INFRARED NEURAL STIMULATION AND FUNCTIONALRECRUITMENT OF THE PERIPHERAL NERVE

Peripheral nerve interfaces have been used to restore motor function to paralyzed limbs. To restore the most natural function to paralyzed muscles requires a very selective interface. Arguably, ideal selectivity would entail independent control over each neuron. Neural interfaces based on electrical stimulation of neurons have made the most progress in restoring movement in paralyzed limbs, but increasing selectivity without increasing invasiveness remains a primary goal in developing stable and chronic nerve interfaces. Interfaces that use infrared light to stimulate may provide selective activation without penetrating the nerve. The work presented in this dissertation explores this concept, measuring sensitivity and motor response in peripheral nerves, and using computational models to investigate mechanisms of activation. The in vivo experimental work presented quantifies motor response to extraneural infrared stimulation in the rabbit sciatic nerve. It was hypothesized that infrared light would selectively stimulate motor response in at least three different regions of the nerve, and do so to a functionally significant level. Combined infrared and electrical stimulation was hypothesized to significantly change full-muscle recruitment over electrical recruitment alone. In this study, only 81% of nerves responded to infrared stimulus, with 1.7±0.5 sensitive regions detected per nerve. Single-muscle selectivity was measured in 79±12% of sensitive regions. Infrared stimulus activated significantly less than 10% of the muscle capability, though. Combined electrical and optical stimulation only yielded significant differences from electrical recruitment in 7% of cases. These results highlight challenges to address before translating infrared stimulation larger nerves. Mechanisms of infrared stimulation were studied using computational models. Intracellular currents generated by changes in membrane capacitance or intracellular calcium release were hypothesized capable of triggering action potentials under conditions determined physiologically possible. Results show that activation with membrane capacitance changes depend on the spatial gradient of evoked currents, and that relatively small changes in intracellular calcium concentrations can trigger action potentials. The results of this study provide insight into how infrared light may activate axons, and how infrared stimulation may be improved over current methods.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Biomedical Engineering

Grantor dc:publisher

Case Western Reserve University School of Graduate Studies

Year dc:date

2013

Author dc:creator

• Peterson, Erik J.

Contributors dc:contributor

• Tyler, Dustin

• Biomedical Engineering
• Biomedical Research
• Optics
• Infrared neural stimulation
• motor recruitment
• selectivity
• electrical stimulation
• peripheral nerve
• sciatic
• extraneural
• membrane capacitance
• computational model

Statement dc:rights

• unrestricted
• This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.

Language dc:language

English

Repository record dc:identifier

http://rave.ohiolink.edu/etdc/view?acc_num=case1363640552

OAI identifier oai:identifier

oai:etd.ohiolink.edu:case1363640552