CNRS USR 3246, Paris, France; Université Paris Descartes, Faculté de médecine, Paris, France; Assistance Publique-Hôpitaux de Paris, Department of C-L Psychiatry, European Georges Pompidou Hospital, Paris, France.
CNRS USR 3246, Paris, France; Pierre et Marie Curie University, Paris, France.
J Affect Disord. 2012 Jan;136(1-2):e1-e11. doi: 10.1016/j.jad.2010.11.034. Epub 2010 Dec 23.
Self-focus (i.e. the process by which one engages oneself in self-referential processing) is a core issue in the psychopathology of major depression. The cortical midline structures, including the medial prefrontal cortex (MPFC), play a key role in self-referential processing in healthy subjects. Four functional magnetic resonance imaging studies recently found either an increased or a decreased MPFC activation during self-referential processing in depressed patients compared to healthy controls. Building on critical differences in experimental settings, we argue that these conflicting results are indeed consistent with two modes of elevated MPFC activation in major depression. An elevated tonic ventral MPFC activation, as uncovered by an event-related design, may embody automatic aspects of depressive self-focus, such as attracting attention to self-relevant incoming information. An elevated phasic dorsal MPFC activation, as uncovered by a block-based design, may embody more strategic aspects of depressive self-focus, such as comparing the self with inner standards. Additionally, strategic self-focus in depression may recruit the anterior cingulate cortex and more lateral regions of the prefrontal cortex. An aberrant functional connectivity of the dorsal MPFC may underlie this lack of reciprocal inhibition between the cognitive control network and the default mode network. Altogether, these results suggest that self-focus in depression may emerge as a process competing for brain resources due to a lack of inhibition of the default mode network, resulting in detrimental effects on externally-oriented cognitive processes. Follow-up studies are warranted to determine the trait vs. state nature of these biomarkers and their ability to predict treatment outcome.
自我关注（即个体进行自我参照加工的过程）是重性抑郁障碍发病机制中的核心问题。皮质中线结构，包括内侧前额叶皮质（MPFC），在健康个体的自我参照加工中发挥关键作用。四项功能磁共振成像研究最近发现，与健康对照组相比，抑郁患者在进行自我参照加工时，MPFC 的激活要么增加，要么减少。基于实验设置的关键差异，我们认为这些相互矛盾的结果确实与重性抑郁障碍中两种升高的 MPFC 激活模式一致。与事件相关设计揭示的升高的紧张性腹侧 MPFC 激活可能体现了抑郁性自我关注的自动方面，例如将注意力吸引到与自我相关的传入信息上。与基于块的设计揭示的升高的相位背侧 MPFC 激活可能体现了抑郁性自我关注更具策略性的方面，例如将自我与内在标准进行比较。此外，抑郁中的策略性自我关注可能会招募扣带前回和前额叶皮层的外侧区域。背侧 MPFC 的异常功能连接可能是认知控制网络和默认模式网络之间缺乏相互抑制的基础。总之，这些结果表明，由于默认模式网络的抑制不足，抑郁中的自我关注可能会作为一个争夺大脑资源的过程出现，从而对外部导向的认知过程产生不利影响。需要进一步的研究来确定这些生物标志物的特质与状态性质及其对治疗结果的预测能力。
