Approaches of Phase Lag Index to EEG Signals in Alzheimer’s Disease from Complex Network Analysis

The brain is organized as neuronal assemblies with hierarchies of complex network connectivity, and its function is consider to be arisen by synchronized rhythmical firing of neurons. Recently, it is suggested that some of the mental disorders are related to the alterations in the network connectivity in the brain and/or of the strength on synchronized rhythm for brain waves. Here we attempt to analyze electroencephalograms of Alzheimer’s disease by Phase Lag Index (PLI) as an index of the synchronization on signals. By regarding values of PLI as the network connectivity among electrodes, we construct a network for PLI in the brain. So, a clustering coefficient describing structural characteristics of the network are also discussed.