| Summary: | One of the aims of medical physics and neuroscientific research is to noninvasively measure primary sensory human brain function with high spatial and temporal resolution. Imaging modalities such as functional magnetic resonance imaging (fMRI) have allowed a better understanding of broad neuronal properties. The Chapters in this thesis focus on high spatial resolution mapping in the visual and somatosensory system using ultra-high field (7 T) fMRI.
Functional MRI measures changes in the blood-oxygenation level that occurs in response to neural activity, eliciting a haemodynamic response function (HRF). This thesis develops novel fMRI paradigms for high spatial and temporal resolution retinotopic and somatotopic mapping. This includes population receptive field (pRF) mapping, to uncover the receptive fields in visual and somatosensory cortices. This is a phase-encoding, computational method that provides additional information beyond traditional retinotopic mapping. The dependency of the HRF on these computational models is also investigated. To accurately characterize the HRF in different sensory brain regions with good spatial coverage, the use of multiband imaging and short TRs are used in this work. It is suggested that pRF mapping is sensitive to model constraints, minimization algorithm and brain region. pRF development in somatosensory cortex requires the use of very careful experimental setups, which are discussed in this thesis. Finally, a battery involving quantitative sensory testing and fMRI paradigms are setup for patient studies. Specifically, future work in this area aims to consider whether there are any differences in Focal Hand Dystonia patients in the cortical representation of the digits, and/or departures from the norm in behavioural tasks.
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