The use of advanced information processing methods in EEG analysis

In the field of medical signal and image processing the usual uncertainties in our knowledge are often compounded by a poor understanding of the physical mechanisms by which the data is generated and a subjective evaluation of the data by a human observer. In the case of the EEG, the effects of scalp, fluid and bone on the tiny electrical currents generated in the cortex may be modelled only poorly and the large size of scalp electrodes and the effects of muscle and instrument noise all contribute to the difficulty of EEG analysis. The belief that the EEG contains some objective information regarding brain state is tantalising. We do not discuss in detail the problems of noise and artifact removal, nor the problems of modelling the passage of the EEG from cortex to scalp, but instead concentrate on the EEG as is and suggest that, even if such problems are not solved, the EEG contains significant objective information regarding cortical functioning. We focus upon two main areas of information processing, namely information extraction from an EEG record (feature extraction and representation) and pattern recognition and inference