RT Journal Article
SR Electronic
T1 Transcranial direct current stimulation elevates the baseline activity while sharpening the spatial tuning of the human visual cortex
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2023.02.07.527461
DO 10.1101/2023.02.07.527461
A1 Ahn, Jeongyeol
A1 Ryu, Juhyoung
A1 Lee, Sangjun
A1 Lee, Chany
A1 Im, Chang-Hwan
A1 Lee, Sang-Hun
YR 2023
UL http://biorxiv.org/content/early/2023/02/08/2023.02.07.527461.abstract
AB Background Although transcranial direct current stimulation (tDCS) is widely used to affect various kinds of human cognition, behavioral studies on humans have produced highly inconsistent results. This requires a clear understanding of how tDCS impacts the system-level neural activity, a prerequisite for the principled application of tDCS to human cognition.Objective Here, we aim to gain such understanding by probing the spatial and temporal cortical activity of the human early visual cortex (EVC) in diverse aspects while controlling the polarity and presence of tDCS. We target EVC to capitalize on its well-established anatomical and functional architecture that is readily accessible with non-invasive quantitative neuroimaging methods.Methods To create an electric field in EVC precisely and effectively, we tailored high-definition stimulation montages for 15 individual brains by running electric field simulations. We then conducted an fMRI (functional magnetic neuroimaging)-tDCS experiment on each brain with a sham-controlled crossover design over multiple days. We quantified tDCS effects with eight measures, tested their significance with mixed ANOVA, and further validated their robustness to across-voxel and across-subject variability.Results The anodal application of tDCS gradually elevated EVC’s baseline BOLD activity and sharpened its spatial tuning by augmenting surround suppression without affecting its evoked activity.Conclusions Comparisons of our and previous findings suggest the fundamental differences in tDCS effects between the visual and motor cortices, inhibitory and excitatory effects predominant in the former and latter, respectively. This calls for considering the differences in the excitatory-inhibitory recurrent network between brain regions in predicting or interpreting tDCS effects.Competing Interest StatementThe authors have declared no competing interest.