Table of Contents
Physiology Journal
Volume 2013, Article ID 254789, 11 pages
http://dx.doi.org/10.1155/2013/254789
Research Article

Noninvasive Evaluation of Nerve Conduction in Small Diameter Fibers in the Rat

1The Saul R. Korey Department of Neurology, Albert Einstein College of Medicine, K322, 1300 Morris Park Avenue, Bronx, NY 10461, USA
2Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA

Received 29 October 2012; Revised 27 December 2012; Accepted 28 December 2012

Academic Editor: Gary Lopaschuk

Copyright © 2013 Elena G. Zotova and Joseph C. Arezzo. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A novel noninvasive technique was applied to measure velocity within slow conducting axons in the distal extreme of the sciatic nerve (i.e., digital nerve) in a rat model. The technique is based on the extraction of rectified multiple unit activity (MUA) from in vivo whole nerve compound responses. This method reliably identifies compound action potentials in thinly myelinated fibers conducting at a range of 9–18 m/s ( axons), as well as in a subgroup of unmyelinated C fibers conducting at approximately 1-2 m/s. The sensitivity of the method to C-fiber conduction was confirmed by the progressive decrement of the responses in the 1-2 m/s range over a 20-day period following the topical application of capsaicin (ANOVA ). Increasing the frequency of applied repetitive stimulation over a range of 0.75 Hz to 6.0 Hz produced slowing of conduction and a significant decrease in the magnitude of the compound C-fiber response (ANOVA ). This technique offers a unique opportunity for the noninvasive, repeatable, and quantitative assessment of velocity in the subsets of and C fibers in parallel with the evaluation of fast nerve conduction.