title: Hemispheric contributions to language reorganisation: An MEG study of neuroplasticity in chronic post stroke aphasia.
abstract: Previous studies have demonstrated that efficient neurorehabilitation in post stroke aphasia leads to clinical language improvements and promotes neuroplasticity. Brain areas frequently implicated in functional restitution of language after stroke comprise perilesional sites in the left hemisphere and homotopic regions in the right hemisphere. However, the neuronal mechanisms underlying therapy-induced language restitution are still largely unclear. In this study, magnetoencephalography was used to investigate neurophysiological changes in a group of chronic aphasia patients who underwent intensive language action therapy (ILAT), also known as constraint-induced aphasia therapy (CIAT). Before and immediately after ILAT, patients' language and communication skills were assessed and their brain responses were recorded during a lexical magnetic mismatch negativity (MMNm) paradigm, presenting familiar spoken words and meaningless pseudowords. After the two-week therapy interval, patients showed significant clinical improvements of language and communication skills. Spatio-temporal dynamics of neuronal changes revealed a significant increase in word-specific neuro-magnetic MMNm activation around 200ms after stimulus identification points. This enhanced brain response occurred specifically for words and was most pronounced over perilesional areas in the left hemisphere. Therapy-related changes in neuromagnetic activation for words in both hemispheres significantly correlated with performance on a clinical language test. The findings indicate that functional recovery of language in chronic post stroke aphasia is associated with neuroplastic changes in both cerebral hemispheres, with stronger left-hemispheric contribution during automatic stages of language processing.
authors.affiliation: Department of Psychiatry, Charité Universitätsmedizin, Campus Benjamin Franklin, Berlin, Germany. Electronic address: bettina.mohr@charite.de.
authors.forename: Bettina
authors.initials: B
authors.lastname: Mohr
authors.affiliation: Medical Research Council, Cognition and Brain Sciences Unit, Cambridge, UK.
authors.forename: Lucy J
authors.initials: LJ
authors.lastname: MacGregor
authors.affiliation: Department of Psychology, Anglia Ruskin University, Cambridge, UK.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Difrancesco
authors.affiliation: Department of Psychology, Anglia Ruskin University, Cambridge, UK.
authors.forename: Karen
authors.initials: K
authors.lastname: Harrington
authors.affiliation: Brain Language Laboratory, Department of Philosophy and Humanities, WE4, Freie Universität Berlin, Germany; Berlin School of Mind and Brain, Humboldt Universität zu Berlin, Germany.
authors.forename: Friedemann
authors.initials: F
authors.lastname: Pulvermüller
authors.affiliation: Institute for Clinical Medicine, Aarhus University, Denmark; Centre for Cognition and Decision Making, NRU Higher School of Economics, Moscow, Russia.
authors.forename: Yury
authors.initials: Y
authors.lastname: Shtyrov
mesh_terms: D000328:Adult; D000368:Aged; D001037:Aphasia / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy*; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D002908:Chronic Disease; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007802:Language; D007808:Language Therapy; D015225:Magnetoencephalography; D008297:Male; D008875:Middle Aged; D009473:Neuronal Plasticity / Q000502:physiology; D020127:Recovery of Function / Q000502:physiology; D013060:Speech / Q000502:physiology; D013067:Speech Perception / Q000502:physiology; D020521:Stroke / Q000150:complications / Q000503:physiopathology*; D000071939:Stroke Rehabilitation; D016896:Treatment Outcome
keywords: Aphasia; Intensive language action therapy; Language; MEG; Mismatch negativity; Neuroplasticity