Abstract
Dependence of spatiotemporal response of the alpha wave on light intensity of white LED flicker stimuli is examined using a complex demodulation method and the Fourier transform. In spite of inter-individual differences in the spontaneous alpha waves, most of the alpha waves show similar response dependency on the light intensity: the alpha wave is not only attenuated but also destabilized to the weak stimuli with intensity less than 10lx, whereas it becomes not only enhanced but stabilized with increasing the stimulus intensity. The attenuated response to the weak stimuli is a novel observation on the dynamics of the alpha wave, while the enhancement of the alpha wave with increasing the stimulus intensity seems to be a reasonable result from the viewpoint of a nonlinear oscillators system. These results may indicate that the interaction or coupling strength between endogenous alpha-generators can be affected by the strength of the external photic stimulation. Furthermore, the observations obtained are useful for modeling the alpha wave by a coupled nonlinear oscillators system.
