Neuromuscular Control of Primate Eye Movements

灵长类动物眼球运动的神经肌肉控制

基本信息

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
项目类别：
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

项目摘要

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.

分析视觉世界需要双眼的细致协调，这是通过六块肌肉来实现的包围每只眼睛。这些肌肉由脑干中的运动神经元控制，快速移动眼睛以获取目标（使用眼跳）或跟踪它们（平滑追踪）。肌肉也会做出较慢的调整以维持正确的双眼深度对准（聚散度）并保持眼睛静止以进行目标检查（固定）。常见的斜视等视觉运动障碍是由神经肌肉系统异常引起的。当前的治疗可以缓解症状，但不能解决根本问题。为治愈该病取得进展疾病，我们需要更多地了解神经肌肉回路的细节。长久以来的好奇心眼外肌纤维有两种主要类型：多神经支配纤维 (MIF) 沿其整个长度接收大量神经肌肉接头和单神经纤维（SIF）在其中部区域接收单条神经肌肉接头带。最近在灵长类动物中发现这两种类型的肌纤维由不同的运动神经元群提供，揭示了 MIF 与 MIF 的区别。 SIF 的区别延伸到完整的运动单位。 MIF 及其运动神经元的解剖特征表明它们控制缓慢的双眼对准（聚散和注视），而 SIF 及其运动神经元控制更快的目标运动（扫视和平稳的追踪）。总体目标是检验这一双假设眼睛的运动控制。这将通过使用线性阵列记录和光遗传学来研究 MIF 来完成和 SIF 运动神经元在猕猴行为中的作用。试点工作表明猕猴眼外运动神经元可以通过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。随后的转基因表达注射后 1 年内将对运动神经元以及任何神经毒性证据进行组织学分析以确定最佳参数。第二个目的是区分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 运动神经元的独立共线位置核，我们将倾斜线性阵列电极以同时对两个群体进行采样。运动神经元活动将根据猕猴的辐辏、扫视和平滑的追逐动作进行分析。米夫将通过体内光遗传学照片标签和组织学分析来识别运动神经元。结果该研究将解决MIF和SIF运动单元是否构成控制运动的双运动系统眼睛。如果 MIF 子系统专门用于双眼对齐，正如预测的那样，它将被暗示为一个轨迹斜视的破坏，提供具体的治疗目标。更一般地说，这项工作将提供新的研究灵长类运动神经元的病毒和神经生理学技术，为灵长类动物建立一个新的测试平台光遗传学，并告知神经肌肉疾病基因治疗的安全性和有效性。