CORTICAL PLANNING AND CONTROL OF SMOOTH PURSUIT

为了保持中心凹物体的清晰视觉，眼睛必须 移到那个物体上。快速眼动，或眼跳，用来 获取静止对象，而平滑跟踪用于稳定 移动对象。当对象保持静止时，高分辨率 信息仅丢失约180毫秒，这是 产生一次扫视。然而，如果对象在移动，则平滑追逐 系统永远不会因为该延迟而获取该对象，如果仅仅是 对视网膜图像运动有反应。要解决这个问题，追求 系统使用过去跟踪熟悉对象轨迹的经验 并对正在进行的运动进行计算以预测未来的位置 移动的目标。基于这一神经计算，眼睛追逐 在适当的时间以适当的速度瞄准目标。这个 预测眼球运动的底物尚不清楚。背内侧表盘 额叶皮质(DMFC)参与计划和其他更高级的活动 运动行为。首席调查员有初步证据表明 该区域可参与规划和实施顺眼追逐 动静。这个项目的目标是研究这一地区 电生理学技术了解预测神经元如何 即将到来的目标运动的编码与移动命令接口 眼睛。具体目标是回答以下问题：1. 内部规划对视觉引导追逐乘性的影响， 还是由交换机实施？当动物被记录到神经元活动时 追逐目标(运动)将与记录的活动进行比较 目标移动，但动物继续凝视(计划)。2.有吗？ 神经元活动在DMFC固定时间中的持续时间？我们将让一个 通过在DMFC中注入针对信号的人工定时信号 眼球运动前的小电流，持续时间不同 从实际的注视时间算起。3.DMFC中的活性增加了吗 从压抑中解脱出来的追求收益？我们建议 使用GABA能药蝇毒酚，它能抑制 皮质功能，和荷包牡丹碱，它产生去抑制 皮层细胞探索抑制性和兴奋性之间的平衡 DMFC中的连接是启动时间追逐所必需的。4.有没有 平滑追踪系统使用正在进行的运动信息来计算 目标的轨迹，从而优化起始点和持久度 追逐？我们将监测眼球运动和单个神经元的活动 以某种方式改变曲率或速度的目标的存在 会使对动议的简单回应变得效率低下。

To maintain clear vision of an object at the fovea, the eyes must be moved to that object. Rapid eye movements, or saccades are used to acquire stationary objects, while smooth pursuit is used to stabilize moving objects. When an object remains stationary, high-resolution information is lost for only about 180 msec, the time required to generate a saccade. However, if an object is moving, the smooth pursuit system could never acquire that object because of this delay if it merely responded to retinal image motion. To solve this problem, the pursuit system uses past experience with tracking a familiar object trajectory and makes computations on ongoing motion to predict the future position of a moving target. Based on this neural computation, the eyes pursue the target at the appropriate time and with the appropriate speed. The substrate for predictive eye movements is not known. The dorsomedial frontal cortex (DMFC) participates in planning and other higher-order motor behavior. The principal investigator has preliminary evidence that this area may participate in planning and execution of smooth pursuit eye movements. The goal of this project is to study this area with electrophysiological techniques to understand how predictive neuronal coding of upcoming target motion is interfaced with the command to move the eyes. Specific aims are to answer the following questions: 1. Is the effect of internal planning on visually-guided pursuit multiplicative, or implemented by a switch? Neuronal activity recorded while the animal pursues a target (motor) will be compared with activity recorded while the target moves, but the animal continues to fixate (planning). 2. Does neuronal activity in the DMFC time fixation duration? We will pit an artificial timing signal against the signal in the DMFC by injecting small currents before an eye movement with durations that are different from the actual fixation period. 3. Does activity in the DMFC increase pursuit gain as a result of a release from inhibition? We propose to employ the GABAergic agents muscimol, which has an inhibitory effect on cortical function, and bicuculline, which produces a disinhibition of cortical cells to explore the balance between inhibitory and excitatory connections in the DMFC necessary to time pursuit initiation. 4. Does the smooth pursuit system use ongoing motion information to compute the trajectory of a target and thereby optimize initiation and perseveration of pursuit? We will monitor eye movements and single-neuron activity in the presence of targets that change curvature or speed in a fashion that would make a simple response to the motion inefficient.