Spatial attention improves reliability of fMRI retinotopic mapping signals in occipital and parietal cortex.
Spatial attention improves reliability of fMRI retinotopic mapping signals in occipital and parietal cortex.
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DOI：
10.1016/j.neuroimage.2010.06.063
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发表时间：
2010-11-01
期刊：
影响因子：
5.7
通讯作者：
Silver, Michael A.
中科院分区：
文献类型：
--
作者：
Bressler, David W.;Silver, Michael A.
空间注意改善视觉感知，增加视皮层神经反应的幅度。此外，空间注意任务和功能磁共振成像已被用来发现地形视野表征的视觉皮层以外的地区。因此，我们假设，要求受试者参加视网膜定位映射刺激将有助于表征的视野表示在一些皮质区。在我们的研究中，受试者要么关注一个中央注视点，要么关注一个围绕注视点旋转的楔形刺激。通过计算fMRI时间序列和与旋转楔形刺激频率相同的正弦曲线之间的相干性来评估反应可靠性。当受试者注意旋转楔而不是忽略它时，视网膜定位映射信号的可靠性在早期视觉皮层区域（V1，V2，V3，V3 A/B，V4）和腹侧枕叶皮层（VO 1）中增加了约50%，在侧枕叶（LO 1，LO 2）和后顶叶（IPS 0，IPS 1和IPS 2）皮层区域中增加了约75%。此外，在注意力-楔形条件下进行一次5分钟的视网膜定位映射，产生的反应与平均3到5次（早期视觉皮层）或5次以上（外侧枕叶、腹侧枕叶和后顶叶皮层）注意力-固定运行的反应一样可靠。这些结果表明，分配注意力的retinotopic映射刺激，大大减少了所需的扫描时间，以确定在枕叶和顶叶地形皮质区的视野表示。注意力显著增加了我们检查的每个皮层区域的反应可靠性，因此可能是在皮层处理层次结构的多个级别上提高感觉刺激的神经表征的保真度的一般机制。
Spatial attention improves visual perception and increases the amplitude of neural responses in visual cortex. In addition, spatial attention tasks and fMRI have been used to discover topographic visual field representations in regions outside visual cortex. We therefore hypothesized that requiring subjects to attend to a retinotopic mapping stimulus would facilitate the characterization of visual field representations in a number of cortical areas. In our study, subjects attended either a central fixation point or a wedge-shaped stimulus that rotated about the fixation point. Response reliability was assessed by computing coherence between the fMRI time series and a sinusoid with the same frequency as the rotating wedge stimulus. When subjects attended to the rotating wedge instead of ignoring it, the reliability of retinotopic mapping signals increased by approximately 50% in early visual cortical areas (V1, V2, V3, V3A/B, V4) and ventral occipital cortex (VO1) and by approximately 75% in lateral occipital (LO1, LO2) and posterior parietal (IPS0, IPS1 and IPS2) cortical areas. Additionally, one 5-minute run of retinotopic mapping in the attention-to-wedge condition produced responses as reliable as the average of three to five (early visual cortex) or more than five (lateral occipital, ventral occipital, and posterior parietal cortex) attention-to-fixation runs. These results demonstrate that allocating attention to the retinotopic mapping stimulus substantially reduces the amount of scanning time needed to determine the visual field representations in occipital and parietal topographic cortical areas. Attention significantly increased response reliability in every cortical area we examined and may therefore be a general mechanism for improving the fidelity of neural representations of sensory stimuli at multiple levels of the cortical processing hierarchy.
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