来自美国霍华德休斯医学研究所的科学家研究证实了树状棘的电性质促进了非线性树状突加工过程及可塑性和存储的相关形式,因此根本上增强了神经元的计算能力。

-2012年11月22日《自然》

中文翻译


【题目】通过树状棘的突触扩增增强了输入协同性

【译文】树状棘是兴奋性突触输入于神经元上的常见位点,因此被精密地定位以影响神经信号的多方面。数十年的理论研究已经指出树状棘可能发挥高效及可修饰的化学和电隔室的作用,以调控突触效率、整合及可塑性。实验研究已经证实了通过树状棘的活性依赖的结构动力学和生化区室作用。然而,对于树状棘对突触传递和树突作用电方面的影响尚存在争论。本研究测量了树图区室范围间树状棘头部对亲本树突电压的振幅比率,并计算了大鼠海马CA1锥体细胞中树突树干顶端上树状棘相关棘颈耐受(Rneck)。我们发现Rneck足以实质地放大单一突触输入相关的树状棘头部去极化,约1.5-4.5倍,这依赖于亲本树突阻抗。形态学上真实的、具有再生振幅比率空间谱能力的房室模型表明了树状棘提供了一种遍及树状分支的持续高阻抗输入结构。最后,我们证实了树状棘产生的这种扩增通过棘头部电压门控电导激活的Rneck依赖性增加促进了限制性输入之间的电相互作用。我们得到如下结论,即树状棘的电性质促进了非线性树状突加工过程及可塑性和存储的相关形式,因此根本上增强了神经元的计算能力。

英文原稿


[Title]: Synaptic amplification by dendritic spines enhances input cooperativity

[Authors]:Mark T. Harnett,1, 4 Judit K. Makara,1, 2, 4 Nelson Spruston,1 William L. Kath3 & Jeffrey C. Magee1

[Abstract]Dendritic spines are the nearly ubiquitous site of excitatory synaptic input onto neurons and as such are critically positioned to influence diverse aspects of neuronal signalling. Decades of theoretical studies have proposed that spines may function as highly effective and modifiable chemical and electrical compartments that regulate synaptic efficacy, integration and plasticity. Experimental studies have confirmed activity-dependent structural dynamics and biochemical compartmentalization by spines. However, there is a longstanding debate over the influence of spines on the electrical aspects of synaptic transmission and dendritic operation. Here we measure the amplitude ratio of spine head to parent dendrite voltage across a range of dendritic compartments and calculate the associated spine neck resistance (Rneck) for spines at apical trunk dendrites in rat hippocampal CA1 pyramidal neurons. We find that Rneck is large enough (~500 MΩ) to amplify substantially the spine head depolarization associated with a unitary synaptic input by ~1.5- to ~45-fold, depending on parent dendritic impedance. A morphologically realistic compartmental model capable of reproducing the observed spatial profile of the amplitude ratio indicates that spines provide a consistently high-impedance input structure throughout the dendritic arborization. Finally, we demonstrate that the amplification produced by spines encourages electrical interaction among coactive inputs through an Rneck-dependent increase in spine head voltage-gated conductance activation. We conclude that the electrical properties of spines promote nonlinear dendritic processing and associated forms of plasticity and storage, thus fundamentally enhancing the computational capabilities of neurons.

原文地址

http://www.nature.com/nature/journal/v491/n7425/full/nature11554.html

 

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