No functional magnetic resonance imaging evidence for brightness and color filling-in in early human visual cortex
No functional magnetic resonance imaging evidence for brightness and color filling-in in early human visual cortex
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DOI：
10.1523/jneurosci.4382-05.2006
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发表时间：
2006-04-05
影响因子：
5.3
通讯作者：
Wandell, BA
中科院分区：
文献类型：
--
作者：
Cornelissen, FW;Wade, AR;Wandell, BA
表面的亮度和颜色取决于其与附近表面的对比度。例如，灰色曲面在被黑色曲面包围时会显得很亮，而在被白色曲面包围时会显得很暗。一些理论认为，感知到的表面亮度和颜色是由皮层视野图中的神经信号明确表示的;这些神经信号不是由刺激本身发起的，而是由边界处的对比度信号发起的。在这里，我们使用功能性磁共振成像（fMRI）来寻找这样的神经“填充”信号。虽然我们发现局部对比度和fMRI反应之间通常存在很强的关系，但当感知的亮度或颜色变化是通过调制周围的场而不是表面本身引起的时，我们发现在初级视觉皮层或其他附近的retinotopic地图中没有相应的局部调制。此外，当我们模型所获得的功能磁共振成像响应，我们发现强有力的证据，本地和远程边缘响应的贡献。我们认为，这种扩展的边缘响应可能是由神经生理学研究中以前确定的神经元作为亮度响应，因此可能需要修改的特性。我们的结论是，视野地图的人V1和V2不包含填充，表面亮度和颜色的地形表示。
The brightness and color of a surface depends on its contrast with nearby surfaces. For example, a gray surface can appear very light when surrounded by a black surface or dark when surrounded by a white surface. Some theories suggest that perceived surface brightness and color is represented explicitly by neural signals in cortical visual field maps; these neural signals are not initiated by the stimulus itself but rather by the contrast signals at the borders. Here, we use functional magnetic resonance imaging (fMRI) to search for such neural "filling-in" signals. Although we find the usual strong relationship between local contrast and fMRI response, when perceived brightness or color changes are induced by modulating a surrounding field, rather than the surface itself, we find there is no corresponding local modulation in primary visual cortex or other nearby retinotopic maps. Moreover, when we model the obtained fMRI responses, we find strong evidence for contributions of both local and long-range edge responses. We argue that such extended edge responses may be caused by neurons previously identified in neurophysiological studies as being brightness responsive, a characterization that may therefore need to be revised. We conclude that the visual field maps of human V1 and V2 do not contain filled-in, topographical representations of surface brightness and color.