Search Abstracts | Symposia | Slide Sessions | Poster Sessions
The Contribution of Right Hemisphere White Matter Tracts in Spelling Performance in Post-stroke Aphasia
Poster Session C, Thursday, October 1, 10:45 am - 12:45 pm, Wangari Maathai
Kyriaki Neophytou1,2, Eleni Kodjayeredou2, Brenda Rapp3; 1Department of Social Sciences, School of Humanities and Social Sciences, University of Nicosia, UNIC Athens, Athens, Greece, 2Department of Psychology, Faculty of Pure and Applied Sciences, Open University of Cyprus, Nicosia, Cyprus, 3Department of Cognitive Science, Krieger School of Arts and Sciences, Johns Hopkins University, Baltimore, USA
Introduction: Acquired dysgraphia is a frequent result of left-hemisphere (LH) stroke, yet the structural substrates supporting residual spelling abilities have been hardly investigated. Most prior research has focused on the contribution of grey matter structures, mainly in the LH (Purcell et al., 2025; Rapp et al., 2016). However, no studies have examined how white matter (WM) integrity, particularly in the right hemisphere (RH), accounts for variability in spelling performance in post-stroke aphasia. Evidence from other LH-damage populations, specifically Primary Progressive Aphasia, suggests that such contributions are likely (Neophytou et al., 2023). The present study addressed this gap by investigating the contribution of RH WM tract integrity in spelling performance in LH-stroke aphasia. Methods: Fourteen English-speaking individuals with chronic post-stroke aphasia performed a spelling-to-dictation task comprising 40 real words and 20 pseudowords. Behavioral outcomes included (i) real word orthographic distance, and (ii) real-word and (iii) pseudoword phonological distance. Distance measures quantified how far each response deviated orthographically from the correct spelling and how phonologically plausible it was relative to the target, as calculated through the OpenBrainAI platform (Themistocleous et al., 2024). RH WM tracts were reconstructed using ROI-based tractography. Tracts of interest included the arcuate fasciculus (AF), middle longitudinal fasciculus, cingulum, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, uncinate fasciculus, superior longitudinal fasciculi I/II/III, and the frontal aslant tract. Tract-wise linear models were fit separately for each measure to test whether standardized tract fractional anisotropy (FA) – indexing tract integrity - predicted spelling performance, covarying age, education, sex and premorbid handedness. Results: Real word orthographic distance showed statistically significant association with SLF II (β=-0.109, p=0.045), FAT (β=-0.107, p=0.036), and AF (β=-0.123, p=0.007). The same tracts also showed statistically significant effects for real word phonological distance: SLF II (β=-0.124, p=0.039), FAT (β=-0.126, p=0.023), and AF (β=-0.143, p=0.003). Pseudoword phonological distance did not show any statistically significant effects. Conclusion: These findings indicate that microstructural integrity of the RH dorsal tracts supports the spelling of real words but not pseudowords. Specifically, higher FA values (indicating greater white matter integrity) were associated with better spelling performance. The fact that the integrity of these tracts was associated with the phonological distance of real words but not of pseudowords suggests that these tracts support both lexical and sublexical (i.e., phoneme-to-grapheme) processing. It was previously suggested that the dorsal tracts specifically support sublexical processing, as they connect frontal to temporo-parietal regions implicated in the sublexical spelling route (DeMarco et al., 2017). However, the lack of associations between the integrity of these tracts and phonological distance for pseudowords contradicts this hypothesis. Prior studies have highlighted the contribution of RH dorsal tracts to spelling performance in healthy young adults with poor spelling skills (Sagi et al., 2024), as well as individuals with developmental dysgraphia (Sagi et al., under review). Together, these studies suggest that RH dorsal tracts contribute to spelling across populations with spelling impairments. Future studies need to investigate in greater detail what specific components of spelling these tracts support, and whether this varies across populations with such impairments.
Topic Areas: Writing and Spelling, Disorders: Acquired