Rotman Research Institute, University of Toronto.
Department of Psychology, Trinity College.
Neuropsychology. 2011 Jul;25(4):535-543. doi: 10.1037/a0022767.
Engagement in tasks requiring vigilant attention is susceptible to modulation by exogenous stimulation, reflected in changes in performance accuracy and speed. The shift from endogenous to exogenous control may be observed not only when the external cue is meaningful to the task, but also when it holds no information about the task or performance. The purpose of this study was to examine how the shift to exogenous engagement is reflected in changes to the well-documented, right-lateralized, frontal-parietal-thalamic vigilant attention network.
Using functional magnetic resonance imaging , healthy participants were scanned as they performed the Sustained Attention to Response Task (SART) in 60-s blocks, some of which were presented with brief, random, auditory tones. The SART requires participants to overcome the tendency to respond in an automatic, task-driven manner in response to infrequent no-go stimuli.
Despite no overall effect on performance, and only a transient increase in response times immediately following the tones, the SART with alerting tones was associated with a diminished pattern of activation in key nodes of the network. The pattern of right-lateralized activity observed with the SART was attenuated with the tones, and activity in the right middle frontal gyrus was significantly diminished, as revealed by region-of-interest analyses.
Alerting tones provided the stimulation to cue the maintenance of the goal-state, reducing reliance on prefrontal control mechanisms and demonstrating the shift from endogenous top-down control to exogenous control. These findings suggest a neural mechanism for the facilitatory effects of exogenous engagement for patients with damaged top-down attentional brain systems.
需要警惕注意力的任务参与容易受到外部刺激的调节，表现在性能准确性和速度的变化上。从内源性控制到外源性控制的转变不仅可以在外部提示对任务有意义时观察到，也可以在外部提示不包含有关任务或性能的信息时观察到。本研究的目的是研究向外部参与的转变如何反映在已有文献记载的、右侧化的、额顶叶丘脑警惕注意网络的变化中。
使用功能磁共振成像，健康参与者在 60 秒的块中执行持续注意反应任务（SART），其中一些块呈现短暂的随机听觉音调。SART 要求参与者克服在响应不频繁的禁言刺激时以自动、任务驱动的方式响应的趋势。
尽管对性能没有总体影响，并且仅在随后的音调后立即增加了响应时间，但带有警报音的 SART 与网络关键节点的激活模式减少有关。SART 观察到的右侧活动模式随着音调而减弱，并且右额中回的活动明显减少，区域兴趣分析显示。
警报音提供了提示维持目标状态的刺激，减少了对前额叶控制机制的依赖，并证明了从内源性自上而下控制到外源性控制的转变。这些发现为受损的自上而下注意脑系统患者的外源性参与的促进作用提供了神经机制。
