Helmstaedter Moritz, Sakmann Bert, Feldmeyer Dirk
Department of Cell Physiology, Max-Planck Institute for Medical Research, Jahnstrasse, Heidelberg, Germany.
Cereb Cortex. 2009 Apr;19(4):951-62. doi: 10.1093/cercor/bhn130. Epub 2008 Sep 18.
For a detailed description of the circuitry of cortical columns at the level of single neurons, it is essential to define the identities of the cell types that constitute these columns. For interneurons (INs), we described 4 "types of axonal projection patterns" in layer 2/3 (L2/3) with reference to the outlines of a cortical column (Helmstaedter et al. 2008a). In addition we quantified the dendritic geometry and electrical excitability of 3 types of the L2/3 INs: "local," "lateral," and "translaminar" inhibitors (Helmstaedter et al. 2008b). Here, we used an iterated cluster analysis (iCA) that combines axonal projection patterns with dendritic geometry and electrical excitability parameters to identify "groups" of INs, from a sample of 39 cells. The iCA defined 9 groups of INs. We propose a hierarchical scheme for identifying L2/3 INs. First, L2/3 INs can be classified as 4 types of axonal projections. Second, L2/3 INs can be subclassified as 9 groups with a high within-group similarity of dendritic, axonal, and electrical parameters. This scheme of identifying L2/3 INs may help to quantitatively describe inhibitory effects on sensory stimulus representations in L2/3 of cortical columns.
为了在单个神经元水平上详细描述皮质柱的电路，定义构成这些柱的细胞类型的身份至关重要。对于中间神经元（INs），我们参照皮质柱的轮廓描述了第2/3层（L2/3）中的4种“轴突投射模式类型”（Helmstaedter等人，2008a）。此外，我们对3种L2/3中间神经元的树突几何形状和电兴奋性进行了量化：“局部”、“侧向”和“跨层”抑制性神经元（Helmstaedter等人，2008b）。在这里，我们使用了一种迭代聚类分析（iCA），将轴突投射模式与树突几何形状和电兴奋性参数相结合，从39个细胞的样本中识别中间神经元的“组”。iCA定义了9组中间神经元。我们提出了一种用于识别L2/3中间神经元的分层方案。首先，L2/3中间神经元可分为4种轴突投射类型。其次，L2/3中间神经元可进一步细分为9组，其树突、轴突和电参数在组内具有高度相似性。这种识别L2/3中间神经元的方案可能有助于定量描述对皮质柱L2/3中感觉刺激表征的抑制作用。
