CROSS-SPECTRAL ANALYSIS OF PHYSIOLOGICAL TREMOR AND MUSCLE-ACTIVITY -II - APPLICATION TO SYNCHRONIZED ELECTROMYOGRAM

We investigated the relationship between synchronized muscle activity and tremor time series in (enhanced) physiological tremor by cross-spe ctral analysis. Special attention was directed to the phase spectrum a nd its potential to clarify the contribution of reflex mechanisms to p hysiological tremor. The phase spectra are investigated assuming that the electromyogram (EMG) synchronization was caused by a reflex or a c entral. oscillator. Comparing these results to phase spectra of measur ed data, we found a significant contribution of reflexes. But reflexes only modify existing peaks in the power spectrum. The main agents of physiological tremor are an efferent pace and the resonant behavior of the biomechanical system.