HAIRY SKIN - PSYCHOPHYSICAL CHANNELS AND THEIR PHYSIOLOGICAL SUBSTRATES

Experiments were conducted in which threshold-frequency characteristic s were measured on the hairy skin of the forearm of human observers. T hresholds were measured with two stimulus probe areas (2.9 and 0.008 c m(2)) at three skin-surface temperatures (15 degrees, 30 degrees, and 40 degrees C). The results suggest that whereas glabrous skin uses fou r distinct channels of information, only three channels may be involve d in mediating the sense of touch for hairy skin. The three channels a re defined as P-h (Pacinian, hairy skin), NPh low (non-Pacinian, hairy skin, low frequencies) and NPh mid (non-Pacinian, hairy skin, middle frequencies). In addition, it is proposed that the neural substrates f or the three psychophysically characterized channels are, respectively , the Pacinian corpuscle (PC) nerve fibers, the slowly adapting type I I (SAII) fibers, and the rapidly adapting (RA) fibers.