Neuromuscular Control of Primate Eye Movements

灵长类动物眼球运动的神经肌肉控制

• 批准号: 9919573
• 负责人: Marc A Sommer
• 金额: $ 19.7万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-05-01 至 2021-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9919573
• 关键词: Anatomy; Basic Science; Binocular Vision; Brain Stem; Cell Nucleus; Cephalic; Characteristics; Curiosities; Data; Disease; Electrodes; Electrophysiology (science); Etiology; Eye; Eye Movements; Fiber; Genes; Goals; Histologic; Histology; Immunohistochemistry; Individual; Injections; Intervention; Lazy Eyes; Learning; Length; Light; Link; Location; Macaca; Methods; Microscopy; Motor; Motor Neurons; Movement; Muscle; Muscle Fibers; Neuromuscular Diseases; Neuromuscular Junction; Neurons; Oculomotor nucleus; Operative Surgical Procedures; Opsin; Outcome; Outcome Study; Pattern; Play; Population; Primates; Protocols documentation; Resolution; Role; Saccades; Safety; Sampling; Simplexvirus; Smooth Pursuit; Strabismus; Structure; Structure-Activity Relationship; Symptoms; System; Techniques; Testing; Time; Viral; Viral Vector; Visual; Work; base; clinical application; conventional therapy; craniofacial; design; effective therapy; experimental study; fluorophore; gaze; gene therapy; in vivo; interest; motor control; nerve supply; neuromuscular; neuromuscular system; neurophysiology; neurotoxicity; nonhuman primate; novel; oculomotor; optogenetics; orbit muscle; sample fixation; success; transgene expression; vector; visual motor

Analyzing the visual world requires the meticulous coordination of both eyes, achieved by six muscles that surround each eye. Controlled by motoneurons in the brainstem, these muscles move the eyes rapidly to acquire targets (using saccades) or track them (smooth pursuit). The muscles also make slower adjustments to maintain proper binocular alignment in depth (vergence) and keep the eyes still for target inspection (fixation). Common visuomotor disorders such as strabismus result from abnormalities in this neuromuscular system. Current treatments mitigate symptoms, but do not fix the underlying problems. To progress toward cures for the disorders, we need to learn more about the details of the neuromuscular circuits. A longstanding curiosity about extraocular muscle fibers has been that they come in two major types: multiply-innervated fibers (MIFs) that receive numerous neuromuscular junctions along their entire length, and singly-innervated fibers (SIFs) that receive a single band of neuromuscular junctions in their middle region. It was discovered recently in primates that these two types of muscle fibers are supplied by distinct groups of motoneurons, revealing that the MIF vs. SIF distinction extends to full motor units. Anatomical characteristics of MIFs and their motoneurons suggest they control slow, binocular alignment (vergence and fixation) whereas SIFs and their motoneurons control faster, targeting movements (saccades and smooth pursuit). The overall goal is to test this hypothesis of dual- motor control of the eyes. This will be accomplished using linear array recordings and optogenetics to study MIF and SIF motoneurons in behaving macaques. Pilot work showed that macaque extraocular motoneurons can be virally transduced to express exogenous genes, setting the stage for the optogenetic approach. The first aim is to achieve reliable, robust viral transduction and opsin expression in macaque motoneurons. Three viral vectors will be injected into orbital muscles at varying volumes and titers. Consequent transgene expression in motoneurons, along with any evidence of neurotoxicity, will be analyzed histologically up to 1 year post-injection to determine optimal parameters. The second aim is to distinguish the functional roles of MIF and SIF motoneurons. Exploiting the separate, colinear locations of MIF and SIF motoneurons in the primate oculomotor nucleus, we will angle linear array electrodes to sample both populations simultaneously. Motoneuron activity will be analyzed in relation to vergence, saccade, and smooth pursuit movements made by the macaques. MIF motoneurons will be identified with in vivo optogenetic phototagging and histological analyses. The outcome of the study will be to resolve whether MIF and SIF motor units constitute a dual-motor system for controlling the eyes. If the MIF subsystem is specialized for binocular alignment, as predicted, it would be implicated as a locus of disruption in strabismus, providing a specific target for treatment. More generally, the work will provide new viral and neurophysiological techniques for studying primate motoneurons, establish a novel testbed for primate optogenetics, and inform the safety and efficacy of gene therapy for neuromuscular disorders.

分析视觉世界需要两只眼睛细致的协调，通过六块肌肉来实现 围着每一只眼睛。由脑干中的运动神经元控制，这些肌肉迅速移动眼睛以获得 目标(使用扫视)或跟踪目标(平滑追逐)。肌肉也会进行较慢的调整以保持 双眼在深度(聚焦)上保持适当的对准，并保持眼睛静止以进行目标检查(固定)。普普通通 视觉运动障碍，如斜视，是由这种神经肌肉系统的异常引起的。当前 治疗可以缓解症状，但不能解决根本问题。朝着治愈疾病的方向前进 我们需要更多地了解神经肌肉回路的细节。由来已久的好奇心 眼外肌纤维主要有两种类型：多神经支配纤维(MIF) 沿其全长接收许多神经肌肉连接，以及单神经纤维(SIF) 在它们的中间区域接受一条单一的神经肌肉连接。它是最近在灵长类动物身上发现的 这两种类型的肌肉纤维是由不同组的运动神经元供应的，这表明MIF与MIF相比。 SIF的区别延伸到了全电机单元。MIF及其运动神经元的解剖特征提示 它们控制缓慢的双眼排列(会聚和注视)，而SIF和它们的运动神经元控制 更快、更有针对性的移动(扫视和平稳追逐)。总体目标是检验这种双重假设-- 眼睛的运动控制。这将使用线性阵列记录和光遗传学来研究MIF 和行为正常猕猴的SIF运动神经元。试点工作表明，猕猴眼外运动神经元可以 病毒转导表达外源基因，为光遗传学方法奠定了基础。第一个目标是 在猕猴运动神经元中实现可靠、稳健的病毒转导和视蛋白表达。三种病毒载体 将以不同的体积和滴度注射到眼眶肌肉中。随后的转基因表达 运动神经元，连同任何神经毒性的证据，将在注射后一年内进行组织学分析。 以确定最佳参数。第二个目标是区分MIF和SIF的功能角色 运动神经元。利用灵长类动眼神经中MIF和SIF运动神经元的分离、共线位置 核，我们将角度线性阵列电极，以同时采样这两个群体。运动神经元活动 将被分析与猕猴的收敛、扫视和平稳的追逐动作有关。MIF 运动神经元将通过体内光遗传光标记和组织学分析进行鉴定。其结果是 这项研究将解决MIF和SIF电机单元是否构成控制 眼睛。如果MIF子系统像预测的那样专门用于双目对准，它将被牵连为一个轨迹 对斜视的干扰，为治疗提供了一个特定的目标。更广泛地说，这项工作将提供新的 病毒和神经生理学技术研究灵长类运动神经元，建立一种新的灵长类实验床 光遗传学，并告知神经肌肉疾病的基因治疗的安全性和有效性。