The Neural Control of Disconjugate Saccades

为了在三维空间中准确地观察近目标和远目标，关于相对深度的信息从视觉皮层发送到脑干中的运动控制中心，这些运动控制中心反过来产生适当的运动命令来移动眼睛。然而，令人惊讶的是，视觉皮层提供的深度信息如何用于精确地将每只眼睛瞄准视觉目标是非常有争议的。因此，这个项目的目的是了解大脑如何控制眼球运动，以准确地看到近和远的物体。我们先前的实验提供了令人信服的证据，即长期被认为是纯粹共轭前运动驱动的来源的脑干扫视发生器实际上提供了时间上适当的聚散信息来驱动近目标和远目标之间的快速扫视眼球运动（即，分离性扫视）。事实上，大多数神经元动态地编码单个眼睛的运动，并且它们的时变放电编码产生精确的非共轭扫视所需的驱动。 在本提案中，我将把这项工作带到下一个层次，并确定与运动前神经元相关的趋同信号的来源。我将集中在两个候选区域：1）上级丘，它接收来自视差敏感皮层区域（如额叶眼野）的输入; 2）小脑（特别是眼蚓部和小脑顶核），其中包含对运动前扫视神经元具有重要投射的神经元。在这些区域编码的眼睛命令信号将在警觉行为的猴子在远近观看任务中进行量化。在我们的实验室开发的系统识别技术将被用来描述神经元的反应动力学。由此产生的研究结果将被用来生成一个新的生理相关模型的双目控制。总之，我们的生理和建模结果也将为理解大脑在控制更复杂的自主运动时协调多块肌肉激活的一般策略提供基础。

To accurately look between near and far targets in 3-dimensional space, information about relative depth is sent from the visual cortex to the motor control centers in the brainstem, which in turn generate appropriate motor commands to move the eyes. Surprisingly, however, how the depth information supplied by the visual cortex is used to precisely aim each eye on a visual target is highly controversial. Accordingly, the objective of this project is to understand how the brain controls eye movements to accurately look between near and far objects. Our previous experiments provided compelling evidence that the brainstem saccadic generator, which was long considered a source of purely conjugate premotor drive, in fact provides temporally appropriate vergence information to drive rapid saccadic eye movements between near and far targets (i.e., disjunctive saccades). Indeed, the majority neurons dynamically encode the movement of an individual eye, and their time-varying discharges encode the drive required to produce accurate disconjugate saccades. In the present proposal, I will take this work to the next level and identify the source of the vergence-related signal to premotor neurons. I will focus on two candidate regions: 1) the superior colliculus, which receives inputs from disparity sensitive cortical regions such as the frontal eye fields, and 2) the cerebellum (specifically, oculomotor vermis and fastigial nucleus), which contain neurons with important projections to premotor saccadic neurons. The eye command signals encoded in these regions will be quantified in alert behaving monkeys during near-far viewing tasks. System identification techniques developed in our laboratory will be used to describe neuronal responses dynamics. The resultant findings will be used to generate a novel physiologically-relevant model of binocular control. Taken together, our physiological and modeling results will also provide a foundation for understanding the general strategies used by the brain to coordinate the activation of multiple muscles in the control of more complex voluntary movements.