正念、正念訓練與心理健康：預設模式網絡之觀點

Mindfulness, Mindfulness Training and Mental Health from the Perspective of Default Mode Network

正念為一種特殊形式之察覺能力，其與諸多心理健康有所連結，近年正念研究亦以神經科學取向進行探究，其中預設模式網絡則是討論關於大腦功能相關議題時相對較新的觀點。本回顧旨在以大腦預設模式網絡觀點探討正念對心理健康影響的大腦神經機制，並著重於功能性磁共振造影與腦電圖等取向在橫斷式、縱貫式和介入性實證研究的角度來進行討論。經文獻回顧後發現，過去正念相關研究指出，正念對心理健康與大腦結構或功能具正向影響；而預設模式網絡和憂鬱症與阿茲海默症等疾病有所關聯。而在功能性磁共振造影方面，正念傾向與正念訓練對預設模式網絡腦區之活化程度有其關聯性存在，並可能增加注意力相關的腦網絡與邊緣系統之間的連結性，藉此對個體的心理健康產生正向影響。此外，在腦電圖方面， 正念傾向與正念訓練造成的預設模式網絡腦區之活化差異與gamma 與theta 波變化有關。整體而言，正念傾向與正念訓練可促使個體從預設模式網絡驅使的思緒漫遊中脫離，並對大腦功能產生正向影響。本文提供國內對該議題有興趣的研究者瞭解其研究發展趨勢，並建議可朝向更嚴謹的實驗設計、樣本普遍性、正念訓練型態影響之差異、預設模式網絡在正念與行為表現間所扮演的中介角色等進行後續研究。

Dispositional mindfulness has been defined as a focused mental process achieved through intentionally focusing on aspectsof the self and being non-judgmental while connecting to one's present moment of experience. Dispositional mindfulness hasbeen linked to mental health outcomes such as stress, emotion, rumination, and executive function. More information on theeffectiveness of current mindfulness-based interventions may have indicated improved mental health outcomes owing toattentional control, emotional regulation, and heightened self-awareness. Designs of previous clinical studies havedemonstrated an amelioration of psychiatric symptoms through exposure to mindfulness training. Furthermore, they haveindicated that the effects of mindfulness training are noticeable, such as changing the structure and functions of the brain.Evidence for the benefits of dispositional mindfulness or mindfulness training has been illustrated in relation to theneurophysiological mechanisms underlying the brain.Recently, imaging and neuroelectric studies targeting mindfulness conditions have been employed to investigate the potentialneuroscience mechanisms associated with mindfulness. The accumulating evidence suggests that mindfulness is associatedwith brain activation and connectivity. The default mode network (DMN) is a relative new discovery among brain networksthat provides a viewpoint useful for discussing operations of brain functions and networks. DMN helps us understand theindividual processes of internal psychological states, cognition, the causes of mental diseases, and behavioral affectedperformance. The DMN is a set of brain regions including the medial prefrontal cortex (mPFC), posterior cingulate cortex (PCC), and precorneal cortices. These regions are those typically deactivated regions during cognitively demanding tasks.Conversely, the increase of activity among these brain regions reflects the individual's mental states as mind wandering andexperiencing thoughts unrelated to the current task. The available evidence indicates the important role of DMN in daily life.This is because of DMN involving self-referential mental activity and manifesting experience with prior recalls, associatedwith psychiatric diseases and negative mental states.