Kim Yee-Joon, Tsai Jeffrey J, Ojemann Jeffrey, Verghese Preeti
Smith-Kettlewell Eye Research Institute, San Francisco, California 94115,
Department of Neurology, University of Washington, Seattle, Washington 98104, and.
J Neurosci. 2017 May 10;37(19):4942-4953. doi: 10.1523/JNEUROSCI.2370-16.2017. Epub 2017 Apr 14.
Selective attention is known to interact with perceptual organization. In visual scenes, individual objects that are distinct and discriminable may occur on their own, or in groups such as a stack of books. The main objective of this study is to probe the neural interaction that occurs between individual objects when attention is directed toward one or more objects. Here we record steady-state visual evoked potentials via electrocorticography to directly assess the responses to individual stimuli and to their interaction. When human participants attend to two adjacent stimuli, prefrontal and parietal cortex shows a selective enhancement of only the neural interaction between stimuli, but not the responses to individual stimuli. When only one stimulus is attended, the neural response to that stimulus is selectively enhanced in prefrontal and parietal cortex. In contrast, early visual areas generally manifest responses to individual stimuli and to their interaction regardless of attentional task, although a subset of the responses is modulated similarly to prefrontal and parietal cortex. Thus, the neural representation of the visual scene as one progresses up the cortical hierarchy becomes more highly task-specific and represents either individual stimuli or their interaction, depending on the behavioral goal. Attention to multiple objects facilitates an integration of objects akin to perceptual grouping. Individual objects in a visual scene are seen as distinct entities or as parts of a whole. Here we examine how attention to multiple objects affects their neural representation. Previous studies measured single-cell or fMRI responses and obtained only aggregate measures that combined the activity to individual stimuli as well as their potential interaction. Here, we directly measure electrocorticographic steady-state responses corresponding to individual objects and to their interaction using a frequency-tagging technique. Attention to two stimuli increases the interaction component that is a hallmark for perceptual integration of stimuli. Furthermore, this stimulus-specific interaction is represented in prefrontal and parietal cortex in a task-dependent manner.
已知选择性注意与知觉组织相互作用。在视觉场景中，清晰可辨的单个物体可能单独出现，也可能成组出现，比如一摞书。本研究的主要目的是探究当注意力指向一个或多个物体时，单个物体之间发生的神经相互作用。在此，我们通过皮层脑电图记录稳态视觉诱发电位，以直接评估对单个刺激及其相互作用的反应。当人类参与者关注两个相邻刺激时，前额叶和顶叶皮层仅对刺激之间的神经相互作用表现出选择性增强，而对单个刺激的反应则没有增强。当只关注一个刺激时，前额叶和顶叶皮层对该刺激的神经反应会选择性增强。相比之下，早期视觉区域通常无论注意力任务如何，都会对单个刺激及其相互作用表现出反应，尽管有一部分反应的调节方式与前额叶和顶叶皮层类似。因此，随着在皮层层级中向上推进，视觉场景的神经表征变得更具任务特异性，根据行为目标，要么表征单个刺激，要么表征它们的相互作用。对多个物体的注意促进了类似于知觉分组的物体整合。视觉场景中的单个物体被视为不同的实体或整体的一部分。在此，我们研究对多个物体的注意如何影响它们的神经表征。以往研究测量单细胞或功能磁共振成像反应，仅获得结合了对单个刺激的活动及其潜在相互作用的总体测量结果。在此，我们使用频率标记技术直接测量与单个物体及其相互作用相对应的皮层脑电图稳态反应。对两个刺激的注意增加了作为刺激知觉整合标志的相互作用成分。此外，这种刺激特异性相互作用以任务依赖的方式在前额叶和顶叶皮层中得到表征。
