Preliminary Observations On The Changes Of Slow Potentials Of Cerebral Cortex Induced By Acupuncture And Pain

Wang Boyang, Yang Boyi, Jiang Deming (Department of Biology, Fudan University)

In the field of research on the mechanism of acupuncture analgesia, a lot of works have been done by means of electrophysiological methods concerned in the speedy events of the nervous system. Nevertheless, in accordance with the fact that there is the necessity of inducing period and its after effect of acupuncture, it is reasonably to consider that there would be slow electrical events existed also in the central nervous system during acupuncture. This report is the preliminary observations about this field.

The quasi-steady potential and the infra-slow potential oscillation have been recorded from the curarized rabbits' cerebral cortex by means of non-polarized electrodes (silver/silver chloride or calomel). Two recording electrodes are placed ipsilaterally or contralaterally on the dura of the cerebral hemispheral 1 cm away from one another, the reference electrode is placed on the spongy bone before the orbit.

The potentials led from the two recording electrodes are amplified simultaneously by a preamplifier and oscilloscope system with a time constant of about 6 sec. and recorded by a camera with film speed of 5 mm/min. The point "Zusanli" is needled by hand manipulation, or an electric stimulator (BT-701) sending out pulsating current to the points "Zusanli" and "Shangjuxu" is used as a substitute for hand manipulation of the needles. To pinch the nasal septum or smear alcohol on the wound is used as pain stimulation.

The results obtained are as follows:

1. The quasi-steady potential shifted in positive direction as the animal to be acupuncture, and shifted in negative direction during "pain" stimulation. The time course of changes is slow and the potential doesn't maintain in a higher level as with prolonged stimulation, but returns to the initial level slowly. The amplitude of the shifts is about 200-400µV rarely more than 1 mV.

2. In the case of the appearance of infra-slow potential oscillation, the decrement of amplitude of oscillation could be induced by "pain" stimulation or acupuncture.

3. No phenomena as well as spreading depression could be detected either during acupuncture or "pain" stimulation.

4. Evidence has been made to show that the slow potential observed is not attributable to the changes of blod pressure, but directly to the acupuncture.