Fig. 15.20 Values of MEG alpha band power (0) in response to flickering light for the three occipital sensor regions shown in Fig. 15.17. Error bars represent 95% confidence. Differences of scale value of preference were (a) 1.5. (b) 1.0. (c) 0.5. ◦ : Higher preference; •: lower preference

2.Preferred flicker stimuli evoke significantly longer effective durations τe of MEG alpha waves than flicker stimuli that are less preferred. There were no clear differences, however, in the average amplitudes of MEG alpha-band signals (0).

3.Averaged values of effective duration τe and regularity φ1 of alpha rhythms from the left area were significantly larger than those from central and right areas.

4.The ratio of high to low preference in terms of effective alpha rhythm duration τe is greater than that of the value of alpha rhythm regularity φ1. The effective duration of alpha rhythms is a better predictor of preference than the regularity of the rhythms.

15.2.2 MEG Correlates of Fluctuating Flicker Rates

As discussed in Section 14.1, the most preferred fluctuation of the flickering light was found in the condition of flicker regularity [φ1]p ≈ 0.46. Okamoto et al. (2007) investigated MEG alpha (8–13 Hz), theta (4–8 Hz) and beta (13–30 Hz) rhythms over the entire head in response to differing degrees of flicker fluctuation.