Cools Roshan, Blackwell Andrew, Clark Luke, Menzies Lara, Cox Sylvia, Robbins Trevor W
Department of Experimental Psychology, University of Cambridge, Cambridge, UK.
Neuropsychopharmacology. 2005 Jul;30(7):1362-73. doi: 10.1038/sj.npp.1300704.
Serotonin (5-HT) is well known to affect the motivational properties of stimuli predictive of rewards as well as the inhibitory control of behavior. Here, central 5-HT depletion was induced by the acute tryptophan (TRP) depletion (ATD) procedure in young healthy volunteers to examine the role of 5-HT in motivated action and prepotent response inhibition. A novel reaction-time task, tailored to individual differences in general cognitive speed, was employed to measure the guidance of behavior by motivationally relevant signals predictive of reinforcement likelihood, while the stop-signal reaction-time task was used to measure response inhibition. Following the TRP-balancing control drink, cues predictive of high-reinforcement certainty induced faster, but less accurate responses compared with cues predictive of lower reinforcement certainty. Depletion of central 5-HT modulated this coupling between motivation and action by slowing responses and increasing accuracy as a function of incentive certainty. These effects of ATD on motivated action correlated highly with individual differences in the personality trait of Nonplanning Impulsiveness (Barratt Impulsivity Scale (BIS-11)), so that strongest effects on motivated action were observed in high-impulsive individuals. By contrast, ATD left unaltered the ability to inhibit prepotent responses. Our findings may have implications for a variety of neuropsychiatric disorders including impulsive aggressive disorders and depression.
血清素（5-羟色胺，5-HT）对预示奖励的刺激的动机特性以及行为的抑制控制具有影响，这一点已广为人知。在此，通过急性色氨酸（TRP）耗竭（ATD）程序在年轻健康志愿者中诱导中枢5-HT耗竭，以研究5-HT在动机性行动和优势反应抑制中的作用。采用了一种根据个体一般认知速度差异量身定制的新颖反应时任务，来测量由预示强化可能性的动机相关信号对行为的引导，同时使用停止信号反应时任务来测量反应抑制。饮用TRP平衡对照饮料后，与预示较低强化确定性的线索相比，预示高强化确定性的线索会引发更快但准确性更低的反应。中枢5-HT的耗竭通过减缓反应速度并根据激励确定性提高准确性，调节了动机与行动之间的这种关联。ATD对动机性行动的这些影响与非计划性冲动（巴雷特冲动量表（BIS-11））人格特质的个体差异高度相关，因此在高冲动性个体中观察到对动机性行动的影响最为强烈。相比之下，ATD并未改变抑制优势反应的能力。我们的研究结果可能对包括冲动攻击性障碍和抑郁症在内的多种神经精神疾病具有启示意义。
