Population receptive field (pRF) measurements of chromatic responses in human visual cortex using fMRI.
Population receptive field (pRF) measurements of chromatic responses in human visual cortex using fMRI.
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DOI：
10.1016/j.neuroimage.2017.11.022
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发表时间：
2018-02-15
期刊：
影响因子：
5.7
通讯作者：
Wade AR
中科院分区：
文献类型：
--
作者：
Welbourne LE;Morland AB;Wade AR
人类视觉系统的空间敏感度取决于刺激颜色：消色差栅格可以在相对较高的空间频率下分辨，而对等照色对比度的敏感度往往更低。早期空间视觉模型通常假设模式敏感神经元的感受野大小与其空间频率敏感性相关--较大的感受野通常与较低的最佳空间频率相关。这个模型的一个强有力的预测是，平均而言，编码等色图案的神经元应该比对无色图案敏感的神经元具有更大的接受视野大小。在这里，我们使用功能磁共振成像(FMRI)来检验这一假设。我们表明，虽然空间频率敏感性以行为测量预测的方式依赖于色度，但群体感受野(PRF)大小测量没有显示出这种依赖关系。在任何给定的偏心率下，由亮度驱动的神经元群体的平均PRF大小与对比红/绿和S锥隔离对比度是相同的。PRF大小的变化(例如，偏心率和可视区域层次的增加)在三种色度条件下也是相同的。这些结果表明，在某些情况下，接受野大小和空间分辨率的fMRI测量可以分离-潜在地反映了这些参数在神经元群体水平上的根本分离。使用彩色刺激的功能磁共振群体感受野(PRF)标测的新用途。FMRI测量早期视觉区域的空间频率敏感度。S视锥和亮度条件下的空间敏感度存在差异。在S视锥和亮度条件下，PRF大小没有显著差异。表明PRF大小和空间分辨率不是耦合的。
The spatial sensitivity of the human visual system depends on stimulus color: achromatic gratings can be resolved at relatively high spatial frequencies while sensitivity to isoluminant color contrast tends to be more low-pass. Models of early spatial vision often assume that the receptive field size of pattern-sensitive neurons is correlated with their spatial frequency sensitivity - larger receptive fields are typically associated with lower optimal spatial frequency. A strong prediction of this model is that neurons coding isoluminant chromatic patterns should have, on average, a larger receptive field size than neurons sensitive to achromatic patterns. Here, we test this assumption using functional magnetic resonance imaging (fMRI). We show that while spatial frequency sensitivity depends on chromaticity in the manner predicted by behavioral measurements, population receptive field (pRF) size measurements show no such dependency. At any given eccentricity, the mean pRF size for neuronal populations driven by luminance, opponent red/green and S-cone isolating contrast, are identical. Changes in pRF size (for example, an increase with eccentricity and visual area hierarchy) are also identical across the three chromatic conditions. These results suggest that fMRI measurements of receptive field size and spatial resolution can be decoupled under some circumstances - potentially reflecting a fundamental dissociation between these parameters at the level of neuronal populations. Novel use of fMRI population receptive field (pRF) mapping, using chromatic stimuli. Spatial frequency sensitivity in early visual areas measured with fMRI. Differences in spatial sensitivity found between S-cone and luminance conditions. No significant differences in pRF sizes between S-cone and luminance conditions. Suggests that pRF sizes and spatial resolution are not coupled.
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