The objective of this study was to investigate how brain plasticity can be expressed following injury to the nervous system. This plasticity can occur after either direct injury to the brain, such as in hemiparetic stroke, or injury to the peripheral nerves, such as in upper-limb amputation. In order to study the neural mechanisms underlying brain plasticity and their link with disabilities after these two situations, we recorded high-density electroencephalographic signals during the performance of motor tasks. Specifically, we 1) developed a novel biomechanics-based method to quantitatively assess muscle coactivation patterns during movement, 2) explored how cortical activity relates to the loss of independent joint control in stroke survivors, and 3) evaluated how cortical representations for the missing limb of amputees change following targeted reinnervation, a surgical procedure that reroutes severed peripheral nerves to alternative muscle groups. Our results were able to provide novel evidence for unique changes in the brain related to the control of movement following injuries to the nervous system. Using our biomechanics-based method, we easily identified the presence of abnormal muscle coactivation patterns in stroke survivors that affect movement of the paretic limb. We then found that the presentation of peripheral deficits is directly related to the expression of brain plasticity following injury. A progressive increase in ipsilateral hemisphere activation within stroke survivors when abduction loads were increased suggests an increased reliance on ipsilateral corticobulbar/bulbospinal pathways. However, when using these resources, there is a clear penalty in terms of the loss of independent joint control, resulting in decreases in kinematic and muscle performance. Lastly, re-mapping of motor representations and re-establishment of sensory representations were found for amputees following targeted reinnervation, suggesting that cortical changes may reflect the return of new motor targets and sensory feedback for the missing limb. Therefore, this study presents important insight into how the brain reorganizes following injury to the nervous system and how these changes can influence recovery. This is expected to have direct neurophysiological implications for the development of novel rehabilitative interventions that can reduce disability and improve the lives of stroke survivors and upper-limb amputees in the future.

Last modified

• 10/04/2018

Creator

• Albert Chen

DOI

• https://doi.org/10.21985/N23X8S

Subject

• Biomedical Engineering

Keyword

• brain plasticity
• EEG
• cortical activity
• upper-limb amputation
• chronic hemiparetic stroke
• movement

Date created

• 2008-10-31

Resource type

• Dissertation

Rights statement

• In Copyright