Abstract
Crossed reflex of the limb, observed in decerebrate or spinal animals, has not been recognized in healthy man, although it occurs in patients with central nervous disorders. The author, however, showed it can also be elicited in healthy man under suitable conditions.
To the subject, seated with legs hanging free, one of the following three kinds of stimuli was given, and the ensuing reflexive movement of the limbs as well as the EMG of relevant muscles were recorded.
1. Mechanical tapping of the patellar tendon of one side, which produced reflex extension of ipsilateral and contralateral knee joints, reflex flexion of ipsilateral elbow, and reflex extension of contralateral elbow. In the ipsilateral femoral rectal muscle, there appeared two series of synchronous discharges, the primary and the secondary, with latency of20-30msec. and90-150msec. respectively. In the contralateral mate, a synchronous discharge occurred90-150 msec. after the stimulation. The primary discharge is obviously responsible for the ipsilateral knee extension, while the secondary discharge is regarded to cause reflex extension or flexion of other limbs.
2. Electric stimulation with a single shock applied to the skin covering the knee extensor muscle of one side, which produced a similar result.
3. Passive flexion of a knee joint, which gave rise to reflex extension of the contralateral knee joint. This conforms with Philippson reflex in pattern. Also the tonic and the phasic patterns of this reflex could be demonstrated by executing passive flexion slowly or abruptly.
4. Central reflex time in these crossed reflexes was calculated from the above mentioned experiment to be 60-90msec. Further, the mechanism of occurrence of the silent period of discharge was discussed.
Acknowledgment. The author wishes to thank Prof. K. Hukuda for helpful suggestions and criticism during the course of this investigation. A part of expenses of this research was defrayed from the Research Fund granted by the Ministry of Education.
