Vestibular and Neck Contribution to Oculomotor Processing in the Frontal Cortex

描述（申请人提供）：过去大量的研究表明，诱发的动眼病矢量反映了视运动坐标变换的过程。最近的一些研究表明，非动眼力变量，如前庭和/或颈部本体感觉，可以改变动眼力坐标。我们的初步研究进一步表明，相对于静态垂直头部位置的变化，前额视野（FEF）神经诱发的跳囊矢量方向向代偿方向移动。这些发现共同表明，即使头部不运动，前庭和/或颈部输入也可能对视觉运动坐标框架的更新至关重要。基于这些发现，我们假设耳石（内耳器官，专门用于检测相对于重力的静态头部位置）可能向额叶皮层提供关键输入，以帮助形成动眼肌坐标。另外，颈部本体感觉输入可能很重要，它通常与前庭信号一起变化。为了确定我们的发现是仅仅由前庭输入（前庭假设），颈部本体感觉输入（颈部假设），还是两者都有，我们开发了一种新的方法，允许在独立控制相关运动变量的基础上分离前庭和颈部影响，例如初始眼位（IEP），初始头位（IHP）和初始颈部位置（INP），在头部不受约束的动物中。工作假设的预测将通过在提出的实验中系统地操纵这些变量来评估。在具体目标1中，我们将评估前庭和/或颈部本体感觉输入是否参与FEF和辅助视野（SEF）的视觉运动协调加工（即决定刺激诱发的跳眼的方向）。在具体目标2中，我们将确定前庭和颈部本体感觉输入是否更新FEF和SEF神经元的运动和/或视觉坐标。这些实验有望为理解空间坐标的皮质加工提供见解，并且这些发现将对进一步理解运动控制的神经机制具有重要意义。

DESCRIPTION (provided by applicant): Vast amounts of research in the past have shown that the evoked oculomotor vectors reflect the process of visuomotor coordinate transformation. Some recent studies have shown that non-oculomotor variables, such as vestibule and/or neck proprioception, can alter the oculomotor coordinates. Our preliminary studies further indicate that the directions of the neurally evoked saccadic vectors in the frontal eye field (FEF) are shifted in the compensatory direction with respect to changes in static vertical head position. These findings together suggest that the vestibule and/or neck inputs may be critical in updating the visuomotor coordinate frames even if the head is not moving. Based on these findings, we hypothesize that the otoliths, the inner ear organs dedicated to the detection of static head position with respect to gravity, may provide critical inputs to the frontal cortex to help shape the oculomotor coordinates. Alternatively, the neck proprioceptive inputs, which often vary together with the vestibular signals, may be important. To determine whether our findings are contributed solely by vestibular inputs (vestibule hypothesis), neck proprioceptive inputs (neck hypothesis), or both, we have developed a novel approach which permits dissociation of vestibular and neck influences based on independent control of the pertinent movement variables, e.g. initial eye position (IEP), initial head position (IHP), and initial neck position (INP), in head-unrestrained animals. The predictions of the working hypotheses will be evaluated by systematic manipulation of these variables in the proposed experiments. Under Specific Aim 1, we will assess whether vestibular and/or neck proprioceptive inputs participate in the visuomotor coordinate processing (i.e. determining the directions of the stimulation-evoked saccades) in the FEF and supplementary eye field (SEF) of head-unrestrained monkeys. Under Specific Aim 2, we will determine if the vestibular and neck proprioceptive input updates the motor and/or visual coordinates of FEF and SEF neurons. These experiments are expected to bring insights into the understanding of cortical processing of spatial coordinates, and the findings will be important to further the understanding of the neural mechanisms of motor control in general.