Neural control of coordinated eye movements

项目摘要/摘要 我们通过进行分离的扫视来观察位于3D视觉环境中的目标之间的关系 目标图像传到两个中心凹上。每一次凝视转移之后都有一段用于视觉分析的注视时间段 必须保持新的收敛级别。大多数研究都集中在控制共轭的电路上 眼跳，而神经控制的分离性眼跳和集中眼球运动收到的较少 学习。几个模型表明，外展运动神经元发送单目命令，携带信息到 每只眼睛都能控制分离的眼跳。其他模型已经提出了眼跳-收敛爆发的存在 投射到内侧直肌运动神经元的神经元(SVBN)，只有在分离性眼跳时才活跃。我们 已经确定了这种新的细胞类型，它只在分离性眼跳时放电，在中央 动眼神经核(OMN)外侧的中脑网状结构(CMRF)。电微刺激 在cMRF的这个区域，会引起分离的眼跳，而失活则会损害聚光凝视的保持。 最近的解剖学发现表明，与近反应相关的前运动神经元位于 在cMRF，它们投射到视上运动区(SOA)和OMN。我们假设 CMRF，特别是SVBN，在分离性眼跳的产生中起着关键作用。我们进一步 假设cmrf和soa之间的投射形成了先前未描述的神经回路的一部分。 这会产生会聚积分，允许在固定过程中保持会聚角度。其他解剖学 电生理结果表明，小脑，特别是尾侧顶核和 后间隔核，在控制眼球运动方面起着重要作用 斜视患者。因此，我们假设小脑对cMRF/SOA复合体的输入有助于 编码或调制分离的眼跳。在这些总体假设的指导下，我们提出了具体的目标 来描述这种神经回路。1.确定SVBNS和cMRF在生产 分离性眼跳；2.检验cMRF/SOA复合体是收敛积分器的假设 负责保持收敛水平；3.确定小脑投射如何 Cmrf/soa回路参与了分离性眼跳和聚光眼的产生。 动静。为了检验我们的具体假设，我们将使用既定的神经生理学技术。 (电生理记录、逆行激活、电微刺激和可逆 药理调节)。我们项目的总体目标是大幅增加我们对 神经回路控制灵长类动物的3D眼球运动，并广泛影响眼动场，导致 新的神经生理学和建模方法。这些发现也将为以下研究提供关键依据 了解斜视等眼球运动功能障碍患者缺乏精确的双眼协调。

Project Summary / Abstract We look between targets located in the 3D visual environment by making disjunctive saccades that bring the target image onto both foveae. Each gaze shift is followed by a fixation period for visual analysis during which the new vergence level must be maintained. Most studies have focused on the circuitry controlling conjugate saccades, whereas the neural control of disjunctive saccades and vergence eye movements has received less study. Several models suggest that abducens motoneurons send a monocular command carrying information to each eye to control disjunctive saccades. Other models have proposed the existence of saccade-vergence burst neurons (SVBNs) that project to medial rectus motoneurons and are active only during disjunctive saccades. We have identified this novel cell type, which only discharge during disjunctive saccades, in the central mesencephalic reticular formation (cMRF) lateral to the oculomotor nucleus (OMN). Electrical microstimulation in this region of the cMRF elicits disjunctive saccades, whereas inactivation impairs vergence gaze holding. Recent anatomical findings have demonstrated that premotor neurons related to the near response are located in the cMRF, and that they project to the supraoculomotor area (SOA) and to the OMN. We hypothesize that the cMRF, and the SVBNs in particular, play a critical role in the generation of disjunctive saccades. We further hypothesize that projections between the cMRF and SOA form part of a previously undescribed neural circuit that produces vergence integration, allowing vergence angle to be maintained during fixation. Other anatomical and electrophysiological findings demonstrate that the cerebellum, specifically, the caudal fastigial nucleus and the posterior interposed nucleus, play a role in controlling vergence eye movements in both normal and strabismic individuals. We therefore hypothesize that the cerebellar input to the cMRF/SOA complex helps encode or modulate disjunctive saccades. Guided by these overarching hypotheses, we propose Specific Aims to characterize this neural circuitry. 1. To determine the role of SVBNs and the cMRF in the production of disjunctive saccades; 2. To test the hypothesis that the cMRF/SOA complex is the vergence integrator responsible for maintaining the level of convergence; 3. To determine how the cerebellar projections to the cMRF/SOA circuitry are involved in the generation of disjunctive saccades and vergence eye movements. To test our specific hypotheses, we will use established neurophysiological techniques (electrophysiological recordings, antidromic activation, electrical microstimulation and reversible pharmacological modulation). The overall goal of our project is to substantially increase our understanding of the neural circuitry controlling 3D eye movements in primates, and to broadly impact the oculomotor field, leading to new neurophysiological and modeling approaches. These findings will also provide a critical basis for understanding the absence of precise binocular coordination in eye movement dysfunctions such as strabismus.