Inter-individual differences in baseline dynamic functional connectivity are linked to cognitive aftereffects of tDCS

Abstract

Transcranial direct current stimulation (tDCS) has the potential to modulate cognitive training in healthy aging; however, results from various studies have been inconsistent. We hypothesized that inter-individual differences in baseline brain state may contribute to the varied results. We aimed to explore whether baseline resting-state dynamic functional connectivity (rs-dFC) and/or conventional resting-state static functional connectivity (rs-sFC) may be related to the magnitude of cognitive aftereffects of tDCS. To achieve this aim, we used data from our double-blind randomized sham-controlled cross-over tDCS trial in 25 healthy seniors in which bifrontal tDCS combined with cognitive training had induced significant behavioral aftereffects. We performed a backward regression analysis including rs-sFC/rs-dFC measures to explain the variability in the magnitude of tDCS-induced improvements in visual object-matching task (VOMT) accuracy. Rs-dFC analysis revealed four rs-dFC states. The occurrence rate of a rs-dFC state 4, characterized by a high correlation between the left fronto-parietal control network and the language network, was significantly associated with tDCS-induced VOMT accuracy changes. The rs-sFC measure was not significantly associated with the cognitive outcome. We show that flexibility of the brain state representing readiness for top-down control of object identification implicated in the studied task is linked to the tDCS-enhanced task accuracy.

Regional specificity of cathodal transcranial direct current stimulation effects on spatial–numerical associations: Comparison of four stimulation sites

“…Considering that the results of Klein et al (2013) support the idea that magnitude information is represented bilaterally in the intraparietal cortices, it is of interest that this has also been reported in fMRI (Arsalidou & Taylor, 2011). Therefore and relevant to our study, as working memory is also coordinated across multiple brain networks (Pupíková et al, 2022), the SNARC effect in the left PFC could be linked to the contralateral hemisphere. As a result, one could speculate that simultaneous bilateral cathodal tDCS of left and right PFC could induce stronger reductions in the SNARC effect.…”

Prenatal exposure to alcohol and its impact on reward processing and substance use in adulthood

“…fMRI data were smoothed using FWHM of 5 mm and all preprocessed data were checked for subject motion. No subject had more than 20% of scans with a framewise displacement of 0.5 mm [ 52 – 54 ].…”