Department of Basic Neurosciences and the Center for Neuroscience, Centre Médical Universitaire (CMU), University of Geneva, 1211 Geneva, Switzerland.
University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, F-33000 Bordeaux, France.
Proc Natl Acad Sci U S A. 2021 Mar 2;118(9). doi: 10.1073/pnas.2024920118.
The organization of sensory maps in the cerebral cortex depends on experience, which drives homeostatic and long-term synaptic plasticity of cortico-cortical circuits. In the mouse primary somatosensory cortex (S1) afferents from the higher-order, posterior medial thalamic nucleus (POm) gate synaptic plasticity in layer (L) 2/3 pyramidal neurons via disinhibition and the production of dendritic plateau potentials. Here we address whether these thalamocortically mediated responses play a role in whisker map plasticity in S1. We find that trimming all but two whiskers causes a partial fusion of the representations of the two spared whiskers, concomitantly with an increase in the occurrence of POm-driven -methyl-D-aspartate receptor-dependent plateau potentials. Blocking the plateau potentials restores the archetypical organization of the sensory map. Our results reveal a mechanism for experience-dependent cortical map plasticity in which higher-order thalamocortically mediated plateau potentials facilitate the fusion of normally segregated cortical representations.
大脑皮层感觉图谱的组织取决于经验，经验驱动皮质-皮质回路的同型和长期突触可塑性。在小鼠初级体感皮层（S1）中，来自高级、后内侧丘脑核（POm）的传入通过去抑制和产生树突峰电位来调节 L2/3 锥体神经元的突触可塑性。在这里，我们探讨了这些丘脑皮质介导的反应是否在 S1 的胡须图谱可塑性中发挥作用。我们发现，剪掉除了两根胡须之外的所有胡须会导致两根保留的胡须的代表区域部分融合，同时 POm 驱动的 -甲基-D-天冬氨酸受体依赖性峰电位的发生增加。阻断峰电位会恢复感觉图谱的典型组织。我们的结果揭示了一种经验依赖性皮质图谱可塑性的机制，其中高阶丘脑皮质介导的峰电位促进了正常分离的皮质代表区域的融合。
