State-dependent presynaptic inhibition regulates central pattern generator feedback to descending inputs.
State-dependent presynaptic inhibition regulates central pattern generator feedback to descending inputs.
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DOI：
10.1523/jneurosci.3011-08.2008
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发表时间：
2008-09-17
期刊：
影响因子：
--
通讯作者：
Nusbaum MP
中科院分区：
文献类型：
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作者：
Blitz DM;Nusbaum MP
中枢模式发生器（CPGs）向它们的投射神经元输入提供反馈。然而，尚不清楚这种反馈是否受到调节，以及它如何影响CPG输出。我们正在研究从幽门CPG到确定的在螃蟹口胃神经系统中调节胃磨坊CPG的投射神经元的反馈。这两个cpg都位于口胃神经节（STG），并受源自配对的联合神经节（CoGs）的投射神经元的影响。两种外部输入（VCN和POC神经元）通过相同的投射神经元（MCN1, CPN2）触发不同的胃磨节律。这些投射神经元受到幽门CPG中间神经元AB的反馈抑制，导致它们在VCN和poc触发的胃磨节律的收缩阶段表现出幽门时间活动。然而，在胃磨延长期，MCN1/CPN2在poc触发的节律期间表现出幽门计时活性，而在vcn触发的节律期间表现出强亢活性。在这里，我们发现后者的强直活性模式是由于消除了AB对MCN1/CPN2的抑制，尽管在STG内持续存在AB作用，并且AB的动作电位仍然传播到每个CoG。幽门定时AB输入的损失可能是由于每个CoG中AB的突触前抑制，因为当CoG中的次级节律性AB爆发起始区被激活时，相关的动作电位在VCN延长阶段被选择性抑制。因此，节律性CPG反馈可以局部调节，以一种状态依赖的方式，使相同的投射神经元能够驱动来自相同神经元回路的多种运动模式。
Central pattern generators (CPGs) provide feedback to their projection neuron inputs. However, it is unknown whether this feedback is regulated and how that might shape CPG output. We are studying feedback from the pyloric CPG to identified projection neurons that regulate the gastric mill CPG, in the crab stomatogastric nervous system. Both CPGs are located in the stomatogastric ganglion (STG) and are influenced by projection neurons originating in the paired commissural ganglia (CoGs). Two extrinsic inputs (VCN and POC neurons) trigger distinct gastric mill rhythms despite acting via the same projection neurons (MCN1, CPN2). These projection neurons receive feedback inhibition from the pyloric CPG interneuron AB, resulting in their exhibiting pyloric-timed activity during the retraction phase of the VCN- and POC-triggered gastric mill rhythms. However, during the gastric mill protraction phase, MCN1/CPN2 exhibit pyloric-timed activity during the POC-triggered rhythm but fire tonically during the VCN-triggered rhythm. Here we show that the latter, tonic activity pattern results from the elimination of AB inhibition of MCN1/CPN2, despite persistent AB actions within the STG and AB action potentials still propagating into each CoG. This loss of pyloric-timed AB input likely results from presynaptic inhibition of AB in each CoG because, when a secondary rhythmic AB burst initiation zone in the CoG is activated, the associated action potentials are selectively suppressed during the VCN protraction phase. Thus, rhythmic CPG feedback can be locally regulated, in a state-dependent manner, enabling the same projection neurons to drive multiple motor patterns from the same neuronal circuit.