David Geffen School of Medicine , University of California, Los Angeles, CA, USA.
Am J Psychiatry. 2012 Aug;169(8):831-40. doi: 10.1176/appi.ajp.2012.11030349.
Although the amygdala and ventrolateral prefrontal cortex have been implicated in the pathophysiology of bipolar I disorder, the neural mechanisms underlying bipolar II disorder remain unknown. The authors examined neural activity in response to negative emotional faces during an emotion perception task that reliably activates emotion regulatory regions.
Twenty-one nonmedicated depressed bipolar II patients and 21 healthy comparison subjects underwent functional MRI (fMRI) while performing an emotional face-matching task. Within- and between-group whole-brain fMRI activation and seed-based connectivity analyses were conducted.
In depressed bipolar II patients, random-effects between-group fMRI analyses revealed a significant reduction in activation in several regions, including the left and right ventrolateral prefrontal cortices (Brodmann's area [BA] 47) and the right amygdala, a priori regions of interest. Additionally, bipolar patients exhibited significantly reduced negative functional connectivity between the right amygdala and the right orbitofrontal cortex (BA 10) as well as the right dorsolateral prefrontal cortex (BA 46) relative to healthy comparison subjects.
These findings suggest that bipolar II depression is characterized by reduced regional orbitofrontal and limbic activation and altered connectivity in a fronto-temporal circuit implicated in working memory and emotional learning. While the amygdala hypoactivation observed in bipolar II depression is opposite to the direction seen in bipolar I mania and may therefore be state dependent, the observed orbitofrontal cortex hypoactivation is consistent with findings in bipolar I depression, mania, and euthymia, suggesting a physiologic trait marker of the disorder.
尽管杏仁核和腹外侧前额叶皮层与双相情感障碍的病理生理学有关，但双相情感障碍 II 型的神经机制仍不清楚。作者在一项情绪感知任务中检查了对负性情绪面孔的神经反应，该任务可靠地激活了情绪调节区域。
21 名未服用药物的抑郁性双相 II 型患者和 21 名健康对照者在执行情绪面孔匹配任务时接受了功能磁共振成像（fMRI）检查。进行了全脑 fMRI 激活和种子连接分析的组内和组间分析。
在抑郁性双相 II 型患者中，随机效应组间 fMRI 分析显示，包括左侧和右侧腹外侧前额叶皮层（Brodmann 区[BA]47）和右侧杏仁核在内的几个区域的激活明显减少，这些区域是预先设定的感兴趣区。此外，与健康对照组相比，双相患者表现出右侧杏仁核与右侧眶额皮层（BA10）以及右侧背外侧前额叶皮层（BA46）之间的负性功能连接显著降低。
这些发现表明，双相情感障碍 II 型抑郁的特征是眶额和边缘区域的激活减少，以及参与工作记忆和情绪学习的额颞叶回路的连接改变。虽然在双相情感障碍 II 型抑郁中观察到的杏仁核激活减少与双相情感障碍 I 型躁狂相反，因此可能是状态依赖性的，但观察到的眶额皮层激活减少与双相情感障碍 I 型抑郁、躁狂和缓解期一致，提示该疾病的生理特征标志物。
