【作者】 沈威；

【导师】 寿天德；

【作者基本信息】 复旦大学 ， 神经生物学， 2005， 博士

【摘要】 猫和猴的视皮层存在着两条将视觉信息由低级视皮层向高级视皮层传递的并行前馈信息处理通路,即形状信息处理通路(腹侧通路)和运动信息处理通路(背侧通路)。大量围绕这些前馈信息输入通路结构与功能的研究早已广泛开展,但对于与前馈输入同样大量存在的、高级视皮层到低级视皮层的反馈投射的功能却仍不清楚。功能上类似于灵长类MT区和V4区(或V3区)的猫的视皮层后内侧部外侧上薛氏区(Posteromedial Lateral Suprasylvian,PMLS)和21a区分别负责运动信息和形状信息的处理,是运动信息处理通路和形状信息处理通路里的两个重要区域。它们与初级视皮层17区之间具有相互的、紧密的突触连接,但它们对初级视皮层17区的反馈作用仍不清楚。在本研究中,我们利用内源信号光学成像技术及定点微量注射药物的可逆失活技术对高级视皮层PMLS区和21a区对17区的反馈作用进行了研究。研究结果显示,不论是PMLS区还是21a区,它们对17区神经元感受野的特性都发挥着兴奋性为主的调控作用,但调控作用的性质并不相同:失活PMLS区显著降低了17区神经元的方向选择性强度而且改变了部分17区神经元的最优方向角,但对于17区神经元的方位选择性却没有作用;与PMLS区不同,失活21a区显著降低了17区神经元的方位选择性强度而且改变了部分17区神经元的最优方位角。此外,PMLS区和21a区对17区的反馈作用还具有一定的感受野特征的倾向性。由于PMLS区与21a区对17区具有明显不同的作用,本研究结果表明,属于不同信息处理通路的高级视皮层对初级视皮层的神经元感受野的基本特性(如方位选择性和方向选择性)具有明显不同的调控作用。更多还原

【Abstract】 In visual cortices of high mammals such as cats and monkeys there are two major, largely parallel, ’feedforward’ processing streams which carry visual information from the primary visual cortices respectively to the parietal and temporal visual cortices. In the present study, using the optical imaging technique based on intrinsic signals combined with pharmacological methods, we examined the influence of ’feedback’ signals both from the posteromedial lateral suprasylvian (PMLS) area which is a dominant motion processing region and area 21a which is a dominant form processing region on the responsiveness of neurons and ’orientational and directional maps’ in area 17 (striate cortex, area V1). Despite the fact that area 17, unlike area PMLS, is mainly involved in the form/pattern rather than motion-processing, the reversible deactivation of both area PMLS and area 21a resulted in the reduction of the magnitude of responses of area 17 cells. Furthermore, whereas inactivation of area PMLS did not affect the basic structure of the ’orientation maps’ in area 17, deactivation of area PMLS virtually abolished the global layout of ’direction maps’ in area 17. By contrast, inactivation of area 21a did affect partial structure of the ’orientation maps’ in area 17. In addition, the feedback functions of both area PMLS and area 21a had somehow specificity. Thus, it appears that higher-order cortical areas in one information processing stream may exert differential modulatory effects on fundamental properties of neurons located in the lower-order areas of another information processing stream.更多还原