Poster D25, Wednesday, August 21, 2019, 5:15 – 7:00 pm, Restaurant Hall
Differential effects of intensive language-action therapy on processing grammatical word class and semantics demonstrated by functional magnetic resonance imaging
Felix R Dreyer1, Lea Doppelbauer1, Benjamin Stahl2, Guglielmo Lucchese3, Bettina Mohr2, Friedemann Pulvermüller1,4,5,6;1Brain Language Laboratory, Freie Universität Berlin, 2Charité Hospital Berlin, 3University Medicine Greifswald, 4Humboldt Universität zu Berlin, Cluster of Excellence Matters of Activity. Image Space Material, Berlin, Germany, 5Berlin School of Mind and Brain, 6Humboldt Universität zu Berlin, Cluster of Excellence Matters of Activity. Image Space Material
Introduction: Previous discussions on the neural correlates of aphasia therapy effects were predominantly centered on the issue of differential hemispheric contributions to aphasia recovery, with studies showing rather heterogeneous results in favor of a compensatory role of perilesional left hemispheric, as well as (homologue) areas on the right hemisphere (Saur & Hartwigsen, 2012). In how far those neural correlates depend on processing of specific semantic and grammatical received less attention in comparison. The current study therefore investigates differential effects of aphasia therapy between semantic and grammatical word types using fMRI and standard behavioural aphasia measures. Methods: Sixteen chronic stroke patients suffering from aphasia received intensive language action therapy (ILAT; also known as Constraint Induced Aphasia Therapy, CIAT) for 32h. Before and after therapy all patients participated in a passive reading fMRI paradigm. Stimuli consisted of Hashmark strings, which served as a visual baseline, as well as nouns and verbs with either abstract or concrete semantics, with categories being matched on psycholinguistic properties. Therapy outcome of each patient was assessed by comparing pre and post therapy results of the Aachener Aphasie Test (AAT) battery. Changes in behavioral performances were correlated with changes in fMRI signal strength across different stimulus categories applied. Results: In a 2 (Time: pre/post therapy) X 2 (Word Class: noun/verb) X 2 (Semantics: abstract/concrete) second level design on first level contrasts of proper words against visual baseline, a main effect of Time was revealed in the Thalamus of both hemispheres at p <.005 (unc.) and k > 50. Furthermore, applying the same statistical thresholds, a Time X Semantics interaction was reported located in frontal regions, the Precuneus and Thalamus of the right hemisphere and the Cingulum in both hemispheres. Correlation analysis revealed exclusively post vs pre signal increase for Abstract Stimuli in Time X Semantics clusters to correlate significantly with language Perception measures; Spearmans Rho = .68, p = .025 (Bonferroni corrected). Cluster specific analysis revealed signal change for Abstract stimuli in the right Precuneus (Spearmans Rho = .71, p = .008, Bonferroni corrected) and the Cingulum (Spearmans Rho = .72, p = .006, Bonferroni corrected) to show strong correlations to increases in AAT Language Perception measures. In contrast, no such correlations were observed for analysis of concrete stimuli signal changes, for noun/verb or general time effects in the respective clusters. Discussion: Current results indicate translational therapy effects between semantic word types. Training material of ILAT consists of pictures showing concrete objects, while abstract material is not used in therapy. In contrast, the passive reading fMRI paradigm showed correlations between fMRI signal change and AAT score improvement specifically for abstract but not for concrete stimuli. Furthermore, in line with previous approaches targeting the neural correlates of conventional therapy (Menke et al. 2009) or CIAT/ILAT effects (Mohr et al. 2014), the current findings highlight activation increase in the right hemisphere to be related to behavioural language improvement.
Themes: Language Therapy, Meaning: Lexical Semantics
Method: Functional Imaging