Analysis of inphase interaction pattern in EEG.
Inphase interactions among EEG signals recorded using eight electrodes were investigated. The inphase interaction parameters are presented in two ways: (1) matrix form in which the number of inphase interactions are tabulated; and (2) histogram in which the number of inphase interactions are plotted pair-wise between two sites as a function of phase delays in milliseconds. The highest number of interactions occurs between 0 and 8 ms in normal brains. The values of interactions parameters are enhanced by various activities. For example, inphase interaction parameters increase in the motor area in the right hemisphere if the EEG is recorded during repeated left fist clenching. Inphase interactions are drastically altered by the presence of a tumor. We studied the inphase interactions of the EEG of a patient having an occipital tumor. The interaction parameters are greatly diminished in this area, indicating a severe impairment of neuronal communications between both hemispheres in the occipital region. The confidence limits of the changes in inphase interaction parameters during fist clenching are tested statistically using the Student's test. The test shows that the interaction parameters increase, in general, with 1-5% confidence limits in respective cortex areas as a result of fist clenching.
D001921:Brain / Q000502:physiology*; D001932:Brain Neoplasms / Q000503:physiopathology; D003201:Computers; D004569:Electroencephalography / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D008433:Mathematics; D009778:Occipital Lobe / Q000503:physiopathology