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Title: Development of fMRI techniques to study sensorimotor plasticity and learning
Author: Aboushoushah, Samia Faisal
ISNI:       0000 0004 2721 9037
Awarding Body: University of Nottingham
Current Institution: University of Nottingham
Date of Award: 2011
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The aim of the work in this thesis is the development of functional magnetic resonance imaging (fMRI) techniques to investigate human brain plasticity and learning in the sensorimotor system. Patterns of cortical and sub-cortical activation in response to active, passive and Electrical Stimulation (ES)-induced Ankle dorsiflexion (ADP) movement were identified using fMRI. Electromyography (EMG)-guided fMRI analysis was shown to improve detection and reduce inter-session variance for active and ES tasks. A significantly greater number of voxels were found to be activated during active and ES-induced ADP compared to passive ADP. The contrast of active greater than ES-induced ADP showed increased activation in brain areas responsible for motor planning, execution and visuomotor co- ordination, conversely ES-induced activation was shown to result in greater activation in bilateral SII and insula than active ADP. Cortical responses to tactile stimulation at flutter (33 Hz) and vibration (250 Hz) frequencies were assessed using electrical (EEG) and haemodynamic (fMRI) measures. Each modality was first assessed individually, and the two modalities then combined using simultaneous EEG/fMRI. The evoked responses in the EEG data showed flutter and vibration evoked an overall similar bilateral activation in SI, similar between unilateral right and left hand stimulation. No significant laterality of the evoked response in SI due to 33 Hz tactile stimulation was found. Analysis of the fMRI data showed that unilateral tactile stimulation, at both 33 and 250 Hz, elicited bilateral activation in SI and SI!, with flutter eliciting a greater BOLD signal in contralateral SI. The SI mean laterality index was shown to be significantly higher for fMRI data than EEG data, indicative of contralateral activity. Simultaneous EEG/fMRI at 7 T resulted in very noisy EEG data, even when precautions were taken and post-processing artefact removal methods used. The effect of short term tactile training on a tactile discrimination task was demonstrated. Behavioural data showed alterations in responses with training. fMRI results showed that passive tactile letter discrimination activated multiple cortical areas, including the somatosensory network, fronto-parietal network, fusiform gyrus and cerebellum. Comparison between trained and untrained groups reveals a significant reduction in response in SI! and fronto-parietal areas to the tactile discrimination task suggestive of a decrease in the monitoring effort required to maintain performance with a shift to more automated performance,.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available