Evidence of the homeostatic regulation with the combination of transcranial direct current stimulation and physical activity

Transcranial direct current stimulation (tDCS) can optimize beneficial effects induced by motor practice in patients with neurological disorders. However, possibly due to homeostatic regulation, the conditioning effects of tDCS are often imprecise and variable, limiting its therapeutic application. Objective to explore the magnitude and direction of the after-effects induced by physical activity (PA) on tDCS-preconditioned cortical excitability (CE). Design First, a crossover experiment was performed with 12 subjects to determine whether a single session of low-, moderate- and high-intensity PA on a treadmill modulates the motor cortical excitability measured by transcranial magnetic stimulation. In a second crossover experiment, we investigated long-lasting changes (until 90 min) of the effects induced by PA (with intensities defined by the first experiment) on motor cortical excitability after the subject had been preconditioned by tDCS (using different polarities). Results and conclusion In Experiment 1, we found that high and moderate-intensity PA modulate the CE. Experiment 2 demonstrated that preconditioning the CE using tDCS homeostatically changes the direction and magnitude of after-effects induced by subsequent PA plasticity caused by motor activity. In conclusion, the results suggest that the direction of after-effects induced by the combination of physical exercise with tDCS on the cortical excitability is regulated within a physiologically defined range. Contact information: Katia Monte-Silva; Applied Neuroscience Laboratory, Universidade Federal de Pernambuco, Department of Physical Therapy. Av. Prof. Moraes Rego s/n 50670-900 Recife, Brazil., phone: +55 81-2126 7579/FAX: +55 81-2126 8491. Funding: Monte-Silva K receives a grant from CNPq (308291/2015-8) Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.

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