[Segmental inhibitory reactions in the spinal cord of the frog in response to orthodromic motor neuron activation].
Ventral root reflexes evoked by a single dorsal root volley were recorded in the isolated frog spinal cord. They varied from asynchronous, low-amplitude response to highly synchronized monosynaptic discharge in different preparations. The response to a testing stimulus could be facilitated or inhibited, respectively. The inhibition was weaker at interstimulus intervals of about 40-50 ms and stronger either at longer (60-100 ms) or at shorter (15-30 ms) intervals, thus testifying to the existence of at least two types of inhibition: early and late. Strychnine effectively blocked the late inhibition and facilitated the early one; d-tubocurarine considerably weakened both types of inhibition. A conclusion is made that the late (presynaptic) inhibition is produced by activation of the inhibitory systems through recurrent motoneuron axon collaterals. Recurrent activation may also take part in the origin of the early (postsynaptic) inhibition.
D000818:Animals; D000870:Anterior Horn Cells / Q000502:physiology; D002118:Calcium / Q000502:physiology; D004558:Electric Stimulation; D009433:Neural Inhibition / Q000187:drug effects; D011896:Rana temporaria; D012023:Reflex, Monosynaptic; D013116:Spinal Cord / Q000502:physiology*; D013126:Spinal Nerve Roots / Q000502:physiology; D013331:Strychnine / Q000494:pharmacology; D013696:Temperature; D014403:Tubocurarine / Q000494:pharmacology
D013331:Strychnine; D002118:Calcium; D014403:Tubocurarine
Segmentarnye tormoznye reaktsii v spinnom mozge liagushki pri ortodromnoĭ aktivatsii motoneĭronov.