Search Abstracts | Symposia | Slide Sessions | Poster Sessions
An exploratory investigation of changes in cerebro-cerebellar white matter tracts and naming improvement after cerebellar tDCS and aphasia treatment
Poster Session C, Friday, October 25, 4:30 - 6:00 pm, Great Hall 3 and 4
Micah A Johnson1, Zafer Keser2, Patrick Sadil1, Martin A Lindquist1, Rajani Sebastian3; 1Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA, 2Mayo Clinic, Rochester, NY, USA, 3Johns Hopkins University School of Medicine, Baltimore, MD, USA
Cerebellar transcranial direct current stimulation (tDCS) combined with language therapy can aid in chronic aphasia recovery (DeMarco et al., 2021; Marangolo et al., 2018; Sebastian et al., 2017, 2020). However, it remains unclear which neural mechanisms are associated with treatment efficacy. We investigated whether naming improvements after cerebellar tDCS and computerized aphasia therapy are related to white matter changes in cerebro-cerebellar tracts. Thirteen participants (2 women, age range: 44–89) with chronic left hemisphere stroke and aphasia were included in this study (ClinicalTrials.gov ID: NCT02901574). In a randomized, double-blind, within-subject, cross-over design, participants received 2 interventional periods of 15 treatment sessions with cerebellar tDCS + computerized aphasia therapy and sham + computerized aphasia therapy, separated by a 2-month wash-out period. The primary outcome variable was confrontational naming assessed via the Philadelphia Naming Test (PNT; Roach et al., 1996) at four time points for each intervention: pre-treatment, post-treatment, 2 weeks, and 2 months post-treatment. tDCS was administered for 20 minutes to the right cerebellum (reference electrode over the right shoulder). Diffusion MRI was acquired at pre- and post-treatment time points for active and sham conditions. Diffusion preprocessing and tractography of cerebro-cerebellar tracts was performed in DSI Studio (version 2024.05.22) following procedures from Keser et al. (2023). Tract measures included fractional anisotropy (FA), mean diffusivity (MD), and volume. Analyses involved nonparametric t-tests and correlations, correcting for false discovery rate. Relative to pre-treatment, naming improved after active tDCS at post-treatment (W = 9.50, p = 0.013, biserial r = 0.79) and gains persisted at 2 weeks (W = 9.50, p = 0.074, biserial r = 0.66) and 2 months (W = 4.50, p = 0.021, biserial r = 0.84). Although improvements were not significantly different from sham at post-treatment (W = 54.50, p = 0.239, biserial r = 0.40), 2 weeks (W = 29.50, p = 0.441, biserial r = 0.31), or 2 months (W = 29.50, p = 0.477, biserial r = 0.289), the overall pattern is consistent with our larger study (Sebastian, 2020). There was no reliable evidence of active tDCS effects on white matter tracts relative to sham. However, naming improvements after 2 months showed trend-level associations (and large effect sizes) with increased MD in the left middle cerebral peduncle (MCP: tau = 0.70, p = 0.107, Fisher’s z = 0.88, SE = 0.15) and bilateral parietopontocerebellar tracts (left PPC: tau = 0.78, p = 0.107, Fisher’s z = 1.05, SE = 0.16; right PPC: tau = 0.65, p = 0.107, Fisher’s z = 0.77, SE = 0.17) as well as decreased FA in the left MCP (tau = 0.65, p = 0.160, Fisher’s z = 0.77, SE = 0.17) and left PPC (tau = 0.78, p = 0.160, Fisher’s z = 1.05, SE = 0.16). Our findings suggest that language improvements after cerebellar neuromodulation may be associated with longitudinal changes of cerebro-cerebellar tracts. These preliminary findings, pending replication in larger studies, support the potential for white matter correlates and biomarkers of cerebellar tDCS efficacy.
Topic Areas: Speech-Language Treatment, Language Production