Motor unit diversity in horizontal eye movement control

水平眼球运动控制中运动单位的多样性

基本信息

批准号：
8582153
负责人：
Paul Douglas Gamlin
金额：
$ 5.55万
依托单位：
UNIVERSITY OF ALABAMA AT BIRMINGHAM
依托单位国家：
美国
项目类别：
财政年份：
2012
资助国家：
美国
起止时间：
2012-08-01 至 2017-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8582153
关键词：
Address Anatomy Animals Brain Characteristics Contact Lenses Data Development Diagnostic radiologic examination Diplopia Electric Stimulation Electrodes Eye Eye Movements Face Fatigue Fiber Generations Histology Image Implant Individual Isometric Exercise Knowledge Lateral Lead Lesion Location Macaca Macaca mulatta Magnetic Resonance Imaging Measurement Measures Medial Methods Modeling Monkeys Motor Motor Neurons Movement Muscle Muscle Fibers Nerve Neurons Ocular Motility Disorders Operative Surgical Procedures Pharmaceutical Preparations Phase Physiological Physiology Plants Positioning Attribute Primates Procedures Property Protein Isoforms Recruitment Activity Reporting Research Personnel Retinal Role Saccades Signal Transduction Site Smooth Pursuit Specificity Speed Staging Strabismus Suction System Techniques Tendon structure Testing Time Transducers Vision design gaze instrument interest motor control nerve supply neuromuscular neuromuscular system neuroregulation nonhuman primate novel oculomotor orbit muscle relating to nervous system

项目摘要

DESCRIPTION (provided by applicant): The oculomotor control system of foveate animals such as primates faces very diverse demands depending on the eye movement task. During some periods of time, the brain must precisely control the extraocular muscles so the eyes steadily fixate and stabilize the retinal image; during other periods, it must control the extraocular muscles to move the eyes rapidly from one position to another (saccades), or track objects of interest at widely differing speeds (smooth pursuit), or precisely change the viewing angle of the two eyes (vergence). It is currently assumed that these eye movements are produced through common pools of motor units (a "motor unit" is a motor neuron and its muscle fibers), recruited irrespective of task. But there is clear anatomic and histological evidence of motor unit diversity with physiological evidence of differential inputs from the oculomotor subsystems. Also, by directly measuring eye muscle forces using muscle force transducers (MFTs) and finding that they could not be predicted from neural innervation, we recently demonstrated that the simple concept of a final common motor path is incorrect ("missing force paradox"), and that this notion likely has impaired our understanding of the neuromuscular control of eye movements. In non-human primates, we propose to investigate how motor units with distinct characteristics and locations are recruited differentially for different horizontal ee motor tasks (saccades, smooth pursuit, and vergence) and task phases (phasic and tonic). We will identify lateral and medial rectus motoneurons using antidromic activation and spike-triggered averaging of electromyograms (STA-EMG), and measure motor unit functional properties using spike-triggered averaging of the muscle force transducer signal (STA-MFT), a new method we have recently validated. We will precisely localize motoneurons with X-ray images registered to MRI and histology, and fully characterize motor unit activity during these horizontal eye movements. Better understanding of eye motor control should lead to better treatment of eye movement disorders, such as strabismus. Drugs that modify eye muscle properties, elsewhere under development, show promise as simple, inexpensive office procedures able to effect corrections not possible with strabismus surgery. Our STA- MFT technique would be suitable to study the fiber type specific functionality of pharmacologically-modified motor units in alert animals. Relevance The novel techniques used in this proposal will allow us, for the first time, to study long-overlooked task specificities in the neuromuscular systems that stabilize and move our eyes for effective vision. These studies should result in more effective and less costly treatments for strabismus and other eye movement disorders that are of a neuromuscular origin.

描述（由申请人提供）：根据眼球运动任务，诸如灵长类动物等中心凹动物的动眼神经控制系统面临着非常不同的需求。在某些时间段内，大脑必须精确控制眼外肌，使眼睛稳定地注视并稳定视网膜图像；在其他时期，它必须控制眼外肌将眼睛快速从一个位置移动到另一个位置（扫视），或者以相差很大的速度跟踪感兴趣的物体（平滑追踪），或者精确地改变两只眼睛的视角（聚散度）。）。目前假设这些眼球运动是通过共同的运动单位池产生的（“运动单位”是运动神经元及其肌纤维），无论任务如何，都会被招募。但有明确的解剖学和组织学证据表明运动单位的多样性，以及生理学证据表明来自动眼子系统的差异输入。此外，通过使用肌肉力传感器（MFT）直接测量眼肌力并发现它们无法通过神经神经支配进行预测，我们最近证明了最终共同运动路径的简单概念是不正确的（“缺失力悖论”），这个概念可能损害了我们对眼球运动的神经肌肉控制的理解。在非人类灵长类动物中，我们建议研究具有不同特征和位置的运动单位如何针对不同的水平EE运动任务（扫视、平滑追踪和聚散）和任务阶段（阶段性和强直性）进行差异性招募。我们将使用逆向激活和肌电图尖峰触发平均 (STA-EMG) 来识别外侧和内侧直肌运动神经元，并使用肌力传感器信号的尖峰触发平均 (STA-MFT) 测量运动单位功能特性，这是一种新方法我们最近验证了。我们将通过 MRI 和组织学配准的 X 射线图像精确定位运动神经元，并充分表征这些水平眼球运动期间的运动单元活动。更好地了解眼球运动控制应该可以更好地治疗眼球运动障碍，例如斜视。改变眼肌特性的药物（其他地方正在开发中）显示出作为简单、廉价的办公室程序的希望，能够实现斜视手术无法实现的矫正效果。我们的 STA-MFT 技术适用于研究警觉动物中药物修饰的运动单位的纤维类型特定功能。相关性本提案中使用的新技术将使我们首次能够研究神经肌肉系统中长期被忽视的任务特异性，这些神经肌肉系统稳定和移动我们的眼睛以获得有效的视力。这些研究将为斜视和其他神经肌肉起源的眼球运动障碍提供更有效且成本更低的治疗方法。