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Dissertation
Representation of sensorimotor information in the rat hindlimb cortex after a complete spinal cord injury
Doctor of Philosophy (Ph.D.), Drexel University
01 Sep 2014
DOI:
https://doi.org/10.17918/etd-6366
Abstract
Spinal cord injury (SCI) is a severe disability that affects 2.5 million people worldwide. A complete SCI results in total loss of sensation and motor paralysis below the level of the lesion, dramatically affecting the quality of life for these patients. One of the principle goals for patients from rehabilitation after SCI is to be able to walk again. SCI effectively disrupts the communication between supraspinal and spinal circuits that are involved in locomotion. Despite this, the isolated spinal circuits retain a certain capacity to produce rhythmic locomotor like movements when reactivated through chemical or electrical stimulation. This rhythm generation alone is not sufficient to restore locomotion, which involves more complex functions such as weight bearing, balance and stability. This is the motivation behind developing therapeutic interventions that can enhance sensorimotor encoding in spared supraspinal locomotor networks. In this thesis, we use two approaches for chronic rehabilitation after a complete T8/T9 mid-thoracic SCI, one is training in a brain machine interface (BMI) paradigm using a hindlimb press task and the other is a combination of 5-HT agonists, bike exercise and treadmill training administered over 12 weeks. The goal of this work is to evaluate changes in the information due to these interventions and more importantly, understand how they influence recovery of lower limb function after SCI in adult rats. . To address this we measure changes in sensorimotor encoding with electrophysiological techniques including recording activity of neuronal populations to sensory stimulation, intracortical microstimulation to study motor map changes and cortical lesioning. Our results show that using therapeutic intervention (BMI training) after SCI preserves the encoding for motor program encoded by neurons in the deafferented cortex, which can potentially be used to control voluntary movement. Secondly, our combination of chronic therapies promote reorganization of sensorimotor circuits in the cortex which leads to significant recovery of locomotor function including weight bearing in the open field. Finally, lesioning this novel cortical sensorimotor network drastically decreases the locomotor recovery, establishing a causal role for the cortical reorganization in promoting recovery of function. This work ascertains the need to optimize therapeutic interventions by targeting supraspinal plasticity to maximize recovery after complete spinal cord injury.
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Details
- Title
- Representation of sensorimotor information in the rat hindlimb cortex after a complete spinal cord injury
- Creators
- Anitha Manohar - DU
- Contributors
- Karen Anne Moxon (Advisor) - Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- School of Biomedical Engineering, Science, and Health Systems (1997-2026); Drexel University
- Other Identifier
- 6366; 991014632840104721