NEUROPHYSIOLOGICAL MECHANISM IN BI-DIGITAL O-RING TEST

Abstract

We carried out a basic study on the neurophysiological response of electroencephalography (EEG) to bi-digital O-ring test. As reported by Omura, physical stimulation of lesions induces the appearance of digital muscle weakening in patients with organ disorders or cerebrovascular circulatory disturbance. Furthermore, the same phenomenon is produced by irradiation of white light of very low intensity except a green light beam.

We experimentally applied the above-mentioned phenomenon to clinical dentistry using EEG, photo-recorder, data-recorder and EEG-frequency analyzer in a shielded room. The subjects consisted of 10 males and 10 females in twenty age group.

We examined the changes in EEG activity before and after application of the stimulation to the right and reft finger thumbs and indexfingers. Two kinds of stimulation were used; tactile stinilation with applied force of less than 1 gm/mm² and stimulation with a white light beam of very low intensity (80 lux).

Data analysis was carried out using an EEG-frequency analyzer (Nihon Koden, MAF-5) for the 5-second intergration values at the δ (1-4 Hz), θ (5-7 Hz), α (8-13 Hz), β_l (14-20 Hz) and β₂ (21-30 Hz) frequency bands.

Statistical significance was determined for the differences in the measered values obtained before and after stimulation.

Variance analysis of the measured values was carried out for the following factors.

Factor A: Difference in EEG activity by the sites of measurement.

Factor B: Difference in EEG activity by the stimulation of the left and right hands.

Factor C: Defference in EEG activity between the left and right brains for the beam stimulation.

Factor D: Difference in EEG activity by the frequency bands of the EEG activity at difference part of the brain.

The following represents the satisfactory results obtained in this researches.

Before stimulation with a white light beam of very low intensity, the EEG activity appeared more strongly at the bilateral occipital regions than other sites of measurement; namely, the mean a band amplitude was 31.12 μV in the right brain and 32.91 μV in the left brain by stimulation of the right hand, and 32.78 μV in the right brain and 35.41 μV in the left brain by stimulation of the left hand. After stimulation, the α band amplitude was also higher in the right and left brains than other sites of measurement; namely, 33.65 μV in the right brain and 38.38 μV in the left brain by stimulation of the right hand, and 33.65 μV in the right brain and 38.38 μV in the left brain by stimulation of the left hand (mean values).

Before tactile stimulation wiht applied force of less than 1 g/mm², the EEG activity appeared more strongly at the bilateral occipital regions than other sites of measurement; namely, the mean band amplitude was 31.02 μ V and 35.26 μV in the right and left brains respectively by stimulation of the right hand, and 27.76 μV and 31.31 μV in the right and left brains respectively by stimulationof the left hand. After stimulation, the same phenomenon occurred, showing the mean α band amplitudes of 36.19 μV and 32.27 μV in the right and left brains respectively by stimulation of the right hand and 34.01 μV and 37.68 μV in the right and left brains respectively by stimulatuon of the left hand.

By ANOVA analysis of the differences in EEG activities before and after light beam stimulation and tactile stimulation, significant differences were demonstrated with a 95% confidence limit (F values 5.39 and 4.45) in EEG activities by white light beam stimulation. However, no demonstrable differences were found by tactile stimulation.

When studying each factor in white light beam stimulation by the Latin square method, singificant differences with a 95% confidence limit were found in EEG activities between the right and left temporal regions, and β₂ was found to have the largest value of amplitude compared to other frequency components. Other factors or levels in light beam stimulation showed no recognizable differences. Similar study of factors in tactile stimuaation also revealed significant differences with a 95% confidence limit in EEG activities between the right and left temporal regions. The θ and α band amplitudes were larger than other frequency components. No recognizable differences were found in other factors or levels in tactile stimulation.