Kinematic analysis of locomotion and skilled reaching to understand motor circuit function in health and post-injury

Spinal cord injury (SCI) often leaves lasting deficits in locomotion, balance, and skilled movement, and the return of motor output rarely reflects recovery of precise or stable motor control. Recent years have provided optimism, however, with electrical epidural stimulation resulting in chronically injured spinal cord injury patients walking, and paired pulse paradigms improving arm and hand function. These results motivate this dissertation, which examines motor recovery across multiple levels of behavior by combining high-resolution kinematic analysis with targeted neural modulation in rodent models, where it is possible to quantify the mechanisms by which these treatments work, and to offer up new clinical directions. In a rat contusion SCI model, chemogenetic excitation of large-diameter afferents was used to mimic aspects of epidural electrical stimulation during treadmill rehabilitation. This resulted in treatment-dependent changes in gait features, like stance duration, duty factor, ankle height, and foot clearance that varied with both recovery stage and treadmill speed; some of these effects diminished during later withdrawal of chemogenetic activation, suggesting that this afferent excitation exerted a time-dependent influence on locomotor output. A second chapter focused on the lateral vestibular nucleus (LVN), where anterograde, retrograde, and a dual-injection tracing experiment confirmed that LVN-associated descending pathways could be reliably targeted in the rat, and subsequent neuromodulation and ablation demonstrated that the targeted population could also be selectively manipulated, although no phenotype was observed under any conditions. The final component examined the lateral reticular nucleus (LRN) in skilled forelimb behavior using bilateral ablation in rats performing a single-pellet reaching task. Here, LRN ablation did not abolish the overall transport trajectory of the limb, but instead produced deficits that were best seen in endpoint covariance, increased trial-to-trial variability, reduced precision, and changes in reach duration. These features are all consistent with the idea that the LRN functions more as a refiner of skilled movement rather than simple movement generation. Taken together, these studies support a common conclusion: meaningful recovery after neurological injury cannot be understood solely in terms of whether the desired movement is present, but must also account for how the desired movement is organized, sequenced, and refined. Across both locomotor and skilled forelimb behaviors, detailed kinematic analysis revealed movement differences and treatment effects that would have been missed by broader observational measures alone. Thus, the value of combining behavioral biomechanics, highly-sensitive kinematic assays, and targeted neural manipulation allowed us to better define how circuits were contributing to recovery and compensation after injury.

Grantor dc:publisher

Temple University. Libraries

Year dc:date.issued

2026

Author dc:creator

• Koma, Gavin Thomas

Advisor dc:contributor.advisor

• Spence, Andrew J.

Committee members dc:contributor.committeemember

• Smith, George M.
• Hsieh, Tonia
• Lemay, Michel A.
• Hiremath, Shivayogi

• Bioengineering
• Neurosciences
• Kinematics
• Locomotion
• Neuroplasticity
• Reaching
• Spinal cord injury
• Virus

Statement dc:rights

• IN COPYRIGHT- This Rights Statement can be used for an Item that is in copyright. Using this statement implies that the organization making this Item available has determined that the Item is in copyright and either is the rights-holder, has obtained permission from the rights-holder(s) to make their Work(s) available, or makes the Item available under an exception or limitation to copyright (including Fair Use) that entitles it to make the Item available.

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

eng

Repository record dc:identifier.uri

https://scholarshare.temple.edu/handle/20.500.12613/12160

OAI identifier oai:identifier

oai:scholarshare.temple.edu:20.500.12613/12160