A central pattern generator producing alternative outputs: Pattern, strength, and dynamics of premotor synaptic input to leech heart motor neurons
A central pattern generator producing alternative outputs: Pattern, strength, and dynamics of premotor synaptic input to leech heart motor neurons
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DOI：
10.1152/jn.00877.2007
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发表时间：
2007-11-01
影响因子：
2.5
通讯作者：
Calabrese, Ronald L.
中科院分区：
文献类型：
--
作者：
Norris, Brian J.;Weaver, Adam L.;Calabrese, Ronald L.
药用水蛭心跳中枢模式发生器（CPG）由7对已识别的心脏节段性中间神经元和1对未识别的中间神经元组成。四对已识别的中间神经元和未识别的中间神经元与节段性心脏运动神经元形成抑制性突触连接。CPG在同侧运动前中间神经元之间产生一种左右不对称的节间协调模式，与心脏运动神经元中类似的不对称的有效运动模式相对应，以及两个管状心脏的不对称收缩模式，同步和蠕动。利用69个分离神经索的运动前中间神经元的细胞外记录和同侧节段运动神经元的电压钳记录，我们评估了运动前抑制性突触输出到整个心脏运动神经元的强度和动力学，以及两种协调模式下相关的传导延迟。我们的结论是，运动前中间神经元建立了一种节间突触连接、强度和动力学的刻板模式，尽管在不同的准备过程中存在很大差异，但这种模式在不同的协调模式中是不变的。这些数据与之前对运动前中间神经元活动的时间模式和两种协调模式下运动神经元活动的相对相位的描述相结合，可以直接评估运动前中间神经元如何通过其时间模式的活动和突触连接的空间模式、强度和动态协调节段运动神经元进入功能模式的活动。
The central pattern generator (CPG) for heartbeat in medicinal leeches consists of seven identified pairs of segmental heart interneurons and one unidentified pair. Four of the identified pairs and the unidentified pair of interneurons make inhibitory synaptic connections with segmental heart motor neurons. The CPG produces a side-to-side asymmetric pattern of intersegmental coordination among ipsilateral premotor interneurons corresponding to a similarly asymmetric fictive motor pattern in heart motor neurons, and asymmetric constriction pattern of the two tubular hearts, synchronous and peristaltic. Using extracellular recordings from premotor interneurons and voltage-clamp recordings of ipsilateral segmental motor neurons in 69 isolated nerve cords, we assessed the strength and dynamics of premotor inhibitory synaptic output onto the entire ensemble of heart motor neurons and the associated conduction delays in both coordination modes. We conclude that premotor interneurons establish a stereotypical pattern of intersegmental synaptic connectivity, strengths, and dynamics that is invariant across coordination modes, despite wide variations among preparations. These data coupled with a previous description of the temporal pattern of premotor interneuron activity and relative phasing of motor neuron activity in the two coordination modes enable a direct assessment of how premotor interneurons through their temporal pattern of activity and their spatial pattern of synaptic connectivity, strengths, and dynamics coordinate segmental motor neurons into a functional pattern of activity.