The Wellcome Trust Centre for Neuroimaging, University College London, London WC1N 3BG, United Kingdom, Centre for Neurocognitive Research and Department of Psychology, University of Salzburg, 5020 Salzburg, Austria, and Neuroscience Institute and Centre for Neurocognitive Research, Christian-Doppler-Klinik, Paracelsus Medical University Salzburg, 5020 Salzburg, Austria.
J Neurosci. 2014 Jan 22;34(4):1271-9. doi: 10.1523/JNEUROSCI.4389-13.2014.
Multiple features of the environment are often imbued with motivational significance, and the relative importance of these can change across contexts. The ability to flexibly adjust evaluative processes so that currently important features of the environment alone drive behavior is critical to adaptive routines. We know relatively little about the neural mechanisms involved, including whether motivationally significant features are obligatorily evaluated or whether current relevance gates access to value-sensitive regions. We addressed these questions using functional magnetic resonance imaging data and a task design where human subjects had to choose whether to accept or reject an offer indicated by visual and auditory stimuli. By manipulating, on a trial-by-trial basis, which stimulus determined the value of the offer, we show choice activity in the ventral striatum solely reflects the value of the currently relevant stimulus, consistent with a model wherein behavioral relevance modulates the impact of sensory stimuli on value processing. Choice outcome signals in this same region covaried positively with wins on accept trials, and negatively with wins on reject trials, consistent with striatal activity at feedback reflecting correctness of response rather than reward processing per se. We conclude that ventral striatum activity during decision making is dynamically modulated by behavioral context, indexed here by task relevance and action selection.
环境的多个特征通常具有激励意义,并且这些特征的相对重要性会因情境而异。能够灵活地调整评估过程,使环境中当前重要的特征单独驱动行为,这对于适应性常规至关重要。我们对涉及的神经机制了解相对较少,包括激励性特征是否必须进行评估,或者当前的相关性是否会限制对价值敏感区域的访问。我们使用功能磁共振成像数据和一项任务设计来解决这些问题,在该任务中,人类受试者必须选择是接受还是拒绝视觉和听觉刺激所表示的要约。通过在每次试验的基础上操纵哪个刺激决定要约的价值,我们发现腹侧纹状体中的选择活动仅反映当前相关刺激的价值,这与一种模型一致,即行为相关性调节感官刺激对价值处理的影响。该区域中的选择结果信号与接受试验中的获胜呈正相关,与拒绝试验中的获胜呈负相关,这与反馈中的纹状体活动一致,反映了反应的正确性,而不是奖励处理本身。我们得出结论,腹侧纹状体在决策过程中的活动受到行为背景的动态调节,这里由任务相关性和动作选择来表示。