Short-term modulation of the lesioned language network.

Gesa Hartwigsen,Anika Stockert,Dorothee Saur,Louise Charpentier,Julian Klingbeil,Max Wawrzyniak,Hellmuth Obrig,Katrin Wrede

doi:10.7554/elife.54277

Gesa Hartwigsen, Anika Stockert + Show 6 more

Open Access

https://doi.org/10.7554/elife.54277

Copy DOI

Abstract

Language is sustained by large-scale networks in the human brain. Stroke often severely affects function and network dynamics. However, the adaptive potential of the brain to compensate for lesions is poorly understood. A key question is whether upregulation of the right hemisphere is adaptive for language recovery. Targeting the potential for short-term reorganization in the lesioned brain, we applied 'virtual lesions' over left anterior or posterior inferior frontal gyrus (IFG) in post-stroke patients with left temporo-parietal lesions prior to functional neuroimaging. Perturbation of the posterior IFG selectively delayed phonological decisions and decreased phonological activity. The individual response delay was correlated with the upregulation of the lesion homologue, likely reflecting compensation. Moreover, stronger individual tract integrity of the right superior longitudinal fascicle was associated with lesser disruption. Our results provide evidence for functional and structural underpinnings of plasticity in the lesioned language network, and a compensatory role of the right hemisphere.

Highlights

Language is sustained by large-scale, left-lateralized neural networks in the human brain
Bonferroni-Holm corrected post-hoc paired t-tests showed that continuous theta burst stimulation (cTBS) over posterior inferior frontal gyrus (pIFG) significantly delayed phonological response times when compared against cTBS over anterior inferior frontal gyrus (aIFG) (t11 = 3.19, p=0.002) or sham cTBS (t11 = 2.99, p=0.009)
Applying focal virtual lesions over the left anterior and posterior inferior frontal gyrus in patients with chronic stroke-induced lesions in the left temporo-parietal cortex, we show task-specific perturbation effects in different networks for language comprehension

Summary

Introduction

Language is sustained by large-scale, left-lateralized neural networks in the human brain. Strokeinduced lesions to key regions for language often severely affect network dynamics and cause language impairment. A controversial debate pertains to the recruitment of contralesional right hemisphere regions (Chrysikou et al, 2013; Hamilton et al, 2011; Hartwigsen and Saur, 2019; Turkeltaub, 2015). Some studies found that (early) upregulation of the right hemisphere was beneficial for aphasia recovery Suppression of right-hemispheric ‘overactivation’ with inhibitory transcranial magnetic stimulation in patients with post-stroke aphasia after left-hemispheric lesions resulted in improved language production Language reorganization appears to be a dynamic process and the contribution of the right hemisphere may change across the time course of recovery (Hartwigsen and Saur, 2019; Saur et al, 2006)

Methods

Results

Conclusion