to improved production. For deficits in functional structure generation, utilizing a structural linking on the basis of VAS may be helpful, as shown in previous treatment studies (Rochon, Laird, Bose, & Scofield, 2005;Thompson, 2007;Thompson, Riley, den Ouden, Meltzer-Asscher, & Lukic, 2013).…”

Contrasting opinions on the role of the right hemisphere in the recovery of language. A critical survey

“…In apparent contrast with the model assuming a different involvement of the RH in phonological, lexical-semantic, and syntactic processing could be the neuroimaging data of treatment studies in which treatment was focused on grammatical processing (e.g., from agrammatism, Thompson, Riley, den Ouden, MeltzerAsscher, & Lukic, 2013) and/or phonological processing (e.g., from apraxia of speech, Kurland, Pulvermüller, Silva, Burke, & Andrianopoulos, 2012). For example, the findings of RH activation after treatment of agrammatism by Thompson et al (2013) and of apraxia of speech by Kurland et al (2012) could challenge the idea that RH has poor syntax or poor phonology, but (as we have noted at the end of Section 2.3 of this survey), it remains unclear if activations observed during the execution of a complex task or at the end of a treatment in aphasic stroke patients are related to language-specific activities or are due to an upregulation of activity in intact domain-general systems for cognitive control and attention. A further aspect of the RH linguistic knowledge that has been extensively investigated in recent years concerns the possibility that the RH may play an important role in higher-level language functions, such as the use of metaphors, to communicate complex, abstract concepts.…”

Grammatical impairments in PPA

“…Individuals with PPA-G exhibit more significant impairment in verb (action) naming than in noun (object) naming (Hillis et al, 2006; Hillis, Oh, & Ken, 2004; Hillis, Tuffiash, & Caramazza, 2002; Thompson, Lukic, King, Mesulam, & Weintraub, 2012). In addition, these speakers name verbs with simpler argument structures (i.e., intransitive verbs such as sweep ) more accurately than verbs with more complex argument structures (i.e., transitive verbs such as carry ) (Thompson et al, 2012b), a pattern that is characteristic of agrammatic aphasia resulting from stroke (Kim & Thompson, 2000, 2004; Luzzatti et al, 2002; Thompson, Lange, Schneider, & Shapiro, 1997; Thompson, Riley, den Ouden, Meltzer-Asscher, & Lukic, 2013). However, verb comprehension, like noun comprehension, is largely preserved in PPA-G (Hillis et al, 2006; Thompson et al, 2012b), suggesting that the lexical-semantic representations of verbs are intact.…”

“…However, converging evidence from several investigations implicate posterior perisylvian regions for verb-argument structure processing (see Thompson & Meltzer-Asscher, 2014, in press). In young and older cognitively healthy adults posterior perisylvian regions including the middle and superior temporal gyri as well as the angular and supramarginal gyri are differentially activated by verbs with more as compared to fewer arguments in studies using lexical decision (Thompson et al, 2007; Thompson, Bonakdarpour, & Fix, 2010; Thompson et al, 2013b) as well as anomaly detection tasks (e.g., Ben-Shachar, Hendler, Kahn, Ben-Bashat, & Grodzinsky, 2003). In addition, integration of verbs with their arguments has been associated with the left posterior middle and superior temporal gyri (Friederici, 2011; Thompson & Meltzer-Asscher, 2014, in press).…”