亮度的誘發：早期視覺區平面亮度的神經相關性研究

Brightness Induction: A Study of Correlates of Surface Brightness in Early Visual Areas

我們對平面知覺的神經機制所知不多，目前相關的動物神經生理學研究及人體的功能性磁振造影（fMRI）研究出現相互衝突的結果。在平面亮度知覺的研究領域中，目前爭論著：對於物理上不存在的訊息仍有平面亮度的知覺感，此知覺感是否來自早期視覺區的亮度內插？我們使用fMRI探討人類的早期視覺區在平面亮度知覺所扮演的角色為何。實驗使用亮度誘發的典範：藉由周圍的動態亮度變化誘發灰色表面上的錯覺亮度改變。我們發現相關的視網膜區域的活動，可能由灰色表面的知覺亮度調控所造成。此發現顯示早期視覺區在知覺平面亮度上扮演重要的角色。目前的資料與貓和猴子的神經生理研究、及人體的fMRI實驗結果一致。後續需要進一步的研究，才能更具體地說明人類平面知覺的內插亮度的相關神經機制。

The neural mechanisms of surface perception are surprisingly poorly understood and ongoing research both in the domain of neurophysiology with animal models and fMRI in humans has led to conflicting results. In the domain of surface brightness perception, it is debated whether surface perception depends on the interpolation of brightness in early visual areas across regions in the visual field, where that information is physically absent. We used functional Magnetic Resonance Imaging (fMRI) in human subjects to test for a possible contribution of early visual areas to the perception of surface brightness. A brightness induction paradigm was employed in which counterphase illusory brightness changes on a grey surface are induced by dynamic luminance changes in the surround. We found fMRI activity in area V2 that may be attributable to the perceived brightness modulation of the constant, grey surface. This finding suggests a role of early visual cortex in the perception of surface brightness. The data are presented within the context of related neurophysiological studies in cat and monkey, as well as other human fMRI studies. Further experiments have to be performed to conclusively demonstrate a correlate of brightness interpolation during surface perception in humans.