Spinal motoneurons exhibit sustained afterdischarges and plateau potentials following a brief high-frequency stimulation of Ia afferents. Also, there is evidence that spinal cord interneurons exhibit plateau potentials. However, to our knowledge, there are no reports about the possible afterdischarge behavior of lumbar spinal interneurons activated by Ia afferents. Given that there are spinal interneurons receiving monosynaptic inputs from Ia afferents, these cells could then be activated in parallel to motoneurons after repetitive muscle stretch. We explored this possibility in cats with a precollicular-postmammillary decerebration. We found that a brief high-frequency stimulation of Ia afferents produces afterdischarges that are highly correlated to a DC slow potential recorded at the cord dorsum. We conclude that in the cat spinal cord, not only the motoneurons but also the interneurons from the superficial and deep dorsal horn produce sustained afterdischarges, thus highlighting the importance of interneurons in the spinal neuronal circuitry. The significance of our finding is that it opens the possibility that the spinal cord interneurons activated by Ia afferents could also exhibit bistability, a relevant phenomenon well-characterized in the motoneurons.

中文翻译：

---

短暂高频刺激猫中的Ia传入神经后神经元的放电。

在短暂高频刺激Ia传入神经后，脊髓运动神经元表现出持续的后放电和高原电位。同样，有证据表明脊髓中神经元表现出平台电位。然而，据我们所知，尚无关于Ia传入激活的腰椎间神经元可能的放电后行为的报道。假设有脊神经中枢从Ia传入接受单突触输入，则这些细胞可在重复肌肉拉伸后与运动神经元平行地被激活。我们探讨了在患有乳头前-后哺乳动物的猫中这种可能性。我们发现，短暂高频刺激Ia传入会产生后放电，该放电与脐带背侧记录的DC慢电位高度相关。我们得出结论，在猫脊髓中，不仅运动神经元，而且浅表和深背角的中神经元都产生持续的后放电，因此突出了中神经元在脊髓神经元回路中的重要性。我们发现的意义在于，它打开了由Ia传入激活的脊髓中间神经元也可能表现出双稳态的可能性，而双稳态是运动神经元中特有的一种相关现象。