The impact of a corticotectal impulse on the awake superior colliculus
The impact of a corticotectal impulse on the awake superior colliculus
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DOI：
10.1523/jneurosci.4402-05.2006
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发表时间：
2006-02-22
影响因子：
5.3
通讯作者：
Swadlow, HA
中科院分区：
文献类型：
--
作者：
Bereshpolova, Y;Stoelzel, CR;Swadlow, HA
第5层皮质顶盖（CTect）神经元是哺乳动物视觉皮层的大而突出的元素，具有上升到第1层的厚顶端树突，“内在爆裂”膜特性，以及终止于多个皮层下域的快速传导下行轴突。这些神经元构成初级视皮层的主要输出通路，但实际上对单个CTect冲动对上级丘（SC）的突触影响一无所知。在这里，我们研究的分布单突触电流产生的表面SC的自发冲动的单个CTect神经元。我们这样做是通过记录的尖峰的CTect神经元和场电位，他们通过SC的深度产生的。尖峰触发的平均和电流源密度分析的方法，然后应用到这些数据。我们发现，在完全清醒的兔子，单CTect脉冲产生强有力的，快速上升的单突触电流在SC类似的感觉皮层中产生的特定丘脑传入。这些电流在深度上是焦点性的，精确地视网膜定位的，并且高度依赖于CTect轴突的传导速度。此外，我们发现，CTect突触，像丘脑皮层突触，遭受慢性抑郁症的状态，在清醒的受试者调制的前interspike间隔。然而，CTect神经元产生了一些“突发”，和突触后反应的SC没有显着影响的转变，从警觉到一个不注意的状态（由海马脑电图）。总之，我们的研究结果表明，单一的CTect神经元可能类似于丘脑皮质神经元的能力，作为有效的“司机”的突触后靶点。
Corticotectal (CTect) neurons of layer 5 are large and prominent elements of mammalian visual cortex, with thick apical dendrites that ascend to layer 1, "intrinsically bursting" membrane properties, and fast-conducting descending axons that terminate in multiple subcortical domains. These neurons comprise a major output pathway of primary visual cortex, but virtually nothing is known about the synaptic influence of single CTect impulses on the superior colliculus (SC). Here, we examine the distribution of monosynaptic currents generated in the superficial SC by spontaneous impulses of single CTect neurons. We do this by recording the spikes of CTect neurons and the field potentials that they generate through the depths of the SC. Methods of spike-triggered averaging and current source density analysis are then applied to these data. We show, in fully awake rabbits, that single CTect impulses generate potent, fast-rising monosynaptic currents in the SC similar to those generated in sensory cortex by specific thalamic afferents. These currents are focal in depth, precisely retinotopic, and highly dependent on the conduction velocity of the CTect axon. Moreover, we show that CTect synapses, like thalamocortical synapses, suffer a chronic state of depression in awake subjects that is modulated by preceding interspike interval. However, CTect neurons generated few "bursts," and postsynaptic responses in the SC were not significantly influenced by a shift from alert to an inattentive state ( indicated by hippocampal EEG). Together, our results suggest that single CTect neurons may resemble thalamocortical neurons in their ability to serve as potent " drivers" of postsynaptic targets.