TOMOGRAPHIC RECONSTRUCTION OF CEREBELLAR GLOMERULUS

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 我们认为，小脑肾小球的结构，主要是包裹颗粒细胞树突和苔藓纤维末端的胶质鞘，导致肾小球外的细胞外空间与肾小球内的ec空间分离。 我们认为，这种几何结构将限制进入肾小球的EC Ca++，从而允许条件下，肾小球内的Ca++浓度主要由位于神经胶质鞘内的Ca++通道和泵的活性调节。我们认为，颗粒细胞树突的突触后活性与肾小球内Ca ~（++）的浓度有直接关系。由于许多细胞过程取决于Ca++，并且由于它们的类型和/或功效取决于ec Ca++的浓度，我们提出，小脑肾小球的几何结构将有助于一种新的类似ICA的学习规则，其中每个颗粒细胞可以通过测量EC Ca++浓度来测量位于同一肾小球内的其他颗粒细胞的树突的活动总和为了更充分地了解小脑肾小球的几何形状，并且为了进行更定量的正确模拟，我们建议对几个肾小球进行EM断层摄影。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We believe that the structure of the cerebellar glomerulus,mainly the glial sheath that envelops the granule cell dendrites and the mossy fiber terminal, leads to the isolation of the extracellular space outsidethe glomerulus from the ec space inside the glomerulus. We believe that such geometry would limit access of ec Ca++into the glomerulus, thus allowing for conditions where the concentration of Ca++ inside the glomerulus is regulated mostly by the activity of the Ca++ channels and pumps localized within the glial ensheathment. Webelieve that in there may be a direct relation between the post-synaptic acticity of the granulecell dendrites and the ec concenatrionof Ca++ inside the glomerulus. Since many cellular processes depend on Ca++ and since their type and/or efficacy depend on the concentration of ec Ca++, we propose that the geometry of the cerebellar glomerulus would lend itself to a new ICA-like learning rule where each granule cell can measure the sum total of the activities of other granule cells whose dendrites are localized within the same glomerulus by gauging the concentration of ec Ca++ inside the glomerulus.In order to more fully appreciate the geometry of the cerebellar glomerulus, and in order to perform more quantitatively correct simulations, we propose to performEM tomograhpy on several glomeruli.