Center for Cognitive Neuroscience, Duke University, Box 90999, Durham, NC 27708, USA.
J Cogn Neurosci. 2011 Dec;23(12):4094-105. doi: 10.1162/jocn_a_00045. Epub 2011 May 12.
Several major cognitive neuroscience models have posited that focal spatial attention is required to integrate different features of an object to form a coherent perception of it within a complex visual scene. Although many behavioral studies have supported this view, some have suggested that complex perceptual discrimination can be performed even with substantially reduced focal spatial attention, calling into question the complexity of object representation that can be achieved without focused spatial attention. In the present study, we took a cognitive neuroscience approach to this problem by recording cognition-related brain activity both to help resolve the questions about the role of focal spatial attention in object categorization processes and to investigate the underlying neural mechanisms, focusing particularly on the temporal cascade of these attentional and perceptual processes in visual cortex. More specifically, we recorded electrical brain activity in humans engaged in a specially designed cued visual search paradigm to probe the object-related visual processing before and during the transition from distributed to focal spatial attention. The onset times of the color popout cueing information, indicating where within an object array the subject was to shift attention, was parametrically varied relative to the presentation of the array (i.e., either occurring simultaneously or being delayed by 50 or 100 msec). The electrophysiological results demonstrate that some levels of object-specific representation can be formed in parallel for multiple items across the visual field under spatially distributed attention, before focal spatial attention is allocated to any of them. The object discrimination process appears to be subsequently amplified as soon as focal spatial attention is directed to a specific location and object. This set of novel neurophysiological findings thus provides important new insights on fundamental issues that have been long-debated in cognitive neuroscience concerning both object-related processing and the role of attention.
几种主要的认知神经科学模型假设，焦点空间注意力是将一个物体的不同特征整合在一起，形成对复杂视觉场景中该物体的连贯感知所必需的。尽管许多行为研究支持这一观点，但也有一些研究表明，即使焦点空间注意力大大减少，也可以进行复杂的感知辨别，从而对没有焦点空间注意力的情况下可以实现的物体表示的复杂性提出质疑。在本研究中，我们通过记录与认知相关的大脑活动来解决焦点空间注意力在物体分类过程中的作用问题，并研究其潜在的神经机制，从而从认知神经科学的角度来解决这个问题。我们特别关注这些注意和感知过程在视觉皮层中的时间级联。更具体地说，我们在人类中记录了电生理脑活动，这些人类参与了一个专门设计的提示视觉搜索范式，以探测对象相关的视觉处理，然后在从分布式到焦点空间注意力的过渡期间进行探测。颜色弹出提示信息的起始时间，指示主体在对象数组内转移注意力的位置，相对于数组的呈现进行参数变化（即，同时发生或延迟 50 或 100 毫秒）。这些电生理结果表明，在将焦点空间注意力分配给它们中的任何一个之前，在空间分布式注意力下，可以并行形成多个对象的某些特定对象的表示。一旦将焦点空间注意力指向特定位置和对象，对象辨别过程似乎会立即增强。因此，这组新的神经生理学发现为认知神经科学中长期以来一直在争论的有关对象相关处理和注意力作用的基本问题提供了重要的新见解。
