Objective: The aim of this study was to test the hypothesis that dual-hemisphere transcranial direct current stimulation (tDCS) over the primary somatosensory cortex (S1) could improve performance in a tactile spatial discriminative task, compared with uni-hemisphere or sham tDCS. Methods: Nine healthy adults participated in this double-blind, sham-controlled, and cross-over design study. The performance in a grating orientation task (GOT) in the right index finger was evaluated before, during, immediately after and 30. min after the dual-hemisphere, uni-hemisphere (1. mA, 20. min), or sham tDCS (1. mA, 30. s) over S1. In the dual-hemisphere and sham conditions, anodal tDCS was applied over the left S1, and cathodal tDCS was applied over the right S1. In the uni-hemisphere condition, anodal tDCS was applied over the left S1, and cathodal tDCS was applied over the contralateral supraorbital front. Results: The percentage of correct responses on the GOT during dual-hemisphere tDCS was significantly higher than that in the uni-hemisphere or sham tDCS conditions when the grating width was set to 0.75. mm (all p<. 0.05). Conclusions: Dual-hemisphere tDCS over S1 improved performance in a tactile spatial discrimination task in healthy volunteers. Significance: Dual-hemisphere tDCS may be a useful strategy to improve sensory function in patients with sensory dysfunctions.
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