| 摘要: | 神經心理學的意識研究主要目的是找出形成意識內容的相關相關神經網路，可以透過後設認知報告的方式來研究此主題。從神經影像和腦傷研究顯示前額頂葉網絡是視覺後設認知覺察的重要媒介。然而，經顱磁刺激提供的因果證據到目前為止並沒有一致結論。前額頂葉網絡是否為意識的神經關聯網絡關鍵取決於前額頂葉網絡是否與後設認知覺察報告相關。若前額頂葉網絡和後設認知覺察報告以外能力有關，則可以排除前額頂葉網絡只全然負責意識形成。
在實驗一，我們使用經顱磁刺激來減少前額頂葉網絡神經興奮性，後設認知能力顯著受到影響，特別是當刺激仰賴週邊資訊。重要的是，經顱磁刺激並沒有減低視知覺評分，但減低後設認知的效率（即，在犯錯時）。實驗中二、使用腦磁波檢測刺激前α腦波的強度和右背側前額葉 和枕葉之間的功能性連結，是否這些指標和目標偵測有關，同時還有視覺後設認知覺察。最後，在實驗三，背側前額葉和確定可見性報告方面發揮了重要作用，可能是來自於由上而下的注意力控制來改善行為一致性。總結來說，前額頂葉網絡似乎涉及認知控制的機制來改變行為連貫性。目前證據不能排除前額頂葉網絡實際上是意識內容的所在地的可能性，但目前研究結果顯示前額頂葉網絡似乎更可能與意識的內容被報告多完整有關連。
The neuropsychological study of consciousness aims at finding the neural structures responsible for the emergence of its contents, mainly through metacognitive reports. Neuroimaging and lesion studies suggest that the prefrontal parietal network (PPN) mediates visual metacognitive awareness. The causal evidence provided by non-invasive brain stimulation, however, is inconsistent. Defining the PPN as a full neural correlate of consciousness (NCC) critically depends on whether the PPN is related to metacognitive reports per se. In turn, the PPN could be ruled out as a full NCC if found to be related to post-conscious metacognitive abilities, or other cognitive functions such as attention.
In experiment one we observe that decreasing the PPN’s neural excitability by use of continuous theta burst stimulation (cTBS), metacognitive abilities are affected, specifically when stimuli rely on contextual information. Importantly, cTBS did not reduce visibility ratings, but increase them in an inefficient way (i.e., while making mistakes). In experiment two, using magnetoencephalography, prestimulus alpha power and functional connectivity between the right dorsolateral prefrontal cortex (DLPFC) and occipital sensors, predicted not only target detection, but also visual acuity. Finally, in experiment three, the DLPFC seems to play an important role not so much in determining visibility reports, but in inducing top-down attentional control leading to improved behavioural consistency (or metacognitive sensitivities). Taken as a whole, the PPN seems involved in cognitive control mechanisms inducing behavioural coherency which is related to metacognitive awareness. Evidence cannot rule out the possibility that the PPN is, in fact, the seat of conscious contents, but based on these observations it seems more likely that the PPN is related to how well conscious contents are reported. |
