THALAMIC CONTROL OF CORTICAL VISUAL PROCESSING

视网膜信号通过外侧皮层传递到大脑皮层 膝状体核（LGN）。LGN分为几层，部分 通过眼睛和视网膜神经节的功能分类分离这些信号 cell.在猫的体内，不同的层次也会有不同的程度， 单个中继细胞将多个视网膜细胞的输出相加，并且 因此，它们以空间为代价获得灵敏度的程度 分辨率该项目的长期目标是了解如何和 为什么LGN被组织成层，这些通道的作用是什么 感知和视觉行为，信息如何通过 它们被整合在大脑皮层，以及中央反馈到LGN 动态地调节信息到皮层的传输。贡献 将通过以下方式简要检查各个层的可视化行为 使猫在执行眼科任务时所选择的层失活。到 测试假设LGN细分的程度不同，他们 专门用于高敏锐度或高敏感度视觉， 将在强调空间重要性的条件下进行， 分辨率或微光视觉。类似的范例将用于测试 假设不同LGN层的相对影响 皮质活动根据任务要求和适应水平而变化。 背侧LGN层的永久性病变将与可逆性 中心层的失活，以检查恢复的性质， 似乎发生这种病变的功能。这种新颖的 可塑性可能揭示知觉缺陷造成的， 异常，特别是传入扫视眼球运动。因为 扫视的目的是将感兴趣的目标移动到中央视网膜 代表中央视网膜的大脑区域可能会受到 独特形式的扫视相关增益变化。这种可能性将是 检查LGN中代表中央区的细胞。更好地 了解指导LGN形态发生的发育规则， 人类LGN的分层模式将通过3D可视化 计算机重建单个细胞核，以确定 为恒河猴开发的形态发生计算模型可以 应用于人类。

Retinal signals are relayed to cerebral cortex through the lateral geniculate nucleus (LGN). The LGN is divided into several layers, in part segregating these signals by eye and functional class of retinal ganglion cell. In the cat, different layers also vary in the degree to which individual relay cells summate the output of multiple retinal cells, and thus the degree to which they gain sensitivity at the expense of spatial resolution. Long term objectives of this project are to understand how and why the LGN is organized into layers, what these channels contribute to perception and visuomotor behavior, how the information relayed through them is integrated in cerebral cortex, and how central feedback to the LGN dynamically regulates transmission of information to cortex. Contributions of individual layers to visuomotor behavior will be examined by briefly inactivating selected layers in cats carrying out oculomotor tasks. To test the hypothesis that LGN subdivisions vary in the degree to which they are specialized for high-acuity or high-sensitivity vision, inactivations will be done under conditions emphasizing the importance of either spatial resolution or dim-light vision. A similar paradigm will be used to test the hypothesis that the relative influence of different LGN layers on cortical activity varies depending on task demands and adaptations levels. Permanent lesions of dorsal LGN layers will be combined with reversible inactivations of central layers to examine the nature of a recovery of function that appears to occur that such lesions. This novel form of plasticity may shed light on perceptual deficits resulting from abnormalities in particular afferent saccadic eye movements. Because the purpose of saccades is to move the target of interest to central retina regions of the brain representing central retina might be subject to unique forms of saccade-elated changes in gain. This possibility will be examined for cells in the LGN representing the area centralis. To better understanding developmental rules guiding LGN morphogenesis, the complex lamination pattern of the human LGN will be visualized thorough 3-D computer reconstructions of individual nuclei to determine if a computational model of morphogenesis developed for the rhesus monkey can be applied to the human.