A Multichannel Single Fiber EMG Recording System

Abstract

A multichannel single fiber EMG recording system has been developed and tested. This system is based on a multichannel needle electrode which has the ability to record EMG signals from multiple sites within the muscle under study without reinsertion. Therefore, not only is the recording volume of the electrode. increased but also enhancement of the single channel electrodes is possible through spatial filtering. The recording system, currently implemented on a PDP-11/34 computer, amplifies, filters and digitally stores the multichannel EMG signals for further signal processing. Signal processing techniques were developed to detect and extract motor unit action potentials from the EMG signal. Due to the large amount of data recorded by the multichannel electrode, slower sampling rates for digitizing the action potentials were required. Even with near Nyquist sampled signals the accuracy of this technique was shown to be nearly equivalent to conventional extraction of action potential features samples at four times the Nyquist rate. Finally, the problem of superpositioning of action potentials was addressed. By modifying the interpolation routine an algorithm for resolving superpositions was developed.