Saudi Cultural Missions Theses & Dissertations
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Item Restricted Neuroplasticity and Systematic Audiovisual Training in Virtual Reality: A Multimodal MRI Investigation(University of Liverpool, 2024-03) Alwashmi, Kholoud; Meyer, GeorgThe integration of information from different sensory modalities is a fundamental process that enhances perception and performance. This study explores the audio-visual (AV) integration and its impact on behavioural performance using virtual reality (VR). The research involved twenty healthy participants who underwent daily VR training for four weeks, focusing on an AV adaptation of a scanning training paradigm used in hemianopia rehabilitation. The investigation aimed to understand how functional brain changes contribute to improvements in behavioural performance during AV learning tasks, and how microstructural changes in white matter (WM) tracts, measured through diffusion tensor and kurtosis imaging (DTI, DKI), are linked to functional connectivity changes in relevant brain areas. The results revealed a significant reduction in the response time (RT) after training for the voluntary eye movement task (the trained task). Behavioural performance was improved in both visual and AV conditions, with the latter exhibiting faster RT facilitated by audio cues. This learning effect transferred to two untrained tasks, a visual search task and an involuntary visual task. Functional magnetic resonance imaging (fMRI) demonstrated increased activation in multisensory brain regions involved in early-stage AV processing, the thalamus, inferior parietal lobe, and cerebellum, which was correlated with behavioural enhancements. DTI analysis indicated a decrease in mean diffusivity (MD) in the superior longitudinal fasciculus II (SLF II), connecting frontal and parietal regions, correlating significantly with observed behavioural gains. Additionally, fractional anisotropy (FA) increased in optic radiations post-training, connecting the thalamus with visual areas. Functional connectivity analysis revealed a significant increase in functional connectivity between primary visual and auditory cortices post-training, supported by DKI microstructural changes in these regions and the sagittal stratum, encompassing WM tracts connecting these lobes. These findings highlight learning-induced functional and microstructural changes in extended brain networks contributing to AV integration and attention. It also demonstrates the complementary nature of the DTI and DKI, providing insights into task-relevant brain networks. Overall, the complex relationship between functional and microstructural brain adaptations, alongside functional connectivity changes, underscores how immersive VR training promotes multisensory integration and neuroplasticity. Understanding these dynamics could inform tailored interventions and optimize training paradigms for enhanced sensory processing and rehabilitation outcomes.16 0