Wiebking Christine, de Greck Moritz, Duncan Niall W, Tempelmann Claus, Bajbouj Malek, Northoff Georg
Cluster of Excellence in Cognitive Sciences, Department of Sociology of Physical Activity and Health, University of Potsdam Potsdam, Germany ; Mind, Brain Imaging and Neuroethics, Institute of Mental Health Research, University of Ottawa Ottawa, ON, Canada.
Department of Psychosomatic Medicine and Psychotherapy, University Medicine Mainz Mainz, Germany.
Front Behav Neurosci. 2015 Apr 10;9:82. doi: 10.3389/fnbeh.2015.00082. eCollection 2015.
Interoceptive awareness (iA), the awareness of stimuli originating inside the body, plays an important role in human emotions and psychopathology. The insula is particularly involved in neural processes underlying iA. However, iA-related neural activity in the insula during the acute state of major depressive disorder (MDD) and in remission from depression has not been explored.
A well-established fMRI paradigm for studying (iA; heartbeat counting) and exteroceptive awareness (eA; tone counting) was used. Study participants formed three independent groups: patients suffering from MDD, patients in remission from MDD or healthy controls. Task-induced neural activity in three functional subdivisions of the insula was compared between these groups.
Depressed participants showed neural hypo-responses during iA in anterior insula regions, as compared to both healthy and remitted participants. The right dorsal anterior insula showed the strongest response to iA across all participant groups. In depressed participants there was no differentiation between different stimuli types in this region (i.e., between iA, eA and noTask). Healthy and remitted participants in contrast showed clear activity differences.
This is the first study comparing iA and eA-related activity in the insula in depressed participants to that in healthy and remitted individuals. The preliminary results suggest that these groups differ in there being hypo-responses across insula regions in the depressed participants, whilst non-psychiatric participants and patients in remission from MDD show the same neural activity during iA in insula subregions implying a possible state marker for MDD. The lack of activity differences between different stimulus types in the depressed group may account for their symptoms of altered external and internal focus.
内感受性觉知（iA），即对源自身体内部刺激的觉知，在人类情绪和精神病理学中发挥着重要作用。脑岛尤其参与了iA背后的神经过程。然而，在重度抑郁症（MDD）急性期及抑郁缓解期，脑岛内与iA相关的神经活动尚未得到研究。
使用一种成熟的功能磁共振成像（fMRI）范式来研究内感受性觉知（iA；心跳计数）和外感受性觉知（eA；音调计数）。研究参与者分为三个独立组：MDD患者、MDD缓解期患者或健康对照组。比较了这些组之间脑岛三个功能亚区的任务诱发神经活动。
与健康参与者和缓解期参与者相比，抑郁参与者在前脑岛区域的iA过程中表现出神经反应减弱。在所有参与者组中，右侧背侧前脑岛对iA的反应最强。在抑郁参与者中，该区域对不同刺激类型（即iA、eA和无任务）没有区分。相比之下，健康参与者和缓解期参与者表现出明显的活动差异。
这是第一项比较抑郁参与者与健康及缓解期个体脑岛内与iA和eA相关活动的研究。初步结果表明，这些组的差异在于抑郁参与者脑岛区域存在反应减弱，而非精神科参与者和MDD缓解期患者在脑岛亚区的iA过程中表现出相同的神经活动，这意味着可能是MDD的一种状态标志物。抑郁组中不同刺激类型之间缺乏活动差异可能解释了他们外部和内部注意力改变的症状。
