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Author ORCID Identifier

https://orcid.org/0000-0002-1167-1091

AccessType

Open Access Dissertation

Document Type

dissertation

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Neuroscience and Behavior

Year Degree Awarded

2022

Month Degree Awarded

February

First Advisor

Julia T. Choi

Second Advisor

Rebecca M.C. Spencer

Third Advisor

Richard E.A. van Emmerik

Fourth Advisor

Rachael D. Seidler

Subject Categories

Biomechanics | Motor Control | Neuroscience and Neurobiology

Abstract

During activities of daily living, locomotor patterns must be continuously adapted according to changes in our body (e.g., bodily injuries, fatigue) and to the changing environment (e.g., walking surface). Plasticity of spinal networks and supraspinal centers, including the cerebellum and cerebral cortex, have been shown to play important roles in human locomotor adaptation. However, the neural control of locomotion and the ability to adapt locomotor patterns are altered in older adults, which may limit activities of daily living and increase fall-related injuries in the elderly population. My dissertation project is focused on understanding the role of corticospinal drive during split-belt treadmill and visuomotor walking adaptation in healthy young and older adults. My central hypothesis is that lower corticospinal drive is associated with reduced kinematic adaptability during locomotion in older adults. In Study 1, I examined the age-related changes in corticospinal control during split-belt locomotor adaptation, which is driven by mismatch of expected and actual proprioceptive input. Older adults adapted step length asymmetry slower, and had lower corticospinal drive compared to younger adults. Higher corticospinal drive to the tibialis anterior was associated to larger step length asymmetry change and smaller double support asymmetry change, and higher corticospinal drive to the tibialis anterior and smaller corticospinal drive to the plantarflexors were associated smaller early change in double support asymmetry during split-belt adaptation. Study 2 examined the age-related changes in corticospinal control during visuomotor locomotor adaptation, which is driven by mismatch between visual and proprioceptive feedback about foot position. Older adults adapted step time asymmetry slower, and had lower corticospinal drive compared to younger adults. Higher corticospinal drive to the tibialis anterior was related to the overall change in step time asymmetry during visuomotor locomotor adaptation. Across both studies, there were age-group differences in some, but not all kinematic adaptation measures, which may suggest that older adults are able to adapt gait kinematics with both the split-belt and the visuomotor locomotor adaptation, but prioritization may differ between the age groups. Corticospinal drive to the lower extremity musculature was associated with kinematic measures independent of age groups, which suggests that the association do not change with age. These findings provide insight into the importance of corticospinal drive during locomotor adaptation, which may have implications for future development of interventions that promote effective recovery in gait in people with neurological injuries.

DOI

https://doi.org/10.7275/27077996.0

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

Available for download on Wednesday, February 01, 2023

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