Synaptic basis for intense thalamocortical activation of feedforward inhibitory cells in neocortex
Synaptic basis for intense thalamocortical activation of feedforward inhibitory cells in neocortex
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DOI：
10.1038/nn1861
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发表时间：
2007-04-01
影响因子：
25
通讯作者：
Connors, Barry W.
中科院分区：
文献类型：
--
作者：
Cruikshank, Scott J.;Lewis, Timothy J.;Connors, Barry W.
丘脑为新大脑皮层提供基本输入。这种输入比兴奋性神经元更强烈地激活抑制性中间神经元，触发强大的前馈抑制。我们用小鼠的体感丘脑皮质制剂研究了这种选择性神经元激活的机制。值得注意的是，抑制性中间神经元的更大反应性并不是由它们独特的内在属性引起的，而是由突触机制产生的。丘脑的轴突与抑制性中间神经元的兴奋性联系比与兴奋性细胞的联系更强、更频繁。此外，电路动力学允许前馈抑制比中间神经元更有效地抑制兴奋性细胞的反应。丘脑皮质兴奋电流在中间神经元中迅速上升，使它们在出现显著的前馈抑制之前激发动作电位。相反，兴奋细胞的丘脑皮质兴奋电流上升缓慢，与抑制动作电位的前馈抑制电流重叠。这些结果证明了选择性突触靶向和精确计时在新皮质加工的初始阶段的重要性。
The thalamus provides fundamental input to the neocortex. This input activates inhibitory interneurons more strongly than excitatory neurons, triggering powerful feedforward inhibition. We studied the mechanisms of this selective neuronal activation using a mouse somatosensory thalamocortical preparation. Notably, the greater responsiveness of inhibitory interneurons was not caused by their distinctive intrinsic properties but was instead produced by synaptic mechanisms. Axons from the thalamus made stronger and more frequent excitatory connections onto inhibitory interneurons than onto excitatory cells. Furthermore, circuit dynamics allowed feedforward inhibition to suppress responses in excitatory cells more effectively than in interneurons. Thalamocortical excitatory currents rose quickly in interneurons, allowing them to fire action potentials before significant feedforward inhibition emerged. In contrast, thalamocortical excitatory currents rose slowly in excitatory cells, overlapping with feedforward inhibitory currents that suppress action potentials. These results demonstrate the importance of selective synaptic targeting and precise timing in the initial stages of neocortical processing.