title: Interhemispheric Plasticity following Intermittent Theta Burst Stimulation in Chronic Poststroke Aphasia.
abstract: The effects of noninvasive neurostimulation on brain structure and function in chronic poststroke aphasia are poorly understood. We investigated the effects of intermittent theta burst stimulation (iTBS) applied to residual language-responsive cortex in chronic patients using functional and anatomical MRI data acquired before and after iTBS. Lateralization index (LI) analyses, along with comparisons of inferior frontal gyrus (IFG) activation and connectivity during covert verb generation, were used to assess changes in cortical language function. Voxel-based morphometry (VBM) was used to assess effects on regional grey matter (GM). LI analyses revealed a leftward shift in IFG activity after treatment. While left IFG activation increased, right IFG activation decreased. Changes in right to left IFG connectivity during covert verb generation also decreased after iTBS. Behavioral correlations revealed a negative relationship between changes in right IFG activation and improvements in fluency. While anatomical analyses did not reveal statistically significant changes in grey matter volume, the fMRI results provide evidence for changes in right and left IFG function after iTBS. The negative relationship between post-iTBS changes in right IFG activity during covert verb generation and improvements in fluency suggests that iTBS applied to residual left-hemispheric language areas may reduce contralateral responses related to language production and facilitate recruitment of residual language areas after stroke.
authors.affiliation: Department of Psychology, University of Alabama at Birmingham, Birmingham, AL 35294-0021, USA.
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Griffis
authors.affiliation: Department of Neurology, University of Alabama at Birmingham, Birmingham, AL 35294-0021, USA.
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Nenert
authors.affiliation: Department of Neurology, University of Alabama at Birmingham, Birmingham, AL 35294-0021, USA.
authors.forename: Jane B
authors.initials: JB
authors.lastname: Allendorfer
authors.affiliation: Department of Neurology, University of Alabama at Birmingham, Birmingham, AL 35294-0021, USA; Department of Neurology, University of Cincinnati Academic Health Center, Cincinnati, OH, USA.
authors.forename: Jerzy P
authors.initials: JP
authors.lastname: Szaflarski
mesh_terms: D001037:Aphasia / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D001921:Brain / Q000473:pathology / Q000503:physiopathology; D002908:Chronic Disease; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009473:Neuronal Plasticity; D017397:Prefrontal Cortex / Q000473:pathology / Q000503:physiopathology*; D020521:Stroke / Q000150:complications* / Q000473:pathology; D050781:Transcranial Magnetic Stimulation / Q000379:methods