Neurophysiology of active vision in humans

 描述(申请人提供)：在自然视觉中，信息是通过直接凝视(“凝视”)兴趣点来主动获取的。人类和其他灵长类动物通常以3-5赫兹的速度扫描视觉场景，以3-5赫兹的速度进行大量的短暂凝视，中间隔着快速的眼球跳动。在每次注视时，一连串的视网膜将课程输出到系统中，并产生大脑激活的时空模式，这是由刺激质量与每个大脑区域内神经元的特性相互作用决定的。尽管有这些众所周知的动力学，但在眼睛运动的背景下分析视觉活动的困难导致了传统的方法，即检查在眼睛保持稳定的情况下呈现的刺激的反应，无论是通过麻醉的非人类受试者的全身瘫痪，还是在研究清醒的受试者(猴子或人类)时，通过在刺激呈现期间稳定凝视的要求。我们和其他人通过跟踪眼睛，并将眼跳或注视的开始作为反应平均和/或单次试验分析的事件触发器，研究了猴子的活跃视力。这些研究清楚地表明，这种活跃的视觉利用了由眼动系统产生的非视网膜“传出复制”信号，该信号重置了整个视觉通路中正在进行的兴奋性波动(振荡)的阶段。由于这一阶段重置使周围神经元振荡的高兴奋性阶段与视觉信息的流入相一致，我们假设1)相同的重置信号增强了不同脑区神经元集合之间的振荡相位一致性，并且这种一致性增强了通过系统的信息流，并增强了大脑对眼睛运动目标对象的表征，以及2)扫视-注视周期为信息编码和转换提供了明确的背景，由基本采样率(即眼动速率)组织，并结合/组织了自下而上的分层信息处理和自上而下的“何时/什么/哪里”预测。我们的广泛目标是开发一种可行的方法来研究人类主动视觉动力学的高分辨率。我们有两个具体的目标：1-确定主动眼跳采样对视觉处理动力学的影响。2-研究在对自然场景进行主动采样时的信息编码和转换。有效地分辨主动视觉的动态是非常重要的，因为除了几种其他形式，如追逐眼球运动之外，短暂的、快照般的注视提供了对视觉环境进行采样的主要手段。对这些术语中的视觉的更好的理解将对改进对视觉功能障碍的机械性理解以及由包括亨廷顿氏症、帕金森氏症、ADHD、胎儿酒精综合症、精神分裂症等一系列疾病的异常视觉搜索行为引起的认知缺陷产生许多影响。

 DESCRIPTION (provided by applicant): In natural vision, information is acquired actively, by directing gaze toward ("fixating on") points of interest. Humans and other primates typically scan a visual scene with a large number of brief fixations, at a rate of 3-5 Hz, separated by rapid ``saccadic'' eye movements. At each fixation, a volley of retinal outputs courses into the system and produces a spatiotemporal pattern of brain activation determined by the interaction of stimulus qualities with properties of neurons within each brain area. Despite these well known dynamics, the difficulties in analyzing visual activity in the context of eye movements has led to the traditional approach of examining responses to stimuli that are presented with the eye held stable, either by systemic paralysis in anesthetized nonhuman subjects, or when studying awake subjects (monkeys or humans), by requirements to fixate steadily during stimulus presentation. We and others have investigated active vision in monkeys by tracking the eyes, and by using the onset of the saccade or the fixation as event triggers for response averaging and/or single trial analysis. These studies clearly show that such active vision exploits non-retinal "efference copy" signals generated by the oculomotor system, which reset the phase of ongoing excitability fluctuations (oscillations) throughout the visual pathways. Because this phase reset aligns the high excitability phase of ambient neuronal oscillations with the inflow in visual information, we hypothesize that 1) the same reset signal enhances oscillatory phase coherence between neuronal ensembles in different brain regions and that this coherence enhances information flow through the system and augments the brain's representation of objects targeted by eye movements, and 2) the saccade-fixation cycle provides an explicit context for information encoding and transformation, organized by a basic sampling rate (i.e., the rate of eye movements), and incorporating/ organizing both bottom-up hierarchical information processing and top-down "when/what/where" predictions. Our broad goal is to develop a workable approach to high-resolution study of Active Vision dynamics in humans. We have two specific aims: 1 - Define the impact of Active Saccadic Sampling on the dynamics of visual processing. 2 - Investigate information encoding and transformation during Active Sampling of naturalistic scenes. Effective resolution of the dynamics of active vision is of fundamental importance because, aside from a few other forms, such as pursuit eye movements, the brief, snapshot-like fixation provides the major means of sampling the visual environment. An improved understanding of vision in these terms will have numerous implications for improved mechanistic understanding of visual dysfunction, as well as cognitive deficits that stem from abnormal visual search behavior in a wide range of disorders including Huntington's, Parkinson's, ADHD, Fetal Alcohol Syndrome, Schizophrenia.