Analysis of point process signals applied to motor unit firing patterns: II. Superposition of phase-locked spike trains

The different possibilities of cross-constraints between the firing patterns of a number of motor units are laid out. Correlated phasic activity is defined, and the effect of phase locking on the superposition of event sequences is being investigated by the simulation model. For superposition of four spike trains, the two cases of phase locking investigated by the model, φ=0.25 and φ=0.0 may represent an asynchroneous and synchroneous motor unit activity, respectively. A filtering method for estimation of the phase, in cases of phase-locked activity, is described.