Affiliations: Department of Clinical Neurophysiology, Georg-August University of Göttingen, Göttingen, Germany | Department of Medical Psychology and Medical Sociology, Georg-August University of Göttingen, Göttingen, Germany | Department of Clinical Psychology and Addiction, Institute of Psychology, Eötvos Loránd University, Budapest, Hungary
Note: [] Corresponding author: Zsolt Turi, Department of Clinical Neurophysiology, Georg-August University of Göttingen, Robert Koch Straße 40, 37075 Göttingen, Germany. Tel.: +49 551 3919265; Fax: +49 551 398126; E-mail: [email protected]
Abstract: Purpose: Transcranial alternating current stimulation (tACS) is a non-invasive stimulation technique for shaping neuroplastic processes and possibly entraining ongoing neural oscillations in humans. Despite the growing number of studies using tACS, we know little about the procedural sensations caused by stimulation. In order to fill this gap, we explored the cutaneous sensation and phosphene perception during tACS. Methods: Twenty healthy participants took part in a randomized, single-blinded, sham-controlled study, where volunteers received short duration stimulation at 1.0 mA intensity between 2 to 250 Hz using the standard left motor cortex – contralateral supraorbital montage. We recorded the perception onset latency and the strength of the sensations assessed by visual rating scale as dependent variables. Results: We found that tACS evoked both cutaneous sensation and phosphene perception in a frequency-dependent manner. Our results show that the most perceptible procedural sensations were induced in the beta and gamma frequency range, especially at 20 Hz, whereas minimal procedural sensations were indicated in the ripple range (140 and 250 Hz). Conclusions: We believe that our results provide a relevant insight into the procedural sensations caused by oscillatory currents, and will offer a basis for developing more sophisticated stimulation protocols and study designs for future investigations.
Keywords: Oscillatory current, transcranial alternating current stimulation (tACS), procedural sensations, cutaneous sensation, phosphene perception, motor cortex
