Signal Transfer in the Tectothalamic Pathway

描述（由申请人提供）：从视网膜到皮层的平行视觉通路，通过外侧膝状核（LGN）或通过上丘（SC）和枕核，可能在编码形式、运动和空间定位信号方面具有不同的功能。在LGN中，解剖和生理上不同的视觉通路的进一步分离已被确定并广泛表征。同样，对各种物种的研究已经注意到存在从SC到丘脑的多种途径，尽管这些途径在很大程度上没有被表征，而且它们的功能仍然未知。树鼩具有扩展的颞窝核系统，是一个理想的物种，可以开始理解SC的通路如何通过投射到枕核来影响皮质活动。先前的研究表明，树鼩枕核中有两个不同的区域，一个背侧区域（Pd）接收来自SC的弥漫性会聚输入并投射到后颞皮质（Tp），一个中央区域（Pc）接收来自SC的特定地形投影并投射到后颞皮质（Td）。我们建议测试这样一种观点，即单独的颞丘-皮层通路被组织起来编码视觉运动的不同特征。为了验证这一假设，我们将：1)使用体内细胞外记录来比较Pd和Pc神经元在演讲期间的活动；2)使用体外全细胞记录来比较Pc和Pc神经元的膜特性及其对SC刺激的反应；3)使用束追踪；免疫细胞化学和电子显微镜解剖表征Pd、Pc和颞叶皮层之间的联系，4)使用体内本征光学成像检查SC、Pd或Pc失活后颞叶皮层反应模式的变化。鉴于树鼩和灵长类视觉通路之间的相似性，这些结果将进一步加深我们对人类运动加工的理解，特别是在颞丘通道和皮层区域MT中。因此，拟议的研究将为运动加工障碍的治疗提供相关信息，如阅读障碍、精神分裂症、自闭症和威廉姆斯综合征。拟议的研究也可能为“盲视”提供见解，即一些患者在没有视觉感知的情况下检测视觉运动的能力。

DESCRIPTION (provided by the applicant): Parallel visual pathways from the retina to the cortex, via the lateral geniculate nucleus (LGN) or via the superior colliculus (SC) and pulvinar nucleus, likely serve distinct functions in the coding of form, movement, and spatial location signals. In the LGN, further segregations of anatomically and physiologically distinct visual pathways have been identified and extensively characterized. Likewise, studies in a variety of species have noted the existence of multiple pathways from the SC to the thalamus, although these pathways are largely uncharacterized, and their functions remain unknown. The tree shrew, with its expanded tectopulvinar system, is an ideal species to begin to understand how pathways from the SC influence cortical activity via their projections to the pulvinar nucleus. Previous studies characterized two distinct zones in the tree shrew pulvinar nucleus, a dorsal region (Pd) which receives diffuse convergent input from the SC and projects to the posterior temporal cortex (Tp), and a central region (Pc) which receives specific topographic projections from the SC and projects to the dorsal temporal cortex (Td). We propose to test the idea that separate tectopulvino- cortical pathways are organized to code distinct features of visual movement. To examine this hypothesis we will 1) use in vivo extracellular recordings to compare the activity of Pd and Pc neurons during the presentation a variety of computer generated stimuli designed to test responses to simple and complex visual motion 2) use in vitro whole cell recordings to compare the membrane properties of Pc and Pc neurons and their responses to stimulation of the SC, 3) use tract tracing, immunocytochemistry and electron microscopy to anatomically characterize the connections between the Pd and Pc and temporal cortex, and 4) use in vivo intrinsic optical imaging to examine temporal cortex response pattern changes following deactivation of the SC, Pd or Pc. Given the similarities between the tree shrew and primate visual pathways, the results should further our understanding of human motion processing particularly within the tectopulvinar pathway, and cortical area MT. Therefore, the proposed studies should provide information relevant to the treatment of disorders of motion processing such as dyslexia, schizophrenia, autism and Williams Syndrome. The proposed studies may also provide insight into "blindsight", the ability of some patients to detect visual motion in the absence of visual perception.