Application of AFE Analog Interfaces for Parametric Estimation of Degree of Synchronization of Electrophysiological Processes

Abstract

A significant amount of information about function al state of the body and health of a person is extracted from electrophysiological signals by processing them with various mathematical methods. Numerous studies have established that important diagnostic information about state of the body for a number of tasks is obtained using methods of correlation analysis. For example, widespread application of correlation analysis is in studying electrical activity of the brain. The main objective of correlation analysis is to establish statistical relationships between the factors and processes studied.It should be noted that while correlation analysis methods are very appealing, informative features allocat ed with their help do not always provide the required quality of solutions of various medical problems, includ ing the problem of forecasting of early and differential diagnosis of the functional state of the human body and health.This disadvantage can be eliminated by allocating additional information on the degree of "similarity" of studied electrophysiological signals using the method of the parametric synchronicity degree of these signals [2]. MethodThe method of parametric estimation of syn chronicity degree is performed by measurement proce dures implemented at fixed intervals of time, determined either by quantization step h q or by special switching points of one or several signals. Minima and maxima of the processes, inflection points, gaps, etc. can be used as the switching points. The quantization step is select ed from the accuracy of signal representation and avail able computational resources. A parameter that charac terizes the directional synchronization is defined as fol lows.If between the i th and (i + 1) th point (Fig. 1) both processes either increase or decrease or remain unmodi fied, the corresponding partial factor in the directional synchronicity S di is accepted equal to "+1", otherwise "-1", i.e. S di(1) Total directional synchronicity of the studied time period is defined by the formula:(2)where n -number of quantization intervals on the stud ied time period.Obviously, the full directional synchronicity (signals on all measurement intervals have the same tendencies in ascending or descending) indicator _ S d = 1, every decrease of _ S d by the value of 1/n can be regarded as a violation of synchronicity in the interval of the quantization step. For _ S d = -1, signals are completely asynchronous, i.e. in all 224 0006 3398/15/4904 0224