EEG changes induced by light stimuli modulated with the subject's alpha rhythm

Abstract

A new method, named the ‘alpha wave modulated light’ (AML) stimulation, has been used for controlling the frequency of sine wave modulated light by the subject's on-going alpha rhythm. The EEG was recorded from 01 and 02. With the AML stimulation using either the left occipital alpha rhythm or the right, two phase differences of 0° and 180° were created between AML and the alpha rhythm. The peak frequency and power of occipital alpha in both hemispheres and the coherence and phase between the left and right occipital EEG were obtained for 7 subjects. The alpha power was larger at a 180° phase shift than at a 0° phase shift with ipsilateral AML stimulation. The ipsilateral increase in the alpha power was greater than the contralateral at a 180° phase shift. Larger coherence value and right phase lead were observed at a 180° phase shift by use of the right alpha rhythm. The possible mechanisms of influences of AML stimulation on the alpha activity were discussed.