Kumar P, Berghorst L H, Nickerson L D, Dutra S J, Goer F K, Greve D N, Pizzagalli D A
Center for Depression, Anxiety and Stress Research, McLean Hospital, Belmont, MA, USA; Department of Psychiatry, Harvard Medical School, MA, USA.
Department of Psychology, Harvard University, Cambridge, MA, USA.
Neuroscience. 2014 Apr 25;266:1-12. doi: 10.1016/j.neuroscience.2014.01.058. Epub 2014 Feb 7.
Anhedonia is one of the core symptoms of depression and has been linked to blunted responses to rewarding stimuli in striatal regions. Stress, a key vulnerability factor for depression, has been shown to induce anhedonic behavior, including reduced reward responsiveness in both animals and humans, but the brain processes associated with these effects remain largely unknown in humans. Emerging evidence suggests that stress has dissociable effects on distinct components of reward processing, as it has been found to potentiate motivation/'wanting' during the anticipatory phase but reduce reward responsiveness/'liking' during the consummatory phase. To examine the impact of stress on reward processing, we used a monetary incentive delay (MID) task and an acute stress manipulation (negative performance feedback) in conjunction with functional magnetic resonance imaging (fMRI). Fifteen healthy participants performed the MID task under no-stress and stress conditions. We hypothesized that stress would have dissociable effects on the anticipatory and consummatory phases in reward-related brain regions. Specifically, we expected reduced striatal responsiveness during reward consumption (mirroring patterns previously observed in clinical depression) and increased striatal activation during reward anticipation consistent with non-human findings. Supporting our hypotheses, significant Phase (Anticipation/Consumption)×Stress (Stress/No-stress) interactions emerged in the putamen, nucleus accumbens, caudate and amygdala. Post hoc tests revealed that stress increased striatal and amygdalar activation during anticipation but decreased striatal activation during consumption. Importantly, stress-induced striatal blunting was similar to the profile observed in clinical depression under baseline (no-stress) conditions in prior studies. Given that stress is a pivotal vulnerability factor for depression, these results offer insight to better understand the etiology of this prevalent disorder.
快感缺失是抑郁症的核心症状之一,并且与纹状体区域对奖励性刺激的反应迟钝有关。压力是抑郁症的一个关键易感性因素,已被证明会诱发快感缺失行为,包括动物和人类的奖励反应性降低,但在人类中,与这些影响相关的大脑过程仍 largely 未知。新出现的证据表明,压力对奖励处理的不同组成部分有可分离的影响,因为已发现它在预期阶段增强动机/“渴望”,但在 consummatory 阶段降低奖励反应性/“喜欢”。为了研究压力对奖励处理的影响,我们使用了金钱激励延迟(MID)任务和急性压力操纵(负面绩效反馈)并结合功能磁共振成像(fMRI)。15 名健康参与者在无压力和压力条件下执行 MID 任务。我们假设压力会对奖励相关脑区的预期和 consummatory 阶段产生可分离的影响。具体而言,我们预计在奖励消费期间纹状体反应性降低(反映先前在临床抑郁症中观察到的模式),并且在奖励预期期间纹状体激活增加,这与非人类研究结果一致。支持我们的假设,在壳核、伏隔核、尾状核和杏仁核中出现了显著的阶段(预期/消费)×压力(压力/无压力)交互作用。事后检验显示,压力在预期期间增加了纹状体和杏仁核的激活,但在消费期间降低了纹状体的激活。重要的是,压力诱导的纹状体迟钝与先前研究中在基线(无压力)条件下临床抑郁症中观察到的特征相似。鉴于压力是抑郁症的一个关键易感性因素,这些结果为更好地理解这种常见疾病的病因提供了见解。