Functional Organization of the Somatosensory Cortical Layer 6 Feedback to the Thalamus
Functional Organization of the Somatosensory Cortical Layer 6 Feedback to the Thalamus
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DOI：
10.1093/cercor/bhp077
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发表时间：
2010-01-01
期刊：
影响因子：
3.7
通讯作者：
Sherman, S. Murray
中科院分区：
文献类型：
--
作者：
Lam, Ying-Wan;Sherman, S. Murray
从皮质层6到丘脑的通路是所有丘脑中继核团的特性。该通路作为一个群体，直接兴奋中继细胞，并通过丘脑网状核间接抑制它们。为了了解这种皮层反馈的电路组织，我们使用激光扫描光刺激，它专门激活胞体或树突，刺激初级躯体感觉皮层在体外丘脑皮层切片制备，同时记录从神经元的腹后内侧核。第6层光刺激诱发的双相兴奋性突触后电流/抑制性突触后电流（EPSC/IPSC）的腹后内侧核的神经元的反应，表明这种光刺激强烈激活网状细胞。这些双突触IPSC被毒蕈碱激动剂乙酰-β-甲基胆碱的浴应用极大地抑制或消除。我们的研究结果表明，从皮层第6层的丘脑神经元的自上而下的调制涉及通过丘脑网状核的抑制成分，并且该成分可以选择性地减少胆碱能输入。最后，我们发现的足迹兴奋性皮质丘脑和抑制性皮质-网状-丘脑输入位于类似的位置，但在某些情况下，他们是抵消。这两种模式对皮质-网状-丘脑回路都有影响。
The pathway from cortical layer 6 to the thalamus is a property of all thalamic relay nuclei. This pathway, as a population, directly excites relay cells and indirectly inhibits them via the thalamic reticular nucleus. To understand the circuit organization of this cortical feedback, we used laser-scanning photostimulation, which specifically activates somata or dendrites, to stimulate the primary somatosensory cortex in an in vitro thalamocortical slice preparation while recording from neurons of the ventral posterior medial nucleus. Layer 6 photostimulation evoked biphasic excitatory postsynaptic current/inhibitory postsynaptic current (EPSC/IPSC) responses in the neurons of the ventral posterior medial nucleus, indicating that such photostimulation strongly activates reticular cells. These disynaptic IPSCs were greatly suppressed or abolished by bath application of the muscarinic agonist acetyl-beta-methylcholine. Our results suggest that the top-down modulation of thalamic neurons from cortical layer 6 involves an inhibitory component via the thalamic reticular nucleus, and this component can be selectively reduced by cholinergic input. Finally, we found the footprints for the excitatory corticothalamic and the inhibitory cortico-reticulo-thalamic inputs to be located in similar positions, though in some cases they are offset. Both patterns have implications for cortico-reticulo-thalamic circuitry.