3A). Except in the occipital lobe, all electrodes showed significant differences between the elderly and MCI groups in the θ band (Fig. 3B). Significant differences were also found between the elderly and younger groups as shown in Figure 3B, whereas the pairs of electrodes included the occipital lobe. In the α band, there were significant differences between the elderly and younger groups in all pairs of electrodes (Fig. 3C), but significant differences in the α band between elderly and MCI groups

were only observed in F7–T3, Inhibitors,research,lifescience,medical C3–CP3, CP3–TP7, P3–T5, CP4–F8, CP4–T4, CP4–TP8, and P4–T6 electrode pairs (Fig. 3C). Significant differences in the β band were found between the elderly and younger groups among the frontal pole, frontal, central, frontocentral, Inhibitors,research,lifescience,medical and this website centroparietal electrodes. However, the significant differences in the β band between the elderly and MCI groups were only in the T3–TP7, C3–CP3, and P4–T6 electrode pairs. Finally, in the γ band, significant differences were discovered between elderly and younger groups in the F3–FP1, F3–FP2, F3–FZ, F4–F8, F4–FP2, F4–FC4, F4–FCZ, and FCZ–PZ electrode pairs. The only significant difference Inhibitors,research,lifescience,medical in the γ band between elderly and MCI groups was found in the CP4–P4 electrode pair. Figure 3 The topographic map describing all of the electrode pairs showing significant differences (unpaired Student’s t-test, P < 0.05)

between two compared groups. The left topographic map of each figure indicates

the comparison between Inhibitors,research,lifescience,medical the elderly and … Oscillations in θ band change during attention focusing (Sauseng et al. 2008), while the phase coupling in θ oscillation is known to reflect memory-related processes (Schack et al. 2002). In addition, the long-range coupling between oscillators of θ activities has also been interpreted as indicating integration of cortical information underlying cognitive processing in the brain (Sauseng et al. 2007), and increased attention has been associated with frontal–posterior coherence of θ oscillations (Aftanas and Inhibitors,research,lifescience,medical Golocheikine 2001). The power values were analyzed to explore the changes of brain oscillation between groups responding to the target stimuli in the various bands (Fig. 4), which demonstrated that power was higher in the young group than in the elderly group in the parietal. not Figure 4 The power value in the frequency bands. In conclusion, the analysis of the topographic map indicated that the corticocortical connections which were both affected by age- and disease-related changes were reflected in θ band. Discussion This study showed that frequency bands including δ, θ, α, and β bands reflect the differences between the younger and elderly groups, and it is the θ band that reflects the differences between the elderly and MCI groups. Besides, only θ bands were able to reflect the differences among the younger, elderly, and MCI groups.