Neural Activity in Guinea Pig Vestibular Nuclei During Volitional Head Movements

描述（由申请人提供）：自愿快速的眼睛和头部运动用于转移空间中的视线。快速眼球运动的持续时间短于头部运动，头部运动需要在头部转动期间进行补偿性眼球反向旋转，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）。前庭眼反射（vestibulo-ocular reflex，VOR）是眼代偿运动的主要机制。然而，最近公布的数据表明，当注视稳定性是行为目标时，豚鼠使用前庭外信号（例如，头部运动的传出副本）来代替VOR以补偿主动头部运动。这种反应是预期性的，因为它相对于头部运动具有零延迟。我们假设，前庭外信号编码在前庭核和/或小脑从预期的头部运动或本体感受反馈的头部运动相关的传出副本。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反馈。我们假设前庭感觉中枢的内部模型用于将前庭外信号转换为取消refference的信号。具体来说，我们假设包括前庭核中的仅前庭（VO）和眼动敏感（ES）神经元子集以及小脑绒球中的浦肯野细胞的神经回路执行这种抵消并产生预期的眼动。该提案的具体目的是：（1）通过记录被动和主动头部转动期间头部不受限制的豚鼠的次级前庭神经元来直接测试该假设;（2）改进和证明两种新型设备的有效性：微型微驱动器和6-dof运动传感器，以记录头部不受限制的动物的单个单元数据和多个维度的头部运动。

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.