Role of Oculomotor Vermis Parallel Fibers in Saccades

描述（由申请人提供）：小脑的输出对于进行准确的自愿快速眼球运动（称为扫视）至关重要。准确的扫视对于我们清楚地看到周围的世界至关重要，因为眼睛的高分辨率部分，中央凹，非常小。为了看得更清楚，我们必须快速准确地将中央凹对准我们想看的东西。小脑的眼球运动部分受损的患者无法进行准确的扫视，并且很难看到周围的世界。 影响扫视水平分量的小脑输出包括来自小脑内的神经元（尾顶核（CFN））的动作电位爆发。小脑一侧的CFN细胞在远离该侧的扫视中早期表现出动作电位爆发（逆向扫视）。 这些早期爆发有助于加速逆向扫视。CFN细胞也会在以后爆发，向它们所在的一侧扫视（同侧扫视）。这些爆发有助于减缓自激扫视。 同向眼跳的后减速爆发比前加速爆发对眼跳的影响更大。它也主要负责使扫视准确。没有任何信号进入小脑类似于这些晚期减速爆发，所以小脑几乎肯定是通过改变它接收到的信号来产生它们的。 我们认为小脑通过延迟来自小脑外部的扫视相关信号来产生迟发的、减速的CFN爆发。它通过平行纤维（p纤维）轴突中小脑的眼球运动部分来延迟这些信号。如果这是真的，那么中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。扫视不会足够减速，所以他们会超过他们的目标。这里提出的工作将最终测试这一假设，通过测量扫视后，我们切断的p-纤维的眼球运动部分的小脑。

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.