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首页> 外文期刊>Journal of Neurophysiology >Hysteresis reduction in proprioception using presynaptic shunting inhibition.
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Hysteresis reduction in proprioception using presynaptic shunting inhibition.

机译：使用突触前分流抑制可减少本体感觉迟滞。

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1. The tonic responses of angular-position-sensitive afferents in the metathoracic chordotonal organ of the locust leg exhibit much hysteresis. For a given joint angle, the ratio of an afferent's tonic firing rate after extension to its firing rate after flexion (or vice versa) is typically between 1.2:1 and 3:1 but can be as large as 10:1. Spiking local interneurons, that receive direct inputs from these afferents, can, by contrast, exhibit much less hysteresis (between 1.1:1 and 1.2:1). We tested the hypothesis that presynaptic inhibitory interactions between afferent axons reduces the hysteresis of postsynaptic interneurons by acting as an automatic gain control mechanism. 2. We used two kinds of neural models to test this hypothesis: 1) an abstract nonspiking neural model in which a multiplicative, shunting term reduced the "firing rate" of the afferent and 2) a more realistic compartmental model in which shunting inhibition presynaptically attenuated the amplitude of the action potentials reachingthe afferent terminals. 3. The abstract neural model demonstrated the automatic gain control capability of a network of laterally inhibited afferent units. A postsynaptic unit, which was connected to the competitive network of afferents, coded for joint angle without saturating as the strength of the afferent input increased by two orders of magnitude. This was possible because shunting inhibition exactly balanced the increase in the excitatory input. This compensatory mechanism required the sum of the excitatory and inhibitory conductances to be much larger than the leak conductance. This requirement suggested a graded weighting scheme in which the afferent recruited first (i.e., at a small joint angle) received the largest inhibition from each of the other afferents because of the lack of active neighbors, and the afferent recruited last (i.e., at a large joint angle) received the least inhibition because all the other afferents were active. 4. The compartmental model demonstrated that presynaptic shunting inhibition between afferents could decrease the average synaptic conductance caused by the afferents onto the spiking interneuron, thereby counterbalancing the afferents' large average firing rates after movements in the preferred direction. Therefore the total postsynaptic input per unit time did not differ much between the preferred and nonpreferred directions.(ABSTRACT TRUNCATED AT 400 WORDS)
机译：1.蝗虫腿的胸廓腱索器官中对角位置敏感的传入神经的强直反应表现出很大的滞后现象。对于给定的关节角度，伸张后的进补的发声速率与屈曲后的发声速率之比（反之亦然）通常在1.2：1和3：1之间，但可以高达10：1。相比之下，从这些传入接收直接输入的尖峰局部中间神经元可以表现出更少的磁滞（在1.1：1和1.2：1之间）。我们测试了一种假设，即传入轴突之间的突触前抑制性相互作用通过充当自动增益控制机制来降低突触后神经元的滞后。 2.我们使用两种神经模型来检验该假设：1）抽象的非尖峰神经模型，其中乘性，分流项降低传入的“发射率”，以及2）更现实的隔室模型，其中先兆分流抑制衰减到达输入端子的动作电位的幅度。 3.抽象的神经模型证明了侧向抑制的传入单位网络的自动增益控制能力。突触后单元连接到传入的竞争网络，随着传入输入的强度增加两个数量级，其关节角度编码不会饱和。这是可能的，因为分流抑制可精确平衡兴奋性输入的增加。这种补偿机制要求兴奋性和抑制性电导的总和要比泄漏电导大得多。该要求提出了一种分级加权方案，其中由于缺乏活跃的邻居，首先被招募的传入（即，在较小的关节角度处）受到其他每个传入的最大抑制，最后被招募的传入（即，处于大关节角）受到的抑制最小，因为所有其他传入都活跃。 4.隔室模型表明，传入神经之间的突触前分流抑制可能会降低传入神经向尖峰中间神经元造成的平均突触电导，从而平衡传入神经向首选方向移动后传入神经的平均平均发射速率。因此，首选和非首选方向之间每单位时间的总突触后输入差异不大。（摘要截断为400字）

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