Affective Touch, Hedonia and Suicidal Behavior

"The experimental task aims to evaluate the hedonic nature of an affective touch by tactile stimulation.~It consists in stimulating two adjacent regions of the left forearm, delimited and marked, of 9 cm x 4 cm each. In order to limit habituation, the stimulation areas will be alternated.~To stimulate these areas, the investigator (previously trained) strokes the participant with a brush at an optimal speed to stimulate the C-fibers (3 cm/s; slow speed) or not (18 cm/s; fast speed).~Touch will consist of 30 seconds blocks of stimulation, performed on one of the two identified areas, from the elbow to the wrist. In total, 6 stimulation blocks will be done (3 slow and 3 fast), the order and location of which will be random in order to limit habituation.~This stimulation is completely painless. After each block, the participant will evaluate the intensity of the stimulation and its pleasantness."