Ikeda A, Nagamine T, Yarita M, Terada K, Kimura J, Shibasaki H
Department of Brain Pathophysiology, Kyoto University School of Medicine, Japan.
Electroencephalogr Clin Neurophysiol. 1998 Jul;107(1):59-63. doi: 10.1016/s0013-4694(98)00003-0.
Subdural electrodes made of stainless steel, which were believed to be unsuitable for recording slow potentials, can still record Bereitschaftspotential (BP) (Neshige, R., Lüders, H. and Shibasaki, H. Recording of movement-related potentials from scalp and cortex in man. Brain, 1988, 11: 719-736) and ictal DC shifts (Ikeda, A., Terada, K., Mikuni, N., Burgess, R.C., Comair, Y., Taki, W., Hamano, T., Kimura, J., Lüders, H.O. and Shibasaki, H. Subdural recording of ictal DC shifts in neocortical seizures in humans. Epilepsia, 1996b, 37: 662-674) sufficiently. In this study, therefore, the effects of different kinds of metals on slow potential recordings were reevaluated. First, slow electro-oculograms (EOGs) were recorded with 3 different levels of input impedance (200 M omega, 470 k omega and 10 k omega) of a DC amplifier by using surface electrodes made of silver (Ag), silver/silver chloride (Ag/AgCl) and stainless steel. Secondly, BP was recorded by using the above electrodes with a long time constant of 3 s and with a fixed input impedance of 100 M omega. As a result: (1) slow EOGs were equally recorded with the input impedance of 200 M omega and 470 k omega regardless of the kind of metals used, although stainless steel electrodes caused baseline fluctuation, (2) low input impedance of 10 k omega allowed only the Ag/AgCl electrode to record slow EOGs without any decay, and (3) electrodes made of stainless steel could record BP as efficiently as the other two types of electrode with high input impedance. In conclusion, electrodes with a large surface area contact such as cup electrodes and an amplifier with a large input impedance, electrodes made of Ag, and even of stainless steel, can record slow potentials reasonably well.
人们认为由不锈钢制成的硬膜下电极不适用于记录慢电位，但它仍能充分记录 Bereitschaft 电位（BP）（Neshige, R., Lüders, H. 和 Shibasaki, H. 《人类头皮和皮层运动相关电位的记录》。《大脑》，1988 年，11 卷：719 - 736 页）以及发作期直流偏移（Ikeda, A., Terada, K., Mikuni, N., Burgess, R.C., Comair, Y., Taki, W., Hamano, T., Kimura, J., Lüders, H.O. 和 Shibasaki, H. 《人类新皮层癫痫发作期直流偏移的硬膜下记录》。《癫痫》，1996b 年，37 卷：662 - 674 页）。因此，在本研究中，重新评估了不同种类金属对慢电位记录的影响。首先，使用由银（Ag）、银/氯化银（Ag/AgCl）和不锈钢制成的表面电极，通过具有 3 种不同输入阻抗水平（200 MΩ、470 kΩ 和 10 kΩ）的直流放大器记录慢眼电图（EOG）。其次，使用上述电极，在 3 s 的长时间常数和 100 MΩ 的固定输入阻抗下记录 BP。结果：（1）无论使用何种金属，在 200 MΩ 和 470 kΩ 的输入阻抗下均能同等记录慢 EOG，尽管不锈钢电极会导致基线波动；（2）10 kΩ 的低输入阻抗仅允许 Ag/AgCl 电极记录慢 EOG 且无任何衰减；（3）不锈钢制成的电极与其他两种具有高输入阻抗的电极一样能够有效地记录 BP。总之，具有大表面积接触的电极（如杯状电极）以及具有大输入阻抗的放大器，由 Ag 甚至不锈钢制成的电极，都能较好地记录慢电位。
