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I work for the Dept of Medical Physics in Westmead Hospital, Sydney, Australia, mainly supporting and contributing to the work of the Brain Dynamics Centre.
I am also an Honorary Associate at the School Of Physics, The University of Sydney.
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Dept of Medical Physics and Brain Dynamics Centre Westmead Hospital Westmead, NSW 2145 Australia Tel: +61 2 9845 8194 Fax: +61 2 9845 8190 |
Rm 465 School of Physics, A28 University of Sydney NSW 2006 Australia Tel: +61 2 9036 7970 Fax: +61 2 9036 7158 |
Email: c.rennie@physics.usyd.edu.au |
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For many years my main responsibilities were to assist the work of the Brain Dynamics Centre by providing hardware and software support. This group used EEG recordings from subjects (both patients and healthy volunteers). These recordings were made during the presentation of stimuli and tasks that exercised various aspects of brain function. Often the measurements involved the simultaneous recording of eye movements, pupil size, skin conductance, ECG, and respiration. The complexity involved in these additional modalities — combined with the problems of generation and synchronization of audio-visual stimuli — made for an interesting job. The job was made even mode interesting by the rapid advances in hardware, which meant that I implemented acquisition and analysis software for several hardware generations:
Then, in a weak moment, I commited to a PhD. My project was to model the EEG - the large-scale electrical activity of the brain. The word 'large-scale' turns out to be crucial, since it makes the undertaking feasible: by considering only the low spatial and temporal frequencies (which is all that is visible in scalp recordings) we are able to make the 'mean field' approximation, whereby only the averaged (or correlated) activity is modelled. This is far simpler to model than single-neuron activity. The reasons are explained in my thesis, which is available in PostScript format and in PDF format.
The thesis is also available from the URI http://hdl.handle.net/2123/816.
This work plus that of my supervisors and colleagues resulted in a Eureka prize. Eureka prizes are awarded annually for scientific research in Australia. Our work was awarded the 2003 Eureka in the category of Interdisciplinary Scientific Research. The team was Professor Peter A Robinson, Professor Jim Wright, Dr Evian Gordon and myself. For more about this award see http://www.amonline.net.au/eureka/
During my PhD candiditure I also gained valuable experience in librarianship. As a result you can see the contents of our Theory library: either the HTML version, the PostScript version or BibTeX version
Compiling and maintaining a reference list is hard work. You are welcome to use mine as a starting point.
| EEG ForwardModelApplet | Our model of EEG is still being refined, and I am particularly involved in the inverse modelling problem. To get some feel for the nature of the task, try running my Java applet, which allows you to vary the model parameters yourself. |
| ERP ForwardModelApplet | Another refinement is to look at impulse responses — as might result from discrete stimuli — and dynamic gains — as might be expected from the transient action of neuromodulators or state changes, following stimuli. Try running my Java applet. |
| Triangulated cortex | The model also needs a better treatment of cortical anatomy, as it can influence the character of signals recorded on the scalp. This involves evaluating the volume conduction of the extracellular currents induced by neuronal activity. |
| Jeda | Another interest is better quantification and classification of EEG signals, using either physiological or phenomenological models. Statistics and data mining come into it, ultimately. |
| A brief guided tour of the Linux command line | Click! |
| How to do PostScript and PDF manipulations | Click! |
| How to generate PostScript conveniently from .tex files | Click! |
| Tutorial on the use of Fourier series for time series analysis | Click! |
| Validate HTML CSS | Last changed 2009/02/22 | Chris Rennie |