Influence Of High-definition Transcranial Direct Current Stimulation To The Parietal Cortex On Posture Control

The parietal lobe is an important cerebral cortex area for sensory information processing to maintain posture control. High-definition transcranial direct current stimulation (HD-tDCS) can improve the excitability of the target brain region through anodal stimulation. The increased excitability of right parietal lobe by HD-tDCS prolongs the latency of automatic postural response and increases the involvement of the right parietal lobe in the postural response. PURPOSES: to explore whether HD-tDCS of unilateral or bilateral parietal lobes would improve postural control and the ability of visual, somatosensory and vestibular system to maintain balance of healthy adults. METHODS: In the study, a single-blind randomized crossover experimental design was used. 18 healthy right-handed adults (21.88 ± 1.96 years; 1.71 ± 0.07 m, 64.97 ± 9.83 kg) were recruited for right-, left- and bilateral-hemisphere anodal HD-tDCS and sham stimulation for 20 minutes. All participants completed the sensory organization test (SOT) and motor control test (MCT) before and immediately after each intervention. Two-way repeated-measures analyses of variance (ANOVAs) with the within-subject factors session and time were used for the dependent variables. RESULTS: For latency, a significant main effect of time emerged (F (1,17) = 17.857, P = 0.001, ηP2 = 0.512), and post hoc tests revealed it increased significantly after right (132.28 ± 8.68 vs 129.78 ± 7.56, P = 0.025) and bilateral (133.11 ± 6.58 vs 130.06 ± 7.29, P = 0.004) stimulation. A significant main effect of time emerged for ES1 (F (1,17) = 11.328, P = 0.004, ηP2 = 0.4), and post hoc tests revealed ES1 decreased significantly after right and sham stimulation (right, 91.52 ± 2.55 vs 93.13 ± 1.90, P = 0.011; sham, 90.96 ± 4.15 vs 92.94 ± 2.32, P = 0.035). CONCLUSION: The right parietal lobe is involved in the modulation of automatic postural response. The increased excitability of the right parietal lobe increases its involvement in the postural response.