A central pattern generator underlies crawling in the medicinal leech
A central pattern generator underlies crawling in the medicinal leech
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DOI：
10.1007/s003590000117
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发表时间：
2000-07-01
影响因子：
2.1
通讯作者：
Kristan, WB
中科院分区：
文献类型：
--
作者：
Eisenhart, FJ;Cacciatore, TW;Kristan, WB
此前人们认为药用水蛭的爬行需要感官反馈，因为完整的行为受到感官反馈的强烈调节，而且半完整的制剂只有在可以自由移动的情况下才会爬行。在这里，我们表明，孤立的水蛭神经索可以产生类似于半完整制剂中所见的爬行运动模式，该模式由每个节段中交替的兴奋性圆形和纵向运动神经元爆发的前后波组成。分离的脊髓还再现了其他几种细胞的半完整制剂中所见的活动模式：背侧抑制细胞 1、腹侧兴奋细胞 4 和环竖立运动神经元。由于这种对应关系如此强烈，因此隔离线中必须有一个中央模式发生器，可以在没有感觉反馈的情况下产生爬行的基本运动模式。然而，对孤立运动模式的定量分析。揭示了孤立和半完整的制剂比完整的行为具有更长的周期，并且孤立模式中运动神经元爆发的时间存在缺陷。这些结果表明，感觉反馈调节孤立的中枢模式发生器，以帮助产生正常的运动模式。
Crawling in the medicinal leech has previously been thought to require sensory feedback because the intact behavior is strongly modulated by sensory feedback and because semi-intact preparations will only crawl if they can move freely. Here we show that an isolated leech nerve cord can produce a crawling motor pattern similar to the one seen in semi-intact preparations, which consists of an anterior-to-posterior wave of alternating excitatory circular and longitudinal motor neuron bursts in each segment. The isolated cord also reproduces the patterns of activity seen in semi-intact preparations for several other kinds of cells: the dorsal inhibitor cell 1, the ventral exciter cell 4, and the annulus erector motor neuron. Because this correspondence is so strong, there must be a central pattern generator in the isolated cord that can produce the basic motor pattern for crawling without sensory feedback. A quantitative analysis of the isolated motor pattern, however. reveals that isolated and semi-intact preparations have longer periods than the intact behavior and that there are deficiencies in the timing of motor neuron bursts in the isolated pattern. These results suggest that sensory feedback modulates the isolated central pattern generator to help produce the normal motor pattern.