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Department of Physiology and Pharmacology, School of Medical Sciences, The University of New South Wales, Sydney, Australia
Submitted 11 May 2005; accepted in final form 23 November 2005
The capacity of single neurons of the dorsal column nuclei (DCN) for coding vibrotactile information from the hairy skin has been investigated in anesthetized cats to permit quantitative comparison first with the capacities of DCN neurons responding to glabrous skin vibrotactile inputs and second with those of spinocervical tract neurons responding to vibrotactile inputs from hairy skin. Dynamically sensitive tactile neurons of the DCN the input of which came from hairy skin could be divided into two classes, one associated with hair follicle afferent (HFA) input, the other with Pacinian corpuscle (PC) input. The HFA-related class was most sensitive to low-frequency (<50 Hz) vibration and had a graded response output as a function of vibrotactile intensity changes. PC-related neurons had a broader vibrotactile sensitivity, extending to
300 Hz and appeared to derive their input from the margins of hairy skin, near the footpads, or from deeper PC sources such as the interosseous membranes or joints. HFA-related neurons had phaselocked responses to vibration frequencies up to
75 Hz, whereas PC neurons retained this capacity up to frequencies of
300 Hz with tightest phaselocking between 50 and 200 Hz. Quantitative measures of phaselocking revealed that the HFA-related neurons provide the better signal of vibrotactile frequency up to
50 Hz with a switch-over to the PC-related neurons above that value. In conclusion, the functional capacities of these two classes of cuneate neuron appear to account for behavioral vibrotactile frequency discriminative performance in hairy skin, in contrast to the limited capacities of vibrotactile-sensitive neurons within the spinocervical tract system.
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D. A. Mahns, N. M. Perkins, V. Sahai, L. Robinson, and M. J. Rowe Vibrotactile Frequency Discrimination in Human Hairy Skin J Neurophysiol, March 1, 2006; 95(3): 1442 - 1450. [Abstract] [Full Text] [PDF] |
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V. Sahai, D. A. Mahns, N. M. Perkins, L. Robinson, and M. J. Rowe Vibrotactile Coding Capacities of Spinocervical Tract Neurons in the Cat J Neurophysiol, March 1, 2006; 95(3): 1465 - 1477. [Abstract] [Full Text] [PDF] |
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