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

• 批准号: 8652536
• 负责人: Paul Douglas Gamlin
• 金额: $ 1.11万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 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/8652536
• 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

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(申请人提供)：中心凹动物如灵长类动物的眼球运动控制系统根据眼动任务的不同而面临非常不同的需求。在某些时间段，大脑必须精确控制眼外肌，以便眼睛稳定地注视和稳定视网膜图像；在其他时间段，它必须控制眼外肌将眼睛从一个位置快速移动到另一个位置(扫视)，或者以非常不同的速度跟踪感兴趣的物体(平滑追逐)，或者精确地改变双眼的视角(聚焦)。目前的假设是，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肉纤维)，与任务无关地被招募。但是，有明确的解剖学和组织学证据表明运动单位的多样性，以及来自动眼运动子系统的不同输入的生理学证据。此外，通过使用肌力传感器(MFT)直接测量眼肌力，并发现它们不能从神经神经支配中预测，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”)，而且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是如何在不同的水平眼动任务(扫视、平稳追逐和集中)和任务阶段(阶段和紧张期)下被不同地招募的。我们将使用反向激活和棘波触发的肌电平均(STA-EMG)来识别外侧和内侧直肌运动神经元，并使用我们最近验证的一种新方法--棘波触发的肌力传感器信号平均(STA-MFT)来测量运动单位的功能特性。我们将通过注册到MRI和组织学的X射线图像来精确定位运动神经元，并充分表征这些水平眼球运动过程中的运动单位活动。更好地了解眼球运动控制应该有助于更好地治疗眼球运动障碍，如斜视。在其他正在开发中的药物中，改变眼肌特性的药物显示出希望是简单、廉价的办公室程序，能够起到矫正斜视手术所不可能的效果。我们的STA-MFT技术将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。相关性这项提议中使用的新技术将第一次使我们能够研究长期被忽视的神经肌肉系统中的任务特异性，该系统稳定和移动我们的眼睛，以获得有效的视力。这些研究应该会为斜视和其他源于神经肌肉的眼球运动障碍带来更有效和更低成本的治疗方法。