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Title: Exploring neuro-vascular responses in the brain to visual stimulation
Author: Wijeakumar, Sobanawartiny
ISNI:       0000 0004 2718 5543
Awarding Body: Glasgow Caledonian University
Current Institution: Glasgow Caledonian University
Date of Award: 2011
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The aim of this thesis was to investigate if haemodynamic function in response to both simple and complex visual stimulation could be quantified using functional near infrared spectroscopy (fNIRS). Event-related potentials (ERPs) were used in conjunction with fNIRS in order to study the nature of neuro-vascular correlates underlying visual processing. Cortical mapping of haemodynamic function in response to simple visual stimulation using reversing checkerboards over the occipital and parieto- . . occipital cortices showed that locations only overlying V1, with the exception of those on the midline, elicited the biggest activation. Neuro-vascular correlates of responses to static random dot stereograms revealed that haemodynamic activity was possibly representative of responses to pattern- onset/global aspects of the stimulus. In general, change in haemodynamic activity was strongly correlated with that of neural activation. Changes in vascular function in response to radial motion and dynamic stereograms, when the effect due to a pattern onset was eliminated, at occipital and parieto-occipital cortices showed that fNIRS was able to detect haemodynamic activation as a result of motion and stereopsis respectively. Finally, investigation of a new complex stimulus encompassing the properties of motion, depth and luminance over parieto-occipital cortices showed that changes in haemoglobin concentration were only representative of the 'global' form of the stimulus. In contrary to ERP results, no motion adaptation effects were observed within the haemodynamic response. The work presented in this thesis has shown how simple and complex visual stimulation over a large proportion of human visual cortex affects absolute concentrations of haemoglobin chromophores and are good indicators of absolute oxygen consumption by the brain. Furthermore, the technique can be used to study the physiological nature of neurovascular coupling in both normal and compromised visual functioning in the future by modifying experimental paradigms presented in this thesis, and with improved probe design. 11.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available