Neuronal mechanisms of attention: changes in sensitivity and decision criterion

描述(由申请人提供)：注意力在人类表现中起着至关重要的作用，使我们能够有选择地处理相关信息，而注意力缺陷是一种严重和普遍的神经疾病。然而，尽管关注人类健康具有重要意义，但人们对关注的神经元基础知之甚少。注意力相关的神经元信号已经在许多大脑区域被发现，特别是前额叶区域和视觉皮质，但它是 目前尚不清楚这些信号是如何促进注意力所带来的行为改善的。在大多数神经生理学研究中，与注意力相关的信号被认为是通过加强对所关注的刺激的感觉处理而导致行为改善的。然而，这些信号是否真的反映了感觉处理的增强尚不清楚。在大多数研究中，人们通过提示目标最有可能出现的位置来引导注意力到某个位置，从而导致更多的目标被检测到，并且在被提示的位置上的反应时间更短。虽然这些改进可能是由于感觉处理的增强，但它们也可能通过改变受试者的决定标准而产生，该标准决定了报告目标需要多少感觉证据。因为目标最有可能出现在提示位置，所以在提示位置需要较少感觉证据的判断标准将导致与增强感觉处理相同的行为改善。心理物理学研究表明，决策标准的改变可以解释很大一部分或全部行为 注意力的改善。这些研究通过对感觉加工质量(“敏感度”)和决策标准提供单独的行为测量方法，表明注意力经常同时改变敏感度和决策标准，很少对两者进行独立的调节。然而，关于注意的神经生理学研究并没有区分敏感性和决策标准。这是一个至关重要的问题。鉴于决策标准可以解释注意力行为改善的很大一部分，许多归因于敏感性的与注意力相关的信号实际上可能是决策标准变化的基础。这个项目将决定与注意力相关的神经元信号是否可以被解析成两个不同的组成部分，分别对应于受试者的敏感度和决策标准的变化。我的具体目标是确定(1)敏感度和判断标准的变化是否与背外侧前额叶皮质中单独的神经元信号有关， 同时涉及注意和决策的区域，以及(2)视觉皮质V4区的注意相关活动，以及V4区与背外侧前额叶皮质之间的相互作用是否因敏感度和决策标准的变化而受到不同的调制。这个项目的结果有可能极大地澄清我们对注意的神经机制的理解，并确定在不同的注意障碍中可能受到不同程度损害的注意的亚模式。

DESCRIPTION (provided by applicant): Attention plays a crucial role in human performance by enabling us to selectively process relevant information, and attention deficit is a serious and prevalent neurological disorder. However, despite the significance of attention to human health, the neuronal basis of attention is poorly understood. Attention-related neuronal signals have been identified in many brain areas, in particular the prefrontal area and visual cortex, but it is unclear how these signals give rise to the behavioral improvements provided by attention. In most neurophysiological studies, attention-related signals are thought to give rise to behavioral improvements by enhancing the sensory processing of the attended stimulus. However, whether these signals in fact reflect enhanced sensory processing is unclear. In most studies, attention is directed to a location by cueing where the target is most likely to appear, resulting n more target detected and shorter reaction times at the cued location. While these improvements could be due to enhanced sensory processing, they could also arise through changes in the subject's decision criterion, which determines how much sensory evidence is required for reporting a target. Because the target is most likely to appear at the cued location, a decision criterion requiring less sensory evidence at the cued location would result in the same behavioral improvements as from enhanced sensory processing. Psychophysics studies have shown that changes in decision criterion could account for a large portion or all of the behavioral improvements of attention. Using methods that provide separate behavioral measures of the quality of sensory processing ("sensitivity") and decision criterion, these studies show that attention often changes both sensitivity and the decision criterion and seldom modulates the two independently. However, neurophysiological studies of attention have not distinguished between sensitivity and decision criterion. This is a crucial issue. Given that decision criterion could account for a large portion of the behavioral improvements of attention, much of the attention-related signals attributed to sensitivity may in fact underlie changes in decision criterion. This project will determine whether attention-related neuronal signals can be parsed into two distinct components that separately correspond to changes in the subject's sensitivity and decision criterion. My specific aims are determine (1) whether changes in sensitivity and decision criterion are associated with separate neuronal signals in dorsolateral prefrontal cortex, an area involved in both attention and decision-making, and (2) whether the attention-related activity in area V4 of visual cortex, where the classic neuronal signals of attention were found, and the interaction between V4 and dorsolateral prefrontal cortex are differentially modulated by changes in sensitivity and decision criterion. The results of this project have the potential to greatly clarify our understanding of the neuronal mechanism of attention and define sub- modalities of attention that might be impaired to unequal extents in different disorders of attention.