Role of Oculomotor Vermis Parallel Fibers in Saccades

描述(由申请人提供)：小脑的输出对于做出准确的自愿快速眼动至关重要，这种运动被称为眼跳。准确的扫视对于我们清楚地看到周围的世界是必不可少的，因为眼睛的高分辨率部分，即中心凹，非常小。为了看得清楚，我们必须将中心凹快速而准确地对准我们想要看到的东西。小脑眼球运动部分受损的患者无法做出准确的眼跳，并且很难看到周围的世界。 影响眼跳水平成分的小脑输出由小脑尾侧顶核(CFN)内神经元的动作电位爆发组成。小脑一侧的CFN细胞在离开该侧的眼跳早期表现出动作电位爆发(对比性眼跳)。这些早期的爆发有助于加速对比性眼跳。CFN细胞也会在晚些时候爆发，以便向其所在的一侧眼跳(自发性眼跳)。这些脉冲有助于减速自发性眼跳。 对于自发性眼跳，后期减速爆发对眼跳的影响比早期加速爆发的影响要大得多。它还在很大程度上负责确保扫视的准确性。进入小脑的任何信号都不像这些晚期减速脉冲，所以几乎可以肯定，小脑通过改变它接收的信号来产生它们。 我们认为，小脑通过延迟来自小脑外部的眼跳相关信号来产生迟发的、减速的CFN爆发。它通过小脑中称为平行纤维(p纤维)的轴突中的眼睛运动部分传导这些信号来延迟这些信号。如果这是真的，那么阻断小脑眼球运动部分的P纤维将消除CFN神经元的晚期爆发。扫视不会减速到足够快，所以他们会超过目标。这里提出的工作将通过测量我们切断小脑眼球运动部分的P纤维后的眼跳来决定性地检验这一假说。

DESCRIPTION (provided by applicant): Output from the cerebellum is critical to making accurate voluntary rapid eye movements, called saccades. Accurate saccades are essential to our clearly seeing the world around us because the high-resolution part of the eye, the fovea, is very small. To see clearly we must aim the fovea quickly and accurately at the things we want to see. Patients with damage to the eye movement part of the cerebellum cannot make accurate saccades and have a very difficult time seeing the world around them. The cerebellar output influencing the horizontal component of saccades consists of action potential bursts from neurons inside the cerebellum, the caudal fastigial nucleus (CFN). CFN cells on one side of the cerebellum exhibit action potential bursts early in saccades away from that side (contraversive saccades). These early bursts help accelerate contraversive saccades. CFN cells also burst later for saccades toward the side they are on (ipsiversive saccades). These bursts help decelerate ipsiversive saccades. The later decelerating, burst for ipsiversive saccades influences saccades much more than the early, accelerating burst does. It is also largely responsible for making saccades accurate. No signal going into the cerebellum resembles these late decelerating bursts so the cerebellum almost certainly produces them by changing the signals that it receives. We propose that the cerebellum generates late, decelerating, CFN bursts by delaying saccade-related signals that come from outside the cerebellum. It delays these signals by conducting them through the eye movement part of the cerebellum in axons called parallel fibers (p-fibers). If this is true, then interrupting p-fibers in the eye movement part of the cerebellum will abolish the late burst in CFN neurons. Saccades will not decelerate enough so they will overshoot their targets. The work proposed here will conclusively test this hypothesis by measuring saccades after we cut the p-fibers in the eye movement part of the cerebellum.