Frontal Cortex Control of Gaze Shifts

额叶皮层对目光转移的控制

• 批准号: 6621612
• 负责人: Longtang Chen
• 金额: $ 36.04万
• 依托单位: BAYLOR COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-02-01 至 2004-01-14
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6621612
• 关键词: Macaca mulatta; computer data analysis; eye movements; frontal lobe /cortex; head movements; microelectrodes; neuroregulation; single cell analysis; visual fields; visual fixation

Gaze shift is an important visuomoter process involving coordinated movements of the eyes and head for learning about the visual environment. A gaze shift involves not only moving the line of sight to foveate visual targets, but also aligning the head position with the gaze to permit2 flexible oculomotor movements with high visual acuity. This process is thought to involve the neural networks of the frontal cortex and those of the brainstem in order to orchestrate coherent movements. Recently, studies in the brainstem have shown that many of the previously assumed "pure oculomoter" structures in fact control movements of both the eyes and the head. These findings pose serious challenges to our current understanding of oculomoter control in the frontal cortex as to whether t he cortex encodes eye movements alone, as the name "oculomoter" claims, or gaze (i.e., coordinated movements of the eyes and head), as in the superior colliculus and other brainstem sites. Verifying these hypothesis will significantly advance our understanding of movement control. Because these issues have not been thoroughly investigated in part due to a lack of satisfying methodology to differentiate the contribution of eye and head during gaze shifts; we will attempt in the proposed experiments to use techniques that separate the contribution of the eyes and head to gaze. The results of electrical microstimulation, reversible inactivation/activation, and chronic single-unit recording will be related to predefined variables, such that the contribution of each movement can be sufficiently elaborated. Under Specific Aim 1, we will study the function of the frontal eye field (FEF) and the supplementary eye field (SEF) on the control of movements of the eyes and head. Based on suggestions of previous studies and our preliminary findings, the FEF and the4 SEF are the most relevant oculomoter areas in the frontal cortex. We ask: both the FEF and the SEF neurons generate signals that control the movements of both the eyes and head, or does each region generate separate signals that control part of the movements? We will train head-unrestrained monkeys in tasks that separate the contribution of the eyes and head to gaze to assess these possibilities. Under Specific Aim 2, we will study the mechanism of maintaining gaze/head alignment following changes in gaze. We hypothesize that a newly discovered region near the SEF participates in the control of this process by evoking head (not eye) movement to center the eyes in the orbit, irrespective of initial gaze positions in space. We will assess this hypothesis in the proposed experiments using the techniques mentioned above. The proposed studies will not only provide new information about how the frontal cortex controls gaze shifts, but also reveal important insights relating to now the neural networks of the cortex and brainstem together control gaze shifts.

目光转移是一个重要的视觉运动过程，涉及眼睛和头部的协调运动，以了解视觉环境。目光转移不仅包括移动视线以聚焦视觉目标，还包括将头部位置与目光对齐，以允许灵活的眼球运动，从而提高视觉敏锐度。这个过程被认为涉及额叶皮层和脑干的神经网络，以协调连贯的运动。最近，对脑干的研究表明，许多先前假设的“纯眼动”结构实际上控制着眼睛和头部的运动。这些发现对我们目前对眼动控制在额叶皮层的理解提出了严峻的挑战，即皮层是否像“眼动”这个名字所声称的那样单独编码眼球运动，或者像在上丘和其他脑干部位那样编码凝视（即眼睛和头部的协调运动）。验证这些假设将大大促进我们对运动控制的理解。因为这些问题还没有得到彻底的调查，部分原因是缺乏令人满意的方法来区分眼睛和头部在凝视转移过程中的贡献；在我们提出的实验中，我们将尝试使用分离眼睛和头部对凝视的贡献的技术。电微刺激、可逆失活/激活和慢性单单元记录的结果将与预定义的变量相关，这样每个运动的贡献可以充分阐述。在具体目标1中，我们将研究前额眼场（FEF）和辅助眼场（SEF）对眼睛和头部运动的控制功能。根据前人的研究建议和我们的初步发现，FEF和4 SEF是额叶皮层中最相关的动眼病区。我们的问题是：FEF和SEF神经元都产生控制眼睛和头部运动的信号，还是每个区域都产生单独的信号来控制部分运动？我们将训练不受头部约束的猴子，将眼睛和头的作用分开，以评估这些可能性。在具体目标2中，我们将研究凝视变化后保持凝视/头部对齐的机制。我们假设一个新发现的靠近SEF的区域参与了这一过程的控制，通过唤起头部（而不是眼睛）的运动来使眼睛在轨道中心，而不管最初的凝视位置在空间中。我们将在使用上述技术的拟议实验中评估这一假设。所提出的研究不仅将提供关于额叶皮层如何控制凝视转移的新信息，而且还将揭示与皮层和脑干的神经网络共同控制凝视转移有关的重要见解。