Direct detection of neuronal currents with MRI

Supervisor(s) - Prof. Graeme Jackson, Dr. David Abbott

Functional MRI (fMRI) utilizing blood oxygenation level dependent (BOLD) contrast has become one of the most widely used methods for the non-invasive mapping of neuronal activity in the human brain. It is however an indirect technique, measuring changes in the vasculature rather than neuronal activity directly. The response of the vasculature is much slower than the underlying neuronal activity, thus limiting to the temporal resolution of fMRI. The spatial extent of fMRI activation is also generally somewhat larger than the presumed localized zone of firing neurons responsible for the change in blood flow. Over the last few years we have developed an MRI technique which could potentially be used to directly detect the localised magnetic effects arising from neuronal currents. This could provide a neuronal mapping method with millimetre spatial resolution and millisecond timing resolution. Our preliminary results are very encouraging, however there is much work still to be done to characterise and further develop the method.

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Do astrocytes play a significant role in information processing in the brain in vivo?

Recent research has begun to show that astroglia, which were considered to only play a supporting role in brain activity, actually integrate neuronal activity and modulate signaling. This is an extremely exciting advance in neuroscience. To date most supportive evidence is from reduced in vitro preparations. We have developed a novel method for altering astroglial activity which will enable us to examine the function of transmitter release from these cells without altering their other critical functions. We will use this approach to determine whether astroglia are playing a role in information processing in the brain, initially in relation to regulation of cardiovascular and respiratory activity. The project will employ surgical methods for microinjection, physiological recording and various approaches to examine gene expression.

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Dynamin activation in acute epileptic seizures and chronically epileptic rats

Co-supervisors: Prof Terry O’Brien, Prof Phil Robinson (University of Sydney)

This project aims to determine the effect of novel anti-epileptic drugs on activation of the vesicle recycling protein dynamin in vivo in models of acquired epilepsy

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EEG assessment of high frequency oscillatory activity in a mouse model of Autism

Co-supervisors: Dr Nigel Jones, Prof Terence O’Brien

This project will investigate high frequency (gamma) brain rhythms in NL3 mice using:

1. Baseline EEG
2. Following administration of low dose ketamine
3. EEG during memory task
4. EEG during behavioural tasks including locomotor, anxiety tests.

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Electrophonic Hearing with a Cochlear Implant

Supervisor:Dr David Grayden

This project will investigate using the cochlear implant to generate electrophonic hearing in the low frequencies that will provide improved speech recognition, sound localisation and music perception to users.

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