Correlation dimension analysis of EEG signals induced by electrical acupuncture

In order to analyze the characteristics of EEG signals collected prior, during and post electrical acupuncture with nonlinear methods and to discuss the nonlinear properties of EEG under these conditions, eleven subjects were involved in the study. The subjects were kept quiet with eyes closed during acupuncture. EEG nonlinear indices correlation dimension were calculated for all the subjects. Results showed that correlation dimension D2 decreased gradually during the processes of acupuncture, and it reached the minimum point after the power was on for 20 minutes. The values of D2 in needle-withdrawal also decreased in comparison to the quiet status of pre-acupuncture. With EEG nonlinear analysis, the changes in brain function could be captured at different status of acupuncture. The results are in accord with the principle of Traditional Chinese Medicine. Stimulation of Neiguan and Shenmen could regulate of both the peripheral and the central nervous systems, providing a potential way of solving emotional issues, such as insomnia and muddled thinking. It was found that EEG nonlinear analysis could characterize the changes of brain functions pre-during- and after acupuncture states and might have some value in exploring the mechanism of acupuncture.