Early advantage of luminance for object representation and its cross-talk with chromatic pathways in human visual scene analysis

目标的检测和识别是人类视觉感知的最重要目标。视觉系统中的几个平行通道处理传入的信息，通过一系列快速分层组织的阶段在双眼中分割图像。这种快速的层级处理流涉及一系列神经活动，包括一系列大脑区域，从分析单独视觉特征的初级感觉区域（低级视觉），到将感知组织成图形和背景的部分（中级视觉），再到存储熟悉物体语义知识的大脑部分（高级视觉）。因此，在不到300毫秒的处理时间内，在一系列高度不同的大脑区域内，我们的环境的连贯表示就形成了。在视觉感知的研究中，重要的是研究大脑如何协调对简单视觉特征（如颜色和亮度）的信息处理，沿着导致物体感知的每个转化阶段（低，中，高水平）。众所周知，从动物的研究中，哺乳动物大脑中的视觉通道分开处理无色和彩色信息：大细胞途径处理亮度信息，而细小和koniocellular途径主要有助于颜色处理。两者对于日常物体视觉都是至关重要的，但它们的贡献不同，亮度被认为与线条，边缘，形状和运动的快速处理更相关，而颜色与视觉场景的分割更相关。但是，即使经过多年的研究，各种视觉通路在视觉处理的不同阶段独立或相互作用的程度仍然是未知的，这是由于以下困难：1）产生选择性地引起沿沿着不同通路的处理的刺激; 2）分析有助于正常人类视觉的快速进化的神经过程。我们打算进行一项研究，通过一种创新的实验方法来克服这些问题，该方法将脑电图（EEG）的能力与颜色心理物理学的工具相结合，从而揭示人类视觉感知的快速神经过程中的毫秒差异，该工具使我们能够通过在三维颜色空间中定义我们的刺激来分离不同的视觉处理流（亮度维度和两个色度维度）。刺激显示将通过视觉刺激发生器进行控制，该发生器将能够系统和同时控制彩色和消色差机制的输入。将确定皮层激活的时间过程及其潜在的发生器，并通过使用在单个（大、小或小）或多个（两个或所有三个组合）通路中引起兴奋的刺激来模拟不同通路之间的相互作用。本研究的结果将为人类大脑在并行视觉处理过程中利用不同类型信息的方式提供重要见解，从而将为当前关于并行（大细胞、小细胞或粒细胞）之间关系的知识做出重大贡献。和分层（低、中、高水平）处理。我们将能够描述允许优先输入亮度信息到对象表示过程中的神经机制，从而使其能够驱动日常视觉。另一个优点将通过描述koniocellular对视觉的贡献来提供，迄今为止还没有被广泛研究，因为该途径最近才成为人类参与者中系统研究的主题。

Detection and identification of objects is the most crucial goal of human visual perception. Several parallel channels in the visual system processes incoming information with that purpose, segmenting the images in both eyes through a series of rapid hierarchically organized stages. This rapid hierarchical processing stream involves a cascade of neural activity that encompasses a series of brain areas, from primary sensory regions that analyse separate visual features (low-level vision), through parts that organise the percept into figures and background (mid-level vision), to parts of the brain that store semantic knowledge on familiar objects (high-level vision). A coherent representation of our environment is thus formed in less than 300 milliseconds of processing time within a range of highly varied brain regions. In the study on visual perception, it is crucial to investigate in which way does the brain manage to coordinate the processing of information on simple visual features such as colour and luminance along each of the transformative stages (low, mid, high-level) that lead to the perception of objects. It is well-known from studies on animals that separate visual channels in mammalian brain process achromatic and chromatic information: magnocellular pathway processes luminance information, while parvo- and koniocellular pathways predominantly subserve colour processing. Both are crucial for everyday object vision but their contributions differ, with luminance considered to be more relevant for rapid processing of lines, edges, shape and motion and colour being more relevant for segmentation of visual scenes. But the extent to which various visual pathways function independently or interactively at different stages of visual processing remains unknown even after many years of study, due to the difficulties in 1) producing stimuli that selectively elicit processing along different pathways and 2) analysing the rapidly evolving neural processes that subserve normal human vision. We intend to conduct a study that will overcome these problems through an innovative experimental approach which joins electroencephalography's (EEG's) ability to divulge millisecond differences in rapid neural processes that underlie human visual perception with the tools of colour psychophysics which allow us to separate out different visual processing streams by defining our stimuli in three-dimensional colour space (a luminance dimension and two chromatic dimensions). The stimulus displays will be controlled through a visual stimulus generator that would enable systematic and concurrent control of inputs into chromatic and achromatic mechanisms. The timecourse of cortical activations and their underlying generators will be identified and the interactions between different pathways modelled by using stimuli that elicit excitations in single (magno-, parvo- or konio-) or multiple (two or all three combined) pathways. The findings of this study will provide an important insight into the ways in which the human brain utilises different types of information during parallel visual processing and will thus significantly contribute to current knowledge on the relations between parallel (magnocellular, parvocellular or koniocellular) and hierarchical (low, mid, high-level) processing. We will be able to describe the neural mechanisms that allow preferential inputs of luminance information into object representation processes and thus enable it to drive everyday vision. A further advantage will be provided by the description of koniocellular contributions to vision which have so far not been studied extensively since this pathway has only recently become the subject of systematic study in human participants.