Noninvasive Motor Unit Discharge Assessment

描述(申请人提供)：临床肌电(EMG)技术用于各种神经源性和肌源性疾病的鉴别诊断。针刺肌电和细丝记录技术也被用于基本的运动控制研究，以更好地了解运动单位(MU)的招募和放电特性。在受控条件下(例如，恒定姿势、缓慢变化的力量、较低的力量收缩)，这些技术可以识别记录电极附近的单个MU。这些侵入性技术的局限性包括感染的一些风险，可能的对象/患者不适，以及需要从一小部分肌肉进行记录。因此，必须在许多肌肉位置获得记录，以获得具有代表性的MU放电行为样本。侵入性电极不适合监测电刺激在肌肉中的传播，这可能会揭示肌肉纤维膜的动态特性。最近，紧密间隔的表面电极阵列已经显示出足够的空间分辨率来监测单个MU的活动。我们的总体目标是开发新的仪器和分析方法，以便在非侵入性表面肌电阵列中进行MU动作电位检测和跟踪。这项新技术将放宽侵入性技术的几个限制，允许同时从多个肌肉区域以及沿肌肉纤维膜的多个位置进行记录。这项技术还有一个额外的优点，那就是提供了对构成单个MU的肌肉纤维的肌肉纤维传导速度(MFCV)的估计。该项目的具体目标是(A)开发一种新型的表面电极阵列记录系统，它可以提供高保真和灵活的电极蒙太奇选择(现有系统要么高保真，要么灵活，但不是两者兼而有之)，(B)利用该阵列开发非侵入性方法来测量标准放电特性以及MFCV(一种目前尚未在临床上测量的MU参数)和MU大小(非侵入性宏观肌电)，以及(C)在一项先导性实验中验证标准放电信息与同时测量的针头EMG，以比较年轻和老年健康受试者在各种力量范围内的MU特性。阵列记录系统将识别同时从留置电极获得的许多MU。在这项工作的实验部分，我们假设：(A)在较低的力量水平下，活跃的MU往往比在较高力量水平下招募的MU具有更慢的发射速率、更小的尺寸(通过宏观肌电测量)和更慢的MFCV；以及(B)与老年受试者相比，年轻的受试者往往具有更高的发射速率、更快的MFCV和更大的MFCV分散。长期目标是开发一种非侵入性系统，用于记录完整的MU放电特性。该系统将在人体工程学、临床肌电和基础运动控制研究等领域得到应用。

DESCRIPTION (provided by applicant):Clinical electromyographic (EMG) techniques are used in the differential diagnosis of various neurogenic and myogenic disorders. Needle EMG and fine wire recording techniques are also used for basic motor control research studies to better understand motor unit (MU) recruitment and discharge properties. Under controlled conditions (e.g., constant posture, slowly force-varying, lower-force contractions), these techniques can identify individual MUs in the vicinity of the recording electrode. Limitations of these invasive techniques include some risk of infection, possible subject/patient discomfort, and the need to record from a small portion of the muscle. Thus, recordings must be obtained at numerous muscle locations to obtain representative MU discharge behavior samples. Invasive electrodes are unsuitable for monitoring the spread of electrical excitation along the muscle, which can reveal dynamic properties of the muscle fiber membrane. Recently, tightly-spaced surface electrode arrays have demonstrated sufficient spatial resolution to monitor the activity of individual MUs. Our overall objective is to develop novel apparatus and analysis methods to permit MU action potential detection and tracking in noninvasive surface EMG arrays. This new technique would relax several restrictions of invasive techniques by allowing simultaneous recording from numerous muscle areas, as well as numerous sites along the muscle fiber membrane. This technique would have the additional advantage of providing estimates of the muscle fiber conduction velocity (MFCV) of muscle fibers comprising individual MUs. The specific aims of this project are to (a) develop a novel surface electrode array recording system that provides both high-fidelity and flexible electrode montage selection (existing systems are either high-fidelity or flexible, but not both), (b) use the array to develop noninvasive methods to measure standard discharge properties along with MFCV (a MU parameter that is not presently measured clinically) and MU size (noninvasive macro-EMG), and (c) validate standard discharge information versus simultaneously measured needle EMG in a pilot experiment comparing MU properties between younger and aged healthy subjects over a range of forces. The array recording system will identify many of the MUs simultaneously obtained from the indwelling electrodes. In the experimental portion of this work, we hypothesize that (a) during lower force levels, the active MUs will tend to have slower firing rates, smaller size (as measured by macroEMG) and slower MFCV than those MUs that are recruited at higher force levels and (b) compared to aged subjects, younger subjects will tend to have higher firing rates, faster MFCVs, and a greater dispersion of MFCVs. The long-term goal is to develop a non-invasive system for recording a complete set of MU discharge characteristics. This system should lead to applications in areas such as ergonomics, clinical EMG, and basic motor control research.