THALAMIC CONTROL OF CORTICAL VISUAL PROCESSING

外侧膝状核(LGN)的层状结构 在解剖学上定义了几个平行的传入通道 信息传到视觉皮质。这个项目的长期目标是 项目的目的是确定每个膝部的贡献 细分到皮质生理学和视觉运动行为，以找到 在什么程度以及在什么情况下传输 通过膝状层的信息是由非 视网膜输入，并更好地了解 皮质内使输入膝曲的机制。 这项建议的第一个具体目标是确定影响 可逆地失活LGN的主要部分(A和C 层)、17区活动和17区视觉运动行为 醒着的猫。灭活将通过注射小剂量的 LGN中注入盐酸利多卡因的量 正试图盯着小的视觉目标。特别的 兴趣是指第4层和第2层中的活动 超颗粒层通过这一过程被解离，并且 空间定向注意力与这种分离的相互作用。 膝状体失活对皮质和眼球运动的影响 扫视的目标出现在伪随机位置将是 与目标出现在预期的 地点。 第二个具体目标是检验这样一个假设，即收益 不同膝状层的动态和独立的 由中央反馈控制。视网膜病变中的单个细胞 膝状层A和C的相应部分将 在动物表演时同时录制 用于特定目标的视觉运动任务1。我们还将确定 膝状体兴奋性的中枢调节程度 在视网膜上被限制在视觉的受关注区域 菲尔德。 第三个具体目标是检验这样一种假设，即 层间核(MIN)在弱光视觉中具有特殊作用。 MIN和MIN的对比度灵敏度和对比度响应函数 将在一定范围内与其他膝曲细胞进行比较 麻醉猫的光照水平。

The lamination pattern of the lateral geniculate nucleus (LGN) anatomically defines several parallel channels of afferent information to the visual cortex. The long-term objectives of this project are to determine the contributions of each geniculate subdivision to cortical physiology and visuomotor behavior, to find out to what extent and under what circumstances the transmission of information through the geniculate layers is modulated by non- retinal inputs, and to obtain a better understanding of the intracortical mechanisms that geniculate inputs feed. The first specific aim of this proposal is to determine the effects of reversibly inactivating the main portion of the LGN (A and C layers), on activity in area 17 and on visuomotor behavior in awake cats. Inactivation will be accomplished by injecting small amounts of lidocaine hydrochloride into the LGN while the animal is attempting to fixate small visual targets. Of particular interest is the extent to which activity in layer 4 and in the supragranular layers is dissociated by this procedure, and the interaction of spatially-directed attention with this dissociation. The cortical and oculomotor effects of geniculate inactivation when the target of a saccade appears in pseudorandom locations will be compared with those when the target appears in an anticipated location. The second specific aim is to test the hypothesis that the gains of different geniculate layers are dynamically and independently controlled by central feedback. Single cells in retinotopically corresponding parts of geniculate layers A and C will simultaneously recorded while animals are performing the same visuomotor tasks used for Specific Aim 1. We will also determine the extent to which central modulation of geniculate excitability is restricted retinotopically to attended regions of the visual field. The third specific aim is to test the hypothesis that the medial interlaminar nucleus (MIN) has a special role in dim-light vision. Contrast-sensitivity and contrast-response functions of MIN and will be compared with those of other geniculate cells over a range of illumination levels in the anesthetized cat.