Neuroscience 2003 Abstract
| Presentation Number: | 493.4 |
|---|---|
| Abstract Title: | Computational model of axon activation evoked from electrode array implanted in cat sciatic nerve. |
| Authors: |
Butson, C. R.*1
; Miller, I. O.2
; Normann, R. A.1
; Clark, G. A.1
1Dept. of Biomed. Engineer, U of Utah, Salt Lake City, UT 2UT, MEB 50 S Central Campus Dr, 84112, |
| Primary Theme and Topics |
Motor Systems - Kinematics and EMG -- Locomotion |
| Secondary Theme and Topics | Motor Systems<br />- Muscle and Motor Unit<br />-- Physiology |
| Session: |
493. Kinematics: Locomotion I Poster |
| Presentation Time: | Monday, November 10, 2003 4:00 PM-5:00 PM |
| Location: | Morial Convention Center - Hall F-I, Board # H16 |
| Keywords: | RECRUITMENT, EXTRACELLULAR, SIMULATION, ELECTRICAL STIMULATION |
Generating graceful yet powerful muscle forces via stimulation of peripheral nerve is complicated by non-selective stimulus mechanisms, as well as indeterminate voltage and current values required for optimal recruitment of individual neurons. To address these issues, we developed a computational model of sciatic nerve stimulation in conjunction with electrophysiological experiments (McDonnall et al, SFN Abstracts 2003). The purpose of the model is to determine axonal recruitment as a function of electrode position and stimulation paradigm. A detailed anatomical model was generated from a stained, digitized slice of nerve. For one fascicle of the nerve, each tissue type was identified and assigned a conductivity tensor; the slice was then extruded in the longitudinal direction to create a 3D volume conductor. The anatomical model was integrated with a biophysical model that combines cell membrane resistance and capacitance with the Poisson equation. The resulting system of equations was solved for time and space-dependent voltages using BioPSE. Preliminary results indicate that larger axons showed higher maximal current density and therefore higher firing probability than smaller diameter axons. Further, current density within the axon decreased roughly with the inverse square law, modified by anisotropies in the realistic volume conductor. Finally, myelination was an effective barrier for axonal activation; thresholds were strongly reduced by decreasing the distance between the stimulating electrode and the closest node of Ranvier. With multi-electrode stimulation, activation varied as a function of electrode separation and stimulus intensity. These results encourage the continued use of the model to better understand and develop effective stimulus protocols for functional electrical stimulation of peripheral nerve.
Supported by U of Utah, NIH NCRR & NIDCD DC-1-2108
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2003 Neuroscience Meeting Planner. New Orleans, LA: Society for Neuroscience, 2003. Online.
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