Neural Activity in Guinea Pig Vestibular Nuclei During Volitional Head Movements

描述(由申请者提供)：在太空中，眼睛和头部的自主快速运动用于转移凝视。快速眼球运动的持续时间比头部运动短，需要在头部转动时进行补偿性的眼睛反旋转，以稳定视网膜图像和空间中的凝视方向(等于眼睛和头部位置的总和)。人们普遍认为前庭-眼反射(VOR)会产生代偿性眼球运动。然而，最近发表的数据表明，当凝视稳定是行为目标时，豚鼠使用前庭外信号(例如，头部运动的传出副本)来代替VOR来补偿主动的头部运动。这种反应是可预见的，因为它相对于头部运动是以零延迟发生的。我们假设，前庭外信号在前庭核和/或小脑中编码，来自预期头部运动的传出副本或与头部运动相关的本体感觉反馈。由于预期反应必须取代VOR，因此也必须取消由主动头部运动引起的再传入。我们假设，前庭感觉区的内部模型被用来将前庭外信号转换为取消再传入的信号。具体地说，我们假设了一个神经回路，它包括前庭核中的仅前庭(VO)和眼动敏感(ES)神经元的子集，以及小脑小叶中的浦肯野细胞，执行这种抵消并产生预期的眼动。这项建议的具体目的是(1)通过记录被动和主动转头时头无约束豚鼠的次级前庭神经元来直接检验这一假说，(2)完善和演示两种新设备的有效性：微型微型驱动器和6自由度运动传感器，以记录头无约束动物在多个维度的单位数据和头部运动。

DESCRIPTION (provided by applicant): Voluntary rapid eye and head movements are used to shift gaze in space. Rapid eye movements are shorter in duration than head movements necessitating compensatory ocular counter-rotation during head turns in order to stabilize the retinal image and direction of gaze in space (equal to the sum of eye and head position). It is widely accepted that the vestibulo-ocular reflex (VOR) produces the compensatory eye movement. However, recently published data demonstrate that when gaze stability is a behavioral goal, guinea pigs use extra-vestibular signals (e.g., efference copy of head movement) in place of the VOR to compensate for active head movement. This response is anticipatory because it occurs with zero latency relative to the head movement. We hypothesize that the extra-vestibular signal is encoded in the vestibular nucleus and/or cerebellum from either an efference copy of the intended head movement or proprioceptive feedback related to the head movement. Since the anticipatory response must replace the VOR, the reafference that results from the active head movement must also be cancelled. We hypothesize that an internal model of the vestibular sensorium is used to transform the extra-vestibular signal into a signal that cancels the reafference. Specifically, we hypothesize a neural circuit that includes a subset of vestibular-only (VO) and eye movement sensitive (ES) neurons in the vestibular nucleus and Purkinje cells in the cerebellar flocculus perform this cancellation and produce the anticipatory eye movement. The specific aims of this proposal are designed (1) to directly test this hypothesis by recording from secondary vestibular neurons of head-unrestrained guinea pigs during passive and active head turns and (2) to refine and demonstrate the effectiveness of two novel devices: a miniature micro-drive and a 6-dof motion sensor to record single unit data and head movements in multiple dimensions from a head unrestrained animal.