Abstract
The types of reciprocal innervation and the pathway of central inhibition of the spinal frog during reflex action was studied by constructing a special electrode enabling an easy recording of the EMG of frog muscle.
1) In flexion reflex of frogs, complete control by reciprocal innervation of the antagonistic muscle is carried out and moreover the double reciprocal innevvation of the right and left is also complete.
2) Reciprocal innervation is not present in flexion reflex with transsectioned preparations of the spinal cord below the fourth intervertebral space. For the inhibition to give rise to reciprocal character to the movement of the lower limbs, the height must be placed at least at the fourth intervertebral space or above.
3) In strychnine treated preparations, reciprocal innervation was completely lost and in all muscles of the whole body, synchronized impulse groups were observed. Therefore it can be thought that strychnine paralyses the inhibition and removes the reciprocal character. The fact that the whole spinal cord is synchronized suggests that there is some sort of an inhibition center present.
4) It is believed that nerve cell of the neuron of the inhibitory pathway is situated chiefly at the height of the third intervertebral segment.
