奖赏性线索启动和调控视觉搜索额顶网络的神经机制

近期关于奖赏性信息与视觉搜索任务的交互作用研究体现在两个层面, 其一是施加外部奖赏能够影响被试的视觉搜索反应时和正确率, 其二是搜索目标本身具有奖赏特性也能够影响行为反应。但是, 奖赏性信息对负责视觉搜索的额顶注意网络的动态启动和调控作用仍不清楚。本研究结合Posner空间预提示范式和视觉搜索范式, 采用快速事件相关功能磁共振成像技术, 分别操纵线索提示阶段的线索奖赏属性(奖赏性vs.非奖赏性)和线索空间注意属性(有效提示目标位置vs.无效提示目标位置), 并操纵目标搜索阶段的目标属性(奖赏性vs.非奖赏性), 探讨以下两个核心问题：(1)在线索提示阶段, 奖赏性线索产生的自上而下注意准备信号的神经基础, 以及该神经基础与传统的空间注意准备信号的异同; (2)在目标搜索阶段, 奖赏性线索对负责视觉搜索的额顶注意网络产生的启动和调控作用, 重点考察对正确的奖赏性信息的定向过程和对错误的奖赏性信息的重新定向过程。

The Brain Mechanisms of Reward Cue in Triggering and Modulating Fronto-parietal Attentional Network in Visual Search

The ability to actively locate potential reward in our environment is highly adaptive.The interaction between reward and visual search was manifested at two levels in recent studies.On the one hand,exerting reward outcome could affect search reaction time and percent correct rate.On the other hand,the to-be-searched target itself with rewarding feature(e.g.,food or money) could also affect behavioral performance.However,it is not clear how reward information dynamically switches on and modulates human fronto-parietal attentional network in visual search.In this project,by combining Posner spatial cueing paradigm and visual search paradigm,we manipulate the cue either predicting the target feature(rewarded vs.non-rewarded) or the target location(directional vs.non-directional),and the target feature(rewarded vs.non-rewarded) in visual search task.By using fast event-related functional magnetic resonance imaging(fMRI) technique,we aim at examining the following two questions:1) at cue-period,the neural substrates of top-down attentional bias toward rewarding information,and how these substrates differed from the neural substrates subserving spatial attentional bias;2) at target-period,the dynamic interaction between rewarding information and fronto-parietal attentional network,specifically,the neural correlates for orienting to correctly-informed target and for re-orienting from the incorrectly-informed target.