Bbrainstem control of slow ocular drifts during gaze fixation

在凝视注视过程中，微小的眼球运动，包括缓慢的眼球漂移和微扫视，持续发生。尽管这些眼球运动已经存在了几十年，但它们的产生机制及其对视觉、知觉和认知的影响仍未得到充分的研究。在过去的15年里，对微眼跳的研究经历了显著的复兴，特别是在神经机制方面，但慢眼漂移的机制仍然是一个主要的研究前沿。我们的研究计划的主要目标是在脑干水平上揭示控制缓慢眼球漂移的神经机制。我们将研究脑干全食神经元(OPN)和上丘(SC)在漂移和微眼跳控制和协调中的因果作用。我们假设SC和OPNS协同作用，SC活动为眼球漂移提供位置估计，而OPN活动影响眼速。我们提案的变革性方面有两个方面。首先，我们将揭示迄今为止未知的与最微小的眼球运动相关的神经生理机制。其次，考虑到系统神经科学研究的很大一部分是在凝视注视条件下进行的，我们的工作将澄清在这类研究中观察到的行为和神经影响在多大程度上可能是阈值下动眼行为的函数。例如，眼球漂移不断地发生，因此不断地转换视网膜图像。如果这些眼球运动被证明是集中控制的，而不是随机的，那么它们的出现可能会对各种视觉处理实验的结果做出贡献。根据我们之前对微眼跳的研究结果，我们预计，由于我们提出的关于眼球漂移的研究，系统神经科学中的几个经典现象最终可能会被赋予不同的、但耐人寻味的光。

During gaze fixation, tiny eye movements, including slow ocular drifts and microsaccades, continuously occur. Even though these eye movements have been known to exist for several decades, both their mechanisms of generation and their impacts on vision, perception, and cognition remain to be heavily under-investigated. During the past ~15 years, research on microsaccades has experienced a significant revival, especially in terms of neural mechanisms, but the mechanisms for slow ocular drifts remain to be a major research frontier. The main goal of our research proposal is to uncover the neural mechanisms for the control of slow ocular drifts at the level of the brainstem. We will investigate the causal role of brainstem omnipause neurons (OPNs) and superior colliculus (SC) in both drift and microsaccade control and coordination. We hypothesize that SC and OPNs engage synergistically such that SC activity provides a position estimate for ocular drifts and OPN activity influences eye velocity. The transformative aspects of our proposal are twofold. First, we will uncover hitherto unknown neurophysiological mechanisms associated with the smallest of eye movements. Second, given that a significant portion of systems neuroscience research with awake, behaving subjects is conducted under gaze fixation conditions, our work will clarify how much of behavioural and neural effects observed in such research may be a function of subliminal oculomotor behaviour. For example, ocular drifts occur incessantly and thus keep translating retinal images. If these eye movements turn out to be centrally controlled and not random, then their occurrence may contribute to the results of a variety of experiments on visual processing. Based on the outcome of our previous work with microsaccades, we anticipate that several classic phenomena in systems neuroscience may likewise eventually be cast in a different, yet intriguing, light as a result of our proposed research on ocular drifts.