Applying coherence analysis to diffuse optical tomography studies using near infrared light in healthy adults

Optical imaging is a relatively novel technique, in which infra-red light is used to investigate oxygenation of blood vessels in the brain. In response to increased neural activity, there is an increase in oxyhemoglobin concentration and a decrease in deoxyhemoglobin concentration. Since oxy- and deoxyhemoglobin have characteristic light absorption spectra, these changes can be determined by measuring attenuation of light at 830 nm and 690 nm. Hence optical imaging is capable of indirectly measuring levels of brain activity. Coherence analysis can determine brain regions whose activities are synchronous, as a means of determining functionally connected brain regions. This has not been investigated to date with optical imaging. In this thesis, I develop a novel coherence analysis technique in application to optical data, and show that this technique is both feasible and applicable to both healthy and patient populations.