The neuroimaging techniques of functional magnetic resonance imaging (fMRI), electroencephalography (EEG) and magnetoencephalography (MEG) are widely used for providing macroscale measurements of neuronal population activity ranging in the mm-cm spatial scale and determining the spatial location and intensity of human brain responses to experimental stimuli such as perceiving visual images, hearing sounds or performing motor movements.
Both increases and decreases in the fMRI, EEG and MEG signals can be measured in response to external stimulation compared to passive rest. But to what extent the activity of excitatory and inhibitory neuronal cell populations contributes to the fMRI/EEG/MEG signals remains poorly understood. The fMRI signal is only an indirect measure of brain function via the slow changes in cerebral blood flow (CBF), blood volume and blood oxygenation which are induced by rapid changes in neuronal activity.
Using multi-modal combinations of these imaging techniques, such as simultaneous EEG-fMRI recordings allows fusion of their complementary strengths and investigation of the neurovascular coupling between changes in neuronal activity and the subsequent changes in haemodynamic signals. Such work aims to provide a better understanding of fMRI signal origins, and the metabolic demands of changes in the synchrony of neuronal oscillations
My primary research interests include:
Investigating how neuronal “inhibition” is represented in fMRI signals. In particular by: a) linking negative fMRI responses to behavioural measures of inhibition such as increased perception thresholds of somatosensory and visual stimuli; b) Linking behavioural and fMRI measures of inhibition to changes in EEG/MEG signals, such as 8-13Hz frequency alpha oscillations.
Simultaneous EEG-BOLD-CBF recordings to study neurovascular coupling and relate changes in neural oscillations to changes in brain oxygen metabolism.
Mathematical modelling of measured fMRI and EEG signals to understand and predict neurovascular coupling.
Studying the relationship between fMRI responses and concentrations of brain metabolites measured using MR spectroscopy.
Studying the effects of TMS and TCDS upon negative BOLD responses.
Interactions between spontaneous EEG and fMRI measures of brain activity and brain responses to subsequent stimulation.
Basic properties of intrinsic resting-state functional and structural connectivity as a measure of the brains functional architecture.
Investigating the neuronal vs vascular origin of global brain fMRI signals.
Investigating the contributions of intrinsic connectivity networks such as the default mode, attention and saliency networks to the brain responses, perception and performance of basic sensory tasks.
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