Cortical feedback signals generalise across different spatial frequencies of feedforward inputs
Cortical feedback signals generalise across different spatial frequencies of feedforward inputs
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DOI：
10.1016/j.neuroimage.2017.09.047
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发表时间：
2018-10-15
期刊：
影响因子：
5.7
通讯作者：
Muckli, Lars
中科院分区：
文献类型：
--
作者：
Revina, Yulia;Petro, Lucy S.;Muckli, Lars
大脑皮层的视觉处理依赖于反馈投射、背景化前馈信息流。初级视觉皮层（V1）具有较小的感受野，并在细粒度的空间尺度上处理前馈信息，而高级视觉区具有较大的空间不变的感受野。因此，反馈可以提供关于全局场景结构的粗略信息，也可以通过针对V1的小感受野来恢复细粒度结构。我们测试了反馈信号是否在前馈输入的不同空间频率上泛化，或者它们是否被调整到视觉场景的空间尺度。利用部分遮挡范式、功能磁共振成像（fMRI）和多体素模式分析（MVPA），我们通过操纵被遮挡图像部分外场景周围的空间频率，研究了对V1的反馈是否包含粗粒度或细粒度信息。我们表明，反馈传递粗粒度和细粒度信息，因为它同时携带低（LSF）和高空间频率（HSF）的信息。此外，包含LSF信息的反馈信号与包含HSF信息的反馈信号相似，即使在HSF和LSF场景的空间频带上没有大的重叠。最后，我们发现在不同的场景中，反馈携带了相似的空间频带信息。我们得出的结论是，皮质反馈信号包含的信息在前馈输入的不同空间频率上泛化。
Visual processing in cortex relies on feedback projections contextualising feedforward information flow. Primary visual cortex (V1) has small receptive fields and processes feedforward information at a fine-grained spatial scale, whereas higher visual areas have larger, spatially invariant receptive fields. Therefore, feedback could provide coarse information about the global scene structure or alternatively recover fine-grained structure by targeting small receptive fields in V1. We tested if feedback signals generalise across different spatial frequencies of feedforward inputs, or if they are tuned to the spatial scale of the visual scene. Using a partial occlusion paradigm, functional magnetic resonance imaging (fMRI) and multivoxel pattern analysis (MVPA) we investigated whether feedback to V1 contains coarse or fine-grained information by manipulating the spatial frequency of the scene surround outside an occluded image portion. We show that feedback transmits both coarse and fine-grained information as it carries information about both low (LSF) and high spatial frequencies (HSF). Further, feedback signals containing LSF information are similar to feedback signals containing HSF information, even without a large overlap in spatial frequency bands of the HSF and LSF scenes. Lastly, we found that feedback carries similar information about the spatial frequency band across different scenes. We conclude that cortical feedback signals contain information which generalises across different spatial frequencies of feedforward inputs.