Wittmann Bianca C, D'Esposito Mark
Helen Wills Neuroscience Institute, University of California, Berkeley, CA, 94720, USA,
Psychopharmacology (Berl). 2015 Jan;232(1):135-44. doi: 10.1007/s00213-014-3646-7. Epub 2014 Jun 13.
Appetitive and aversive processes share a number of features such as their relevance for action and learning. On a neural level, reward and its predictors are associated with increased firing of dopaminergic neurons, whereas punishment processing has been linked to the serotonergic system and to decreases in dopamine transmission. Recent data indicate, however, that the dopaminergic system also responds to aversive stimuli and associated actions.
In this pharmacological functional magnetic resonance imaging study, we investigated the contribution of the dopaminergic system to reward and punishment processing in humans.
Two groups of participants received either placebo or the dopamine precursor levodopa and were scanned during alternating reward and punishment anticipation blocks.
Levodopa administration increased striatal activations for cues presented in punishment blocks. In an interaction with individual personality scores, levodopa also enhanced striatal activation for punishment-predictive compared with neutral cues in participants scoring higher on the novelty-seeking dimension.
These data support recent indications that dopamine contributes to punishment processing and suggest that the novelty-seeking trait is a measure of susceptibility to drug effects on motivation. These findings are also consistent with the possibility of an inverted U-shaped response function of dopamine in the striatum, suggesting an optimal level of dopamine release for motivational processing.
奖赏和厌恶过程具有许多共同特征，例如它们与行动和学习的相关性。在神经层面，奖赏及其预测因素与多巴胺能神经元的放电增加有关，而惩罚处理则与血清素能系统以及多巴胺传递的减少有关。然而，最近的数据表明，多巴胺能系统也会对厌恶刺激及相关行为做出反应。
在这项药物功能磁共振成像研究中，我们调查了多巴胺能系统对人类奖赏和惩罚处理的作用。
两组参与者分别接受安慰剂或多巴胺前体左旋多巴，并在交替的奖赏和惩罚预期阶段进行扫描。
服用左旋多巴增加了惩罚阶段出现的线索所引起的纹状体激活。在与个体人格分数的交互作用中，与中性线索相比，左旋多巴还增强了在寻求新奇维度得分较高的参与者对惩罚预测线索的纹状体激活。
这些数据支持了最近关于多巴胺有助于惩罚处理的观点，并表明寻求新奇特质是衡量药物对动机影响易感性的一个指标。这些发现也与纹状体中多巴胺呈倒U形反应函数的可能性相一致，表明多巴胺释放存在一个促进动机处理的最佳水平。
