EEG activity induced by patterns of color change

Abstract

We have investigated the effect of diffuse color illumination on human brain activity by monitoring EEG. We expected some pattern of diffuse color illumination might have soothing effect on our brain activity level. The light from a number of LED was projected on a white screen which had half-circular shape with the height of 1.8 m. The continuous change of color of emitted light was controlled by a computer. A subject sat in the mid-point of hemi-circle and kept looking at a fixation point. Color was changed continuously along the hue circle (red-yellow-green-cyan-blue-magenta-) for 150 s duration in 2 cycles: rapid (7.5 s/cycle) and slow (15 s/cycle), and in 2 stages of color saturation (hypochromatic and primary colors). EEG was recorded according to the international 10-20 system using EEG-1100 (Nihon Kohden). Eye blinks and movements were digitally cancelled out by Spike2 software (CED). Only theta to gamma regions (4 Hz to 80 Hz) of EEG was analyzed by ATAMAP II (Kissei Comtech). The result from 10 subjects showed that the suppression of alpha and beta, or alpha only or beta only occurred in 7 out of 10 subjects. The luminance of the screen was twice strong with hypochromatic colors and the suppression occurred in the same degree by both color saturation levels, the effect could be resulted from the cyclic color change. Descriptions of subjects when they watched the screen indicated loss of spatial and temporal discrimination, which is different from being in complete darkness. [J Physiol Sci. 2008;58 Suppl:S144]