Language Mapping in Aphasia

Abstract

Purpose Recovery from aphasia is thought to depend on neural plasticity, that is, functional reorganization of surviving brain regions such that they take on new or expanded roles in language processing. To make progress in characterizing the nature of this process, we need feasible, reliable, and valid methods for identifying language regions of the brain in individuals with aphasia. This article reviews 3 recent studies from our lab in which we have developed and validated several novel functional magnetic resonance imaging paradigms for language mapping in aphasia. Method In the 1st study, we investigated the reliability and validity of 4 language mapping paradigms in neurologically normal older adults. In the 2nd study, we developed a novel adaptive semantic matching paradigm and assessed its feasibility, reliability, and validity in individuals with and without aphasia. In the 3rd study, we developed and evaluated 2 additional adaptive paradigms—rhyme judgment and syllable counting—for mapping phonological encoding regions. Results We found that the adaptive semantic matching paradigm could be performed by most individuals with aphasia and yielded reliable and valid maps of core perisylvian language regions in each individual participant. The psychometric properties of this paradigm were superior to those of other commonly used paradigms such as narrative comprehension and picture naming. The adaptive rhyme judgment paradigm was capable of identifying fronto-parietal phonological encoding regions in individual participants. Conclusion Adaptive language mapping paradigms offer a promising approach for future research on the neural basis of recovery from aphasia. Presentation Video https://doi.org/10.23641/asha.10257584

Spectral Resting-State EEG (rsEEG) in Chronic Aphasia Is Reliable, Sensitive, and Correlates With Functional Behavior

“…Also, neuroimaging studies have long utilized hemispheric comparisons and/or examined hemispheric differences and related behaviors (e.g., French and Beaumont, 1984 ; Bolduc et al, 2003 ; Szaflarski et al, 2006 ; Learmonth et al, 2017 ; Othman et al, 2020 ). Hemispheric comparisons are frequent in the aphasia literature where lesions affect a behavior (e.g., language) that is typically strongly lateralized to the left hemisphere (e.g., Gow and Ahlfors, 2017 ; Piai et al, 2017 ; Sandberg, 2017 ; Wilson et al, 2019 ). By providing hemispheric results in this investigation, we pave the road for future investigations that seek to compare individuals with left and right hemisphere strokes, or to compare individuals with either left or right hemisphere strokes to healthy controls or other clinical populations.…”

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

“…This is not a panacea, because if processing is more difficult for individuals with aphasia, then even correct trials may have longer reaction times, with attendant consequences for functional activation (Binder et al, 2005;Yarkoni et al, 2009;Wilson et al, 2016). Another potential approach is to use adaptive paradigms in which item difficulty is tailored to individual performance, such that tasks are similarly challenging for all participants, yet within their competence (Wilson et al, 2018;Wilson et al, 2019;Yen et al, 2019).…”

“…Besides validity of the regions activated, it is also important to consider reliability (test-retest reproducibility) and feasibility for individuals with aphasia to perform tasks. One possibility is to use adaptive semantic and phonological matching paradigms, which have been shown to be valid, reliable, and feasible for identifying language regions in individuals with aphasia (Wilson et al, 2018;Wilson et al, 2019;Yen et al, 2019), but many other kinds of paradigms are surely possible, and the field will benefit from a diverse set of approaches.…”

“…Progress in understanding neuroplasticity in post-stroke aphasia will depend on developing approaches that address three important methodological issues: task performance confounds (Geranmayeh et al, 2014), contrast validity (Wilson et al, 2018), and correction for multiple comparisons (Eklund et al, 2016). Adaptive language mapping paradigms offer one promising approach, as these paradigms minimize task performance confounds and selectively activate lateralized language regions (Wilson et al, 2018;Wilson et al, 2019;Yen et al, 2019). Correction for multiple comparisons is not technically challenging, but large samples of participants are needed to derive findings that are robust enough to survive correction.…”

Simultaneous Normalization and Compensatory Changes in Right Hemisphere Connectivity during Aphasia Therapy

“…These techniques enable us to track the neural correlates of language rehabilitation. While language recovery in the subacute phase after stroke is often related to the restoration of temporary dysfunctional perilesional regions, longer-term recovery is thought to reflect neuroplasticity through functional reorganization [4]. Studies in this field are engaged in an ongoing discussion about the nature of the neural changes underlying recovery from left hemisphere damage [5][6][7][8].…”