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Brain Network Connectivity and Behavioral Improvements After Intensive Aphasia Treatment
Poster D80 in Poster Session D, Wednesday, October 25, 4:45 - 6:30 pm CEST, Espace Vieux-Port
Evan Houldin1,2, Edna Babbitt1,2, Rosalind Hurwitz1, Marwan Baliki1,2, Leora Cherney1,2; 1Shirley Ryan AbilityLab, 2Northwestern University
INTRODUCTION: Neuroimaging studies indicate that aphasia is associated with large-scale reorganization of brain network functional connectivity (FC), as measured with resting-state fMRI (rsfMRI), and that connectivity changes can partially explain different behavioral symptoms in and across various patient groups. Despite these observations, the specific networks involved in aphasia recovery following intensive treatment remain relatively obscure. Here, we use rsfMRI to examine the role of FC in determining aphasia recovery following intensive therapy in stroke patients. METHODS: We studied 19 aphasia patients with left hemispheric lesions who completed an intensive comprehensive aphasia program (ICAP), which included treatment for 6 hours/day, 5 days/week, for 4 weeks (120 hours total). All participants completed pre- and post-treatment rsfMRI scanning and behavioral testing, including the Western Aphasia Battery Revised (WAB-R). The WAB-R comprises a number of subscores (e.g., Fluency and Repetition), as well as overall quotients, i.e., Aphasia, Language and Cognitive Quotients (AQ, LQ, CQ). Behavioral score improvements were assessed using a paired t-test. The Brain Connectivity Toolbox was used to compute a variety of graph measures, including local and modular changes, before and after treatment. A multiple regression model was used to identify the relationship between behavioral subscores and the AQ. Within- and between-network FC was assessed with a paired t-test. Finally, changes in behavior were correlated with FC changes. RESULTS: Overall, patients showed significant improvement across several behavioral subscores following treatment, including Fluency (p<0.01), Sequential Commands (p<0.01), Repetition (p<0.001), Information Content, Object naming and Responsive Speech (last 3; p<0.05). Additionally, AQ (p<0.001) and LQ (p<0.001) showed significant improvement. Multiple regression indicated that Fluency, Sequential Commands, Repetition and Object Naming improvements best predicted those of AQ. These subscore improvements were also found to significantly positively correlate with brain FC changes involving salience, attention, top-down control and default mode networks (DMN). In particular, Object Naming was positively correlated with decreased auditory-salience network FC (r=0.6, p<0.01), and increased DMN-dorsal attention network FC (r=0.65, p<0.01). AQ improvement was significantly positively correlated with reduced FC between the salience and the auditory-language network (r=0.6, p<0.01). More generally, FC involving salience and attention networks changed significantly across the intervention, independent of the correlations with these specific behavioral measures. FC within the salience and ventral attention network (VAN) increased significantly, as did salience-VAN FC, and salience-task control network FC (all p<0.05). Dorsal attention network (DAN)-visual and DAN-auditory network FC also decreased significantly (P<0.05). Graph measures did not show significant changes across the intervention. CONCLUSIONS: These results suggest that salience and attention network FC plays a key role in determining the behavioral improvements of aphasia patients participating in an ICAP. Importantly, externally-focused attention is an essential factor for the successful completion of several WAB-R tasks, many of which involve command following. It therefore follows that salience and attention networks would be significant to the recovery of language functions requiring this faculty. More studies are needed to further describe the relationship between aphasia recovery and brain network connectivity changes, however.
Topic Areas: Speech-Language Treatment,