Temporal frequency and chromatic processing in humans: An fMRI study of the cortical visual areas
Temporal frequency and chromatic processing in humans: An fMRI study of the cortical visual areas
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DOI：
10.1167/11.8.8
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发表时间：
2011-01-01
影响因子：
1.8
通讯作者：
Lee, Barry B.
中科院分区：
文献类型：
--
作者：
D'Souza, Dany V.;Auer, Tibor;Lee, Barry B.
心理物理敏感性等亮度色调制下降超过4 Hz的时间频率，而传入视觉通路的色对手细胞（长到中波长（L-M）锥对手或短波长（S）锥细胞）显示在更高的时间频率的反应，表明在时间处理能力的中央限制。在这里，我们试图将这种限制定位在皮层视网膜视区。我们使用功能磁共振成像研究人类外侧膝状体核和皮层视觉区对等亮度色调制的反应，作为时间频率（2-12 Hz）的函数。我们的研究结果表明，L-M锥对手和S锥信号处理LGN高达12 Hz。在所有的视觉领域，除了MT（中颞叶）和V3 a，S-锥反应急剧下降的时间频率，这意味着心理物理敏感性损失的蓝黄调制可能发生在这些领域的早期。虽然V1表现出强大的L-M响应高达12 Hz，有一个渐进的衰减的时间频率的响应信息从V1转移到更高的地区（V2，V3和V4），这表明，在人类中，时间限制的红色-绿色的色彩调制的感知可能是有限的处理能力较高的腹侧纹外区的结果。
Psychophysical sensitivity to isoluminant chromatic modulation declines at temporal frequencies beyond 4 Hz, whereas chromatically opponent cells of the afferent visual pathway (long-to middle-wavelength (L-M) cone-opponent or short-wavelength (S) cone cells) show responses at much higher temporal frequencies, indicating a central limitation in temporal processing capacity. Here, we sought to localize this limit in cortical retinotopic visual areas. We used fMRI to investigate responses of lateral geniculate nucleus and cortical visual areas in humans to isoluminant chromatic modulation as a function of temporal frequency (2-12 Hz). Our results suggest that L-M cone-opponent and S-cone signals are processed in LGN up to 12 Hz. In all visual areas except MT (middle temporal) and V3a, S-cone responses declined steeply with temporal frequency, implying that psychophysical sensitivity loss to blue-yellow modulation might occur early within these areas. While V1 showed robust L-M responses up to 12 Hz, there was a progressive falloff of responses with temporal frequency as information is transferred from V1 to higher areas (V2, V3, and V4), suggesting that, in humans, temporal limitation in perception of red-green chromatic modulation likely results from limited processing capacity of higher ventral extrastriate areas.