Spatio-Temporal Behavior of Brain Alpha Rhythms

Kouhei Harada, Shoichi Kai and Kazuyoshi Hirakawa

¹Faculty of Commerce, Kurume University, Kurume 830, Japan
²Department of Electrical Engineering, Kyushu Institute of Technology, Kitakyushu 804, Japan
³Department of Electronics, Faculty of Engineering, Kyushu University, Fukuoka 812, Japan

(Received November 18, 1988; Accepted December 25, 1988)

Keywords: Alpha Wave, Phase Pattern, Dynamic Property, Mapping

Abstract. The instantaneous amplitude and phase of the human brain's alpha waves are evaluated by the complex demodulation method, and the behavior with regard to time and space is examined by topographic and chronotopographic representations. Our results suggest that the alpha wave is never stable but fluctuates dynamically both in space and in time, which seems to be caused by the change of its phase relation on the scalp. Investigation based on the coupled oscillators system must proceed.