Hickey Clayton, Peelen Marius V
Center for Mind/Brain Sciences, University of Trento, Trento 38068, Italy, and
VU University Amsterdam, Amsterdam 1081BT, The Netherlands.
J Neurosci. 2017 Aug 2;37(31):7297-7304. doi: 10.1523/JNEUROSCI.0684-17.2017. Epub 2017 Jun 19.
Theories of reinforcement learning and approach behavior suggest that reward can increase the perceptual salience of environmental stimuli, ensuring that potential predictors of outcome are noticed in the future. However, outcome commonly follows visual processing of the environment, occurring even when potential reward cues have long disappeared. How can reward feedback retroactively cause now-absent stimuli to become attention-drawing in the future? One possibility is that reward and attention interact to prime lingering visual representations of attended stimuli that sustain through the interval separating stimulus and outcome. Here, we test this idea using multivariate pattern analysis of fMRI data collected from male and female humans. While in the scanner, participants searched for examples of target categories in briefly presented pictures of cityscapes and landscapes. Correct task performance was followed by reward feedback that could randomly have either high or low magnitude. Analysis showed that high-magnitude reward feedback boosted the lingering representation of target categories while reducing the representation of nontarget categories. The magnitude of this effect in each participant predicted the behavioral impact of reward on search performance in subsequent trials. Other analyses show that sensitivity to reward-as expressed in a personality questionnaire and in reactivity to reward feedback in the dopaminergic midbrain-predicted reward-elicited variance in lingering target and nontarget representations. Credit for rewarding outcome thus appears to be assigned to the target representation, causing the visual system to become sensitized for similar objects in the future. How do reward-predictive visual stimuli become salient and attention-drawing? In the real world, reward cues precede outcome and reward is commonly received long after potential predictors have disappeared. How can the representation of environmental stimuli be affected by outcome that occurs later in time? Here, we show that reward acts on lingering representations of environmental stimuli that sustain through the interval between stimulus and outcome. Using naturalistic scene stimuli and multivariate pattern analysis of fMRI data, we show that reward boosts the representation of attended objects and reduces the representation of unattended objects. This interaction of attention and reward processing acts to prime vision for stimuli that may serve to predict outcome.
强化学习和趋近行为理论表明，奖励能够提高环境刺激的感知显著性，确保未来能够注意到结果的潜在预测因素。然而，结果通常在对环境进行视觉处理之后出现，即使潜在的奖励线索早已消失也会发生。奖励反馈如何能在事后使现在不存在的刺激在未来变得引人注意呢？一种可能性是，奖励和注意力相互作用，启动对所关注刺激的持久视觉表征，这些表征在分隔刺激和结果的时间间隔中持续存在。在这里，我们使用从男性和女性人类受试者收集的功能磁共振成像（fMRI）数据进行多变量模式分析来检验这一想法。在扫描仪中时，参与者在短暂呈现的城市景观和风景图片中搜索目标类别的示例。正确的任务表现之后会有奖励反馈，奖励大小可能随机为高或低。分析表明，高幅度奖励反馈增强了目标类别的持久表征，同时减少了非目标类别的表征。每个参与者中这种效应的大小预测了奖励对后续试验中搜索表现的行为影响。其他分析表明，对奖励的敏感性——如在一份人格问卷中所表达的以及在多巴胺能中脑对奖励反馈的反应性——预测了奖励引发的持久目标和非目标表征的差异。因此，奖励结果的功劳似乎被归于目标表征，从而使视觉系统在未来对类似物体变得敏感。奖励预测性视觉刺激是如何变得显著并引人注意的呢？在现实世界中，奖励线索先于结果出现，而奖励通常在潜在预测因素消失很久之后才会收到。环境刺激的表征如何受到稍后出现的结果的影响呢？在这里，我们表明奖励作用于在刺激和结果之间的时间间隔中持续存在的环境刺激的持久表征。使用自然场景刺激和fMRI数据的多变量模式分析，我们表明奖励增强了所关注物体的表征并减少了未关注物体的表征。注意力和奖励处理的这种相互作用起到了为可能用于预测结果的刺激启动视觉的作用。
