IDENTIFYING RELIABLE CORTICAL TARGETS FOR ENHANCING NOVEL WORD LEARNING WITH TDCS: AN FMRI STUDY

Linking word forms to their meanings is a fundamental aspect of language learning [1]. Transcranial direct current stimulation (tDCS) has shown promise in supporting this process, although its effects have been inconsistent [2]. This study aimed to identify reliable and functionally meaningful cortical targets for tDCS to enhance novel word learning, and to evaluate the test–retest-reliability (TRR) of behavioral and neural measures. Twenty healthy participants completed two functional magnetic resonance imaging (fMRI) sessions with parallel versions of a picture–pseudoword association task, alongside a lexical decision control task. Learning occurred across four blocks. Behavioral performance was analyzed using linear mixed models, and imaging data were examined using whole-brain and region-of-interest analyses. TRR was assessed using intraclass correlation coefficients [3]. Participants successfully acquired novel word forms, as reflected in increasing accuracy and faster response times, with behavioral measures demonstrating good-to-excellent TRR across sessions. The learning task elicited robust language-related brain activity, and changes across learning stages were associated with performance, whereas the control task did not show consistent activity changes. Despite some variability, approximately 81% of voxels within significant clusters demonstrated moderate-to-excellent reliability. Ongoing analyses examine task-based functional connectivity and its relationship to learning. Overall, these findings identify reliable cortical targets for tDCS and support the suitability of this paradigm for future combined tDCS–fMRI research, highlighting the importance of reliability-driven approaches in brain stimulation studies.

References
[1] Shtyrov et al. (2012). The Neuroscientist
[2] Meinzer et al. (2024). Frontiers in Neuroscience
[3] Kocataş et al. (2025). bioRxiv