A Review on Treatment-Related Brain Changes in Aphasia

Abstract

<jats:p> Numerous studies have investigated brain changes associated with interventions targeting a range of language problems in patients with aphasia. We strive to integrate the results of these studies to examine (1) whether the focus of the intervention (i.e. phonology, semantics, orthography, syntax or rhythmic-melodic) determines in which brain regions changes occur, (2a) whether the most consistent changes occur within the language network or outside, and (2b) whether these are related to individual differences in language outcomes. The results of 32 studies with 204 unique patients were considered. Concerning (1), the location of treatment-related changes does not clearly depend on the type of language processing targeted. However, there is some support that rhythmic-melodic training has more impact on the right hemisphere than linguistic training. Concerning (2), we observed that language recovery is not only associated with changes in traditional language-related structures in the left hemisphere and homolog regions in the right hemisphere. Treatment-related changes also occurred more medially and subcortically (e.g. precuneus and basal ganglia). Although it is difficult to draw strong conclusions, because there is a lack of systematic large-scale studies on this topic, this review highlights the need for an integrated approach to investigate how language interventions impact on the brain. Future studies need to focus on larger samples preserving subject-specific information (such as lesion effects) to cope with the inherent heterogeneity of stroke-induced aphasia. In addition, recovery-related changes in whole-brain connectivity patterns need more investigation to provide a comprehensive neural account of treatment-related brain plasticity and language recovery. </jats:p>

Resting-State Functional Connectivity following Phonological Component Analysis: The Combined Action of Phonology and Visual Orthographic Cues

“…Although Fr-PCA promotes phonological strategies, no changes in functional connectivity between ROIs in the dorsal stream of the language network were observed. This observation is in line with a recent meta-analysis on treatment-related brain changes in aphasia; Schevenels et al [ 71 ] discuss how phonological therapies induce neurofunctional changes beyond regions typically associated with phonological processing such as the SCC. Moreover, the location of treatment-related changes does not clearly depend on the type of language processing targeted [ 71 ].…”

Neuroplasticity in Post-Stroke Aphasia: A Systematic Review and Meta-Analysis of Functional Imaging Studies of Reorganization of Language Processing

“…We take full responsibility for any and all misunderstandings or mischaracterizations of the studies that we reviewed. Second, the manner in which we evaluated the studies, and the specific data items that we defined, were informed by our own perspective on what is important, and we appreciate that other researchers may evaluate studies with respect to different priorities (see, e.g., Crosson et al, 2007;Cocquyt, De Ley, Santens, Van Borsel, & De Letter, 2017), or may elect to aggregate findings without prejudice as to methodological quality (e.g., Schevenels, Price, Zink, De Smedt, & Vandermosten, 2020). Moreover, some of the decisions involved in data extraction were partially subjective.…”

Changes in the language system as amyloid-β accumulates

“…It is widely accepted that the right temporal neocortex contralateral to the left language network can contribute to word comprehension. [55][56][57] The right posterior middle temporal gyrus and STS has been previously reported to show fMRI response changes in language recovery following stroke 58 (for review see 59 ). An increase in the right STS and GTm has also been reported in amyloid PET positive Alzheimer's disease in the early dementia stage 17 .…”

“…Non-invasive inhibitory brain stimulation of right inferior frontal gyrus or right superior temporal sulcus has not allowed to resolve this issue unequivocally yet. 59,61 Based on the published studies, overall there seems to be a potential beneficial effect of inhibitory non-invasive stimulation of these regions in post-stroke aphasia but publication bias and small effect sizes render interpretation difficult.…”