DIRECTIONALLY SENSITIVE INPUT TO OCULOMOTOR PATHWAYS

前庭眼反射（VOR）通常使眼睛与 头部旋转以稳定视网膜上的视觉图像。VOR 已知增益（响应刺激）适应于改变一个新的值， 长期修改的感觉输入，从而稳定视网膜 图像，以促进视觉处理在大脑的其他地方进行。 这项建议将研究这种神经可塑性的起源， 小脑和脑干在视觉和前庭不匹配产生的 体外 使用一种新的体外龟脑制剂， 骨骼附着的自然感觉刺激将为长期的 VOR适应。整个视野视觉运动的视觉模式将是 成像到整个视网膜表面上，而整个制备被 在速率表上旋转。初步结果显示，在这些 正常的视觉和前庭反应是由 脑干中的一级神经元视觉模式的速度 运动编码在辅助视神经系统（基底视神经）的神经元中 核）和顶盖前（中脑豆状核），而volcity的 头部旋转的头部旋转被编码在前庭神经核中。 对这些感觉信号的反应也被记录在 小脑皮层这种龟脑制剂仍然对 这些自然的感官刺激在体外几天后。 这个项目有三个目标。首先，神经元将在 参与VOR适应性变化的通路;小脑皮质 和前庭神经核。第二，正常的视觉和前庭反应 将使用正弦刺激来表征这些神经元。最后， 大脑将同时暴露于两种感官刺激， 连续地，使得视觉运动将发出在视觉运动中的不稳定性的信号。 视网膜图像沿着与驱动头部旋转相同的轴 眼球反射在暴露于这些成对的感觉器官的数小时内， 信号，预计仅对前庭刺激的反应 将改变，试图减少视网膜图像的不稳定性。 这项研究将确定适应性细胞，它们的反应特性， 以及适应的时间进程。该项目还开发了一个 实验准备，在未来的细胞内研究， 确定神经可塑性产生的突触机制 并且可以识别其突触前和突触后成分。全 了解这种神经过程可能会导致更好的治疗方法， 视觉和平衡障碍。

The vestibuloocular reflex (VOR) normally moves the eyes opposite that of head rotation in order to stabilize the visual image on the retina. VOR gain (response-stimulus) has been known to adapt to a new value alter a long-term modification of the sensory input and thus stabilize the retinal image to facilitate visual processing performed elsewhere in the brain. This proposal will study the origins of this neural plasticity in the cerebellum and brainstem during visual and vestibular mismatch produced in vitro. Using a novel in vitro turtle brain preparation with the eyes and temporal bone attached, natural sensory stimuli will provide inputs for long-term VOR adaptation. Visual patterns of whole field visual motion will be imaged onto the entire retinal surface, while the entire preparation is rotated on a rate table. Preliminary results show that under these conditions, normal visual and vestibular responses are elicited by the first order neurons in the brainstem. The velocity of visual pattern motion is encoded in neurons of the accessory optic system (Basal Optic Nucleus) and pretectum (Mesencephalic Lentiform Nucleus), while volcity of the head rotation of head rotation is encoded in the vestibular nucleus. Responses to either of these sensory signals have also been recorded in the cerebellar cortex. This turtle brain preparation remains responsive to these natural sensory stimuli after days in vitro. There are three aims of this project. First, neurons will be identified in pathways involved in adaptive changes of the VOR; the cerebellar cortex and vestibular nucleus. Second, the normal visual and vestibular responses of these neurons will be characterized using sinusoidal stimuli. Finally, the brain will be exposed to both sensory stimuli simultaneously and continuously, such that visual motion will signal an instability in the retinal image along the same axis as the rotation of the head that drives the oculomotor reflex. Within hours of exposure to these paired sensory signals, it is expected that the response to vestibular stimulation alone will change, in an attempt to reduce the instability in the retinal image. This study will identify the adaptive cells, their response properties, and the time course of adaptation. This project also develops an experimental preparation in which future intracellular studies can determine the synaptic mechanisms by which neural plasticity is generated and can identify its presynaptic and post-synaptic components. A full understanding of this neural process may lead to better treatments for visual and balance disorders.