Formation of Cortical Areas and Circuits

这项建议的总体目标是确定小鼠纹外视皮层的区域图，如何 视野显示在这些区域，无论不同的区域连接到背侧和腹侧 路径以及它们是否代表功能专门化的处理流。初步研究，在 我们已经追踪了同一动物V1的三个不同点的输出，揭示了十个 视觉皮层的地形图。多单位记录的感受野映射表明，每个区域 包含一张有序的视野地图。对每个地区产出的顺行追踪进一步 揭示了一个联系的网络，这表明地区是按等级组织的，并通过 腹流和背流交织在一起。腹流区和背流区的初步单单位记录 结果表明，方向选择神经元在背侧流中的出现率较高。结果表明， 腹侧和背侧通路代表不同的视觉处理流，可能对应于“什么”。 以及灵长类动物中的“Where”溪流。这是第一次证明小鼠的视皮层共享几个 灵长类动物的皮质组织原理，并表明小鼠是人类的良好模型 大脑。最近的分子遗传学研究已经确定了数十种影响大脑皮层的基因突变。 此外，已经证实了影响背部功能的失认症的遗传易感性。 和腹侧流区。为了研究这些疾病的潜在分子和突触机制，它 对于理解小鼠模型中视皮层的结构和功能是必不可少的。考虑到 Felleman和Van Essen(1991)视觉神经科学的面积图，这必须包括第一和 最重要的是确定地区、描述地区等级和描述 正在处理数据流。尽管有老鼠和老鼠的区域地图，但在和中它们有很大的差异 在物种之间。这些分歧是由于动物之间的共享和部分地图登记不善造成的 使用不充分的解剖地标。我们建议通过一种新的方法来解决这些冲突 直接结合解剖路径追踪(目标1)和生理感受野映射(目标2) 来定义区域。以前还没有在啮齿动物身上研究区域间溪流。因此，拟议的跟踪 背侧和腹侧流连接的研究(目标3)结合单单位记录方向 背侧和腹侧流区的选择性反应(目标#4)在概念上是新的。的重要意义。 拟议的研究是为了补充灵长类皮质的功能研究，并提供一个小鼠模型。 未来对人类视觉系统的分子和突触基础的研究。

The overall goal of this proposal is to determine the area map of mouse extrastriate visual cortex, how the visual field is represented in these areas, whether different areas are connected to dorsal and ventral pathways and whether they represent functionally specialized processing streams. Preliminary studies, in which we have traced the outputs from three different points of V1 in the same animal, have revealed ten topographic maps in visual cortex. Receptive field mapping by multiunit recording has shown that each area contains an orderly map of the visual field. Anterograde tracing of outputs from each area have further revealed a network of connections, which suggests that areas are hierarchically organized and are linked by intertwined ventral and dorsal streams. Preliminary single unit recordings in ventral- and dorsal-stream areas show that the incidence of direction selective neurons is higher in the dorsal stream. The results suggest that ventral and dorsal pathways represent distinct visual processing streams, which may correspond to 'what' and 'where' streams in primates. This is the first demonstration that mouse visual cortex shares several principles of cortical organization with primates and suggests that the mouse is a good model of the human brain. Recent molecular genetic studies have identified dozens of gene mutations that affect cerebral cortex. In addition, genetic predispositions have been demonstrated for agnosias that affect the functioning of dorsal and ventral stream areas. To study the underlying molecular and synaptic mechanisms of these disorders it is essential to understand the structure and function of visual cortex in the mouse model. Given the impact of the Felleman and Van Essen (1991) area diagram for visual neuroscience, this must include first and foremost the identification of areas, the characterization of the areal hierarchy and the description of processing streams. Although area maps are available for rat and mouse, they differ enormously within and between species. The disagreements are due to pooling across animals and poor registration of partial maps using inadequate anatomical landmarks. We propose to resolve these conflicts with a novel approach that directly combines anatomical pathway tracing (Aim#1) and physiological receptive field mapping (Aim#2) to define areas. Interareal streams have previously not been studied in rodents. Thus, the proposed tracing studies of dorsal- and ventral-stream connections (Aim#3) combined with single unit recording of direction selective responses in dorsal and ventral stream areas (Aim#4) are conceptually novel. The significance of the proposed investigation is to complement functional studies in primate cortex and provide a mouse model for future studies of the molecular and synaptic basis of the human visual system.