Model Based Decomposition of MUAPs into their Constituent SFEAPs Preliminary Findings

The motor unit action potential (MUAP) represents the spatial and temporal summation of single fibre extracellular action potentials (SFEAPS) generated from the same motor unit. In this study, a model based decomposition of MUAPS into their constituent SFEAPS is investigated. The aim of this study has been to develop a system that will give to the neurophysiologist a visualization of an “estimated” structural organisation of the motor unit, which includes information about number of fibres, fibre distribution and positioning and fibre diameter. The mathematical model developed in two dimensions by Dimitrova and Dimitrov [1], [2] was used to generate SFEAPS. In addition, this model was extended to three dimensions. Two-dimensional and three-dimensional models of MUAPS consisting of 1 to 10, and 50 fibres were developed and decomposed for a small recoding radius up to 5 mm. The non linear least squares optimization procedure based on the Levenberg-Marquardt algorithm was used to obtain a solution to the MUAP decomposition problem i.e. fibre distribution, positioning and diameter. Using this method, a satisfactory solution to the decomposition problem was obtained. Future work will investigate the usefulness of the proposed analysis on MUAPS recorded from normal subjects and subjects suffering with neuromuscular disorders.