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Developing a Model of Dyslexia in Neurotypical Adults: A Transcranial Temporal Interference Stimulation Study
Poster Session A - Sandbox Series, Thursday, October 24, 10:00 - 11:30 am, Great Hall 3 and 4
This poster is part of the Sandbox Series.
Daniel Gallagher1, Zian Huang1, Shinri Ohta1; 1Kyushu University, Fukuoka, Japan
Developmental dyslexia (DD) is a hereditary and multifactorial neurodevelopmental disorder affecting fundamental literacy skills (reading, writing, spelling) independently of general intelligence and educational opportunities. DD is estimated to affect around 7% of individuals (Yang et al., 2022), making it one of the most prevalent learning disabilities. In past decades, much of dyslexia research has focused on phonological deficits (Smirni et al., 2020) with a more recent trend towards integrating other causal factors such as visual deficits, visual attention, and epigenetic factors (e.g., Antzaka et al., 2017; Share, 2021; Theodoridou et al., 2021; Werth, 2021; Zoccolotti, 2022). While the mechanism of DD is not fully understood, certain studies have shown that DD is associated with reduced activation in the left ventral occipito-temporal (vOT) cortex, which corresponds to the visual word form area (VWFA) (Brem et al., 2020; Conant et al., 2020). We therefore propose that by modulating neural activation in the VWFA, we can replicate the expression of DD in neurotypical participants, thereby opening new avenues for research into therapeutic interventions for individuals with DD. In order to manipulate neural activation, we will employ non-invasive brain stimulation, which uses magnetic fields or electric currents to non-invasively stimulate a targeted region of the brain. Traditional methods face a trade-off: they can either be precise but unable to reach deep brain areas or reach deep brain areas but with less spatial precision. This trade-off is resolved by a novel technique called transcranial temporal interference stimulation (tTIS). Unlike other methods, tTIS uses two (or more) interfering high-frequency alternating currents (> 1 kHz) to achieve low-frequency stimulation precisely at any depth in the brain. This is advantageous for stimulating the VWFA, since conventional methods have limited efficacy targeting regions on the ventro-medial regions of the brain due to the need to avoid stimulating overlying cortical areas. Additionally, by co-registering electroencephalography (EEG) data during behavioral tasks, we can observe the neurophysiological effects induced by tTIS, as has been done in previous tES-EEG co-registration studies (e.g., Gallagher et al., 2023). By using tTIS to downregulate activity in the VWFA, we expect to inhibit cognitive performance on literacy tasks, resulting in poorer reading comprehension and slower reading times. EEG data measured during tasks will reveal the neurophysiological effects induced by tTIS. Since ERP research has shown that individuals with DD do not exhibit certain ERPs such as the N170 and N320 (Premeti, Bucci, & Isel, 2022), we can empirically assess the efficacy of our DD model. We hope that by creating a model for DD in neurotypical individuals, we will help elucidate the neural basis of DD while facilitating investigation into novel therapeutical interventions for DD, which will in turn hasten their implementation in clinical settings. Finally, by demonstrating the efficacy of tTIS here, we will enable future investigations into various deep brain regions and their roles in language processing.
Topic Areas: Disorders: Developmental, Methods