Interictal "spikes" are abnormal transient features appearing in the Electroencephalogram (EEG) and Electrocorticogram (ECoG) of epileptic patients. Although tentative characterizations of these transients have been offered in terms of their temporal sharpness (second derivative with respect to time), duration, and amplitude, the implementations of detectors for these transients have only achieved limited success because of the amounts of false positive detectionís that occur.
It has been suggested that the measurement of temporal sharpness at varied temporal resolution scales can provide a comprehensive measurement of the typical temporal pattern observed by these phenomena. In this study we apply a wavelet transformation to the digitized ECoG of epileptic patients towards that goal. A mother wavelet provides the basic measure of sharpness, so that its replicas at D progressively increasing dilations will capture the components of sharpness at progressively decreasing temporal resolutions. Then, patterns are sought in the D-dimensional space that indicate a simultaneous increase in many levels of sharpness. When such patterns occur the detection of target feature is suspected.
Typically, true interictal spikes display temporal sharpness in a wide range of temporal resolution scales, while other transients (which may be erroneously detected by other detection approaches) display sharpness at the high temporal resolution level only.
Keywords: multiresolution analysis, ECoG, spike detection, sharpness, wavelet transform, epilepsy, transient detection