Interhemispheric dysfunction in Alzheimer's disease revealed by mutual information of multi-channel EEG

A new idea of information transmission was presented and applied to EEGs recorded from each group of Alzheimer's disease (AD) patients and normal controls. To monitor the general interdependence of EEG channels, time-delayed mutual information was computed using the Fraser-Swinney algorithm (Phy. Rev. A 1986). To manage the stochastic nature of mutual information and global connectivity of the brain, the modified Karhunen-Loeve decomposition method, which was conducted as an quantification method of the resulting stochastic mutual information, was used. Compared with normal aged controls, AD patients showed significantly different local and global pattern behaviors of information transmission in EEG demonstrating the inter-hemispheric disconnection syndrome. A noticeable inter-hemispheric asymmetry of information transmission was observed in AD patients. They also show a peculiar pattern of information flows from the successive monitoring. This study ran be a tool to monitor a direct information transport between the hemispheres.