The results of this study confirm some previous studies but stand in contrast to others. Some studies on coherence (e.g., Besthorn et al. 1994) have demonstrated that the δ band could not reflect the difference between elderly people and MCI patience, but the other research (Huang et al. 2000) obtained adverse findings. In this study, we found no significant difference in the CMI data of the δ band between elderly and MCI

groups, which supports the results found in the previous study (Kowalski et al. 2001). Additionally, past studies have suggested that the δ band of the frontal lobe could discriminate between MCI patients Inhibitors,research,lifescience,medical and healthy elders (Penttilä et al. 1985; Coben et al. 1990; Schreiter-Gasser et al. 1993); however, the topographic map generated from this study showed that only the electrodes near the parietal and occipital lobes displayed significant differences between the elderly and MCI groups in the δ band. These inconsistent findings might be caused by the AZD2014 mouse different conditions under which the data were collected Inhibitors,research,lifescience,medical and the authors’ definition of the δ band. First, in this study, we analyzed

task-related brain oscillations by using mutual information while a resting awake condition was applied in the previous studies. The greater attention paid to respond to the task may cause the different oscillatory activity in the brain Inhibitors,research,lifescience,medical of the participant (Phillips and Andrés 2010). In the previous study under resting conditions, Stam et al. (2003) showed that loss of β-band synchronization Inhibitors,research,lifescience,medical occurs early in mildly affected AD patients and correlates with cognitive impairment. In our study, the older group with mild AD had significantly decreased functional connectivity of the brain when attempting to respond to the target stimuli, especially in θ band, providing further evidence that as disease progresses there is less efficient processing (Grady 1998). These Inhibitors,research,lifescience,medical disease-related deficits in efficiency correlated with the reduced connections in our study, suggesting severe impairment in the information processing ability. This would explain this group’s longer mean reaction time and a lower correct response. Furthermore,

many studies have suggested the importance DNA ligase of the θ band for discriminating among normal elders, MCI, and AD patients (Kowalski et al. 2001; Osipova 2003; Pijnenburga et al. 2004), and this was supported by the results of this study. Additionally, this study suggested that θ band reflects not only the difference in disease-related changes but also the difference in age-related changes, especially in the parietal and occipital lobe. Some studies have also indicated that the α band was significantly different between normal elderly and AD patients in power (Hogan et al. 2003; Moretti 2004) and in connectivity (Pijnenburga et al. 2004). Unexpectedly, we did not find any statistically significant differences in the α band between the elderly group and the MCI group.