Sterzer Philipp, Kleinschmidt Andreas
Cognitive Neurology Unit, Department of Neurology, Johann Wolfgang Goethe University, Frankfurt-am-Main, Germany.
Eur J Neurosci. 2005 Jun;21(11):3097-106. doi: 10.1111/j.1460-9568.2005.04133.x.
The 'correspondence problem' refers to the ambiguity of apparent motion (AM) paths if several similar objects are displaced across successive displays. We investigated the effect of intrinsic object properties such as colour and luminance on AM paths, and used functional magnetic resonance imaging to localize neural correlates of correspondence matching in visual cortical regions. Human subjects looked at an AM display where two dots in diagonally opposite corners of an implicit rectangle were flashed in alternation with two dots in the other two corners, yielding spontaneous alternations between horizontal and vertical AM. The dots differed in colour or luminance, or were identical. Neural activity was analysed as a function of whether the perceived AM path matched the dots' colour or luminance, and was also compared to activity during bistable AM displays without correspondence cues. When AM paths matched colour and luminance cues, activity in early visual cortex was the same as during perception of uncued displays, whereas it was suppressed when perceived AM paths violated colour or luminance cues. Colour-sensitive extrastriate cortex (V4 complex) transiently activated whenever AM perception switched from a pattern violating colour correspondence to one consistent with colour. We propose that the neural correlate of correspondence in early visual cortex reflects regulatory mechanisms that flexibly gate early visual feature processing in accord with an overriding perceptual decision. Conversely, activation of feature-selective extrastriate regions depends on the type of cue used for correspondence matching and may reflect the salience of percepts that match in colour and motion.
“对应问题”指的是,如果几个相似物体在连续的显示画面中发生位移,表观运动(AM)路径就会存在模糊性。我们研究了颜色和亮度等物体固有属性对AM路径的影响,并使用功能磁共振成像来定位视觉皮层区域中对应匹配的神经关联。人类受试者观看一个AM显示画面,其中一个隐含矩形对角的两个点与另外两个角的两个点交替闪烁,从而在水平和垂直AM之间产生自发交替。这些点在颜色或亮度上有所不同,或者完全相同。根据感知到的AM路径是否与点的颜色或亮度相匹配来分析神经活动,并且还将其与没有对应线索的双稳态AM显示期间的活动进行比较。当AM路径与颜色和亮度线索相匹配时,早期视觉皮层的活动与无线索显示感知期间相同,而当感知到的AM路径违反颜色或亮度线索时,活动则受到抑制。每当AM感知从违反颜色对应的模式切换到与颜色一致的模式时,颜色敏感的纹外皮层(V4复合体)就会短暂激活。我们提出,早期视觉皮层中对应关系的神经关联反映了调节机制,该机制根据首要的感知决策灵活地控制早期视觉特征处理。相反,特征选择性纹外区域的激活取决于用于对应匹配的线索类型,并且可能反映了在颜色和运动方面匹配的感知的显著性。