Simultaneous measures of brain and blood oxygenation: Revealing the function behind ‘functional’ brain mapping signals

A technique called blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) can determine levels of different activity in parts of the living human brain and how malfunctions can occur in disease. However, currently the changes in task related brain tissue oxygenation changes that directly influence blood oxygenation signals are not well characterised and as such, the time course and spatial extent of the fMRI signal is difficult to interpret in terms of the underlying neurometabolic changes and brain activity. The classic technique of polarographic electrode recording of extra cellular tissue oxygen concentration has become in vogue as it is well suited to address this issue. However, no studies have combined this technique with optical imaging spectroscopy measurements of blood oxygenation and as such, the direct relevance of polarographic electrode data to fMRI is uncertain. Thus the present proposal seeks to combine these techniques to further our understanding of the temporal, spatial and functional role of the task evoked changes in cerebral blood oxygenation and as such, directly aid the interpretation of fMRI data.