Cortical sources of Vernier acuity in the human visual system: An EEG-source imaging study
Cortical sources of Vernier acuity in the human visual system: An EEG-source imaging study
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DOI：
10.1167/17.6.2
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发表时间：
2017-06-01
影响因子：
1.8
通讯作者：
Verghese, Preeti
中科院分区：
文献类型：
--
作者：
Hou, Chuan;Kim, Yee-Joon;Verghese, Preeti
视觉特征的精度优于视网膜锥体受体的采样分辨率。由于游标位移被认为是由定向调节机制介导的，游标敏锐度被认为是由纹状视觉皮层（V1）处理的。然而，有相当多的证据表明，游标敏锐度不仅取决于V1的结构，还取决于皮层外区域的加工。本研究采用功能磁共振成像-脑电图源成像技术对视力正常的观察者进行游标敏锐度皮质源定位。我们在视觉皮层层次的不同阶段，包括V1、hV4、外侧枕皮质（LOC）和中颞皮质（hMT+），测量了游标启动/偏移刺激的阈上和近阈反应。这些反应与光栅开/关刺激的反应以及游标任务中控制横向运动的刺激的反应进行了比较。我们的研究结果表明，所有的视觉皮层感兴趣区域（roi）都对阈上游标和光栅刺激有反应。然而，与hV4和hMT+相比，V1和LOC的游标位移阈值（游标敏锐度）最低，而所有视觉roi的空间频率阈值（光栅敏锐度）和相对运动阈值相同。皮层对游标位移敏感性的选择性提供了强有力的证据，证明LOC除了V1外，还参与游标敏锐度加工。LOC的鲁棒激活可能与对特征相对位置的敏感性有关，这在游标位移和某些类型的纹理分割中是常见的。
visual features with a precision better than the sampling resolution of cone receptors in the retina. Because Vernier displacement is thought to be mediated by orientation-tuned mechanisms, Vernier acuity is presumed to be processed in striate visual cortex (V1). However, there is considerable evidence suggesting that Vernier acuity is dependent not only on structures in V1 but also on processing in extrastriate cortical regions. Here we used functional magnetic resonance imaging-informed electroencephalogram source imaging to localize the cortical sources of Vernier acuity in observers with normal vision. We measured suprathreshold and near-threshold responses to Vernier onset/offset stimuli at different stages of the visual cortical hierarchy, including V1, hV4, lateral occipital cortex (LOC), and middle temporal cortex (hMT+). These responses were compared with responses to grating on/off stimuli, as well as to stimuli that control for lateral motion in the Vernier task. Our results show that all visual cortical regions of interest (ROIs) responded to both suprathreshold Vernier and grating stimuli. However, thresholds for Vernier displacement (Vernier acuity) were lowest in V1 and LOC compared with hV4 and hMT+, whereas all visual ROIs had identical thresholds for spatial frequency (grating acuity) and for relative motion. The cortical selectivity of sensitivity to Vernier displacement provides strong evidence that LOC, in addition to V1, is involved in Vernier acuity processing. The robust activation of LOC might be related to the sensitivity to the relative position of features, which is common to Vernier displacement and to some kinds of texture segmentation.