Dynamic-clamp analysis of the effects of convergence on spike timing. II. Few synaptic inputs.
Dynamic-clamp analysis of the effects of convergence on spike timing. II. Few synaptic inputs.
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收敛对尖峰时序影响的动态钳位分析。
DOI：
10.1152/jn.01308.2004
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Regehr,WadeG
中科院分区：
文献类型：
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作者：
Xu-Friedman,MatthewA;Regehr,WadeG
神经系统中的感觉通路具有降低尖峰时序变异性(“抖动”)的机制，可能是为了增加敏锐度。大多数抖动抑制的研究都集中在多个亚阈值输入的收敛。然而，许多神经元在任何给定的时间只接收少量的活动输入，并且在这些条件下的抖动减少并不是很好地理解。我们用小鼠听觉脑干切片上的动态钳位记录研究了这个问题。只要输入有几个特性，只需两个输入就可以显著降低抖动。首先，对于超过阈值的输入，抖动减少是最大和最可靠的。第二，当输入时间的分布具有快速开始时，即对于阿尔法分布的输入，而不是对于高斯分布的输入，显著的抖动减少。第三，除非延迟输入被细胞的不应期抑制，否则抖动减少会受到影响。这些结果与前一篇论文中的发现相反，在前一篇论文中，许多亚阈值输入对抖动的减少做出了贡献，无论是阿尔法分布还是高斯分布。此外，当输入的分布超过细胞的不应期时，许多亚阈值输入的汇聚可能无法引发任何突触后反应。这些显着的差异表明，每种减少抖动的方法都有优缺点，根据其输入的属性，对不同的神经元可能更有效。
Sensory pathways in the nervous system possess mechanisms for decreasing spike-timing variability (“jitter”), probably to increase acuity. Most studies of jitter reduction have focused on convergence of many subthreshold inputs. However, many neurons receive only a few active inputs at any given time, and jitter reduction under these conditions is not well understood. We examined this issue using dynamic-clamp recordings in slices from mouse auditory brain stem. Significant jitter reduction was possible with as few as two inputs, provided the inputs had several features. First, jitter reduction was greatest and most reliable for supra-threshold inputs. Second, significant jitter reduction occurred when the distribution of input times had a rapid onset, i.e., for alpha- but not for Gaussian-distributed inputs. Third, jitter reduction was compromised unless late inputs were suppressed by the refractory period of the cell. These results contrast with the finding in the previous paper in which many subthreshold inputs contribute to jitter reduction, whether alpha- or Gaussian-distributed. In addition, convergence of many subthreshold inputs could fail to elicit any postsynaptic response when the input distribution outlasted the refractory period of the cell. These significant differences indicate that each means of reducing jitter has advantages and disadvantages and may be more effective for different neurons depending on the properties of their inputs.