A closed-loop self-righting controller for seated balance in the coronal and diagonal planes following spinal cord injury

The contributions of intrinsic (passive) and extrinsic (active) properties of the human trunk, in terms of the simultaneous actions about the hip and spinal joints, to the control of sagittal and coronal seated balance were examined. Able-bodied (ABD) and spinal-cord-injured (SCI) volunteers sat on a moving platform which underwent small amplitude perturbations in the anterior-posterior (AP) and medial-lateral (ML) directions while changes to trunk orientation were measured. A linear parametric model that related platform movement to trunk angle was fit to the experimental data by identifying model parameters in the time domain. The results showed that spinal cord injury leads to a systematic reduction in the extrinsic characteristics, while most of the intrinsic characteristics were rarely affected. In both SCI and ABD individuals, passive characteristics alone were not enough to maintain seated balance. Passive stiffness in the ML direction was almost 3 times that in the AP direction, making more extrinsic mechanisms necessary for balance in the latter direction. Proportional and derivative terms of the extrinsic model made the largest contribution to the overall output from the active system, implying that a simple proportional plus derivative (PD) controller structure will suffice for restoring seated balance after spinal cord injury.

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Feasibility of closed-loop controller for righting seated posture after spinal cord injury

The Journal of Rehabilitation Research and Development ◽

10.1682/jrrd.2013.09.0200 ◽

2014 ◽

Vol 51 (5) ◽

pp. 747-760 ◽

Cited By ~ 16

Author(s):

Julie O. Murphy ◽

Musa L. Audu ◽

Lisa M. Lombardo ◽

Kevin M. Foglyano ◽

Ronald J. Triolo ◽

...

Keyword(s):

Spinal Cord ◽

Spinal Cord Injury ◽

Closed Loop ◽

Cord Injury ◽

Seated Posture

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Vagus Nerve Stimulation Paired With Rehabilitative Training Enhances Motor Recovery After Bilateral Spinal Cord Injury to Cervical Forelimb Motor Pools

Neurorehabilitation and Neural Repair ◽

10.1177/1545968319895480 ◽

2020 ◽

Vol 34 (3) ◽

pp. 200-209 ◽

Cited By ~ 2

Author(s):

Michael J. Darrow ◽

Miranda Torres ◽

Maria J. Sosa ◽

Tanya T. Danaphongse ◽

Zainab Haider ◽

...

Keyword(s):

Spinal Cord ◽

Spinal Cord Injury ◽

Vagus Nerve ◽

Motor Neurons ◽

Nerve Stimulation ◽

Vagus Nerve Stimulation ◽

Closed Loop ◽

Neurological Injury ◽

Injury Model ◽

Cord Injury

Closed-loop vagus nerve stimulation (VNS) paired with rehabilitative training has emerged as a strategy to enhance recovery after neurological injury. Previous studies demonstrate that brief bursts of closed-loop VNS paired with rehabilitative training substantially improve recovery of forelimb motor function in models of unilateral and bilateral contusive spinal cord injury (SCI) at spinal level C5/6. While these findings provide initial evidence of the utility of VNS for SCI, the injury model used in these studies spares the majority of alpha motor neurons originating in C7-T1 that innervate distal forelimb muscles. Because the clinical manifestation of SCI in many patients involves damage at these levels, it is important to define whether damage to the distal forelimb motor neuron pools limits VNS-dependent recovery. In this study, we assessed recovery of forelimb function in rats that received a bilateral incomplete contusive SCI at C7/8 and underwent extensive rehabilitative training with or without paired VNS. The study design, including planned sample size, assessments, and statistical comparisons, was preregistered prior to beginning data collection ( https://osf.io/ysvgf/ ). VNS paired with rehabilitative training significantly improved recovery of volitional forelimb strength compared to equivalent rehabilitative training without VNS. Additionally, VNS-dependent enhancement of recovery generalized to 2 similar, but untrained, forelimb tasks. These findings indicate that damage to alpha motor neurons does not prevent VNS-dependent enhancement of recovery and provides additional evidence to support the evaluation of closed-loop VNS paired with rehabilitation in patients with incomplete cervical SCI.

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