感覺とその神經機構

Sensation and its Neural Mechanism.

まえがき

　人間の感覺は云う迄もなく意識現象であるからその内容は心理學の對照となる可きもので，生理學はその根底に横はる機構を明かにするのが當面の任務であろう。勿論感覺は人間獨自のもので，動物に於ける感覺存否の證明は今日不可能であるが両者の基礎機構が全く無關係であるとは考えられない。

　感覺生理學の一面は古くから行われている如く刺激とそれによる感覺との關係の追求であろうが生體内に見られる現象の追求はより一層その意義を明かにする。この意味で動物に於ける求心性神經の生理學は，感覺機構の解明に重要な役割を演ずる。感覺生理學にかゝる面を導入したのは英のAdrianで，氏の最初の著書The Basis of Sen-sation （1928）にはその立場が明記されている。筆者も生理學に志して以來その主張に共鳴し，この線に沿つて研究を進めてきたがこゝにかゝる研究の進展の概觀と併せて筆者の實驗結果を記して見よう。

Recent advance of the electrophysiology of afferent nerve fibres has remarkedly contribu-ted to the clarification of the mechanism of human sensation.

The author has also attempted to solve this problem from the phylogenetical point of view. In order to make the human anditory mechan-ism more clear, he explored the lateral-line organ of the fiish because the latter was thou-ght as the origin of human cochlea. By lead-ing off the action potential the activity of each lateral-line nerve fiber was investigated.

From the experimental results by various kinds of stimuli to this organ, namely pressure, water flow, mechanical vibration and electrical stimuli, the author has concluded that thinner fibers, which have the lower threshold to weak stimuli, may be probably related to the thres-hold and thicker fibers, which respond to ra-ther quick changes of stimuli, to the discrimi-nation of sensation.

Histological studies on this organ was also made. Each thick fiber innervated several sensory cells of more central part of the end-organ and each thin fiber branched repeatedly and were connected with many peripheral cells.

The similar mode of innervation has been described in other sense organs: i. e., vestibu-lar, auditory and visual apparatuses,

The author is of the opinion that this may be the common and fundamental neural me-chanism of sensory organs.