Modeling and analysis of the impact of nTMS on the EMG signal of laryngeal muscles

This paper describes a methodology for the analysis of electromyographic signals. Biosignal measurements were performed with the application of electromagnetic stimulation of specific regions of the cerebral cortex and the response was recorded from electrodes hooked to laryngeal muscles. Analysis of the resulting signal is needed to identify markers in the measured signal relating to electromagnetic stimulus and thus provide background for mapping brain regions characteristic for the production of speech. Given the fact that the neurosurgical priority is to preserve these regions (eloquent or critical regions of the cortex) of injury during surgery because such injury can cause permanent damage, it is necessary to pay great attention to operation planning. This requires high-quality mapping. Methods of electrical stimulation produce results, but are applied intraoperatively. The aim is to develop a non-invasive method and for this purpose electromagnetic stimulation is more appropriate. The paper describes the model of stimulus propagation and acquisition as well as signal analysis using methods of principal components analysis for blind source separation and spectrogram analysis filtered with with wavelet packets. Software tool MATLAB is used for signal processing.