ネコの錐体刺激の脊髄運動性諸反射およびGSR，血圧におよぼす効果の分析

ANALYSIS OF EFFECTS OF PYRAMID STIMULATION UPON SPINAL MOTOR REFLEXES, GALVANIC SKIN RESPONSE AND BLOOD PRESSURE

I．はじめに

　錐体路に関する臨床的，基礎的研究は，古来多数発表されているが，まだ不明確な点が少なくないようである。たとえば，臨床的には本来弛緩性麻痺をきたすはずの錐体路傷害が，どうして腱反射の亢進を伴う緊張性麻痺を起こすかの問題があり，また最近の神経生理学的実験においても，その成績は必ずしも一致していないようである。たとえば錐体路刺激の伸屈筋性前柱細胞におよぼす効果についてPrestonとWhitlock （1960, 1961）とLundbergとVoorhoeve （1961）の報告に違いがみられる。

　さて錐体路の刺激法としては，延髄錐体部の刺激によつて，最も純粋な刺激効果が得られるといわれるが，このような錐体刺激実験の場合には，錐体路を下降するいわば直接効果のほかに電流滑走とか，錐体路線維の側枝を介する脳幹組織の間接刺激効果とか，末梢においてはいわゆるγ—loopを介する間接効果が加わり得るので，実験条件をよほど吟味してかからないといけないわけである。

In order to investigate the function of the pyramidal tract, effects of pyramid stimula-tion upon flexor and extensor monosynaptic and polysynaptic reflexes and upon firing indexes of flexor and extensor motoneurones were analysed, either the peroneal or tibial nerve being stimulated.

Effects of pyramid stimulation upon galva-nic skin response and blood pressure were also observed.

For the pyramid stimulation, single pulse as well as repetitive stimulations were em-ployed.

It is characterized in the present experi-ment that procedures were taken to eliminate all the possible indirect effects of pyramid stimulation upon above noted phenomena due to current spread, through collaterals of the pyramidal fibres to the brain stem structures and through the gamma loop in the peri-phery.

As to the results, facilitatory effects of pyramid stimulation upon flexor motoneuro-nes were observed, whereas distinct in hibi-tory effects were recognized upon extensor motoneurones, although an initial facilitatory effect was obtained in some of extensor mo-toneurones following single pulse stimulation to the pyramid.

On the basis of these results, it was sug-gested that the pyramidal tract as a whole has a stronger facillitatory effect upon flexor motoneurones and that facilitatory fibres to the flexor motoneurones may exert reciprocal inhibitory effect upon extensor motoneuro-nes.

Neither galvanic skin response nor change in blood pressure was elicited by pyramid stimulation under the present experimimental conditions.