Evoked potentials

Japanese: 誘発電位

Evoked potentials are transient potential fluctuations that appear in the sensory areas of the cerebral cortex in response to sensory stimuli. In animals, evoked potentials can be recorded from the surface of the cerebral cortex by stimulating light or sound or by stimulating the peripheral nerves, resulting in a sufficiently large evoked potential. However, in humans, recording is performed by placing recording electrodes on the scalp, so the evoked potentials obtained have a very small amplitude (usually 0.3 to 20 μV) and are difficult to detect because they overlap with spontaneous electroencephalograms, which have a larger amplitude. Therefore, if the same stimulus is applied dozens or more times using a computer and the average is taken, the electroencephalograms that appear unrelated to the stimulus can be eliminated as noise, and the amplitude of the evoked potential increases in proportion to the number of times it is added.

Source: Heibonsha World Encyclopedia, 2nd Edition Information

Japanese:

感覚刺激に応じて大脳皮質の感覚領域に現れる一過性の電位変動をいう。動物では光や音の刺激あるいは末梢神経を刺激して，大脳皮質の表面から記録することができるため，十分大きな誘発電位が得られる。しかしヒトの場合は記録電極を頭皮上に置いて記録するため，得られる誘発電位は振幅が非常に小さく(通常0.3～20μV)，それより大きな振幅をもつ自発性の脳波と重なって検出しにくい。そこで，コンピューターを用いて数十回からそれ以上の同じ刺激を加えて加算平均をすると，刺激と無関係に現れる脳波は雑音として消すことができるとともに，誘発電位の振幅は加算回数に比例して増大する。

出典　株式会社平凡社世界大百科事典第２版について　情報

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