State-dependent modulation of gap junction signaling by the persistent sodium current.

Thalamic neurons fluctuate between two states: a hyperpolarized state associated with burst firing and sleep spindles, and a depolarized state associated with tonic firing and rapid, reliable information transmission between the sensory periphery and cortex. The thalamic reticular nucleus (TRN) plays a central role in thalamocortical processing by providing feed-forward and feedback inhibition to thalamic relay cells; TRN cells participate in the generation of sleep spindles, and have been suggested to focus the neural “searchlight” of attention. The mechanisms underlying synchrony in the TRN during different behavioral states are largely unknown. TRN cells are densely interconnected by electrical synapses. Here we show that activation of the persistent sodium current (INaP) by depolarization causes up to fourfold changes in electrical synaptic efficacy between TRN neurons. We further show that amplification of electrical synaptic responses strongly enhances tonic spike synchrony but, surprisingly, does not affect burst coordination. We use a Hodgkin–Huxley model to gain insight into the differences between the effects of burstlets, spikelets, and amplification on burst and spike times.

丘脑神经元在两种状态之间波动：一种是与爆发式放电和睡眠纺锤波相关的超极化状态，另一种是与紧张性放电以及感觉外周和皮层之间快速、可靠的信息传递相关的去极化状态。丘脑网状核（TRN）通过对丘脑中继细胞提供前馈和反馈抑制，在丘脑 - 皮层处理过程中起着核心作用；TRN细胞参与睡眠纺锤波的产生，并被认为可聚焦注意力的神经“探照灯”。在不同行为状态下TRN同步的潜在机制在很大程度上是未知的。TRN细胞通过电突触紧密相连。在此我们表明，去极化对持续性钠电流（INaP）的激活会导致TRN神经元之间电突触效能发生多达四倍的变化。我们进一步表明，电突触反应的放大强烈增强了紧张性峰电位同步，但令人惊讶的是，并不影响爆发式协调。我们使用霍奇金 - 赫胥黎模型来深入了解爆发式小波、峰电位小波以及放大对爆发和峰电位时间的影响之间的差异。