Influence of Head and Eye Movements on Retinal Input and Early Neural Encoding

人类通常不会意识到他们的眼睛和头部总是在运动。小的不自觉的头部和眼睛的运动不断发生在自愿的重新定位凝视的时间，甚至当试图保持稳定的凝视在一个点。如果这些运动是由场景中的物体引起的，而不是观察者的行为引起的，那么视网膜上的刺激会以一种立即可见的方式发生变化。基于大量最近的发现，这个项目调查了这样一种假设，即固定的头部和眼睛运动不是运动不稳定，而是精确控制的运动策略的一部分，促进了精细空间细节的视觉处理。这一假设的阐明不仅对推进视觉感知基本机制的知识很重要，而且还因为它意味着一些视力障碍可能有未被识别的运动起源，相反，运动障碍可能有未被怀疑的感觉后果。该研究可能对在头部运动受限的情况下人类视觉表现的优化具有启示意义。此外，通过阐明如何通过协调运动实现视觉信息的最佳采样，该研究也可能对人工视觉系统的设计产生影响。该项目将采用理论和实验相结合的方法，结合人类受试者的心理物理实验、视网膜刺激的统计分析和视觉系统早期阶段的神经元建模，以研究头部和眼睛运动对精细空间信息获取和编码的共同影响。具体来说，研究人员将测量在正常执行高灵敏度视觉任务时的头和眼的注视运动。他们将研究这些动作是如何相互作用的，相互作用中涉及的控制程度，以及这种相互作用的本质。与此同时，研究人员将通过重建观察者视网膜所经历的视觉输入信号，并通过分析这些信号对视觉系统中神经元计算模型的反应的影响，来进行定量预测。这种实验和理论方法的协同作用将导致在感觉知觉和运动控制领域的新知识。它将提供关于注视头和眼睛运动的关节特征及其视觉功能的关键信息，并有助于确定空间信息在大脑中表示的感觉-运动策略。

Humans are normally not aware that their eyes and head are always in motion. Small involuntary head and eye movements continually occur in the periods between voluntary relocations of gaze, even when attempting to maintain steady gaze on a single point. These movements shift the stimulus on the retina in ways that would be immediately visible had the motion originated from objects in the scene rather than the observer's behavior. Building on a large body of recent findings, this project investigates the hypothesis that fixational head and eye movements are not motor instabilities, but part of a precisely controlled motor strategy that facilitates the visual processing of fine spatial detail. Elucidation of this hypothesis is important not only for advancing knowledge on the fundamental mechanisms of visual perception, but also because it implies that some visual acuity impairments may have unrecognized motor origins, and, conversely, that motor disturbances may have unsuspected sensory consequences. The research could have implications for the optimization of human visual performance in situations of restricted head movement. Also, by shedding light on how to achieve optimal sampling of visual information through coordinated movement, the research could also have implications for the design of artificial vision systems.This project will follow an integrated theoretical and experimental approach, which combines psychophysical experiments with human subjects, statistical analysis of the stimulus on the retina, and modeling of neurons in the early stages of the visual system to examine the joint consequences of head and eye movements on the acquisition and encoding of fine spatial information. Specifically, the investigators will measure fixational head and eye movements during the normal execution of high-acuity visual tasks. They will study how these movements interact, the degree of control involved in their interplay, and the nature of this interplay. In parallel, the investigators will develop quantitative predictions by reconstructing the visual input signals experienced by the observers' retinas and by analyzing the impact of these signals on the responses of computational models of neurons in the visual system. This synergy of experimental and theoretical methods will result in new knowledge in the fields of sensory perception and motor control. It will contribute critical information on the joint characteristics of fixational head and eye movements, their visual functions, and help in identifying the sensory-motor strategies by which spatial information is represented in the brain.