Matching pursuit parametrization of sleep spindles

Sleep spindles are transients important in the evaluation of sleep EEG. Matching Pursuit (MP) is a recently introduced adaptive time-frequency method of signal analysis. Iterative algorithm fits to the local signal structure waveforms from a large and redundant set were performed. 21 channels of an overnight EEG recordings were subjected to the MP decomposition. Structures corresponding to sleep spindles were chosen from waveforms fitted to the signal. In this way sleep spindles were described in terms of natural parameters, i.e. position in time and frequency, width in time, amplitude and phase. Comparison of this automatic detection with visual analysis showed concordance decreasing with threshold amplitude. Characteristics of spindles occurrence in time, frequency and space were evaluated. Results confirmed several of the hypotheses reported in literature.