Neural Control of Interceptive Movements

项目摘要 一个高速的眼球运动或扫视通常是第一个运动动作，我们作出定向到一个物体， 兴趣虽然对静止目标眼跳产生的神经机制已被彻底研究， 调查，很少有人知道的神经控制拦截扫视，获得移动目标。 基于对静止目标的扫视的研究的当前教条指出， 上级丘（SC），在眼神经轴的主要枢纽，是代表高斯; 群体活动集中在编码目标位置的部位，并且等效地，集中在编码期望扫视的部位 向量;其宽度在不同的目标位置和扫视向量之间保持不变;并且这些 空间特征来自于通过内在的、层内的 连通性。当目标移动时，基本上必须涉及非重叠机制， 因为只有在目标速度信息被合并到扫视中时才能发生准确的拦截 命令我们的理由是，当一个移动目标的图像划过视网膜时，活动扫过SC 也我们假设，人口活动，这开始作为一个高斯代表初始视觉 反应，变得偏斜，因为它席卷整个SC;在何种程度上SC人口活动是 修改取决于层内连接权重，SC中视觉空间的对数图，以及 目标速度;改变的空间分布在运动爆发期间持续存在;并且 适当的计算算法必须能够从偏斜的群体中解码扫视目标 反应我们建议使用实验和计算相结合的方法来测试这些假设 方法。具体目标1将采用一种创新的方法，同时记录神经活动， 许多SC神经元在非人类灵长类动物的功能层执行眼科任务，并比较 在对静止和移动目标（不同的）扫视期间群体活动的时空特性 速度和方向）。具体目标2将构建一个模拟人口活动的计算模型 在SC和相关的扫视静止和移动的目标。我们将采用分布式架构， SC的表层和深层以及脑干爆发的集中框图电路 生成器元素，如Arai及其同事所做的（Neural Networks，7：1115-1135，1994）。总的来说， 这些项目将提供一个深入的洞察机制，产生拦截眼跳， 能够与对静止目标的扫视机制进行比较。

PROJECT SUMMARY A high-velocity eye movement or saccade is typically the first motor action we make to orient to an object of interest. While the neural mechanisms of saccade generation to stationary targets have been thoroughly investigated, very little is known about the neural control of interceptive saccades that acquire moving targets. Current dogma based on studies of saccades to stationary targets states that the visual and motor bursts in the superior colliculus (SC), a major hub in the oculomotor neuraxis, are represented as Gaussians; that the population activity is centered at the site encoding the target location and, equivalently, desired saccade vector; that its width remains invariant across different target locations and saccade vectors; and that these spatial features emerge from a balance of excitation and inhibition mediated through intrinsic, intra-laminar connectivity. Fundamentally non-overlapping mechanisms must be involved when the target is moving, because accurate interception can only occur if target velocity information is incorporated in the saccade command. We reason that as a moving target’s image streaks across the retina, activity sweeps across the SC too. We hypothesize that the population activity, which starts as a Gaussian to represent the initial visual response, becomes skewed as it sweeps across the SC; that the extent to which SC population activity is modified depends on the intra-laminar connectivity weights, the logarithmic map of visual space in SC, and target speed; that the altered spatial distribution persists during the peri-movement burst; and that an appropriate computational algorithm must be able to decode the saccade goal from the skewed population response. We propose to test these hypotheses using a combination of experimental and computational approaches. Specific Aim 1 will employ an innovative method for simultaneously recording neural activity of many SC neurons within a functional layer in nonhuman primates performing oculomotor tasks and compare the spatiotemporal properties of population activity during saccades to stationary and moving targets (different speeds and directions). Specific Aim 2 will construct a computational model that simulates population activity in SC and associated saccades to stationary and moving targets. We will employ a distributed architecture for the superficial and deeper layers of the SC and a lumped block-diagram circuit for the brainstem burst generator elements, like that done by Arai and colleagues (Neural Networks, 7:1115-1135, 1994). Collectively, these projects will provide an in-depth insight into the mechanisms for generation of interceptive saccades and enable a comparison with mechanisms of saccades to stationary targets.