MRC Cognition and Brain Sciences Unit, Cambridge, UK.
Department of Systems Neuroscience, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany.
Sci Rep. 2017 Aug 2;7(1):7128. doi: 10.1038/s41598-017-07036-8.
The orientation of a visual grating can be decoded from human primary visual cortex (V1) using functional magnetic resonance imaging (fMRI) at conventional resolutions (2-3 mm voxel width, 3T scanner). It is unclear to what extent this information originates from different spatial scales of neuronal selectivity, ranging from orientation columns to global areal maps. According to the global-areal-map account, fMRI orientation decoding relies exclusively on fMRI voxels in V1 exhibiting a radial or vertical preference. Here we show, by contrast, that 2-mm isotropic voxels in a small patch of V1 within a quarterfield representation exhibit reliable opposite selectivities. Sets of voxels with opposite selectivities are locally intermingled and each set can support orientation decoding. This indicates that global areal maps cannot fully account for orientation information in fMRI and demonstrates that fMRI also reflects fine-grained patterns of neuronal selectivity.
使用功能磁共振成像 (fMRI) 在常规分辨率（2-3 毫米体素宽度，3T 扫描仪）下，可以从人类初级视觉皮层 (V1) 解码视觉光栅的方向。目前尚不清楚这种信息在多大程度上源自不同空间尺度的神经元选择性，从方向柱到全局区域图。根据全局区域图的说法，fMRI 方向解码仅依赖于 V1 中表现出径向或垂直偏好的 fMRI 体素。相比之下，我们在这里表明，在四分之一场表示的 V1 的一小片区域内的 2 毫米各向同性体素表现出可靠的相反选择性。具有相反选择性的体素集在局部混合，并且每个集都可以支持方向解码。这表明全局区域图不能完全解释 fMRI 中的方向信息，并证明 fMRI 还反映了神经元选择性的精细模式。
