建立V1上缺口的橋樑：盲點的知覺填補和填整的神經反應

Bridging Gaps at V1: Neural Responses for Filling-in and Completion at the Blind Spot

在盲點（BS）並無任何視網膜訊號的輸入，然而我們卻不會知覺到視野有一個洞出現。相反地，我們仍然能夠知覺到盲點中存在與周圍視野相同的顏色、輪廓或質地，這就是所謂盲點的知覺填補或填整現象。填補和填整的現象不止發生在盲點，也出現在視網膜受損的區域、及正常視野的各種知覺現象中。這表示在我們的視覺系統中，有某些機制可內插填補不完整的視網膜訊號而形成連續的平面和輪廓。為說明在知覺填補和填整中，初級視皮層（V1）的角色，我們分析獼猴V1表徵盲點的腦皮質區域的神經反應，意欲瞭解兩個問題：（1）是否在沒有直接的視網膜反應輸入的V1區域，V1的神經細胞仍可引發知覺填補和填整的現象？（2）V1對此類刺激的神經反應是否與當下的知覺有關？我們發現：上述兩個問題的答案是「肯定」的。研究結果顯示V1在盲點的填補和填整扮演重要的角色。

No retinal input exists at the blind spot (BS). However, we do not perceive a hole in the visual field. Instead, within the BS, we perceive the same color, contour or texture as the stimuli surrounding the BS. This is called perceptual fillingin or completion at the BS. Filling-in and completion occurs not only at the BS but also in the retinal scotoma and in various phenomena in the normal visual field. This suggests that there are some mechanisms in our visual system that could interpolate incomplete retinal signals to form contiguous surface and contour. To elucidate the role of the primary visual cortex (V1) in perceptual filling-in and completion, we analyzed neural responses at the retinotopic representation of the BS in macaque V1. We addressed two questions: (1) Do V1 neurons respond to stimuli inducing filling-in or completion even though there is no direct retinal input to this region? (2) Do the responses of V1 neurons to such stimuli correlate with perception? We found that the answers to both of the above questions are 'yes.' Our results suggest that V1 plays an important role in the occurrence of filling-in and completion at the BS.