G. Chiba

Component Activities in the Autoregressive Activity of Physiological Systems

The higher-order autoregressive (AR) activity of a physiological system (Sato 1975a,b; Sato et al., 1977) was decomposed into first- and second-order activities. The former time-pattern displays a fast rise and an exponential decay, while the latter exhibits a damped sine wave. Application of this component analysis to EEG showed the first-order activity to coincide with the nonoscillatory delta component. The frequency distribution of the natural, damped and resonance frequencies of the second-order activities was found to show one, two or three modes in each frequency range of the delta, theta and beta rhythms in ninety normal adult EEGs. Hence, the second-order activities agree with the oscillatory delta, theta, alpha and beta rhythms. Some changes were induced not only in the frequency of theta and beta rhythms but also in that of alpha rhythm by over-breathing for about three minutes.

On some methods for EEG pattern discrimination.

Two methods of statistical inference for EEG pattern discrimination are described with examples of their application. One concerns whether an arbitrary EEG pattern belongs to a standard EEG group or not, and the other concerns whether a group of EEG belongs to the standard EEG group.

On Some “Higher Order Autoregressive Activities” of Physiological Systems

Physiological significance was given to the autoregressive process in order to elucidate the various complex and manifold activities of higher order hidden in a physiological phenomenon. The activity of higher order was obtained in this process as a dynamical generalization of the judging and transforming activities, which has been defined as an extension of excitability in physiology.Examples of the activity of higher order in the frequency domain and that in terms of the amount of bioinforming activity of physiological systems were demonstrated not only in the case of the EEG potential and the sway in human standing posture, but also in the case of heart beats during a relaxed state and during the step test.