The Critical Role of V2 Population Receptive Fields in Visual Orientation Crowding
The Critical Role of V2 Population Receptive Fields in Visual Orientation Crowding
复制标题
V2 群体感受野在视觉定向拥挤中的关键作用
DOI：
10.1016/j.cub.2019.05.068
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发表时间：
2019-07-08
期刊：
影响因子：
9.2
通讯作者：
Fang, Fang
中科院分区：
文献类型：
--
作者：
He, Dongjun;Wang, Yingying;Fang, Fang
拥挤，即在附近侧翼存在的情况下难以识别目标，是物体识别和视觉感知的重要瓶颈[1,2]。正如众多行为研究表明的那样，拥挤的发生是因为视觉系统缺乏必要的分辨率（例如，小的接受野或高分辨率的空间注意）来将目标与侧翼分离，因此错误地将它们整合在一起[3-12]。然而，这个想法很少被神经科学方法直接验证。在这里，使用基于fmri的群体接受野（pRF）技术[13,14]，我们发现，在个体受试者中，V2中响应目标的体素的平均pRF大小可以预测视觉方向拥挤的程度。pRF越小，拥挤效应越弱。此外，我们还操纵了受试者内部拥挤效应的大小。在弱拥挤条件下，V2的pRF大小比强拥挤条件下要小，这种差异与注意有关。更重要的是，我们发现知觉训练可以缓解方向拥挤，并导致V2中pRF大小的缩小。综上所述，这些发现为V2 pRFs在视觉定向拥挤中的关键作用提供了强有力的证据。我们推测，与空间注意力协同作用，V2 pRFs的动态和塑性特性通过调整其大小来防止侧翼的干扰，从而减少视觉拥挤。
Crowding, the identification difficulty for a target in the presence of nearby flankers, is an essential bottleneck for object recognition and visual awareness [1, 2]. As suggested by multitudes of behavioral studies, crowding occurs because the visual system lacks the necessary resolution (e.g., small receptive field or high resolution of spatial attention) to isolate the target from flankers and therefore integrates them mistakenly [3-12]. However, this idea has rarely been tested with neuroscience methods directly. Here, using the fMRI-based population receptive field (pRF) technique [13, 14], we found that, across individual subjects, the average pRF size of the voxels in V2 responding to the target could predict the magnitude of visual orientation crowding. The smaller the pRF size, the weaker the crowding effect. Furthermore, we manipulated the magnitude of the crowding effect within subjects. The pRF size in V2 was smaller in a weak crowding condition than in a strong crowding condition, and this difference was attention dependent. More importantly, we found that perceptual training could alleviate the orientation crowding and causally shrink the pRF size in V2. Taken together, these findings provide strong and converging evidence for a critical role of V2 pRFs in visual orientation crowding. We speculate that, synergistic with spatial attention, the dynamic and plastic nature of the V2 pRFs serves to prevent interference from the flankers through adjusting their size and consequently reduces visual crowding.