Automated, quantitative analysis of interdigestive small intestinal myoelectric activity in rats

Quantitative analysis of myoelectric activity (EMG), to investigate small intestinal motility in rats, is normally based on manual classification into sequences of phase I, phase II and phase III. This classification is partly subjective. We aimed to develop a more objective method for the analysis of the migrating myoelectric complex (MMC). From the EMG, a derived signal is calculated as a measure of activity. Depending on the level of this derived signal, the EMG is classified into 'quiescent phase', 'irregular phase' or 'activity front'. The threshold levels for these phases are automatically calculated from the EMG data. A proposal for subdivision into MMCs is automatically generated. To calculate MMC length, the user must manually reject nonpropagated activity fronts. While developing the method, more than 19 derived signals were tested. These included variants of spike frequency, signal power and spike-burst length. The spike frequency signal was chosen because it gave minimal deviation from manual classification. Using the new automated method, recordings from the jejunum of 15 healthy rats were analysed (6 h each). The calculated phase lengths were consistent with the results of manual analysis. The presented method allows objective analysis of the interdigestive EMG signals of the small intestine.