Synaptic properties of thalamic and intracortical inputs to layer 4 of the first- and higher-order cortical areas in the auditory and somatosensory systems
Synaptic properties of thalamic and intracortical inputs to layer 4 of the first- and higher-order cortical areas in the auditory and somatosensory systems
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DOI：
10.1152/jn.90391.2008
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发表时间：
2008-07-01
影响因子：
2.5
通讯作者：
Sherman, S. Murray
中科院分区：
文献类型：
--
作者：
Lee, Charles C.;Sherman, S. Murray
丘脑是哺乳动物前脑的重要结构，将信息从感觉周边传递到初级新皮质区域。除了这个初始处理阶段之外，“高阶”丘脑皮质连接被认为仅起到调节作用，或者在功能上被忽视。在这里，我们证明这些“高阶”丘脑核与“一级”丘脑核具有相似的突触特性。使用小鼠体感和听觉系统丘脑皮质切片制剂中第 4 层神经元的全细胞记录，我们发现所有丘脑核团的电刺激都会引发大的谷氨酸能兴奋性突触后电位 (EPSP)，该电位会响应重复刺激而抑制，并且无法激活代谢型谷氨酸反应。相比之下，从第 6 层到第 4 层的皮质内输入表现出促进 EPSP 的作用。这些数据表明，高阶丘脑皮质投射可能发挥与一级核团类似的功能作用，而两者在生理上都与皮质内第 6 层输入不同。这些结果提出了通过皮质丘脑皮质通路在皮质区域之间进行信息传递的替代途径。
The thalamus is an essential structure in the mammalian forebrain conveying information topographically from the sensory periphery to primary neocortical areas. Beyond this initial processing stage, "higher-order" thalamocortical connections have been presumed to serve only a modulatory role, or are otherwise functionally disregarded. Here we demonstrate that these "higher-order" thalamic nuclei share similar synaptic properties with the "first-order" thalamic nuclei. Using whole cell recordings from layer 4 neurons in thalamocortical slice preparations in the mouse somatosensory and auditory systems, we found that electrical stimulation in all thalamic nuclei elicited large, glutamatergic excitatory postsynaptic potentials (EPSPs) that depress in response to repetitive stimulation and that fail to activate a metabotropic glutamate response. In contrast, the intracortical inputs from layer 6 to layer 4 exhibit facilitating EPSPs. These data suggest that higher-order thalamocortical projections may serve a functional role similar to the first-order nuclei, whereas both are physiologically distinct from the intracortical layer 6 inputs. These results suggest an alternate route for information transfer between cortical areas via a corticothalamocortical pathway.