BioCircuits Institute, University of California San Diego, La Jolla, California, United States of America.
PLoS One. 2010 Aug 3;5(8):e11920. doi: 10.1371/journal.pone.0011920.
Neurons display a high degree of variability and diversity in the expression and regulation of their voltage-dependent ionic channels. Under low level of synaptic background a number of physiologically distinct cell types can be identified in most brain areas that display different responses to standard forms of intracellular current stimulation. Nevertheless, it is not well understood how biophysically different neurons process synaptic inputs in natural conditions, i.e., when experiencing intense synaptic bombardment in vivo. While distinct cell types might process synaptic inputs into different patterns of action potentials representing specific "motifs" of network activity, standard methods of electrophysiology are not well suited to resolve such questions. In the current paper we performed dynamic clamp experiments with simulated synaptic inputs that were presented to three types of neurons in the juxtacapsular bed nucleus of stria terminalis (jcBNST) of the rat. Our analysis on the temporal structure of firing showed that the three types of jcBNST neurons did not produce qualitatively different spike responses under identical patterns of input. However, we observed consistent, cell type dependent variations in the fine structure of firing, at the level of single spikes. At the millisecond resolution structure of firing we found high degree of diversity across the entire spectrum of neurons irrespective of their type. Additionally, we identified a new cell type with intrinsic oscillatory properties that produced a rhythmic and regular firing under synaptic stimulation that distinguishes it from the previously described jcBNST cell types. Our findings suggest a sophisticated, cell type dependent regulation of spike dynamics of neurons when experiencing a complex synaptic background. The high degree of their dynamical diversity has implications to their cooperative dynamics and synchronization.
神经元在电压门控离子通道的表达和调节方面表现出高度的可变性和多样性。在低水平的突触背景下，大多数脑区中可以识别出许多具有不同生理特性的细胞类型，它们对标准形式的细胞内电流刺激有不同的反应。然而，人们并不清楚生理上不同的神经元在自然条件下，即在体内经历强烈的突触轰炸时，是如何处理突触输入的。虽然不同的细胞类型可能会将突触输入处理成不同的动作电位模式，代表特定的网络活动“模式”，但标准的电生理方法并不适合解决这些问题。在当前的论文中，我们对大鼠终纹床核旁区（jcBNST）中的三种类型的神经元进行了模拟突触输入的动态钳实验。我们对放电的时间结构的分析表明，在相同的输入模式下，三种类型的 jcBNST 神经元不会产生定性不同的放电反应。然而，我们观察到在单个放电水平上，存在着一致的、细胞类型依赖性的放电精细结构变化。在毫秒分辨率的放电结构中，我们发现整个神经元范围内存在高度的多样性，无论其类型如何。此外，我们还发现了一种具有内在振荡特性的新型细胞类型，它在突触刺激下产生有节奏和规则的放电，这使其与之前描述的 jcBNST 细胞类型区分开来。我们的研究结果表明，在经历复杂的突触背景时，神经元的放电动力学受到细胞类型依赖性的精细调节。它们的动态多样性程度很高，这对它们的协同动力学和同步有影响。
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