Neuroscience 2000 Abstract
| Presentation Number: | 260.10 |
|---|---|
| Abstract Title: | Are movement primitives determined by spinal cord circuitry or biomechanics? |
| Authors: |
Aoyagi, Y.*1
; Mushahwar, V. K.1
; Stein, R. B.1
; Prochazka, A.1
1Div Neuroscience, Univ Alberta, Edmonton, Canada |
| Primary Theme and Topics |
G. Motor Systems and Sensorimotor Integration - 92. Spinal cord and brainstem |
| Secondary Theme and Topics | G. Motor Systems and Sensorimotor Integration<br />- 93. Control of posture and movement |
| Session: |
260. Spinal cord and brainstem: spinal cord injury Poster |
| Presentation Time: | Monday, November 6, 2000 9:00 AM-10:00 AM |
| Location: | Hall G-J |
| Keywords: | spinal stimulation, biomechanics, movement primitives |
Under some experimental conditions spinal cord microstimulation (SCμstim) produces 4 or 5 patterns of isometric force fields. This is interpreted as evidence for the existence of 4 or 5 movement primitives hard-wired in the spinal cord (Giszter et al., J Neurosci, 1993; Lemay & Grill, SFN Proc, 1999). However, the biomechanical actions and relative strengths of available muscles may limit the number of possible force vectors, making movement primitives a product of the actuator properties rather than the controller. In this study, we compared hindlimb movement vectors produced by SCμstim to those generated by direct nerve and muscle stimulation. In 2 pentobarbital-anesthetized cats, cuff electrodes were placed around nerve branches innervating the main limb flexors and extensors. Pairs of intramuscular (IM) electrodes were placed in the same muscles. SCμstim was delivered through microwires inserted to depths of 3-4.5mm along the lumbar enlargement. The foot was attached to a spring-loaded lever presenting a constant stiffness in the sagittal plane. Movements generated by SCμstim, nerve and IM stimulaton were recorded and endpoint (paw) movement vectors were calculated. Vectors obtained by nerve and muscle stimulation were clustered in 4 distinct directions in the sagittal plane: up, down, forward and backward. Vectors generated by SCμstim were clustered in the same directions, though with smaller magnitudes in some cases. This suggests that the biomechanical actions of the limb muscles set limitations on movements that can be generated through central commands, so preferred movement vectors could reflect biomechanical groupings rather than spinal primitives.
Supported by AHFMR, Canadian MRC
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2000 Neuroscience Meeting Planner. New Orleans, LA: Society for Neuroscience, 2000. Online.
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