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):926-37. doi: 10.1093/cercor/bhn141. Epub 2008 Oct 1.
In the neocortex, inhibition by gamma-aminobutyric acidergic (GABAergic) interneurons is essential for shaping cortical maps, which represent sensory signals. For a detailed understanding of the stream of excitation evoked, for example, by a sensory stimulus, interneurons must be identified with reference to their impact on excitatory neurons located in different laminae of the same (home) and surround columns. We analyzed the axonal projection of layer 2/3 (L2/3) interneurons with reference to geometric landmarks of cortical columns by staining neurons in acute slices of rat barrel cortex (P20-P29) and a subsequent cluster analysis using morphological parameters that described the spatial distribution of axons. The cluster analysis defined 4 main axonal projection "types" referred to as 1) "local inhibitors" (including "chandelier neurons"), 2) "lateral inhibitors," 3) "translaminar L2/3-to-L4/5 inhibitors," and 4) "translaminar L2/3-to-L1 inhibitors." The putative innervation domains established by axonal projections of the 4 types of interneurons and the dendritic domains of their target excitatory neurons were 1) L2/3 of the home column, 2) L2/3 of both the home and neighboring columns, 3) L4 and L5A of the home column, and 4) L1 and L2/3 of the home column. The quantitative analysis of the axonal projection patterns of an unselected sample of 51 interneurons located in L2/3 thus defined anatomical correlates for local, lateral, and translaminar inhibition within and between cortical columns.
在新皮层中，γ-氨基丁酸能（GABA能）中间神经元的抑制作用对于塑造代表感觉信号的皮层图谱至关重要。为了详细了解例如由感觉刺激诱发的兴奋流，必须根据中间神经元对位于同一（本位）柱和周围柱不同层中的兴奋性神经元的影响来识别它们。我们通过对大鼠桶状皮层（P20 - P29）急性切片中的神经元进行染色，并使用描述轴突空间分布的形态学参数进行后续聚类分析，参考皮层柱的几何地标分析了第2/3层（L2/3）中间神经元的轴突投射。聚类分析定义了4种主要的轴突投射“类型”，分别称为1）“局部抑制性神经元”（包括“吊灯神经元”），2）“侧向抑制性神经元”，3）“跨层L2/3至L4/5抑制性神经元”，以及4）“跨层L2/3至L1抑制性神经元”。由这4种类型中间神经元的轴突投射及其靶兴奋性神经元的树突域所确定的假定神经支配域分别为：1）本位柱的L2/3，2）本位柱和相邻柱的L2/3，3）本位柱的L4和L5A，以及4）本位柱的L1和L2/3。对位于L2/3的51个未选择的中间神经元样本的轴突投射模式进行定量分析，从而确定了皮层柱内和柱间局部、侧向和跨层抑制的解剖学相关性。
