Changes of right-hemispheric activation after constraint-induced, intensive language action therapy in chronic aphasia: fMRI evidence from auditory semantic processing.

Bettina Mohr,Samuel Evans,Stephanie Difrancesco,Friedemann Pulvermüller,Karen Harrington

doi:10.3389/fnhum.2014.00919

Abstract

The role of the two hemispheres in the neurorehabilitation of language is still under dispute. This study explored the changes in language-evoked brain activation over a 2-week treatment interval with intensive constraint induced aphasia therapy (CIAT), which is also called intensive language action therapy (ILAT). Functional magnetic resonance imaging (fMRI) was used to assess brain activation in perilesional left hemispheric and in homotopic right hemispheric areas during passive listening to high and low-ambiguity sentences and non-speech control stimuli in chronic non-fluent aphasia patients. All patients demonstrated significant clinical improvements of language functions after therapy. In an event-related fMRI experiment, a significant increase of BOLD signal was manifest in right inferior frontal and temporal areas. This activation increase was stronger for highly ambiguous sentences than for unambiguous ones. These results suggest that the known language improvements brought about by intensive constraint-induced language action therapy at least in part relies on circuits within the right-hemispheric homologs of left-perisylvian language areas, which are most strongly activated in the processing of semantically complex language.

Highlights

A highly disputed issue in cortical reorganization and language recovery after post stroke aphasia (PSA) is the role of the right hemisphere (RH) as opposed to perilesional brain regions in the left language-dominant hemisphere (LH)
This study explored the changes in language-evoked brain activation over a 2-week treatment interval with intensive constraint induced aphasia therapy (CIAT), which is called intensive language action therapy (ILAT)
In an event-related Functional magnetic resonance imaging (fMRI) experiment, a significant increase of BOLD signal was manifest in right inferior frontal and temporal areas. This activation increase was stronger for highly ambiguous sentences than for unambiguous ones. These results suggest that the known language improvements brought about by intensive constraint-induced language action therapy at least in part relies on circuits within the right-hemispheric homologs of left-perisylvian language areas, which are most strongly activated in the processing of semantically complex language

Summary

Introduction

A highly disputed issue in cortical reorganization and language recovery after post stroke aphasia (PSA) is the role of the right hemisphere (RH) as opposed to perilesional brain regions in the left language-dominant hemisphere (LH). Consistent with the primary role of the LH in language, a majority of studies report evidence of language reorganization in perilesional areas within the LH in PSA patients (Heiss et al, 1999; Price and Crinion, 2005; Breier et al, 2007; Meinzer et al, 2008). There is evidence that at least some of these new language substrates in patients with large lesions may be located in the non-dominant RH (Cappa and Vallar, 1992; Crosson et al, 2005; Heiss and Thiel, 2006; Turkeltaub et al, 2012). Apart from etiology, lesion size and site, time post lesion and other variables, language recovery, and cortical reorganization in aphasia seems to be influenced significantly by pre-morbid language use and therapeutic intervention (Crosson et al, 2005; Marcotte and Ansaldo, 2010)

Methods

Results

Conclusion