Effect of Aging and Hemispheric Functional Disorder on the Anisotropy of the Control Characteristics in the Two Dimensional Manual Tracking System

The integration function of multi-sensory information in the central nervous system is discussed by analyzing the human operator's control characteristics in the two-dimensional manual tracking system. The tracking error, the nonlinearity index and the anisotropy index are used to analyze the operator's control characteristics. In the case of normal subjects, large tracking error was observed together with large anisotropy. The comparison between young and old normal subjects revealed that the depression of the central nervous system due to aging promoted the anisotropy of the control characteristics. The patients with hemiparesis, who were pointed out the lesions in the basal ganglia or the thalamus on computed tomography, had a large amount of tracking error through they had small degree of anisotropy. To account for the results mentioned above, a model of the integration function of multi-sensory information is proposed for the central hemispheric disorders. This model is used to ascertain the adequacy of the hypothesis that the anisotropy is derived from the bilaterality which is a basic structure for the connection of the neuronal network in the brain.