Idoux Erwin, Eugène Daniel, Chambaz Antoine, Magnani Christophe, White John A, Moore Lee E
Laboratoire de Neurobiologie des Réseaux Sensorimoteurs, UMR 7060, Université Paris Descartes (Paris 5) CNRS, 45 rue des Saints-Pères, 75270 Paris Cedex 06, France.
J Neurophysiol. 2008 Sep;100(3):1278-86. doi: 10.1152/jn.90559.2008. Epub 2008 Jul 16.
Neural integrators and working memory rely on persistent activity, a widespread neural phenomenon potentially involving persistent sodium conductances. Using a unique combination of voltage-clamp, dynamic-clamp, and frequency-domain techniques, we have investigated the role of voltage-dependent conductances on the dendritic electrotonic structure of neurons of the prepositus hypoglossi nucleus (PHN), which is known to be involved in oculomotor integration. The PHN contains two main neuronal populations: type B neurons with a double afterhyperpolarization and type D neurons, which not only are oscillatory but also have a greater electrotonic length than that of type B neurons. The persistent sodium conductance is present in all PHN neurons, although its effect on the dynamic electrotonic structure is shown to significantly differ in the two major cell types present in the nucleus. The electrotonic differences are such that the persistent sodium conductance can be almost perfectly manipulated in a type B neuron using an on-line dynamic clamp to add or subtract virtual sodium ion channels. The dynamic-clamp results are confirmed by data-fitted models, which suggest that the persistent sodium conductance has two different roles depending on its somatic versus dendritic location: perisomatic conductances could play a major role in maintaining action potential discharge and dendritic conductances would be more involved in other computational properties, such as those involving remote synaptic processing or bistable events.
神经整合器和工作记忆依赖于持续性活动，这是一种广泛存在的神经现象，可能涉及持续性钠电导。我们运用电压钳、动态钳和频域技术的独特组合，研究了电压依赖性电导对舌下前置核（PHN）神经元树突电紧张结构的作用，已知该核参与眼球运动整合。PHN包含两个主要神经元群体：具有双后超极化的B型神经元和D型神经元，D型神经元不仅具有振荡性，而且其电紧张长度比B型神经元更长。所有PHN神经元中都存在持续性钠电导，尽管其对动态电紧张结构的影响在该核中存在的两种主要细胞类型中显示出显著差异。电紧张差异使得在B型神经元中使用在线动态钳添加或减去虚拟钠离子通道，几乎可以完美地操纵持续性钠电导。动态钳结果得到了数据拟合模型的证实，该模型表明持续性钠电导根据其在胞体与树突的位置具有两种不同作用：胞体周围电导可能在维持动作电位发放中起主要作用，而树突电导可能更多地参与其他计算特性，如涉及远程突触处理或双稳态事件的特性。
