The subcellular organization of neocortical excitatory connections
The subcellular organization of neocortical excitatory connections
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DOI：
10.1038/nature07709
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发表时间：
2009-02-26
期刊：
影响因子：
64.8
通讯作者：
Svoboda, Karel
中科院分区：
文献类型：
--
作者：
Petreanu, Leopoldo;Mao, Tianyi;Svoboda, Karel
理解皮层回路将需要映射特定神经元群体之间的连接（1），以及确定突触出现的树突位置（2）。单个皮层神经元的树突与许多类型的局部和远程兴奋性轴突重叠，但轴-树突重叠并不总是实际连接强度的良好预测因子（3-5）。在这里，我们开发了一种有效的通道视紫红质-2（ChR 2）辅助方法（6-8），以绘制记录神经元树突分支内突触输入的空间分布，由突触前ChR 2表达定义。我们在两个丘脑核团，胡须运动皮层和局部兴奋性神经元表达ChR 2，并映射它们与小鼠桶皮层第3，5A和5 B层（L3，L5 A和L5 B）锥体神经元的突触。在L3细胞的树突状分支中，单个输入冲击到不同的单域上。这些领域排列在一个有序的，单调的模式沿着顶端轴：轴突从更中心的起源目标逐步更高的地区的顶端树突。在L5分支中，不同的输入靶向单独的基底和顶端结构域。L1中L3和L5树突的输入与触须的运动和位置有关，这表明这些信号在控制其靶神经元的增益中起作用（9）。我们的实验揭示了兴奋回路的亚细胞组织的高度特异性。
Understanding cortical circuits will require mapping the connections between specific populations of neurons(1), as well as determining the dendritic locations where the synapses occur(2). The dendrites of individual cortical neurons overlap with numerous types of local and long-range excitatory axons, but axodendritic overlap is not always a good predictor of actual connection strength(3-5). Here we developed an efficient channelrhodopsin-2 (ChR2)-assisted method(6-8) to map the spatial distribution of synaptic inputs, defined by presynaptic ChR2 expression, within the dendritic arborizations of recorded neurons. We expressed ChR2 in two thalamic nuclei, the whisker motor cortex and local excitatory neurons and mapped their synapses with pyramidal neurons in layers 3, 5A and 5B (L3, L5A and L5B) in the mouse barrel cortex. Within the dendritic arborizations of L3 cells, individual inputs impinged onto distinct single domains. These domains were arrayed in an orderly, monotonic pattern along the apical axis: axons from more central origins targeted progressively higher regions of the apical dendrites. In L5 arborizations, different inputs targeted separate basal and apical domains. Input to L3 and L5 dendrites in L1 was related to whisker movement and position, suggesting that these signals have a role in controlling the gain of their target neurons(9). Our experiments reveal high specificity in the subcellular organization of excitatory circuits.