INHIBITORY NETWORKS IN BARREL CORTEX

我们已经发现了一个大的GABA能神经元的选择群体， 啮齿动物大脑皮层的IV-V层边界， 行为动物的显著特征。 首先，这些细胞是 2-脱氧葡萄糖（2DG）标记比任何其他细胞都要重得多 人口在皮层。 第二，在胡须定义的背景下， 在皮质桶场，这些神经元在内部和外部都被激活， 对应于选择性刺激晶须的外部列;即， 细胞表现出“异位”代谢活化。 的这种模式 激活意味着一种整合功能或一组整合功能， 这些抑制性神经元的功能。 一种可能性是， 这些细胞为躯体皮层提供“音调”或增益控制 前馈兴奋性通路中的活性在适当的范围内， 可解释的动态范围 我们希望测试一些特定的 旨在阐明功能和输入/输出的假设 这些神经元之间的关系。 我们将评估这些假设， 大量使用我们新开发的2DG/免疫染色方案。 然后，我们将使用大量的CORE软件例程， 控制CORE B扫描显微镜载物台，自动生成 高分辨率图像中感兴趣区域的蒙太奇， 从高分辨率图像中自动提取标记的细胞。 我们 将在PND 7或 成年人消除特定的胡须输入，而不影响 丘脑皮层传入，从而选择性地限制感觉 我们已经证明，对于正常的皮质内轴突， 乔木。 在这种发展背景下，我们将评估2DG的模式 在大的GABA能细胞（下文称为E细胞， 对于异位）在下层IV和上层V中。 我们将联合收割机传统的追踪方法与 免疫组织化学方法和/或2DG方案。 我们将隔离 皮质内与丘脑皮质输入对E细胞的影响 通过在第四层或桶状皮质中制造损伤。 最后，我们将分析 用电子显微镜观察E细胞的突触输入。

We have discovered a select population of large GABAergic neurons at the layer IV-V border of rodent cerebral cortex which exhibits two distinguishing properties in the behaving animal. First, these cells are much more heavily labeled with 2-deoxyglucose (2DG) than any other cell population in the cortex. Second, within the whisker-defined context of the cortical barrel field, these neurons are activated both inside and outside columns corresponding to selectively stimulated whiskers; i.e. the cells exhibit "ectopic" metabolic activation. This pattern of activation implies an integrative function or a battery of integrative functions for these inhibitory neurons. A likely possibility is that these cells provide "tone" or gain control for the somatic cortex to hold activity in the feedforward excitatory pathway within the appropriate and interpretable dynamic range. We wish to test a number of specific hypotheses designed to clarify the functions and input/output relationships of these neurons. We will evaluate these hypotheses by making heavy use of our newly developed 2DG/immunostaining protocols. We will then use an extensive battery of CORE software routines to control the CORE B scanning microscope stage, to automatically generate montages of areas of interest from high-resolution images, and to automatically extract the labeled cells from high-resolution images. We will ablate specified combinations of whisker follicles at PND7 or in adults to eliminate specific whisker inputs without affecting the thalamocortical afferents, thereby selectively limiting the sensory inputs we have shown are necessary for normal intracortical axonal arbors. In this developmental context we will assess the pattern of 2DG labeling in the large GABAergic cells (hereafter referred to as E cells, for ectopic) in lower layer IV and upper layer V. In some experiments we will combine traditional tract-tracing methods with immunohistochemical methods and/or the 2DG protocols. We will isolate the effects of intracortical vs. thalamocortical inputs to the E cells by making lesions in layer IV or barrel cortex. Finally, we will analyze the synaptic inputs to E cells with the electron microscope.