Department of Psychiatry, Campus Charité Mitte, Charité - Universitätsmedizin Berlin, Berlin, Germany.
Hum Brain Mapp. 2014 Jul;35(7):3036-51. doi: 10.1002/hbm.22383. Epub 2013 Dec 5.
Although neural signals of reward anticipation have been studied extensively, the functional relationship between reward and attention has remained unclear: Neural signals implicated in reward processing could either reflect attentional biases towards motivationally salient stimuli, or proceed independently of attentional processes. Here, we sought to disentangle reward and attention-related neural processes by independently modulating reward value and attentional task demands in a functional magnetic resonance imaging study in healthy human participants. During presentation of a visual reward cue that indicated whether monetary reward could be obtained in a subsequent reaction time task, participants either attended to the reward cue or performed an unrelated attention-demanding task at two different levels of difficulty. In ventral striatum and ventral tegmental area, neural responses were modulated by reward anticipation irrespective of attentional demands, thus indicating attention-independent processing of reward cues. By contrast, additive effects of reward and attention were observed in visual cortex. Critically, reward-related activations in right anterior insula strongly depended on attention to the reward cue. Dynamic causal modelling revealed that the attentional modulation of reward processing in insular cortex was mediated by enhanced effective connectivity from ventral striatum to anterior insula. Our results provide evidence for distinct functional roles of the brain regions involved in the processing of reward-indicating information: While subcortical structures signal the motivational salience of reward cues even when attention is fully engaged elsewhere, reward-related responses in anterior insula depend on available attentional resources, likely reflecting the conscious evaluation of sensory information with respect to motivational value.
虽然奖励预期的神经信号已经被广泛研究，但奖励与注意力之间的功能关系仍不清楚：与奖励处理相关的神经信号可能反映了对动机显著刺激的注意力偏向，或者独立于注意力过程进行。在这里，我们通过在健康人类参与者的功能磁共振成像研究中独立调节奖励值和注意力任务需求，试图分离奖励和与注意力相关的神经过程。在呈现视觉奖励线索时，该线索表示在随后的反应时间任务中是否可以获得货币奖励，参与者要么关注奖励线索，要么在两个不同难度水平上执行不相关的注意力任务。在腹侧纹状体和腹侧被盖区，神经反应不受注意力需求的调节，这表明奖励线索的处理是独立于注意力的。相比之下，在视觉皮层中观察到奖励和注意力的附加效应。关键的是，右侧前岛叶的与奖励相关的激活强烈依赖于对奖励线索的关注。动态因果建模表明，前岛叶中奖励处理的注意力调节是由腹侧纹状体到前岛叶的增强有效连接介导的。我们的结果为涉及奖励指示信息处理的大脑区域提供了证据，表明它们具有不同的功能作用：虽然皮质下结构即使在注意力完全集中在其他地方时也会发出奖励线索的动机显著性信号，但前岛叶的与奖励相关的反应取决于可用的注意力资源，这可能反映了对与动机价值相关的感觉信息的有意识评估。
