Department of Psychology, Rutgers University, Newark, New Jersey
Department of Psychology, Rutgers University, Newark, New Jersey.
J Neurophysiol. 2015 Jan 1;113(1):4-13. doi: 10.1152/jn.00086.2014. Epub 2014 Oct 22.
For the consequences of our actions to guide behavior, the brain must represent different types of outcome-related information. For example, an outcome can be construed as negative because an expected reward was not delivered or because an outcome of low value was delivered. Thus behavioral consequences can differ in terms of the information they provide about outcome probability and value. We investigated the role of the striatum in processing probability-based and value-based negative feedback by training participants to associate cues with food rewards and then employing a selective satiety procedure to devalue one food outcome. Using functional magnetic resonance imaging, we examined brain activity related to receipt of expected rewards, receipt of devalued outcomes, omission of expected rewards, omission of devalued outcomes, and expected omissions of an outcome. Nucleus accumbens activation was greater for rewarding outcomes than devalued outcomes, but activity in this region did not correlate with the probability of reward receipt. Activation of the right caudate and putamen, however, was largest in response to rewarding outcomes relative to expected omissions of reward. The dorsal striatum (caudate and putamen) at the time of feedback also showed a parametric increase correlating with the trialwise probability of reward receipt. Our results suggest that the ventral striatum is sensitive to the motivational relevance, or subjective value, of the outcome, while the dorsal striatum codes for a more complex signal that incorporates reward probability. Value and probability information may be integrated in the dorsal striatum, to facilitate action planning and allocation of effort.
为了使行为受到行动后果的指导，大脑必须能够表示出不同类型的与结果相关的信息。例如，一个结果可能被认为是负面的，因为预期的奖励没有兑现，或者因为兑现的结果价值较低。因此，行为后果可以根据它们提供的关于结果概率和价值的信息而有所不同。我们通过训练参与者将线索与食物奖励联系起来，并采用选择性饱和程序来降低一种食物结果的价值，以此来研究纹状体在处理基于概率和基于价值的负面反馈方面的作用。我们使用功能磁共振成像技术，检查了与预期奖励的获得、被贬低结果的获得、预期奖励的缺失、被贬低结果的缺失以及结果的预期缺失相关的大脑活动。与被贬低的结果相比，伏隔核对奖励性结果的激活更强，但该区域的活动与奖励获得的概率无关。然而，右尾状核和壳核的激活在奖励性结果相对于预期奖励缺失时最大。反馈时的背侧纹状体（尾状核和壳核）也表现出与奖励获得的试验概率呈参数性增加的趋势。我们的研究结果表明，腹侧纹状体对结果的动机相关性或主观价值敏感，而背侧纹状体则编码了一种更复杂的信号，其中包含了奖励的概率。价值和概率信息可能在背侧纹状体中整合，以促进行动规划和努力分配。
