Evers E A, Stiers P, Ramaekers J G
Department of Neuropsychology and Psychopharmacology, Faculty of Psychology and Neuroscience, Maastricht University, Universiteitssingel 40, Maastricht 6229 ER, The Netherlands.
Soc Cogn Affect Neurosci. 2017 Feb 1;12(2):311-318. doi: 10.1093/scan/nsw124.
Dopamine plays an important role in goal-directed behavior, through its modulatory influence on striatal neurons. It is unclear whether tonic dopamine levels, which regulate the vigor of acting, interact with the phasic dopamine response to reward that drives instrumental behavior. In a randomized placebo-controlled study in healthy volunteers, we show that methylphenidate, a drug that increases tonic dopamine levels, systematically reduced striatal phasic BOLD responses to gain and loss in a gambling task as measured with fMRI. It also increased response vigor and reward expectancy-related BOLD signals in the ventral striatum. These findings suggest that striatal tonic dopamine levels constitute an average reward expectation signal that modulates the phasic dopaminergic response to reward. This offers opportunities for treatment of behavioral disorders associated with abnormal reward sensitivity.
多巴胺通过对纹状体神经元的调节作用，在目标导向行为中发挥重要作用。目前尚不清楚调节行为活力的持续性多巴胺水平，是否与驱动工具性 行为的奖励性多巴胺相位反应相互作用。在一项针对健康志愿者的随机安慰剂对照研究中，我们发现，哌甲酯作为一种能提高持续性多巴胺水平的药物，在用功能磁共振成像（fMRI）测量的赌博任务中，系统性地降低了纹状体对输赢的相位BOLD反应。它还增强了反应活力，并增加了腹侧纹状体中与奖励预期相关的BOLD信号。这些发现表明，纹状体持续性多巴胺水平构成了一个平均奖励预期信号，该信号调节对奖励的相位多巴胺能反应。这为治疗与异常奖励敏感性相关的行为障碍提供了机会。
