CORTICAL PLANNING AND CONTROL OF SMOOTH PURSUIT

为了在中央凹处保持对物体的清晰视觉，眼睛必须 移动到这个对象。快速的眼球运动，或扫视， 捕获静止目标，而平滑追踪用于稳定 移动物体当物体保持静止时，高分辨率 信息仅丢失约180毫秒， 产生扫视。然而，如果一个物体是移动的， 如果系统仅仅是 对视网膜图像运动有反应。为了解决这个问题，追求 系统使用过去跟踪熟悉物体轨迹的经验 并对正在进行的运动进行计算以预测未来的位置 一个移动的目标。基于这种神经计算，眼睛会追踪 在适当的时间和适当的速度。的 用于预测眼睛运动基质是未知的。背内侧 额叶皮层（DMFC）参与计划和其他高阶 运动行为首席调查员有初步证据表明 该区域可参与平滑追踪眼的规划和执行 动作该项目的目标是研究这一领域， 电生理技术来了解预测神经元 即将到来的目标运动的编码与移动命令相接口 眼睛具体目的是回答以下问题：1.是 内部计划对视觉引导追踪的影响 还是通过交换机实现的？记录的神经元活动， 追求目标（电机）将与记录的活动进行比较， 目标移动，但动物继续注视（计划）。2.并 神经元活动在DMFC时间固定持续时间？我们将坑一个 人工定时信号对DMFC中的信号通过注入 在眼睛运动之前持续时间不同的小电流 从实际的固定期。3. DMFC中的活性是否增加 从抑制中释放出来的结果？我们建议 使用GABA能药物蝇蕈醇，其对 皮质功能，和荷包牡丹碱，它产生一个去抑制， 皮层细胞探索抑制和兴奋之间的平衡 DMFC中的连接对于时间追踪启动是必要的。4.是否 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，从而优化启动和持续 追求？我们将监测眼球运动和单神经元活动， 目标的存在改变曲率或速度， 会让简单的回应变得低效

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.