神経系の信号伝達の一面的観察—ザリガニの腹部神経節の働作機構

Functional organization in the ganglion of the crayfash

　最近における中枢神経系の機能，とくに電気生理学的方法による研究は著るしく進歩し，その成果もまた数多く報告されている。

　周知の如く，中枢神経系の構造は非常に複雑な様相の上に成立つており，その機能もまた広範囲にわたる情報伝達の入り組んだ輻輳さの中にあつて，高次に統合されて整然たる機能を果している。とくに高等動物のそれはわれわれに多くの問題を提供すると同時に，動作機構の解析に立入ることの出来ない困難さを感じさせることもしばしばである。このような，われわれの知識の限界を救つて，さらに問題を一歩前進させるためには，いくつかの方法論的試みがなされているが，その一つに比較生理学的方法がある。その意図の根底には，中枢神経系の発展過程における単純相と複雑相との分化の様相を理解して，高等な生理的機能の機構分析に一役を演じさせようとするにある。

　The organization of the central nervous system of crayfish, Procambarus clarkii. has been investigated in isolated ganglion preparations using electrical stimulation and aid of histo-logical methods.

　1.The abdominal ganglion was composed of four histological divisions; outermost shea-th of connective tissue, cell bodies of the monopolar neurones just within the sheath, tracts of nerve fibers and neuropiles.

　2.Intracellular micro-electrodes have been used to record activity in synapses of the abdominal ganglion. Ganglionic activity involved typical synaptic transmission, both excita-tory and inhibitory. Then it was modified by spatial and temporal interactions among the synaptic responses.

　3.Transfer characteristics of the ganglionic transmission were analysed from the fre-quency responses of the ganglion. The monosynaptic transmission had the similar transfer function as the first-order rate system. It is supposed that various combinations of the monosynaptic systems determine the complex patterns of the ganglionic responses.

　4.The site of origin of the synaptic response was determined by the electrophoretic inje-ction of a staining substance through a microelectrode into the ganglion. The remarkable synaptic responses were found in the dense dendritic structure of the neuropile.