Abstract
Grapheme-color synesthesia (GC-S) is a neurological condition in which the perception of a grapheme elicits the experience of color or even the visual representation of that grapheme as colored. Previous research using transcranial magnetic stimulation on GC-synesthetes demonstrated enhanced excitability of the visual cortex. Consequently, we hypothesized that using anodal "offline" transcranial direct current stimulation on the visual cortex in area V4 followed by visual training could boost cortical excitability in the target areas and thus produce effects similar to GC-S in non-synesthetes. We discovered that after anodal stimulation, participants had a considerably smaller mean change in reaction time on white symbols than after sham and cathodal stimulation. Our findings indirectly support the cross-activation hypothesis.
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Acknowledgements
This article is an output of a research project implemented as part of the Basic Research Program at the National Research University Higher School of Economics (HSE University) which was carried out using HSE Automated system of non-invasive brain stimulation with the possibility of synchronous registration of brain activity and registration of eye movements.
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A.S., M.V. and G.A. conceived the design. A.S., M.V. acquired the data. A.S., M.V. analyzed the data. A.S., M.V. prepared the figures. A.S., M.V., Z.O. and G.A. contributed to the interpretation of the results. A.S., M.V., Z.O. drafted the manuscript. All authors revised critically the manuscript.
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Andreev, S., Moskvoretskiy, V., Gorin, A. et al. Grapheme-color synesthesia induction with V4 transcranial direct current stimulation. Curr Psychol (2024). https://doi.org/10.1007/s12144-024-06068-4
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DOI: https://doi.org/10.1007/s12144-024-06068-4