Control of saccades in health and disease

健康和疾病中眼跳的控制

基本信息

批准号：
7802827
负责人：
REZA SHADMEHR
金额：
$ 20.3万
依托单位：
JOHNS HOPKINS UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2009
资助国家：
美国
起止时间：
2009-05-01 至 2012-04-30
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): It is commonly assumed that saccades are ballistic and stereotypical. Yet, there is structured variability in the motor commands that initiate a saccade to a target. We propose that this variability is partly a reflection of a systematic change in the internal value that the brain associates with a visual stimulus. That is, our brain assigns a value to targets of our eye movements, and this relative value modulates the motor commands that move our eyes. If this variability was uncompensated, that is, if saccades were open-loop, then the variability in the motor commands that initiated the saccade would affect saccade endpoints. In healthy people, however, saccade endpoints are accurate despite the fact that the motor commands that initiate the saccade are variable. We suggest that this is because control of saccades is strongly dependent on internal models through the cerebellum, monitoring the outgoing motor commands and effectively `steering' the saccade by adding motor commands late in the saccade's trajectory. The compensation is effective only if this internal model is calibrated, which links the problem of control with adaptation. Here, we propose a single principle of control for saccades: Expected costs and rewards of a movement are evaluated by the basal ganglia, resulting in an internal value that modulates the motor commands that initiate the saccade. As the motor commands are generated, the cerebellum monitors them and predicts their sensory consequences, producing adjustments that steer the movement to the goal. If successful, our project may produce a major shift in oculomotor research by linking variability in trajectory of saccades with expected rewards and internal models. These concepts have proven fundamental in understanding control of other movements like reaching. As a result, we may be able to produce a single conceptual framework for how the brain controls movements in general. PUBLIC HEALTH RELEVANCE: Our aim is to produce a new, coherent theory of how various brain structures like the basal ganglia and the cerebellum contribute to control of saccades. While cerebellar patients exhibit dysmetria in their saccades, our proposal suggests that dysmetria is not random, but related to the intrinsic value that the brain assigns to the visual stimulus. The role of basal ganglia in control of movements has remained a deep puzzle; our proposal suggests that there may be a link between this structure and the internal value that the brain assigns to a visual stimulus, and that this factor accounts for some of the variability in the motor commands that initiate saccades.

描述（由申请人提供）：通常认为扫视是弹道和刻板印象的。然而，电动机命令中有结构性变异性，可以向目标启动扫视。我们建议这种变异性部分反映了大脑与视觉刺激相关的内部价值的系统变化。也就是说，我们的大脑为眼睛运动的目标分配了一个值，并且这种相对值调节了动动我们眼睛的电动机命令。如果这种变异性是无偿的，也就是说，如果扫视是开环，则启动扫视的电动机命令的可变性会影响扫视端点。但是，在健康的人中，尽管启动扫视的电动机命令是可变的，但扫视端点还是准确的。我们建议这是因为对扫视的控制很大程度上取决于小脑的内部模型，监视传出的电动机命令，并通过在扫视轨迹中添加电动机命令来有效地“转向”扫视。仅当对该内部模型进行校准时，补偿才有效，这将控制问题与适应性联系起来。在这里，我们提出了扫视的单一控制原则：基底神经节评估了运动的预期成本和奖励，导致内部价值调节启动扫视的电动机命令。随着电动机命令的产生，小脑会监视它们并预测其感官后果，从而产生将运动转向目标的调整。如果成功的话，我们的项目可能会通过将扫视轨迹的变异与预期的奖励和内部模型联系起来，从而产生动眼研究的重大转变。这些概念已证明是理解对其他运动（如触及）的控制的基本基础。结果，我们可能能够为大脑如何控制运动的方式产生一个概念框架。公共卫生相关性：我们的目的是建立一种新的，连贯的理论，即诸如基底神经节和小脑等各种大脑结构如何有助于控制扫视。尽管小脑患者在扫视中表现出空气障碍，但我们的建议表明，障碍障碍不是随机的，而是与大脑分配给视觉刺激的内在价值有关的。基底神经节在控制运动中的作用仍然是一个深刻的难题。我们的建议表明，这种结构与大脑分配给视觉刺激的内部价值之间可能存在联系，并且该因素解释了启动扫视的电动机命令中的某些可变性。