Conclusion
This study examined the modulatory effects of different tDCS intensities on HRV in healthy individuals. The findings support the dose-dependent effects of tDCS, with the highest electric current intensity (3.0mA) demonstrating a significant increase in HRV compared to both sham and 1.5mA current. While the individual amount of electric current penetrating the brain did not appear to significantly influence the tDCS effects on HRV modulation, E-field modeling analysis suggests that the heterogeneity of tDCS protocols may contribute to the variability in tDCS effects on cardiovascular measures. This study highlights the effects of tDCS on parasympathetic activity of healthy subjects via prefrontal tDCS, showing a dose-dependent effect. Based on our results, we believe that further research is warranted to investigate the optimal tDCS parameters for HRV modulation.
Acknowledgement
LBR is currently supported by a Research Foundation Flanders (FWO) grant (G0F4619N). RDR and MMP received support from the Research Foundations FWO and F.R.S.-FNRS under the Excellence of Science (EOS) program (EOS 40007528). MAV received funding from FWO-Flanders for research projects for fundamental research (Grant Numbers: G044222N; G044019N). ARB receives grants from the National Council for Scientific and Technological Development (PQ-1B), and FAPESP (Grants: 2018/10861-7, 2019/06009-6). ARB has a small equity of Flow™, whose devices were not used in the present study. The LIM-27 laboratory receives grants from the Associação Beneficente Alzira Denise Hertzog da Silva. SDS is funded by a FWO-Flanders PhD fellowship (Grant Number: 11J7521N).The other authors have no conflicts of interest to disclose.