Neuroscience Department, Laboratory for Behavioral Neurology and Imaging of Cognition, University of Geneva, Geneva, Switzerland; Neurology Department, University Hospital of Geneva, Geneva, Switzerland.
Neuroscience Department, Laboratory for Behavioral Neurology and Imaging of Cognition, University of Geneva, Geneva, Switzerland; Neurology Department, University Hospital of Geneva, Geneva, Switzerland; Département de Psychologie, Université de Montréal, Montréal, Québec, Canada.
Cortex. 2018 Dec;109:260-271. doi: 10.1016/j.cortex.2018.09.015. Epub 2018 Oct 5.
Recent studies suggest that motivational cues such as rewards may be a powerful determinant of attentional selection, both in healthy subjects and in brain-damaged patients suffering from neglect. However, the exact brain mechanisms underlying these effects and their relation to other well-known attentional systems are still poorly known.
We designed a visual search paradigm to examine how value-based attentional priority could modulate spatial orienting in patients with pathological biases due to neglect after right hemispheric stroke. Targets were preceded by exogenous valid or invalid spatial cues, in the presence or absence of distractors that were associated with high reward values subsequent to an initial reinforcement training phase.
We found that the learned reward value of distractors interfered with spatial reorienting toward the left (neglected) side when neglect patients were invalidly cued to the right side. Moreover, the presence of reward-associated distractors in the contralesional field interfered most with the detection of task-relevant targets on the same side, and this interference was exaggerated with more severe neglect. Voxelwise anatomical lesion analysis indicated that damage to the right angular gyrus, as well as lateral occipital and inferior temporal areas of the right hemisphere, were associated with stronger value-driven attentional effects.
Visual stimuli previously associated with rewards receive higher attentional priority during visual search despite pathological spatial biases due to neglect, and thus interfere with orienting to contralesional targets, presumably by competing with top-down mechanisms controlling exogenous spatial attention. Reward signals may bias neural activity evoked by visual stimuli, independent of conscious control, through a common priority map integrating several different attentional influences. These results do not only provide novel insights to link spatial orienting and motivational signals within current models of attention, but also open new perspectives that may usefully be exploited for neurological rehabilitation strategies in patients suffering from attentional deficits and neglect.
最近的研究表明，奖励等动机线索可能是健康受试者和右脑损伤忽视症患者注意力选择的强大决定因素。然而，这些影响的确切大脑机制及其与其他著名注意力系统的关系仍知之甚少。
我们设计了一个视觉搜索范式，以检查基于价值的注意力优先级如何在右半球中风后因忽视而产生病理性偏向的患者中调节空间定向。在存在或不存在与初始强化训练阶段后具有高奖励值的分心物的情况下，目标之前会出现外源性有效或无效的空间线索。
我们发现，当忽视患者被无效地提示到右侧时，分心物的习得奖励值会干扰向左（忽视）侧的空间重新定向。此外，在对侧场中存在奖励相关的分心物会最干扰同侧任务相关目标的检测，并且这种干扰随着更严重的忽视而加剧。体素水平的解剖损伤分析表明，右侧角回以及右侧外侧枕叶和下颞叶区域的损伤与更强的价值驱动注意力效应相关。
尽管存在由于忽视而导致的病理性空间偏向，但与奖励相关的视觉刺激在视觉搜索过程中会获得更高的注意力优先级，因此会干扰对侧目标的定向，这可能是通过控制外源性空间注意力的自上而下机制进行竞争的结果。奖励信号可能会在不依赖于意识控制的情况下，通过整合几种不同注意力影响的共同优先级图，对视觉刺激引起的神经活动产生偏见。这些结果不仅为将空间定向和动机信号联系起来提供了新的见解，而且为注意力缺陷和忽视症患者的神经康复策略开辟了新的视角，可能会有所帮助。
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