Segmental synaptic responses in the canine spinal cord for stimulation of the nerves of trunk muscles

躯干肌α运动神经元的反应在去脑脊髓型猫的背肌（多裂肌、最长肌、髂肋肌、腹外肌和腹直肌）上，通过电刺激这些干神经或皮神经，观察背肌运动神经元的变化。（多裂肌，最长肌和髂肋肌）和腹肌（腹外肌和腹直肌）通过刺激背部或腹部肌肉的神经和皮神经而双侧兴奋。主要兴奋为等于或大于3个突触的多突触反应。在左右背部肌肉或腹部肌肉之间没有交叉的Ia IPSP反应。刺激腹肌神经后，仅少数背肌运动神经元存在IPSP双突触反应，刺激背肌神经后，仅少数腹肌运动神经元存在IPSP双突触反应。结果表明，同侧背腹肌、左右背腹肌、斜背腹肌不是相互作用的肌肉，而是协调性肌肉。由于刺激最长肌神经后在多裂肌运动神经元中发现单突触EPSP，刺激髂肋肌神经后在最长肌运动神经元中发现单突触EPSP，因此夜间肌肉之间存在较强的联系。α-氯阿洛糖麻醉下猫的节段性突触反应很复杂，与脊髓猫不同。虽然多突触EPSP反应在大多数被检查的运动神经元中占主导地位，但多突触IPSP反应在氯醛糖麻醉猫中比在脊髓猫中存在得更多。刺激同侧多裂肌神经后，在最长肌运动神经元中发现了显性多突触IPSP反应。这些结果表明，下行输入可能对躯干运动神经元产生抑制作用。

Responses of alpha-motoneurons of trunk muscles (multifidus, longissimus, iliocostalis, obliquus externus abdominis and rectus abdominis) were investigayted intracellularly by stimulation of these trunk nerves or cutaneous nerves in decerebrate spinal cats.Motoneurons of the back muscles (multifidus, longissimus and iliocostalis) and abdominal muscles (obliquus externus abdominis and rectus abdominis) were excited bilaterally by stimulation of the nerves of the back or abdominal muscles and the cutaneous nerves. The dominant excitations were polysynaptic responses equal to or over 3 synapses. There were no crossed Ia IPSP responses between the left and right back muscles or abdominal muscles. Only a few bisynaptic IPSP responses existed in motoneurons of the back muscles after stimulation of the abdominal muscle nerves, and in those of the abdominal muscles after stimulation of the back muscles. These results indicated that ipsilateral back and abdominal muscles, left and right back or abdominal muscles and diagonal back and abdominal muscles act not as reciprocal muscles but as coordinate muscles. Tere were strong connections between nieghboring muscle because monosynaptic EPSPs were found in motoneurons of the multifidus after stimulationof the longissimus muscle nerve and in those of the longissimus after stimulation of the iliocostalis muscle nerve.Segmental synaptic responses in cats under alphs-chloralose anesthesia was complex and fifferent from those in spinal cats. Although polysynaptic EPSP responses were dominant in most of examined motoneurons in chloralose anesthtized cats, polysynaptic IPSP responses existed much more in chloralose anesthetized cats than in spinal cats. Dominant polysynaptic IPSP responses were found in the longissimus motoneurons after stimulation of the ipsilateral multifidus nerve. These results indicate that descending inputs from the brain may give inhibitory effects on the trunk motoneurons.