Electrotonic architecture of hippocampal CA1 pyramidal neurons based on three-dimensional reconstructions
Electrotonic architecture of hippocampal CA1 pyramidal neurons based on three-dimensional reconstructions
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DOI：
10.1152/jn.1996.76.3.1904
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发表时间：
1996-09-01
影响因子：
2.5
通讯作者：
Brown, TH
中科院分区：
文献类型：
--
作者：
Mainen, ZF;Carnevale, NT;Brown, TH
1.通过多房室模型的基础上，这些细胞的三维形态重建的传播的电信号在锥体神经元从大鼠海马CA 1区进行了研究。这些模型被用来解剖这些神经元的电紧张结构，并评估本实验室和其他人以前应用于它们的等效圆柱体方法。结果的稳健性通过使用宽范围的比膜电阻（R（m））和细胞质连续性值来验证。解剖显示出极端偏离等效圆柱模型的一个关键假设，即所谓的“3/2幂定律”。''3.房室模型表明，稳态电紧张的索马和树突终端之间的距离的频率分布是多模态的，具有很大的范围和相当大的变异系数。这违反了等效圆柱体模型的另一个核心假设，即所有终端与索马的电张力距离相等。这一发现在电信号的“离心"（远离索马）和”向心“（朝向索马）传播中均被观察到，表明整个树突树的等效电紧张长度的概念不适用于这些神经元。电紧张距离分布的多个峰值，无论是离心还是向心电压传递，都与CA 1区突触传入纤维的层状结构明显相关.前面三段的结果揭示了这些神经元的电紧张结构很少被简单的等效圆柱模型所捕获。多室模型更适合于探索CA 1锥体神经元的突触信号和瞬时事件。当突触电位、电流和电荷从树突树向索马扩散时，它们有显著的衰减。电荷衰减最小，电压衰减最大。衰减弱依赖于R（m）和强烈的突触位置。峰值时间延迟对于电压比对于电流更失真，并且更受R（m）的影响。对于这些细胞上的大多数突触来说，适当的空间箝位是不可能的。体细胞电压钳的应用对突触下膜的电压瞬变没有显著影响。树突树内可能存在陡峭的电压梯度，这与神经元可能存在某种程度的局部处理以及神经元的不同区域可能半自主地起作用的想法一致。这些空间梯度可能与海马体中的突触可塑性有关，并且它们还建议在解释某些神经生理学结果时要谨慎。
1. The spread of electrical signals in pyramidal neurons from the CA1 field of rat hippocampus was investigated through multicompartmental modeling based on three-dimensional morphometric reconstructions of four of these cells. These models were used to dissect the electrotonic architecture of these neurons, and to evaluate the equivalent cylinder approach that this laboratory and others have previously applied to them. Robustness of results was verified by the use of wide ranges of values of specific membrane resistance (R(m)) and cytoplasmic resistivity.2. The anatomy exhibited extreme departures from a key assumption of the equivalent cylinder model, the so-called ''3/2 power law.''3. The compartmental models showed that the frequency distribution of steady-state electrotonic distances between the soma and the dendritic terminations was multimodal, with a large range and a sizeable coefficient of variation. This violated another central assumption of the equivalent cylinder model, namely, that all terminations are electrotonically equidistant from the soma. This finding, which was observed both for ''centrifugal'' (away from the soma) and ''centripetal'' (toward the soma) spread of electrical signals, indicates that the concept of an equivalent electrotonic length for the whole dendritic tree is not appropriate for these neurons.4. The multiple peaks in the electrotonic distance distributions, whether for centrifugal or centripetal voltage transfer, were clearly related to the laminar organization of synaptic afferents in the CA1 region.5. The results in the three preceding paragraphs reveal how little of the electrotonic architecture of these neurons is captured by a simple equivalent cylinder model. The multicompartmental model is more appropriate for exploring synaptic signaling and transient events in CA1 pyramidal neurons.6. There was significant attenuation of synaptic potential, current, and charge as they spread from the dendritic tree to the soma. Charge suffered the least and voltage suffered the most attenuation. Attenuation depended weakly on R(m) and strongly on synaptic location. Delay of time to peak was more distorted for voltage than for current and was more affected by R(m).7. Adequate space clamp is not possible for most of the synapses on these cells. Application of a somatic voltage clamp had no significant effect on voltage transients in the subsynaptic membrane.8. The possible existence of steep voltage gradients within the dendritic tree is consistent with the idea that there can be some degree of local processing and that different regions of the neuron may function semiautonomously. These spatial gradients are potentially relevant to synaptic plasticity in the hippocampus, and they also suggest caution in interpreting some neurophysiological results.