MEASUREMENTS OF DETECTION THRESHOLDS PRESENTING NORMAL AND TANGENTIAL VIBRATIONS ON HUMAN HAIRY SKIN
The purpose of present study was to measure vibrotactile thresholds presenting normal and tangential vibrations to hairy skin and to investigate the mechanoreceptive mechanisms that determine the threshold curve shapes. The normal and tangential thresholds were measured for five subjects at the volar forearm. The normal threshold curve showed a U-shape with the lowest threshold at 100 Hz. The tangential threshold curve decreased linearly from 4 to 50 Hz, increased to 75 Hz, and decreased again above 75 Hz. Based on the results of present and previous studies, it was supposed that the shape of the normal threshold curve was determined by the RA (the hair-follicle receptors) and that the shape of the tangential threshold curve was determined by the SA II and FA II.