Investigating the origin and role of the post-stimulus response
Functional Magnetic Resonance Imaging (fMRI) is widely used to study brain function in neuroscience. However the origin of the blood oxygen level dependent (BOLD) signal measured with fMRI is still not fully understood limiting the utility of fMRI. The post-stimulus undershoot is a well recognised part of the BOLD fMRI response which occurs after a stimulus has ceased. In MEG and EEG, which measure electrical signals from the neurons in the brain, there is also a well document rebound effect post-stimulation which is measured in specific frequency bands. However these signals are commonly ignored because their neurophysiological origins remain poorly understood. Consequently, over half of the response timecourse is vastly under-exploited for understanding human brain function. We have recently shown that the post-stimulus BOLD and EEG responses are linked and therefore the BOLD post-stimulus response is neuronal in origin, rather than due to poor vascular compliance, as previously thought. This work also suggested that this fMRI response has a functional role and there is a longer lasting electrophysiological response than previously thought.
The findings of our previous work raise a number of important questions which would be addressed using multi-modal methods in this PhD, enabling this response to be used in the investigation of brain function. The mechanisms behind the BOLD post-stimulus response would be investigated in greater depth using 7T MRI to understand to a greater extent if this response is driven by similar or different mechanisms of the main BOLD response using a range of MRI techniques to measured BOLD, CBF and CBV in combination with EEG. We would also investigate the functional relevance of this response by modulating the post-stimulus response and see how this affects the response to other stimuli. A greater understanding of the role of this response in stimulus processing will be important to help the investigation of neurological diseases such as schizophrenia where this response may differ.
Applicants should have a background in the physical sciences or neuroscience with a good understanding of programming in MATLAB. Experience with neuroimaging and data analysis is desirable.
For Further information contact: Karen Mullinger [Email Address Removed]
Self-funded students may wish to apply.
There are a number of currently open competitive studentship schemes at the University of Birmingham, and students are welcome to discuss their eligibility for these with the supervisor or the PG Admissions Tutor.
Poststimulus undershoots in cerebral blood flow and BOLD fMRI responses are modulated by poststimulus neuronal activity By: Mullinger, Karen J.; Mayhew, Stephen D.; Bagshaw, Andrew P, Bowtell, R., Francis, S.T., PNAS Volume: 110 Issue: 33 Pages: 13636-13641
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