CEREBELLAR MODULES AND EYE MOVEMENT CONTROL

小脑模块和眼球运动控制

• 批准号: 6273633
• 负责人: JOHN I SIMPSON
• 金额: $ 29.91万
• 依托单位: NEW YORK UNIVERSITY SCHOOL OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-12-01 至 1998-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6273633
• 关键词: cerebellar Purkinje cell; cerebellum; extraocular muscle; eye movements; granule cell; head movements; laboratory rabbit; olivary body; proprioception /kinesthesia; sensorimotor system; stretch reflex; vestibular nerve; visual fields; visual pathways; visual stimulus; visual tracking

The long-term objective is to better understand cerebellar function by investigating the neuronal signal processing underlying eye movements elicited by natural stimulation. The experiments will focus on the flocculus of the rabbit. The central theme is that signal processing in the flocculus entails mapping within and between intrinsic reference frames related to the geometry of the semicircular canals and the extraocular muscles, and that these reference frames have an anatomical counterpart in the modular organization of the cerebellum. The modular organization is seen in the cortex as anatomically distinguishable compartments containing physiologically distinct climbing fibers and their associated Purkinje cells. The modules are woven together by the parallel fibers, which traverse several modules. For the most part, the experimental method will be manipulation of extracellularly recorded Purkinje cell activity by presentation of natural visual, vestibular, and proprioceptive stimuli. The relative contribution of the ascending and parallel fiber segments of granule cell axons to generation of Purkinje cell simple spikes will be assessed by recording multi-unit granule cell activity and single unit Purkinje cell activity in the anesthetized rabbit in response to stimulation of extraocular proprioceptors. Distribution of this activity will be determined in relation to the floccular modules that differentially control particular extraocular muscles. If, as hypothesized, stretch of a particular eye muscle activates granule cells only in those modules that control that muscle, then the distribution of Purkinje cell activity across modules will provide a measure of the relative influence of the two parts of the granule cell axon. A similar study will be done using natural visual stimulation to investigate the generality of the findings. Two studies will provide a more unified view of climbing fiber function. In one study, extraocular proprioceptive stimulation will be used in the anesthetized rabbit to determine the conditions under which climbing fiber activation of Purkinje cells produces a short-lasting enhancement of simple spike modulation. In another study, pairs of floccular Purkinje cells will be recorded simultaneously in the awake rabbit to determine how the capacity of the inferior olive to discharge synchronously and rhythmically is influenced by eye movements evoked by natural visual and vestibular stimuli. In preparation for studying floccular participation in control of eye movements made in combination with head movements, contributions of neck muscle proprioceptors to signal processing will be investigated by recording from Purkinje cells in both the anesthetized and awake rabbit whose body can be rotated about a vertical axis while the head is stationary. One of the five floccular modules differs from the other four because its climbing fibers are not modulated by retinal image motion. The anatomy of the projections to the part of the inferior olive providing the climbing fibers to this module suggests that it may be related to voluntary gaze shifts. This hypothesis will be evaluated by recording from Purkinje cells in the awake rabbit allowed to move its head about the vertical axis to produce voluntary gaze shifts, which in the rabbit normally occur as combined eye/head movements.

长期目标是通过以下方法更好地了解小脑功能： 研究眼球运动背后的神经元信号处理 由自然刺激引起的。 实验将集中在 兔子的绒毛 中心主题是信号处理在 絮状物需要内在参照物内部和内部参照物之间的映射 与半规管的几何形状和 眼外肌，并且这些参考框架具有解剖学上的 小脑模块组织中的对应物。 模块化 组织在皮层中被视为解剖学上可区分的 含有生理上不同的攀援纤维和它们的 相关的浦肯野细胞。 模块通过平行线编织在一起 纤维，其穿过几个模块。 这其中大部分都 实验方法将是操纵细胞外记录 浦肯野细胞的活动，通过呈现自然的视觉，前庭， 本体感受刺激 提升者的相对贡献， 颗粒细胞轴突的平行纤维节段到浦肯野氏细胞的产生 通过记录多单位颗粒细胞来评估细胞简单峰电位 活动和单个单位浦肯野细胞活动在麻醉兔 对眼外本体感受器刺激的反应。 分布 该活性将相对于絮状物模块来确定，絮状物模块 不同地控制特定的眼外肌。 如果像 一个假设，一个特定的眼肌拉伸激活颗粒细胞 只有在那些控制肌肉的模块中， 跨模块的浦肯野细胞活性将提供对细胞的测量。 颗粒细胞轴突两部分的相对影响。 类似的 研究将使用自然视觉刺激来调查 调查结果的一般性。 两项研究将提供一个更统一的观点 攀爬纤维的功能。 在一项研究中，眼外本体感受 刺激将用于麻醉家兔，以确定 浦肯野细胞攀缘纤维激活的条件 产生简单尖峰调制的短暂增强。 在 在另一项研究中，将记录成对的絮状浦肯野细胞， 同时在清醒的兔子，以确定如何的能力， 下橄榄核同步节律性放电受影响 通过自然视觉和前庭刺激引起的眼球运动。 在 用于研究絮状物参与眼睛控制的制剂 与头部运动相结合的运动，颈部的贡献 肌肉本体感受器的信号处理将研究， 麻醉和清醒家兔浦肯野细胞的记录 其主体可绕垂直轴旋转，而头部 静止的 五个絮状模块中的一个与其他四个不同 因为它的攀爬纤维不受视网膜图像运动的调制。 下橄榄体提供部的投影解剖 这个模块的攀爬纤维表明它可能与 随意的目光转移 这一假设将通过记录 从清醒的兔子的浦肯野细胞中提取， 垂直轴，以产生自愿的凝视转移，这在兔子 通常以眼睛/头部运动的组合形式发生。