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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Hebbian Neuroplasticity in the Human Corticospinal Tract as Induced by Specific Electrical and Magnetic Stimulation Protocols

McGie, Steven 13 August 2014 (has links)
Conventional functional electrical stimulation (FES) therapy, if provided shortly after an incomplete spinal cord injury, is able to help an individual to restore voluntary hand function. This is thought to occur through the induction of neuroplasticity. However, conventional FES therapy employs a push-button-based control scheme, which does not fully require the recipient to generate volitional movements. The first study in this thesis therefore sought to determine, in an early proof-of-concept test with able-bodied participants, whether control strategies which are triggered by volitional activity (including an electroencephalography-based brain-machine interface (BMI-FES) and an electromyogram-based control scheme (EMG-FES)) might provide greater benefits to hand function. The results offer relatively weak evidence to suggest that BMI-FES, and especially EMG-FES, were able to induce greater neuroplasticity than conventional treatments in the corticospinal tract leading to the hands, but that this did not immediately translate to more functional improvements such as maximum grip force. ii The second study in this thesis focussed on spinal associative stimulation (SAS), which involves paired stimulation pulses at both the head (via transcranial magnetic stimulation), and the wrist (via peripheral nerve stimulation). The purpose of this, as with the first study, was to induce neuroplasticity and upregulate the corticospinal tract leading to the hands. While limited research has suggested that it is possible to produce neuroplasticity through SAS, all such studies have provided stimulation at a fixed frequency of 0.1 or 0.2 Hz. The present study therefore sought to compare the effectiveness of a typical 0.1 Hz paradigm with a 1 Hz paradigm, and a paradigm which provided stimulation in 5 Hz “bursts”. None of the paradigms were able to successfully induce neuroplasticity in a consistent manner. The increased variability in this study as compared to the previous one, despite the nearly identical assessment methodology, suggests that responses to the SAS treatment may have been highly individual. This serves to highlight a potential limitation of the treatment, which is that its effectiveness may not be universal, but rather dependent on each specific recipient. This may be a challenge faced by SAS should it continue to be tested as a novel therapy.

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