Commissural interneurons in rhythm generation and intersegmental coupling in the lamprey spinal cord
Commissural interneurons in rhythm generation and intersegmental coupling in the lamprey spinal cord
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DOI：
10.1152/jn.1999.81.5.2037
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发表时间：
1999-05-01
影响因子：
2.5
通讯作者：
Buchanan, JT
中科院分区：
文献类型：
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作者：
Buchanan, JT
为了测试脊髓连合中间神经元在七鳃鳗游泳节律产生中的必要性，对分离的脊髓标本进行了纵向中线切割。然后通过用兴奋性氨基酸进行浴灌注来诱导虚拟游泳，同时记录腹根活动。当脊髓标本沿中线完全切成两个侧半索时，虚构游泳的节律性活动就会消失，通常被连续的腹侧根尖刺所取代。虚构游泳节奏的丧失并不是由于切割产生的非特异性损伤，因为当分裂区域仍然附着在完整的脊髓上时，脊髓的分裂区域中存在节律活动。这种持续节律活动的质量，用自相关方法量化，随着分裂脊髓节段与剩余完整脊髓的距离的增加而下降。节律恶化的特点是爆发持续时间延长和爆发间静默期缩短。这种恶化模式表明节律性抑制输入的丧失。与尾端切割的标本相比，在脊髓头端切割的标本中观察到相同的节律恶化模式。这项研究的结果表明，连合中间神经元对于七鳃鳗脊髓中游泳节律的产生是必需的，并且游泳节律的无声间歇期的特征性丧失与抑制性连合中间神经元的丧失是一致的。结果还表明，下降和上升连合中间神经元对于游泳节律的产生都很重要。因此，在分裂的脊髓中持续存在的游泳节律，同时仍然附着在脊髓的完整部分上，是由从完整的脊髓区域突出到分裂区域的中间神经元施加的。这些投射在功能上很短，因为在脊髓完整区域的大约五个脊髓节段内失去了节律活动。
To test the necessity of spinal commissural interneurons in the generation of the swim rhythm in lamprey, longitudinal midline cuts of the isolated spinal cord preparation were made. Fictive swimming was then induced by bath perfusion with an excitatory amino acid while recording ventral root activity. When the spinal cord preparation was cut completely along the midline into two lateral hemicords, the rhythmic activity of fictive swimming was lost, usually replaced with continuous ventral root spiking. The loss of the fictive swim rhythm was not due to nonspecific damage produced by the cut because rhythmic activity was present in split regions of spinal cord when the split region was still attached to intact cord. The quality of this persistent rhythmic activity, quantified with an autocorrelation method, declined with the distance of the split spinal segment from the remaining intact spinal cord. The deterioration of the rhythm was characterized by a lengthening of burst durations and a shortening of the interburst silent phases. This pattern of deterioration suggests a loss of rhythmic inhibitory inputs. The same pattern of rhythm deterioration was seen in preparations with the rostral end of the spinal cord cut compared with those with the caudal end cut. The results of this study indicate that commissural interneurons are necessary for the generation of the swimming rhythm in the lamprey spinal cord, and the characteristic loss of the silent interburst phases of the swimming rhythm is consistent with a loss of inhibitory commissural interneurons. The results also suggest that both descending and ascending commissural interneurons are important in the generation of the swimming rhythm. The swim rhythm that persists in the split cord while still attached to an intact portion of spinal cord is thus imposed by interneurons projecting from the intact region of cord into the split region. These projections are functionally short because rhythmic activity was lost within approximately five spinal segments from the intact region of spinal cord.