Vibrotactile thresholds of the Non-Pacinian I channel: I. Methodological issues.
Thresholds of the Non-Pacinian I (NP I) channel were measured using a two-interval forced-choice paradigm, a technique independent of the subject's criterion. The studies were performed using the terminal phalanx of the human middle finger with a 40-Hz vibratory stimulus. Unlike most of the previous experiments performed in our laboratory, a contactor surround was not used. This was done to enable comparison with population models of mechanoreceptive fibers in the literature. Since the Pacinian (P) channel and NP I channel have similar vibrotactile thresholds at 40?Hz, a forward-masking procedure was used to elevate the thresholds of the P channel with respect to the NP I channel. While it has been established that the Pacinian fibers are entrained at high stimulus levels, the P channel can be perceptually masked using a 250-Hz stimulus presented prior to the 40-Hz test stimulus. The masking functions were found to be approximately linear on log-log axes and the threshold shifts were found to increase as the masking-stimulus levels increased. The results are discussed in relation to previous studies that were performed at various stimulation sites by using a contactor surround or not. A companion paper presents the variation of NP I-channel thresholds, measured using the methods described herein, and addresses the effects of stimulation along the proximo-distal axis of the phalanx. The companion paper also discusses the predictions of a computational model, recently proposed, in light of the empirical results presented.
Güçlü
Burak
B
Institute for Sensory Research, Syracuse, NY, USA.
Bolanowski
Stanley J
SJ
D000222:Adaptation, Physiological / Q000502:physiology; D000328:Adult; D005260:Female; D005385:Fingers / Q000294:innervation; D006801:Humans; D008297:Male; D008465:Mechanoreceptors / Q000502:physiology*; D010470:Perceptual Masking / Q000502:physiology; D011601:Psychophysics / Q000379:methods*; D012684:Sensory Thresholds / Q000502:physiology*; D014110:Touch / Q000502:physiology*; D014732:Vibration