Short-term modulation of the lesioned language network

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.

Functional specialization within the inferior parietal lobes across cognitive domains

“…inhibition of alternative responses). This constellation of task-induced connectivity modulations is consistent with an interpretation of fine-grained interactions between left and right IPL subregions, rather than an exclusive role of the dominant left hemisphere in language processing (see also Binder et al, 2009;Hartwigsen, 2018;Hartwigsen et al, 2020).…”

Variables and Mechanisms Affecting Response to Language Treatment in Multilingual People with Aphasia

“…The mechanisms underlying treatment-related improvement in aphasia have been studied in recent years, but much is still not well understood [16,17]. The evidence suggests that neuroplasticity allows for reorganization of portions of the neuronal networks, and that regions adjacent to or homologous to the affected regions take on language-related processing [18,19]. Similar processes can be assumed to account for changes observed in multilingual PWA, but an additional consideration is required.…”

Dissociable contributions of frontal and temporal brain regions to basic semantic composition

“…Setting an overly liberal threshold of acceptance after lesions to the left aIFG would support its pivotal role in processes at the final stage of response selection in challenging linguistic-semantic tasks. 47 , 48 We do not wish to suggest that the role of the left aIFG in semantic processing is restricted to the allocation of executive control. However, the role of this area in making semantic judgements may be crucial when decisions on conflicting input are required (two meaningful words but meaningless combination).…”

“…A promising way to address this issue is the combination with reversible functional impairment by neurostimulation. 48 Additionally, the role of the right hemisphere in semantic processing is clearly only beginning to be experimentally addressed, an avenue which is worth following in future studies.…”