To ignore or explore: Top-down modulation of novelty processing
To ignore or explore: Top-down modulation of novelty processing
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DOI：
10.1162/jocn.2008.20.1.120
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发表时间：
2008-01-01
影响因子：
3.2
通讯作者：
Daffner, Kirk R.
中科院分区：
文献类型：
--
作者：
Chong, Hyemi;Riis, Jenna L.;Daffner, Kirk R.
注重新鲜感是人类行为和学习的关键要素。新奇的事件可以作为与任务无关的分心事物，也可以通过有趣或重要的环境方面作为参与的潜在来源。一个功能最佳的大脑应该有能力对新事件做出不同的反应，这取决于它们发生的环境。在本研究中，在两种不同的条件下采用了受试者控制的视觉新颖性古怪范式，其中新奇刺激被描述为从主要任务中分心或被描述为潜在有意义的探索环境的“邀请”。由于任务指令的侧重点不同而产生的背景差异强烈地调节了对新奇事物的行为和电生理反应。对于早于P3分量的处理，没有观察到这种调制。那些遇到新奇事件分散注意力的受试者限制了他们所占用的注意力和处理资源。值得注意的是，在这种情况下，罕见的新事件和频繁的标准事件在总体P3波幅、晚期正向慢波活动或观看持续时间方面没有差异。相比之下，那些遇到新奇事件作为潜在探索机会的受试者，增加了对这些事件的注意力和加工资源(反映在较大的P3波幅、较晚的正向慢波活动和较长的观看持续时间)。我们的结果表明，视觉通道中的新颖性加工包括几个阶段，包括：(1)对不熟悉的新刺激的相对自动检测(以N_2为索引)；(2)由发生新事件的更广泛的背景决定的自愿资源分配(以P3为索引)；以及(3)对新颖性的持续加工(以晚期正向慢波活动为索引)。这项研究提供了证据，证明大脑有能力根据遇到新事件的环境对它们产生不同的反应。它还指出，与之前强调的相比，在处理新奇事物的过程中，自上而下的调制程度更大。我们认为，较少研究的变量，如受试者控制，可能会为处理新奇事物的不同方式提供额外的洞察力。
Attending to novelty is a critical element of human behavior and learning. Novel events can serve as task-irrelevant distracters or as potential sources of engagement by interesting or important aspects of one's environment. An optimally functioning brain should have the capacity to respond differentially to novel events depending on the circumstances in which they occur. In the present study, a subject-controlled variant of the visual novelty oddball paradigm was employed under two different conditions in which novel stimuli were characterized either as distracters from a main task or as potentially meaningful "invitations" to explore the environment. Differences in context, derived from varying the emphasis of task instructions, strongly modulated both the behavioral and electrophysiological response to novelty. This modulation was not observed for processing earlier than the P3 component. Subjects who encountered novel events that served as distracters limited the amount of attention and processing resources they appropriated. Remarkably, under this condition, there were no differences in overall P3 amplitude, late positive slow-wave activity, or viewing duration between rare novel and frequent standard events. In contrast, subjects who encountered novel events as potential opportunities to explore augmented the attention and processing resources directed toward these events (as reflected by a larger P3 amplitude, late positive slow-wave activity, and longer viewing durations). Our results suggest that the processing of novelty within the visual modality involves several stages, including: (1) the relatively automatic detection of unfamiliar, novel stimuli (indexed by, the N2); (2) the voluntary allocation of resources determined by the broader context in which a novel event occurs (indexed by the P3); and (3) the sustained processing of novelty (indexed by late positive slow-wave activity). This study provides evidence of the brain's ability to generate differential responses to novel events according to the circumstances under which they are encountered. It also points to a greater degree of top-down modulation of the processing of novelty than has been previously emphasized. We suggest that less commonly studied variables, such as subject control, may provide additional insight into the different ways in which novelty is processed.