Nonlinear dynamics of involuntary shaking of the human hand under motor dysfunction

Abstract

Using nonlinear dynamic methods we examined wavelet and multifractal features of involuntary shaking (tremor) arising during the performance the motor task (sustaining effort of fingers under isometric conditions). The wavelet score (the maximum of the global wavelet spectrum) and multifractal parameters (the width and asymmetry of the singularity spectrum) significantly differ in tremor of healthy subjects and patients with akinetic-rigid form of Parkinson's disease. The relations between the change of the patient state connected with the drug relief of parkinsonian symptoms and the variations of the parameter values have been obtained. The suggested analytic approach for noninvasive study of integrative activity of the central nervous system, formed as the motor exit during realization of the motor task, enables not only to estimate quantitatively the degree of deviation of the motor function from the healthy one, but it can help to a clinician to choose the optimal treatment in every particular case.