High Definition tDCS Effect on Postural Control in Healthy Individuals: Entropy Analysis of a Crossover Clinical Trial

Abstract

Objective: Converging evidence supporting an effect of transcranial direct current stimulation (tDCS) on postural control and human verticality perception highlights this strategy as promising for post-stroke rehabilitation. We have previously demonstrated polarity-dependent effects of high-definition tDCS (HD-tDCS) on weight-bearing asymmetry. However, there is no investigation regarding the time-course of effects on postural control induced by HD-tDCS protocols. Thus, we performed a nonlinear time series analysis focusing on the entropy of the ground reaction force as a secondary investigation of our randomized, double-blind, placebo-controlled, crossover clinical trial. Materials and Methods: Twenty healthy right-handed young adults received the following conditions (random order, separate days); anode center HD-tDCS, cathode center HD-tDCS or sham HD-tDCS at 1, 2, and 3 mA over the right temporo-parietal junction (TPJ). Using summarized time series of transfer entropy, we evaluated the exchanging information (causal direction) between both force plates and compared the dose-response across the healthy subjects with a Generalized Linear Hierarchical/Mixed Model (GLMM). Results: We found significant variation during the dynamic information flow (p < 0.001) among the dominant bodyside (and across time). A greater force transfer entropy was observed from the right to the left side during the cathode-center HD-tDCS up to 2 mA, with a causal relationship in the information flow (equilibrium force transfer) from right to left that decreased over time. Conclusions: HD-tDCS intervention induced a dynamic influence over time on postural control entropy. Right hemisphere TPJ stimulation using cathode-center HD-tDCS can induce an asymmetry of body weight distribution towards the ipsilateral side of stimulation. These results support the clinical potential of HD-tDCS for post-stroke rehabilitation.

Dataset of middle cerebral artery blood flow stability in response to high-definition transcranial electrical stimulation

“…The sham condition (anode or cathode center) was determined using simple balanced randomization. The same stimulation protocol was applied previously to investigate its effects on verticality perception, postural balance and EEG [6 , 7] .…”

Distúrbio de verticalidade visual após acidente vascular cerebral: estudo coorte e efeitos da estimulação elétrica por corrente contínua de alta definição

“…Ademais, as comorbidades do AVC observadas nos dois casos corroboram com os principais fatores de risco para o AVC, como idade, hipertensão arterial, sexo masculino, tabagismo, sedentarismo, dislipidemia, fibrilação atrial, estenose de carótida e histórico familiar (ARSAVA et al, 2017;RODGERS et al, 2004). Os efeitos induzidos pelo protocolo de HD-ETCC descrito acima no controle postural foram comprovados por meio de inovadora análise não linear de séries temporais com foco na força de reação ao solo (FAVORETTO et al, 2022). PONTELLI et al, 2016;SANTOS et al, 2018) dão suporte para a elaboração de ensaios clínicos fase II com uso da HD-ETCC sobre a JTP visando a recuperação do distúrbio de percepção de verticalidade (negligência graviceptiva) e melhora do equilíbrio postural após AVC.…”

“…O peso corporal foi deslocado para o mesmo lado da estimulação cerebral. Os mecanismos neurofisiológicos explicados pelas medidas da entropia asseguraram ser um protocolo potencialmente apto para a reabilitação de pacientes com desequilíbrios posturais após AVC(FAVORETTO et al, 2022).Stefano et al (2022) utilizaram o mesmo protocolo de estimulação transcraniana não-invasiva de Santos et al (2018) e Favoretto et al (2022) em 11 adultos jovens saudáveis, 6 participantes do sexo feminino. Foram mensuradas as velocidades do fluxo sanguíneo da artéria cerebral média (VFSC-ACM) de forma discreta em diversos tempos de avaliação (antes, durante e após HD-ETCC) para verificar os efeitos nos dois hemisférios encefálicos concomitantemente.…”