In regard to delta band, alpha group had more suppression in anterior areas. Likewise, in regard to high-frequency band, alpha group showed more enhancements in anterior areas compared to beta group. However, in regard to low-frequency beta band, beta group showed significant enhancement in posterior areas. Figures 2 and 3 depict cortical activity in anterior and central regions. In these two figures, powers of delta, theta, alpha1, alpha2, and beta1 bands are given in separate lines. The values before and after the training by the two protocols (alpha training and beta training) are also given in separate lines.