Quantitative Analysis Of Electroencephalograph In Depression Based On Phase Synchronization

Conventional quantitative EEG (qEEG) analysis can reveal the EEG differences between depression patients and normal persons, such as enhanced alpha waves (8-13Hz) and beta waves (13-30Hz), weakenedδ-waves (0.5-4Hz), and decrease of inter-hemispheric coherence. However, conventional qEEG analyses appear to be weak in investigating the relationship of multichannel EEGs and the inter-dependences of the large-scale cortex. In this thesis, we perform qEEG analysis to EEGs of depression patients and control subjects by applying Phase synchronization (PS), which is a powerful method in quantifying the interaction between multichannel signals.Research indicated that the EEG of depression patients is abnormal, especially the beta waves, which is more obvious under the task of mental arithmetic. Moreover, the structural differences of depression patients distribute mainly among frontal and parietal cortex. Based on these results, this thesis investigates the EEG difference in frontal and parietal cortexes between depressed and normal subjects in two states, i.e., the states of closed eye and the state of mental arithmetic. Investigation on EEGs measured from 14 depression patients and 14 normal persons suggests that the global PS index of depression in the two states are much lower than that of controls, and the left hemisphere PS index and the inter-hemisphere PS index show significant difference from that of controls, while the right hemisphere PS index shows no significant difference.