Regulatory mechanism of synaptic plasticity in the abnormally developed visual cortex

异常发育的视觉皮层突触可塑性的调节机制

基本信息

批准号：
12670149
负责人：
IMAMURA Kazuyuki
金额：
$ 2.11万
依托单位：
RIKEN (The Institute of Physical and Chemical Research) (2001)Osaka Bioscience Institute (2000)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

项目摘要

We have used experimental hydrocephalus induced by Keolin injection to study the functional reorganization of the cerebral cortex. We confirmed enlargement of cerebral ventricles and thinner cortical layers by several imaging methods and maintained model animals in good conditions by performing cerebral ventricular-peritoneal cavity shunting operation. By using an intrinsic optical imaging method, we found that the orientation maps in areas 17 and 18 were formed almost in normal manner in these model animals. By introducing a microelectrode in the abnormally thinner visual cortex, we succeeded to record single unit activities and found that some neurons showed normal receptive field properties. However, most of them were monocular, indicating the neuronal circuits required for binocular vision were poorly developed in these animals. In vitro slice experiments showed that visuocortical neurons in hydrocephalus cats could generate normal action potentials responding to the depolarizing currents injected into the cells. Their dendritic structures were poorly developed in these cells. We further examined metabolic activity of the visual cortex of hydrocephalus cats by use of positron emission tomography. PET imaging using F18-labelled deoxyglucose showed that medial bank of the visual cortex has relatively higher uptake activity of the tracer, however general metabolic activity in the visual cortex was clearly lower in these animals. These results indicate that the functional reorganization was induced during development to compensate the structural and metabolic abnormality.

我们已经使用了Keolin注射诱导的实验脑积水来研究大脑皮层的功能重组。我们通过几种成像方法证实了脑室心室和较薄的皮质层的扩大，并通过进行脑室心室 - 腹腔腔分流操作，使模型动物保持良好状态。通过使用固有的光学成像方法，我们发现在这些模型动物中几乎以正常方式形成区域中的方向图。通过在异常较薄的视觉皮层中引入微电极，我们成功地记录了单个单位活动，并发现一些神经元显示出正常的接受场特性。但是，其中大多数是单眼的，表明这些动物中双眼视力所需的神经元回路发育不良。体外切片实验表明，脑积水猫中的粘皮层神经元可以产生正常的作用电位，以应对注入细胞中的去极化电流。它们的树突结构在这些细胞中发育不良。我们通过使用正电子发射断层扫描，进一步检查了脑积水猫的视觉皮层的代谢活性。使用F18标记的脱氧葡萄糖进行宠物成像表明，视觉皮层的内侧库具有相对较高的示踪剂摄取活性，但是在这些动物中，视觉皮质中的一般代谢活性显然较低。这些结果表明，在开发过程中诱导了功能重组，以补偿结构和代谢异常。