The aim of the present study is, through observing the power spectrum and topography of EEG, to research on the frequency and distribution change of electroencephalogram during the qigong state with the help of a computer.

In a well shielded room, 27 practicers (22 men and 5 women) with an average age of 28 years old and with 5 years in the average in qigong practice were tested with a rheoencephalograph and a signal processor. Polygram and real time analysis were adopted. 12 recorded electrodes were fixed respectively at points Fp1, FP2, F7,F8,T5,T6,01,02, Fz, Pz 10—70 international system). The reference electrodes were fixed on the two earlobes (A1+ A2). Hamming window and linear average method were adopted. The number of averaging is 10 times. The total sampling time was 50 seconds. Samples were taken twice before entering the quiescent state. Samples were also taken 20-30 minutes after the qigong state at least every five minutes for once. Then 3 samples were taken 5-20 minutes after the practice. The power value was compared with the tested results of the average samples taken before, during and after the practice. Moreover, 12 cases, who were not qigong practicers sat quietly with closed eyes, were tested in the same way.

The practicers were divided into two groups according to their psychological characteristics of different ways in entering the qigong state. One group was doing 'Yi Shou Gong' and the other 'Non Yi Shou Gong'. Experimental results showed that the change of the brain wave during the qigong state occurred mainly in theta and alpha ranges and there were some differences of changes between the two groups.

In most of the first group, there appeared theta rhythm. In topography of EEG, theta power around the frontal mid-line increased markedly. In the power spectrum graph, theta peak which showed concentration of energy appeared. The peak reached its maximum point at F2, even higher than the main peak of alpha at the point. The phenomenon could generally continue during the practice and disappeared completely after the practice. It Was found by 't test' on the theta power value at point Fz, that there was a significant difference between them before and during the practice (P<0.01), while no significant difference before and after that (P>O.l) . The theta power at Fz point of 13 cases in the second group, however, had no significant difference between that before and during the practice (P>0.05), even though the theta power increased a little for a few of them. The control group which did not do qigong exercise had no changes in the theta power (P>O.1).

It was reported that the appearance of the theta rhythm on the frontal mid-line related to 'inner experience', such as 'thinking on something in earnest' was the same as that in the first group. The increase of the theta power on the frontal mid-line and good meditation feeling of the qigong practices are synchronous. The increase of the theta power, especially appearing of the theta peak, is suggested to be used as an indication of entering the qigong state for the first group.

The change of power and topography of alpha are complicated. Both increase and decrease of alpha power can be seen. On the topography, it was found that alpha superiority of 6 cases transferred from the occipital area to the frontal area, 4 cases from the left to the right and that 5 cases showed alpha double peaks during the qigong state, because of dissynchronization between alpha, and alpha-2

Observation of the power spectrum and topography of EEG in the qigong state