This pre-registered study employed a double-blind, randomized, sham-controlled, within-subject crossover design to systematically examine frequency-dependent modulation of thermal pain using tTIS targeted to the left M1. Participants received tTIS at envelope frequencies of 10, 20, and 70 Hz, as well as sham stimulation. Stimulation effects were assessed using individually calibrated noxious heat stimuli, maximizing sensitivity to stimulation-related changes while reducing between-participant variability.
