Dillon Daniel G, Dobbins Ian G, Pizzagalli Diego A
Center for Depression, Anxiety and Stress Research & McLean Imaging Center, McLean Hospital, Harvard Medical School, Belmont, MA 02478, USA and Department of Psychology, Washington University in Saint Louis, Saint Louis, MO 63130, USA
Center for Depression, Anxiety and Stress Research & McLean Imaging Center, McLean Hospital, Harvard Medical School, Belmont, MA 02478, USA and Department of Psychology, Washington University in Saint Louis, Saint Louis, MO 63130, USA.
Soc Cogn Affect Neurosci. 2014 Oct;9(10):1576-83. doi: 10.1093/scan/nst155. Epub 2013 Sep 26.
Reward responses in the medial temporal lobes and dopaminergic midbrain boost episodic memory formation in healthy adults, and weak memory for emotionally positive material in depression suggests this mechanism may be dysfunctional in major depressive disorder (MDD). To test this hypothesis, we performed a study in which unmedicated adults with MDD and healthy controls encoded drawings paired with reward or zero tokens during functional magnetic resonance imaging. In a recognition test, participants judged whether drawings were previously associated with the reward token ('reward source') or the zero token ('zero source'). Unlike controls, depressed participants failed to show better memory for drawings from the reward source vs the zero source. Consistent with predictions, controls also showed a stronger encoding response to reward tokens vs zero tokens in the right parahippocampus and dopaminergic midbrain, whereas the MDD group showed the opposite pattern-stronger responses to zero vs reward tokens-in these regions. Differential activation of the dopaminergic midbrain by reward vs zero tokens was positively correlated with the reward source memory advantage in controls, but not depressed participants. These data suggest that weaker memory for positive material in depression reflects blunted encoding responses in the dopaminergic midbrain and medial temporal lobes.
内侧颞叶和多巴胺能中脑的奖赏反应可促进健康成年人的情景记忆形成，而抑郁症患者对情绪积极材料的记忆较弱，这表明该机制在重度抑郁症（MDD）中可能功能失调。为了验证这一假设，我们进行了一项研究，让未服药的MDD成年人和健康对照者在功能磁共振成像期间对与奖赏或零代币配对的图画进行编码。在识别测试中，参与者判断图画之前是与奖赏代币（“奖赏源”）还是零代币（“零源”）相关联。与对照组不同，抑郁症患者未能表现出对来自奖赏源的图画比对零源的图画有更好的记忆。与预测一致，对照组在右侧海马旁回和多巴胺能中脑对奖赏代币比对零代币也表现出更强的编码反应，而MDD组在这些区域表现出相反的模式——对零代币比对奖赏代币有更强的反应。奖赏代币与零代币对多巴胺能中脑的差异激活与对照组中奖赏源记忆优势呈正相关，但与抑郁症患者无关。这些数据表明，抑郁症患者对积极材料的记忆较弱反映了多巴胺能中脑和内侧颞叶编码反应的减弱。
