Development of simultaneous electroencephalography and near-infrared optical topography for applications to neurovascular coupling and neonatal seizures
This thesis describes the development and preliminary application of
methods for performing simultaneous electroencephalography (EEG) and
near-infrared (NIR) imaging of the brain. The simultaneous application of
EEG and NIR imaging has many benefits because of the complementary
nature of the two modalities, and has significant potential in the study of the
relationship between neuronal activity and cerebral haemodynamics.
This work goes beyond previous experiments which have combined EEG
and limited-channel near-infrared spectroscopy by designing and
implementing an arrangement which allows dense near-infrared optical
topography and EEG to be performed over the same cortical area, with as
simple an application method as possible. These application methods are
described in detail, as is their extensive testing using novel dual-modality
phantoms and an in-vivo EEG-NIR imaging experiment in a healthy adult.
These methods are subsequently applied to the study of neonates in the
clinical environment. An intricate EEG-NIR imaging experiment is
designed and implemented in an investigation of functional activation in the
healthy neonatal visual cortex. This series of experiments also acts as a
further test of the suitability of our EEG-NIR imaging methods for clinical
application. The results of these experiments are presented.
The EEG-NIR imaging arrangement is then applied to four neurologically
damaged infants in the neonatal intensive care unit, each of whom had been
diagnosed with seizures. The results of these studies are presented, and a
potentially significant haemodynamic feature, which is not present in agematched
controls, is identified. The importance and physiological
implications of our findings are discussed, as is the suitability of a combined
EEG and NIR imaging approach to the study and monitoring of neonatal
brain injury