Visually Modulated Endogenous Activity

描述(申请人提供)：该项目的目标是在警觉的人类观察者身上测试一个自上而下的非侵入性视觉处理模型。根据这一模型，中枢神经系统主动探索视觉输入，通过其内源性活动与其互动。这种相互作用导致视觉信息的时间编码，这将被称为视觉调制内源性活动(VMEA)。这种反应成分不需要与刺激特征的突然变化直接相关，因此避开了常用的刺激锁定平均技术。在输入与快速内生过程非线性相互作用的任何系统中，都可以预测到这种成分的存在，并在我们使用非常规分析工具进行的初步研究中得到了证明。它与动物研究中发现的依赖刺激的同步高频振荡有许多相似之处。本研究使用的方法是通过非线性运算解调内源载体以恢复其视觉内容。我们的目标之一是针对手头的问题优化刺激和解调技术。其他目的是调查 VMEA成分的特点及其在人类视觉感知中可能发挥的作用。具体地说，我们将研究它对受试者注意力状态的依赖。我们将研究VMEA对刺激几何形状和颜色的依赖性，并将VMEA对随机图案的响应与对具有相似亮度对比度分布的有意义图像的响应进行比较。

DESCRIPTION (provided by applicant): The goal of this project is to test a model of top-down visual processing by noninvasive means in alert human observers. According to this model, the CNS actively explores the visual input, interacting with it through its endogenous activity. The interactions result in a temporal encoding of visual information that will be called visually modulated endogenous activity (VMEA). This response component does not need to correlate directly with abrupt changes in stimulus features and therefore eludes the commonly used techniques of stimulus-locked averaging. The existence of this component can be predicted in any system where the input interacts nonlinearly with fast endogenous processes and has been demonstrated in our pilot study using unconventional analysis tools. It shares many properties with the stimulus dependent synchronized high frequency oscillations found in animal studies. The method used in this study demodulates the endogenous carrier by means of nonlinear operations to retrieve its visual content. One of our aims is to optimize the stimulation and demodulation technique for the problem at hand. Other aims are to investigate the characteristics of the VMEA component and the role it may play in human visual perception. Specifically, we will study its dependence on the attentional state of the subject. We will investigate its dependence on stimulus geometry and color and we will compare the VMEA responses to random patterns with those to meaningful images with similar brightness contrast distributions.