Behavioral Medicine, Tohoku University Graduate School of Medicine, Tohoku University, 2-1 Seiryo-cho, Aoba-ku, Sendai, 980-8575, Japan.
Biopsychosoc Med. 2013 Jan 9;7(1):1. doi: 10.1186/1751-0759-7-1.
Alexithymia is a personality trait characterized by difficulties in identifying and describing feelings and is associated with psychiatric and psychosomatic disorders. The mechanisms underlying the link between emotional dysregulation and psychosomatic disorders are unclear. Recent progress in neuroimaging has provided important information regarding emotional experience in alexithymia. We have conducted three brain imaging studies on alexithymia, which we describe herein. This article considers the role of emotion in the development of physical symptoms and discusses a possible pathway that we have identified in our neuroimaging studies linking alexithymia with psychosomatic disorders. In terms of socio-affective processing, alexithymics demonstrate lower reactivity in brain regions associated with emotion. Many studies have reported reduced activation in limbic areas (e.g., cingulate cortex, anterior insula, amygdala) and the prefrontal cortex when alexithymics attempt to feel other people's feelings or retrieve their own emotional episodes, compared to nonalexithymics. With respect to primitive emotional reactions such as the response to pain, alexithymics show amplified activity in areas considered to be involved in physical sensation. In addition to greater hormonal arousal responses in alexithymics during visceral pain, increased activity has been reported in the insula, anterior cingulate cortex, and midbrain. Moreover, in complex social situations, alexithymics may not be able to use feelings to guide their behavior appropriately. The Iowa gambling task (IGT) was developed to assess decision-making processes based on emotion-guided evaluation. When alexithymics perform the IGT, they fail to learn an advantageous decision-making strategy and show reduced activity in the medial prefrontal cortex, a key area for successful performance of the IGT, and increased activity in the caudate, a region associated with impulsive choice. The neural machinery in alexithymia is therefore activated more on the physiologic, motor-expressive level and less in the cognitive-experiential domains of the emotional response system. Affects may play an important role in alleviating intrinsic physiologic reactions and adapting to the environment. Deficient development of emotional neural structures may lead to hypersensitivity to bodily sensations and unhealthy behaviors, a possible mechanism linking alexithymia to psychosomatic disorders.
述情障碍是一种以识别和描述感受困难为特征的人格特质，与精神和心身障碍有关。情绪调节障碍与心身障碍之间联系的机制尚不清楚。神经影像学的最新进展为述情障碍的情绪体验提供了重要信息。我们已经进行了三项关于述情障碍的脑影像学研究，本文对此进行了描述。本文考虑了情绪在躯体症状发展中的作用，并讨论了我们在神经影像学研究中发现的可能的途径，将述情障碍与心身障碍联系起来。在社会情感处理方面，述情者在与情绪相关的大脑区域表现出较低的反应性。许多研究报告说，与非述情者相比，当述情者试图感受他人的感受或回忆自己的情绪事件时，边缘区域（如扣带回皮质、前岛叶、杏仁核）和前额叶的激活减少。对于疼痛等原始情绪反应，述情者在被认为与身体感觉有关的区域表现出增强的活动。此外，在内脏疼痛期间，述情者的荷尔蒙唤醒反应增强，并且在岛叶、前扣带回皮质和中脑报告了增加的活动。此外，在复杂的社会情境中，述情者可能无法适当地使用感受来指导他们的行为。爱荷华赌博任务（IGT）是为评估基于情绪引导评估的决策过程而开发的。当述情者执行 IGT 时，他们无法学习到有利的决策策略，并且在中前额叶皮质（成功执行 IGT 的关键区域）的活动减少，而在尾状核（与冲动选择相关的区域）的活动增加。因此，述情障碍的神经机制在生理、运动表达水平上的激活更多，而在情绪反应系统的认知体验领域的激活较少。情感可能在缓解内在生理反应和适应环境方面发挥重要作用。情绪神经结构的发育不足可能导致对身体感觉的过度敏感和不健康的行为，这可能是将述情障碍与心身障碍联系起来的一种机制。
