Surface Electromyography (sEMG) will be recorded through one channel that is sampled at 2048 Hz using a bipolar electrode (Myotronics-Noromed, Inc., Tukwila, WA, USA). The bipolar electrode will be positioned on the skin over the suprahyoid muscle to precisely detect the start and end of TENS and to detect the numbering tasks, thus allowing the correct selection of study epochs.