Mitigating Cutaneous Sensation Differences During tDCS: Comparing Sham Versus Low Intensity Control Conditions

• Main Authors: Tad T. Brunyé, Julie Cantelon, Amanda Holmes, Holly A. Taylor, Caroline R. Mahoney
• Format: Article
• Language: English
• Published: Elsevier 2014-11-01
• Series: Brain Stimulation
• Subjects: Brain stimulation; Methodology; Cutaneous sensation; Inhibitory control
• Online Access: http://www.sciencedirect.com/science/article/pii/S1935861X1400326X

Background: Cutaneous sensations at electrode sites during the administration of direct current brain stimulation may inadvertently influence participants' subjective experience and task performance. Objective: The present study evaluated the utility of a methodological variation that substitutes sham administration with very low intensity (0.5 mA) current delivery. Methods: We used a 4 × 1 high-definition ring electrode transcranial direct current (HD-tDCS) system to target the left dorsolateral prefrontal cortex (Brodmann's Area 9). Four stimulation conditions were compared in a repeated-measures design: sham 2.0 mA and 0.5 mA intensity, versus active 2.0 mA and 0.5 mA intensity. During stimulation participants performed a cognitive interference task that activates the cingulo-frontal-parietal network, and periodically provided perceived sensation ratings. Results: We demonstrate that a relatively low intensity control condition attenuates otherwise large differences in perceived sensation between active and sham conditions. Critically, behavioral task differences maintained between the two active conditions. Conclusion: A low intensity control stimulation condition may prove a viable methodological alternative to conventional sham techniques used in repeated-measures designs, though important limitations are discussed.