Author ORCID Identifier
Semester
Summer
Date of Graduation
2024
Document Type
Dissertation
Degree Type
PhD
College
School of Medicine
Department
Not Listed
Committee Chair
Valeriya Gritsenko
Committee Co-Chair
Paul Chantler
Committee Member
Jessica Allen
Committee Member
Nicholas Brandmeir
Committee Member
Peter Konrad
Abstract
Mechanisms of voluntary motor control are complex and require inputs via cortical centers, peripheral sensory systems, and spinal inputs such as central pattern generators. It is hypothesized that control is simplified via utilization of motor primitives, which may rely on structures within the spinal cord, however this remains unknown in both human and non-human primates. The goal of this dissertation is to characterize muscle activity in the upper extremity in relation to the corresponding anatomical organization of spinal motoneurons to provide insight into how primitives are both organized and activated to produce movement.
The first aim of this work was to quantify the relationship between the anatomical location of motoneuron pools in the spinal cord and agonistic or antagonistic activity of the corresponding muscles. I hypothesize that the anatomical substrate of motoneurons in the spinal cord embeds musculoskeletal organization for simplified sensorimotor control. To test this hypothesis, a three-dimensional model of motoneurons innervating upper extremity musculature in the macaque was developed and compared to simulated muscle activity from musculoskeletal models. Using these models, it was demonstrated that spinal motoneuron pools innervating muscles with agonistic activity or shared innervation were positioned relatively close together in the cord. Additionally, antagonistic muscles were primarily located adjacent to these agonistic pairs. This structure-function relationship supports the hypothesis that organization of spinal structures helps to simplify motor control.
The second aim of this thesis was to characterize changes in muscle activity as it relates to spinal motoneuron anatomy across reaching versus grasping tasks, in healthy subjects and those with a history of nontraumatic spinal cord injury. Changes in muscle activation patterns were briefly characterized in a patient with a history of degenerative cervical myelopathy performing a functional assessment of upper extremity function. Compared to the healthy controls, the myelopathy patient exhibits distinct patterns of muscle activity that display less task-specific bursting. Furthermore, muscle coactivation is distinct in the DCM patient, both when compared to controls and during different movement phases of reaching and grasping tasks. Data generated from the models and simulations developed here will potentially aid in design and construction of devices utilizing neural interfaces or aiding in improvement of diagnosis and assessment of various neurological injuries.
Recommended Citation
Taitano, Rachel I., "Investigating the role of spinal motoneuron organization in human motor control" (2024). Graduate Theses, Dissertations, and Problem Reports. 12616.
https://researchrepository.wvu.edu/etd/12616
Embargo Reason
Publication Pending