Leibniz-Institute for Neurobiology, Magdeburg, Germany.
Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Netherlands.
Sci Adv. 2023 Mar 10;9(10):eade7996. doi: 10.1126/sciadv.ade7996. Epub 2023 Mar 8.
Shifting the focus of attention without moving the eyes poses challenges for signal coding in visual cortex in terms of spatial resolution, signal routing, and cross-talk. Little is known how these problems are solved during focus shifts. Here, we analyze the spatiotemporal dynamic of neuromagnetic activity in human visual cortex as a function of the size and number of focus shifts in visual search. We find that large shifts elicit activity modulations progressing from highest (IT) through mid-level (V4) to lowest hierarchical levels (V1). Smaller shifts cause those modulations to start at lower levels in the hierarchy. Successive shifts involve repeated backward progressions through the hierarchy. We conclude that covert focus shifts arise from a cortical coarse-to-fine process progressing from retinotopic areas with larger toward areas with smaller receptive fields. This process localizes the target and increases the spatial resolution of selection, which resolves the above issues of cortical coding.
将注意力从一个位置转移到另一个位置而不移动眼睛，这对视觉皮层中的信号编码在空间分辨率、信号路由和串扰方面提出了挑战。目前还不太清楚在进行焦点转移时这些问题是如何解决的。在这里，我们分析了人类视觉皮层的神经磁活动的时空动态，作为视觉搜索中焦点转移大小和数量的函数。我们发现，较大的转移会引起从最高（IT）到中间（V4）再到最低层次（V1）的活动调制。较小的转移会导致调制从层次结构的较低级别开始。连续的转移涉及通过层次结构的重复向后进展。我们得出结论，隐蔽焦点转移是从具有较大感受野的视网膜区域到具有较小感受野的区域的皮层粗到精过程的结果。这个过程定位了目标，并提高了选择的空间分辨率，从而解决了上述皮层编码问题。
