Neural Activity in Guinea Pig Vestibular Nuclei During Volitional Head Movements

描述（由申请人提供）：自愿的快速眼睛和头部运动用于在空间中转移视线。快速眼球运动的持续时间比头部运动短，因此需要在头部转动时补偿性眼球反旋转，以稳定视网膜图像和凝视的空间方向（等于眼睛和头部位置的总和）。前庭眼反射（VOR）产生代偿性眼动，这一理论已被广泛接受。然而，最近发表的数据表明，当凝视稳定是一个行为目标时，豚鼠使用前庭外信号（例如，头部运动的参考拷贝）代替VOR来补偿头部运动。这种反应是预期的，因为相对于头部运动，它发生的潜伏期为零。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输出拷贝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，因此由主动头部运动产生的参考也必须取消。我们假设前庭感觉的内部模型被用来将前庭外信号转换为抵消参考的信号。具体来说，我们假设一个神经回路，其中包括前庭核中的一个前庭神经（VO）和眼动敏感（ES）神经元子集以及小脑小叶中的浦肯野细胞执行这种取消并产生预期的眼动。本提案的具体目的是：(1)通过记录头部不受约束的豚鼠被动和主动头部转动时的次级前庭神经元来直接验证这一假设；(2)改进和证明两种新型设备的有效性：微型微型驱动器和6自由度运动传感器，用于记录头部不受约束动物的单个单元数据和多维度头部运动。

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.