- 學位論文
疼痛知覺決策歷程之神經關聯：功能性磁振造影研究
Neural Correlates for the Perceptual Decision Making of Pain: an fMRI study
摘要
為了適應外界環境刺激的迅速變化，分辨痛覺強度的能力對於正常人來說是至關重要的功能。過去的研究證據顯示異常的認知功能(包含決策歷程)可能與慢性疼痛 (Chronic pain) 的致病機制相關。然而迄今為止，大腦分辨疼痛強度的複雜神經機制仍舊尚未明朗，過去的相關研究結果也不一致。本研究的目的在於探索執行電痛 (electrical pain) 刺激相關的決策時，腦部所參與的特定神經基質。在本研究中，我們招募了二十二位年輕的健康受試者，並使用功能性磁振造影作為腦部功能性活動的成像工具。掃描的期間，受試者需要分辨兩個連續刺激的強度，或者判斷一個刺激是否會疼痛。影像資料的分析結果顯示，受試者分辨疼痛時引起了角迴(angular gyrus)、額下迴(inferior frontal gyrus)、額中迴(middle frontal gyrus) 和頂下小葉 (inferior parietal lobule) 的神經活動。另外在個別的試驗中，我們發現額上迴(superior frontal gyrus) 的神經活化與前後兩刺激的相對強度差異有關。更重要的是，相較於分辨非疼痛刺激，分辨疼痛強度時大腦的額上迴和角迴之間有顯著較強的功能性連結。此外，角迴和疼痛處理相關區域，包含初級體感覺皮質 (primary somatosensory cortex)、次級體感覺皮質 (secondary somatosensory cortex)、前扣帶迴皮質 (anterior cingulate cortex) 和腦島皮質 (insular cortex) 之間，在分辨疼痛時有額外的功能性互動。這些結果不僅補足了疼痛認知調節的神經基礎，也顯示額頂葉網絡 (fronto-parietal network) 與大腦痛覺區域之間的交互作用，參與了人類分辨疼痛刺激強度的歷程。
並列摘要
To discriminate the intensity of painful stimuli is essential to healthy survival. Evidence suggests that aberrant cognitive operations of pain, including the decision process, underlie the pathogenesis of chronic pain. However, neural mechanisms related to the discrimination of pain intensity in healthy humans remain unclear. The current study aims to investigate pain-specific neural substrates during the decision process of electrical pain. Twenty-two young healthy adults participated in this functional magnetic resonance imaging (fMRI) study. During scanning, subjects were required to either discriminate the intensity of two sequentially applied stimuli or categorize a stimulus as painful or not painful. Behavioral results indicated that subjects adopted different strategies during discrimination and categorization. Functional imaging data revealed that pain discrimination entailed the response in the angular gyrus (AG), inferior and middle frontal gyri, and inferior parietal lobule. Activity in the superior frontal gyrus (SFG) was parametrically modulated by the difference in pain intensity of the two sequential stimuli on a trial-by-trial basis. Importantly, compared with the discrimination of innocuous stimuli, the functional connectivity between SFG and AG was enhanced during pain discrimination. Moreover, AG was functionally linked with pain-processing regions – the primary somatosensory cortex – during pain discrimination. These findings complement the neural basis underlying the cognitive modulation on pain and suggest that discrimination of pain intensity engages an interaction between fronto-parietal networks and cerebral nociceptive centers.