Tectal influences on visual thalamic activity: an optogenetic approach

描述(由申请人提供)：关于视网膜以外的来源的输入如何影响丘脑视网膜信号在到达视觉皮质的路线中的传递，人们已经知道了很多。它们来自不同的皮质下和皮质来源，组成了与丘脑中继细胞的大量突触，并作为调节器影响视网膜原基信号传递的增益。上丘(SC)是视网膜的主要受体结构，也向背外侧膝状核(DLGN)发出突出的投射，dLGN是将视网膜信号传递到视觉皮质的一级核。然而，SC输入是作为帮助塑造dLGN中继神经元感受野结构的驱动力，还是作为抑制或放大丘脑信息流的调制器，仍未得到测试。为了了解来自SC的信息如何影响dLGN的功能以及特定的SC细胞类型如何对此做出贡献，我们将利用小鼠转基因来可视化或靶向细胞类型和构造发育途径的投射，利用光遗传学来光激活SC输入以激发dLGN细胞的突触后活动，以及利用体外和体内记录技术来评估SC输入是否作为dLGN活动的驱动或调节器。这些结合的方法将使我们能够选择性地控制顶盖膝状体通路的神经元活动，并阐明两个视网膜受体皮质下结构之间的相互作用如何影响视觉信息的处理和传递。

DESCRIPTION (provided by applicant): Much is known about how inputs from sources other than the retina affect the thalamic relay of retinal signals in route to the visual cortex. They arse from a variety of subcortical and cortical sources, comprise the bulk of synapses onto thalamic relay cells and act as modulators to affect the gain of retinogeniculate signal transmission. The superior collliculus (SC), a primary retino-recipient structure, also sends a prominent projection to the dorsal lateral geniculate nucleus (dLGN), the first order nucleus that conveys retinal signals to visual cortex. However, whether SC input acts as a driver to help shape the receptive field structure of dLGN relay neurons or as a modulator to dampen or amplify the flow of thalamic information remains untested. To understand how information arising from the SC influences dLGN function and how particular SC cell types contribute to this, we shall make use of mouse transgenics to visualize or target cell types and projections of the tectogeniculate pathway, optogenetics to photo-activate SC inputs to evoke postsynaptic activity in dLGN cells, and in vitro and in vivo recording techniques to assess whether SC inputs behave as drivers or modulators of dLGN activity. These combined approaches will allow us to selectively control the neuronal activity of the tecto-geniculate pathway and shed light on how interactions between two retino- recipient subcortical structures affect the processing and transfer of visual information.