Left and right temporal language activations independently contribute to aphasia outcomes
Poster No:
811
Submission Type:
Abstract Submission
Authors:
Sarah Schneck1, Deborah Levy1, Jillian Entrup1, Melodie Yen1, Dana Eriksson2, Marianne Casilio1, Anna Kasdan1, Lily Walljasper1, Caitlin Onuscheck1, L. Davis1, Howard Kirshner1, Michael de Riesthal1, Stephen Wilson3
Institutions:
1Vanderbilt University Medical Center, Nashville, TN, 2University of Arizona, Tucson, AZ, 3University of Queensland, Brisbane, Queensland
First Author:
Co-Author(s):
Introduction:
Recovery from aphasia after stroke is thought to depend on functional reorganization of language processing in surviving brain regions (Hartwigsen & Saur, 2019). Many studies have investigated this process, but progress has been impeded by methodological limitations relating to task performance confounds, contrast validity, and sample sizes (Wilson & Schneck, 2021). Furthermore, few studies have accounted for the complex relationships that exist between patterns of structural damage, distributed networks of functional activity, and behavioral outcomes (Turkeltaub, 2019). The present study aimed to overcome these critical methodological limitations and to elucidate the connections between structure, function, and behavior.
Methods:
We recruited 70 individuals with subacute to chronic post-stroke aphasia and 45 neurologically normal comparison participants. Language function was assessed with the Quick Aphasia Battery (QAB; Wilson et al., 2018a). The participants with aphasia varied widely in terms of lesion extent and location, and aphasia severity (QAB overall 7.0 ± 2.6, range 0.7 – 9.9 on a 10-point scale). We used a valid and reliable adaptive language mapping fMRI paradigm that contrasted semantic matching and perceptual matching tasks (Wilson et al., 2018b). Stimuli were selected dynamically based on each participant's real-time task performance, overcoming challenges of task performance and contrast validity. Whole-brain analyses were thresholded with a cluster-defining threshold of p < .005 and corrected for multiple comparisons with permutation testing (p < .05). We also carried out hypothesis-driven analyses of individually defined functional regions of interest (ROIs) (Fedorenko et al., 2010) in temporal and frontal language areas and their homotopic counterparts, facilitating the detection of language activations that may be displaced from typical locations, due to functional reorganization. In our key analyses, the dependent variable was aphasia outcome (QAB overall score) and the explanatory variables included language activations across multiple brain regions, lesion load estimates derived from support vector regression, and covariates of age, sex, handedness, education, stroke type, and time post onset.
Results:
We found that individuals with aphasia showed reduced language activations relative to comparison participants in left temporal language areas (p = .002), left frontal language areas (p = .002) as well as diaschitic effects in right temporal cortex (p = .029) and the right cerebellum (p = .042). Whole-brain analyses incorporating structural and functional imaging measures revealed that language activations in left mid-posterior temporal cortex were predictive of aphasia outcomes above and beyond what could be explained by lesion load (p = .031) (Fig. 1). The ROI analyses (Fig. 2) confirmed this finding, and additionally showed that left temporal language activations were predictive of aphasia outcomes above and beyond not only lesion load, but also above and beyond activation of other brain regions (p = .004, medium effect size: Cohen's f2 = 0.32). Due to their increased sensitivity, the ROI analyses revealed additionally that language activations in right mid-posterior temporal cortex independently contributed to aphasia outcomes (p = .035, small effect size: f2 = 0.13). Left frontal language activations were associated with aphasia outcomes when modeled in isolation, but were not independently predictive once temporal activity was accounted for (p = .32).
·Figure 1
·Figure 2
Conclusions:
By overcoming critical methodological challenges and integrating structural imaging, functional imaging, and behavior, we affirmed the critical importance of language activations in the left mid-posterior temporal cortex for aphasia outcomes (Saur et al., 2006), and provided the strongest evidence to date that the right temporal lobe makes a unique and independent contribution to aphasia outcomes (Crinion & Price, 2005).
Disorders of the Nervous System:
Neurodegenerative/ Late Life (eg. Parkinson’s, Alzheimer’s)
Language:
Language Comprehension and Semantics 2
Language Other 1
Modeling and Analysis Methods:
Activation (eg. BOLD task-fMRI)
Keywords:
Aphasia
FUNCTIONAL MRI
Language
Plasticity
STRUCTURAL MRI
1|2Indicates the priority used for review
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2. Fedorenko, E., et al. (2010). New method for fMRI investigations of language: Defining ROIs functionally in individual subjects. Journal of Neurophysiology, 104(2), 1177–1194.
3. Hartwigsen, G., & Saur, D. (2019). Neuroimaging of stroke recovery from aphasia – Insights into plasticity of the human language network. NeuroImage, 190, 14–31.
4. Saur, D., et al. (2006). Dynamics of language reorganization after stroke. Brain, 129(6), 1371–1384.
5. Turkeltaub, P. E. (2019). A taxonomy of brain-behavior relationships after stroke. Journal of Speech, Language, and Hearing Research, 62(11), 3907–3922.
6. Wilson, S. M., et al. (2018). A quick aphasia battery for efficient, reliable, and multidimensional assessment of language function. PLoS One, 13(2), e0192773.
7. Wilson, S. M., & Schneck, S. M. (2021). Neuroplasticity in post-stroke aphasia: A systematic review and meta-analysis of functional imaging studies of reorganization of language processing. Neurobiology of Language, 2(1), 22–82.
8. Wilson, S. M., et al. (2018). An adaptive semantic matching paradigm for reliable and valid language mapping in individuals with aphasia. Human Brain Mapping, 39(8), 3285–3307.