著者

増田 正 遠藤 博史 武田 常広

出版者

バイオメカニズム学会

雑誌

バイオメカニズム (ISSN:13487116)

巻号頁・発行日

vol.15, pp.63-73, 2000-06-15 (Released:2016-12-05)

参考文献数

17

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In recent years SQUID (Superconducting Quantum Interference Device) technology has developed rapidly in both sensitivity and number of recording channels. Biomagnetic measurements based on SQUID technology are considered to have great potential in the analysis of brain and heart functions. They are also applicable to skeletal muscles and may provide a new method for diagnosing neuromuscular functions. To clarify the capability for biomagnetic measurements, the magnetic recording technique was applied to the vastus lateralis and the vastus medialis of three healthy male adults. Magnetic fields were measured with a 64-channel SQUID system. Discharges of single motor units were simultaneously detected by surface electromyography under a weak voluntary contraction. The magnetic signals were averaged for 64 to 158 times at the zero-crossings in the surface electromyogram. Six motor units were detected in the three subjects. The isofield maps of magnetic fields showed current sources arising from the motor endplate regions and spreading in opposite directions to the tendons. A current octupole moving along muscle fibers explains these magnetic fields. Because the magnitude of the magnetic fields is directly proportional to the intensity of the currents in the muscle fibers and is independent of the conductivity of the surrounding medium under certain conditions, it is possible to calculate the intensity of the currents in the muscle fibers. To improve the accuracy of such calculations, a model of the muscle fiber action currents was developed, taking into consideration the intensity and duration of the current source. A magnetic field was calculated from an octupole current model. The measured magnetomyographic signal waveform was deconvoluted with the calculated magnetic field signal produced by a single muscle fiber. The area of the deconvoluted waveform represents the number of active muscle fibers, which was estimated at 708 to 1,791 (average 1,088±480) for the six motor units detected. These numbers were 6.5 times larger than those estimated from the intensity of the current source alone without considering its duration, and were close to the invasively obtained values. The number of muscle fibers contained in a muscle or a motor unit has until now been estimated only by an anatomical method. Noninvasive magnetic measurement should therefore contribute to the diagnosis of neuromuscular diseases that cause the decrement or shrinkage of muscle fibers.

著者

橋本 佳三 武田 常広 比留間 伸行 伊藤 由美子 梶田 雅義

雑誌

視覚の科学 = Japanese journal of visual science (ISSN:09168273)

巻号頁・発行日

vol.18, no.2, pp.49-54, 1997-08-01

参考文献数

12

被引用文献数

5

著者

武田 常広

出版者

公益社団法人 計測自動制御学会

雑誌

計測と制御 (ISSN:04534662)

巻号頁・発行日

vol.31, no.9, pp.980-985, 1992-09-10 (Released:2009-11-26)

参考文献数

19

著者

比留間 伸行 橋本 佳三 武田 常広

出版者

一般社団法人映像情報メディア学会

雑誌

テレビジョン学会誌 (ISSN:03866831)

巻号頁・発行日

vol.48, no.10, pp.1293-1300, 1994-10-20

被引用文献数

13

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両眼融合式立体テレビの試作番組を観視している被験者の調節応答を, 眼球運動を追尾して測定可能なTDO III(Three-Dimensional Optometer III)で測定を行った.試作番組は, 2系統のハイビジョンカメラとVTRで制作してNTSCにダウンコンバートし, 液晶シャッタを用いた時分割立体ディスプレイで提示した.番組観視中は, 通常の平面のディスプレイの場合に比べ, 被験者の眼球の焦点位置が近方に調節される傾向があること, また, シーンのカット切り換えの直後に被写体が画面いっぱいに現われ, 距離感が急激に変化するような演出の立体画像や, 主な被写体がスクリーン面より手前にある画像では, この効果が強く現れることが計測された.これらの知見は, 立体画像の視覚への影響の解明や立体テレビ番組の制作に役立つであろう.