An Expanded Visual Cortex for the Superior Colliculus

项目摘要 哺乳动物大脑皮层视觉处理的研究传统上主要集中在 通过丘脑外侧膝状核(LGN)从视网膜上升到初级视觉皮质(V1)， 即所谓的膝状通路。然而，视觉信息也可以通过另一个 “膝外”视觉通路，视网膜向上丘(SC)的投射通过 丘脑枕核(PN)，在辐射到视觉皮质的不同区域之前。虽然这件事 膝外通路在灵长类和猫科动物中被广泛地描述，它对视觉的贡献 高阶视觉皮层的诱发活动通常被认为比视觉诱发活动的后果要轻。 膝曲通路，至少在那些迄今研究过的高级视觉皮质中是这样。然而，在鼠标中，最近 我们实验室的实验已经证明，这种外遗传途径实际上是 视觉诱发的活动在一个更高级的视觉区域称为后脑皮层(POR)。这一发现为我们提供了 有了一个明确的系统来研究膝外通路在皮质视觉处理中的作用，一个 进化神经解剖学家认为祖先视觉输入大脑皮层的途径。这只老鼠有 到目前为止，大约有10个高级皮质视觉区域的视觉反应被认为主要依赖于 膝曲通路。这项建议的目标是使用解剖学和功能方法来确定 小鼠较高视觉区域的视觉诱发反应对膝外膝状体的依赖程度 路径。小鼠高级视觉皮质膝外通路的这些特性的阐明 可能最终在更经典的哺乳动物视觉模型中提供对它们功能的更好理解， 这种进化保守途径的作用在某种程度上仍然难以捉摸。 使用跨突触病毒追踪和广域钙成像，我将评估功能性和 小鼠SC经枕区向高级视觉皮质双突触投射的解剖学特征 原子核。我将利用SC对运动视觉刺激的独特反应特性来识别 推测是一组依赖SC的高级视觉皮质。此外，我会将这些功能图与 通过LP将SC与高级视觉皮质进行双突触连接的解剖投影图。然后我将使用 遗传学和药理学工具使SC沉默，并因果地证明候选皮质的依赖 在这个输入上。最后，我将研究外基因视觉加工在辨别中的潜在作用 在视野中的自我和外在产生的运动之间。 综上所述，本研究将加深我们对供应链与供应链之间关系的理解 在高级视觉加工背景下的视觉皮质。拟议的实验将提供丰富的 在世界领导人的密切指导下，用来撰写成功的博士论文的数据集 加州大学旧金山分校的皮质神经生物学。

Project Abstract Studies of cortical visual processing in mammals have traditionally focused on the visual pathway that ascends from the retina to primary visual cortex (V1) via the lateral geniculate nucleus of the thalamus (LGN), the so-called geniculate pathway. However, visual information can also reach cortex through an alternate “extrageniculate” visual pathway in which retinal projections to the superior colliculus (SC) are relayed through the pulvinar nucleus of the thalamus (PN) before radiating to various regions of the visual cortex. While this extrageniculate pathway has been extensively characterized in primates and cats, its contribution to visually evoked activity in higher-order visual cortices is generally considered of lesser consequence than that of the geniculate pathway, at least in those higher-order visual cortices studied thus far. In the mouse, however, recent experiments from our lab have demonstrated that this extrageniculate pathway is actually the principal driver of visually evoked activity in a higher-order visual area called postrhinal cortex (POR). This discovery provides us with a well-defined system for studying the role of the extrageniculate pathway in cortical visual processing, a pathway that evolutionary neuroanatomists consider the ancestral visual input to the cortex. The mouse has about ten higher cortical visual areas whose visual response are thus far considered to largely rely on the geniculate pathway. The goal of this proposal is to use anatomical and functional approaches to determine the extent to which visual evoked responses in higher visual areas of the mouse rely on the extra-geniculate pathway. Elucidating these properties of the extrageniculate pathways to higher visual cortices of the mouse may ultimately provide a better understanding of their function in more classical mammalian models of vision, where the role of this evolutionary conserved pathway has remained somewhat elusive. Using transsynaptic viral tracing and widefield calcium imaging, I will assess the functional and anatomical characteristics of the mouse SC’s disynaptic projections to higher visual cortices via the pulvinar nucleus. I will take advantage of the unique response properties to moving visual stimuli of the SC to identify a putative set of SC-dependent higher visual cortices. Furthermore, I will compare those functional maps with the maps of the anatomical projections that disynaptically link the SC, via LP, to higher visual cortices. I will then use genetic and pharmacological tools to silence the SC and causally demonstrate the reliance of candidate cortices on this input. Finally, I will investigate a potential role of extrageniculate visual processing in discriminating between self and exogenously generated movement in the visual field. Taken together, this research will deepen our understanding of the relationship between the SC and visual cortex in the context of higher-order visual processing. The proposed experiments will provide a rich dataset from which to develop a successful doctoral dissertation under the close mentorship of world-leaders in cortical neurobiology at the University of California, San Francisco.