Year: 1997
Type: dissertation
Abstract: Tripolar circumferential recording nerve cuffs that allow for the derivation of pressure and touch related information from cutaneous and proprioceptive nerves in the cat paw have been designed in our laboratory.At present, there is conflicting evidence with respect to the safety of nerve cuff implantation.We were unable to extrapolate any conclusions about the safety of our nerve cuffs from past literature for two reasons.First, our cuff design was different from the cuffs used in past studies and, second, previous morphometric studies possessed a number of methodological limitations that made their findings inconclusive.As part of this thesis, a computer based experimental methodology was developed to carry out the quantitative assessment of neural tissues following the long-term (183 to 373 days) implantation of circumferential slit tube type nerve cuff electrodes on the median nerve of the cat forelimb.Morphological assessment was made by comparing a given cat's implanted limb with its own contralateral unoperated control limb.This thesis addressed many of the weaknesses found in previous studies in the literature.It was unique in trying to correlate morphometric variables with changes in compound action potential (CAP) data recorded over the implant period.Four key messages emerged from this thesis.First, our nerve cuffs were found to be associated with small but statistically significant decreases in axon diameter, fiber diameter, and myelin thickness.Second, cuffed axons located near the perimeter of the nerve experienced somewhat larger differences (as compared to control) than did axons located closer to the center of the nerve.Third, all axon sizes showed the same magnitude of difference with respect to control (i.e.larger axons did not seem to be affected more than smaller axons located in the same cross section).Finally, morphometric differences with respect to control were found to be correlated with CAP changes but this correlation was opposite to what was expected.CAP amplitudes exhibited statistically significant (p<0.05)negative correlations with fiber diameter and myelin thickness differences measured in the Perimeter Zone.
Author: Paul Richard Christensen
Language: English
Subfield: Cellular and Molecular Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W129180672