憂慮的功能性神經迴路: 初探研究

Abstract

憂慮被視為廣泛性焦慮症的主要特徵，其以語言為主的特質在憂慮的逃避理論中佔有重要地位。根據這個理論，憂慮具有動態歷程且涉及多個不同系統。然而，先前的功能性磁振造影研究並未系統性地探討這個複雜動態歷程的神經機制。藉由此技術，本研究的結果提供神經機制上的證據來支持先前的憂慮研究，並更加了解憂慮的本質。首先、兩側的顳頂葉區及中前額葉可能共同負責一個複雜的語言神經網絡。第二、憂慮時所活化並非全為語言相關區域，而是涉及一些與視覺影像形成相關的區域。第三、高憂慮組在語言以及與視覺影像形成相關的區域有較多活化。最後、負向結果預期歷程相關的腦區在調節語言處理及視覺影像在不同互動模式中可能扮演重要角色。對於高憂慮組，其右背側前額葉利用抽象語言歷程來做為逃避負向情緒的方式。相較於高憂慮組，低憂慮組的腹內側前額葉可能經由抑制杏仁核而產生一個更完整的削弱歷程。綜合上述，本研究的結果提供了一個憂慮的神經迴路基礎。

Worry has been regarded as the central phenomenon of generalized anxiety disorder (GAD), and proven to be predominantly in the verbal-linguistic form, which plays an important role in the avoidance theory of worry. According to this theory, worry may involve several different systems with a dynamic process. However, no previous functional magnetic resonance imaging (fMRI) study has systematically examined the underlying functional mechanisms of this complex dynamic process. Using fMRI, findings from the present study provided evidence from neural substrates to support several lines of behavioral research in worry and furthered our understanding about the nature of worry. First, bilateral temporo-parietal regions and anterior medial PFC might engage in a complex verbal-linguistic neuro-network. Second, the worrisome mentation is not purely verbal-linguistic in nature, but also involved regions closely related to visual mental imagery formation. Third, our analogue GAD group had greater activations in areas related to both verbal-linguistic processing and mental imagery. Lastly, the neural substrates related to anticipation of negative consequences might play a crucial role in modulating the different dynamic patterns of activations observed between verbal-linguistic processing and mental imagery. For the high worriers, the right dorsolateral prefrontal cortex (DLPFC) is thought to employ verbal-linguistic processes as an avoidance action against negative affect. In contrast, the ventromedial prefrontal cortex (vmPFC) might execute a more complete extinction process through inhibiting the amygdala in low worriers. The above, thus provided a basis for the functional neurocircuitry of worry.