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Lookup NU author(s): Dr Quoc Vuong, Dr Ilona Obara
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).
© 2021 The Authors. Neuromodulation: Technology at the Neural Interface published by Wiley Periodicals LLC on behalf of International Neuromodulation Society. Objectives: The study aimed to assess the feasibility of recording electrically evoked compound action potentials (ECAPs) from the rat spinal cord. To achieve this, we characterized electrophysiological responses of dorsal column (DC) axons from electrical stimulation and quantified the relationship between ECAP and motor thresholds (ECAPTs and MTs). Material and Methods: Naïve, anesthetized and freely behaving rats were implanted with a custom-made epidural spinal cord stimulation (SCS) lead. Epidural stimulation and recordings were performed on the same lead using specifically designed equipment. Results: The ECAPs recorded from the rat spinal cord demonstrated the expected triphasic morphology. Using 20 μsec pulse duration and 2 Hz frequency rate, the current required in anesthetized rats to generate ECAPs was 0.13 ± 0.02 mA, while the average current required to observe MT was 1.49 ± 0.14 mA. In unanesthetized rats, the average current required to generate ECAPs was 0.09 ± 0.02 mA, while the average current required to observe MT was 0.27 ± 0.04 mA. Thus, there was a significant difference between the ECAPT and MT in both anesthetized and unanesthetized rats (MT was 13.39 ± 2.40 and 2.84 ± 0.33 times higher than ECAPT, respectively). Signal analysis revealed average conduction velocities (CVs) suggesting that predominantly large, myelinated fibers were activated. In addition, a morphometric evaluation of spinal cord slices indicated that the custom-made lead may preferentially activate DC axons. Conclusions: This is the first evidence demonstrating the feasibility of recording ECAPs from the rat spinal cord, which may be more useful in determining parameters of SCS in preclinical SCS models than MTs. Thus, this approach may allow for the development of a novel model of SCS in rats with chronic pain that will translate better between animals and humans.
Author(s): Dietz BE, Mugan D, Vuong QC, Obara I
Publication type: Article
Publication status: Published
Journal: Neuromodulation
Year: 2022
Volume: 25
Issue: 1
Pages: 64-74
Print publication date: 01/01/2022
Online publication date: 05/07/2021
Acceptance date: 17/05/2021
Date deposited: 19/07/2021
ISSN (print): 1094-7159
ISSN (electronic): 1525-1403
Publisher: Wiley
URL: https://doi.org/10.1111/ner.13480
DOI: 10.1111/ner.13480
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