An MEG study of cortical responses related to subjective preference for different regularities of a fluctuating light
Yosuke Okamoto, Seiji Nakagawa, Takashi Yano and Yoichi Ando

Human cortical activities in regard to flickering lights with different regularities of luminance fluctuations were investigated. The regularities of luminance fluctuations were changed by utilizing a sinusoidal wave of 1-Hz frequency and band noises with different bandwidths centered on 1 Hz. A pair of the most- and less-preferred stimuli, which were selected according to the results of subjective preference tests, was presented to the subject via a single, green light-emitting diode (LED). Whole-head MEG signals in the theta, alpha, and beta ranges were analyzed by autocorrelation function (ACF). Significant results were found regarding the alpha activity over the left occipital region: the values of effective duration (t_e) of the MEG signals in the alpha range were significantly larger for the most-preferred stimuli than those for the less-preferred stimuli. Given that the value of t_e represents a repetitive feature contained within the signal, the results indicate that the stable rhythm of the alpha activity over the left occipital region persists longer for morepreferred regularity of a fluctuating light.

Key words: fluctuating light, subjective preference, magnetoencephalography, brain rhythm, autocorrelation function