OCULOMOTOR SYSTEM--NEURAL STRUCTURE AND FUNCTION

描述：(改编自申请人的摘要。)前庭眼科 反射(VOR)对正常视力是必不可少的，因为它的作用是 使视网膜上的视觉图像不受头部运动的影响 尸体。头部和身体的运动由半规管感觉到。 (角加速计)和耳石器官(线加速计)。 最短的神经路径是一个由3个神经元组成的弧形，由初级 前庭核团中的感受性神经元、中间神经元和运动神经元 驱动眼部肌肉的物质。这种反射是非常快的， 在猴子身上表现出短至8ms的潜伏期。一般来说，如果有人是 观察远处的目标，补偿眼球的运动应该是 大小相同，但方向与扰动头相反 运动(增益--1)。然而，人们经常在中查看对象 个人以外的空间，例如，手中握有的东西。对于近距离目标 这样，VOR不存在单一的正确增益，因为轴 头部旋转的角度不能与眼睛的旋转轴重合。 正常情况下，旋转中心在眼睛后面(例如，脊柱上方 用于左头或右头转动的绳索)，几何考虑表明 VOR的增益必须大于1才能完全稳定视觉 图像。头部围绕相对于眼睛移位的轴的运动引起 眼睛在空间中的平移和旋转，并导致 耳石和神经管传入信号。然而，耳石和耳道 信号不足以确定正确的VOR增益；信息 关于目标位置也是必需的。这项提议的中心目标是 确定计算VOR增益的地点(S)，以及 然后分析了神经通路和生理机制。 在产生补偿性眼球运动方面。这项工作涉及到以下问题 我们如何确定空间位置，以及涉及的神经机制 双眼控制眼球运动。

DESCRIPTION: (Adapted from the applicant's abstract.) The vestibulo-ocular reflex (VOR) is essential for normal visual acuity because it acts to stabilize visual images on the retina against movements of the head and body. Head and body movements are sensed by the semicircular canals (angular accelerometers) and the otolith organs (linear accelerometers). The shortest neural pathway is a 3-neuron arc consisting of primary receptor neurons, interneurons in the vestibular nuclei, and motoneurons that drive the muscles of the eye. The reflex is extremely fast, exhibiting a latency as short as 8 ms in the monkey. In general, if one is viewing a target in the distance, the compensatory eye movements should be equal in magnitude but opposite in direction to the perturbing head movement (Gain - -1). Frequently, however, one views an object in extrapersonal space, e.g., something held in the hands. For near targets such as these, there is no single correct gain for the VOR, since the axis of head rotation cannot be coincident with the rotational axes of the eyes. Normally the center of rotation is behind the eyes (e.g., above the spinal cord for left or right head turns), and geometric considerations show that the gain of the VOR must be greater than one to fully stabilize a visual image. Head movements about axes displaced with respect to the eye cause translation as well as rotation of the eyes in space, and give rise to otolith as well as canal afferent signals. However, the otolith and canal signals are insufficient to determine the correct VOR gain; information about target location is also required. The central goal of this proposal is to identify the site(s) where the computation of VOR gain occurs, and then to analyze the neural pathways and physiological mechanisms involved in producing compensatory eye movements. This work relates to issues of how we determine spatial location, and to neural mechanisms involved in binocular control of eye movements.