Visual perception during movements of the eyes and head

这个正在进行的研究项目的目标是对凝视转移和视觉感知之间的相互作用进行严格的理解。在过去的100年里进行的行为实验已经注意到，在被称为扫视的快速眼球运动期间，视觉感知发生了广泛的变化。这些包括刺激位置、时间甚至形状的虚幻变化。对于被称为平滑追踪的较慢的眼球运动，也发现了类似的感知效果。综上所述，这些效应揭示了动眼肌信号对视觉感知的明显影响。然而，它们通常是在相当人工的条件下进行研究的，在这种条件下，受试者被指示做一个单一的眼球运动，同时呈现一个孤立的视觉刺激。******我们假设这些知觉错觉是神经机制的副作用，实际上是在更自然的条件下改善视觉功能。本提案的主要目标是用定量的细节来检验这个想法。******我们用来理解视觉和眼球运动相互作用的模型是猕猴的视觉皮层。我们特别研究了V4区、IT区、MT区和MST区的神经元，这些神经元参与了视觉信息与与扫视和平滑追踪相关的动眼肌信号的整合。我的实验室和其他人之前的工作已经证明，在眼球运动前后，这些区域的视觉处理发生了深刻的变化。然而，很少有人试图将这些神经变化与人类受试者的感知变化正式联系起来。此外，这些变化的功能益处尚不清楚：动眼肌对视觉处理的特定影响模式如何提高我们定位和识别物体的能力？很少有人试图回答这个问题，有些人认为动眼肌输入根本不能改善视力。******提出的研究将通过开发一个新的框架来解释眼动过程中的视觉处理来解决这个问题。这将基于眼球运动和稳定注视时的多电极记录。这些数据将被用来描述视觉皮层神经元群中刺激信息编码的数学特征。重要的是，这个框架导致了关于动眼肌影响在自然视觉中的作用的具体预测：用于定位空间中的物体，用于识别它们，以及用于估计它们的速度。当动物自由地观看自然场景时，我们将通过记录相同的神经元来测试这些预测。然后，这个框架将扩展到眼-头联合运动的研究，以确定视觉-动眼力整合的计算优势是否也转化为眼-头凝视的移动。综上所述，这些结果将有助于深入了解灵长类动物大脑中视觉和动眼肌信号之间的功能相互作用。

The goal of this ongoing research program is to develop a rigorous understanding of the interaction between gaze shifts and visual perception. Behavioral experiments conducted over the last 100 years have noted a wide range of changes in visual perception around the time of fast eye movements called saccades. These include illusory changes in stimulus position, timing, and even shape. A similar range of perceptual effects has been found for slower eye movements known as smooth pursuit. Together these effects reveal a clear influence of oculomotor signals on visual perception. Yet they have typically been studied under rather artificial conditions, in which subjects are instructed to make a single eye movement, while an isolated visual stimulus is presented.******We hypothesize that these perceptual illusions are a side effect of neural mechanisms that actually improve visual function under more natural conditions. The main goal of this proposal is to examine this idea in quantitative detail.******Our model for understanding the interaction of vision and eye movements is the visual cortex of the macaque monkey. In particular, we study neurons in areas V4, IT, MT, and MST, which have are involved in integrating visual information with oculomotor signals related to saccades and smooth pursuit. Previous work from my lab and others has demonstrated profound changes in visual processing in these areas around the time of eye movements. However, there has been little attempt to formally link these neural changes to the perceptual changes that are seen in human subjects. Moreover, the functional benefit of these changes is unknown: How does the specific pattern of oculomotor influences on visual processing improve our ability to localize and recognize objects? There has been little attempt to answer this question, and some have argued that vision is not improved by oculomotor inputs at all.******The proposed research will address this issue by developing a novel framework for interpreting visual processing during eye movements. This will be based on multi-electrode recordings during eye movements and during steady fixation. Together these data will be used to characterize mathematically the coding of stimulus information in neuronal populations in the visual cortex. Importantly, this framework leads to specific predictions about the role of oculomotor influences in natural vision: for localizing objects in space, for identifying them, and for estimating their velocity. We will test these predictions by recording from the same neurons while the animals freely view natural scenes. This framework will then be extended to the study of combined eye-head movements, to determine whether the computational advantages of visual-oculomotor integration translate to eye-head gaze shifts as well. Together these results will provide insight into the functional interaction between visual and oculomotor signals in the primate brain.