EEG導出用無侵襲キャップ型ゲル塩橋電極の開発とそのパワースペクトル分析

A Newly Designed Salt Bridge Cap-Type, a Variable, and Non-invasive EEG Lead Electrode and the Analytical Power Spectrum

　2％アガロースゲルと5％NaCl水溶液の基本塩橋を任意の数だけ電極にした脳電位図EEG導出用可変式キャップ電極を考案して，作成した。12本電極と耳朶2電極，アース電極の総重量は約100gの軽量であり，その機構は簡便迅速，one-touch形式である。この塩橋電極を用いてEEGを計測した。健常人を椅子座位，安静，閉眼にしたEEGは，ゲル塩橋のNaCl水溶液濃度差により，パワースペクトルのパワーに違いがみられた。パワーのパターンは，20％NaCl塩橋がJ字型に，5％NaCl塩橋がU字型に，0.9％NaCl塩橋がL字型に変化した。人体液と等張性の0.9％NaClより高濃度は高張性水溶液に分類されるが，20％NaCl塩橋を頭皮上に接すると痛みを感じる人がいたので，20％NaCl塩橋は「浸透性痛覚用電極」として他の電極実験に供した。5％NaCl塩橋を用いた時，波形加算を10回に設定した計測結果は，確率計算の期待値に近似した値であった。

A newly devised, variable EEG cap-style elect-rode that has an electrical salt bridge with 2% agarose gel and 5% NaC1 solution was developed. The number of electrodes can be increased as required. The weight of 15 electrodes is about 100g. The electrode is simple, fast and in a one-touch form for measuring the EEG. An EEG using this electrode system was recorded in a healthy man in a sitting position on a chair, at rest, and with eyes closed. The power spectrum showed different pat-terns for the power at different concentrations of aqueous solution in the matrix of the salt bridge. The power changed to a pattern of J-type with 20% NaC1 solution, to a pattern of U-type with 5% NaC1 solution, and to a pattern of L-type with 0.9% NaC1 solution, respectively. The matrix of the salt bridge that has a concentration higher than 0.9% NaC1, is a hypertonic solution for the isotonic body liquid. One person felt pain in half of the part of the experiment when a 20% NaC1 hypertonic solution was applied to the scalp, so a 20% NaC1 solution of the salt bridge was used in experiments concerning osmosis. When a salt bridge of 5% NaC1 solution was used, the same results of the wave measurement was obtained 10 times. It was a value close to the expected measurement so it has a high probability of being correct. At this time the power spectrum shows a U-type pattern consistently.