Neural Control of a Complex Oculomotor Plant

复杂动眼植物的神经控制

• 批准号: 7104952
• 负责人: Joel M Miller
• 金额: $ 47.68万
• 依托单位: SMITH-KETTLEWELL EYE RESEARCH INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-10 至 2009-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7104952
• 关键词: Macaca mulatta; biomechanics; connective tissue; electrostimulus; eye movements; magnetic resonance imaging; motor neurons; muscle; muscle contraction; neuroregulation; oculomotor nerve; oculomotor nuclei

DESCRIPTION (provided by applicant): Significance: Almost 40 years of oculomotor physiology have been based on the powerful simplifying notion that the oculomotor nuclei, their cranial nerves, and the extraocular muscles (EOMs) constitute a simple, homogeneous Final Common Path (FCP), in which supernuclear signals controlling the several types of eye movement combine anonymously. It was, therefore, surprising when studies of vergence eye movement using direct muscle force measurements and magnetic resonance imaging (MRI) failed to confirm predictions that would follow from earlier, well-replicated motoneuron (MN) studies, if the FCP hypothesis were correct. This hypothesis now appears untenable, and the oculomotor plant ripe for exploration of its long-neglected functional richness. Supernuclear disorders are mostly inaccessible to treatment, whereas functions localized to the oculomotor periphery may be readily subject to pharmacologic, surgical and genetic manipulations. An understanding of related motoneuron and muscle fiber specializations would make it possible to effect subtle changes, compared to the gross manipulations of muscle action currently available to treat strabismus and related disorders. Studies: Our first overall aim is to delineate failures of the FCP hypothesis: (1) We will strongly verify the "missing lateral rectus (LR) force paradox" by recording identified abducens MNs and simultaneously measuring LR forces in vergence, continuing (2) to distinguish changes in slopes and Y-intercepts of MN rate-position curves, and to study the variation of LR and medial rectus (MR) convergence forces across the horizontal gaze plane. (3) We will replicate in monkeys, an MRI study in humans that found no globe retraction in convergence, and will extend it using "gold bead fiducials" (GBFs) to visualize orbital contents. (4) Using our muscle force transducers (MFTs) we will determine if LR and MR forces are consistent with globe translation, muscle paths and connective tissue movements observed with GBFs. Our second overall aim is to characterize complex articulations of the oculomotor plant. (5) We will determine if decreases in LR path length offset the convergence-related increase in contractile force predicted by the MN studies. (6) We will microstimulate MNs and use GBFs to visualize globe, pulley and other tissue movements, (7) determine if MN recruitment order varies with vergence state, and (8) if muscle forces vary with fixation accuracy. (9) We will study EOM unit summation in-vivo using multi-electrode stimulation and MFTs.

描述（由申请人提供）：意义：近40年的眼生理学一直基于一个强大的简化概念，即眼神经核、它们的颅神经和眼外肌（EOM）构成一个简单、均匀的最终共同路径（FCP），其中控制几种类型的眼球运动的超核信号匿名联合收割机。 因此，令人惊讶的是，使用直接肌肉力量测量和磁共振成像（MRI）进行的聚散眼球运动研究未能证实早期重复性良好的运动神经元（MN）研究的预测，如果FCP假设是正确的。 这个假设现在看来是站不住脚的，而眼药水植物的成熟探索其长期被忽视的功能丰富性。 超核性疾病大多无法治疗，而位于眼球周围的功能可能很容易受到药理学，外科手术和遗传操作。 与目前可用于治疗斜视和相关疾病的肌肉动作的粗略操作相比，对相关运动神经元和肌纤维专门化的理解将使实现细微变化成为可能。 研究：我们的第一个总体目标是描述FCP假设的失败：（1）我们将通过记录已识别的外展肌MN并同时测量在聚散时的LR力来有力地验证“缺失的外直肌（LR）力悖论”，继续（2）区分MN速率-位置曲线的斜率和Y截距的变化，并研究水平注视平面上LR和内直肌（MR）会聚力的变化。 (3)我们将在猴子身上重复一项在人类身上进行的MRI研究，该研究发现在会聚时没有地球仪回缩，并将使用“金珠基准点”（GBF）扩展该研究，以可视化眼眶内容物。 (4)使用我们的肌力传感器（MFT），我们将确定LR和MR力是否与GBF观察到的地球仪平移、肌肉路径和结缔组织运动一致。 我们的第二个总体目标是表征复杂的关节的oculopathy植物。(5)我们将确定LR路径长度的减少是否抵消了MN研究预测的收缩力的会聚相关增加。 (6)我们将微刺激MN并使用GBF来可视化地球仪、滑轮和其他组织运动，（7）确定MN募集顺序是否随聚散状态而变化，以及（8）肌肉力量是否随固定精度而变化。 (9)我们将使用多电极刺激和MFT在体内研究EOM单位总和。