TOPOGRAPHY OF COVERT ATTENTION IN HUMAN SUPERIOR COLLICULUS

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 研究中心，而研究中心不一定是研究者所在的机构。 简介：在灵长类动物的上级丘（SC）中进行的神经微刺激实验以空间选择性的方式增强了表现，同时它们保持固定，这表明了SC中隐蔽视觉注意的作用（例如，M ller等人，2004年; Cavenaugh等人，2006年）。先前的功能磁共振成像实验已经显示了人类SC中对应于直接视觉刺激的粗糙视网膜组织（Shneider & Kastner，2005）。我们进行了实验，以确定是否retinotopically组织的信号对应于隐蔽的视觉注意存在于人类SC。在同一时间，我们开发的方法来检查层流分布的血液动力学活动的深度SC。 方法：我们测量了视网膜组织的SC直接视觉刺激使用楔形闪烁点（偏心19 <$，方位角宽度144 <$），其围绕固定标记缓慢旋转（24秒周期）。为了测量内隐注意的视网膜反应，我们使用了60%对比度的全场闪烁（4 Hz）光栅（1 cpd）刺激。 受试者被提示执行一个困难的对比度递减辨别任务， 区域（偏心率19 <$，方位角宽度90 <$），缓慢旋转（24秒周期）， 方位围绕固定。采集高分辨率fMRI（1.3 mm立方体素）数据 （3 s/体积）在SC内的8个切片上（垂直于神经轴方向），使用3 拍摄螺旋序列和45毫秒的TE。然后将这些数据与高分辨率 （0.6 mm体素）T1加权参考体积。SC在此体积中被分段， SC的表面可以在计算上变平，并允许计算 用于层流分析的深度图

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Introduction: Neural microstimulation experiments in the superior colliculus (SC) of primates enhanced performance in a spatially selective manner while they maintained fixation, suggesting a role for covert visual attention in SC (e.g., M¿ller et al, 2004; Cavenaugh, et al., 2006). Previous fMRI experiments have shown a rough retinotopic organization in human SC corresponding to direct visual stimulus (Shneider & Kastner, 2005). We performed experiments to determine if retinotopically organized signals corresponding to covert visual attention were present in human SC. At the same time, we developed methods to examine the laminar distribution of hemodynamic activity in the depth of the SC. Methods: We measured the retinotopic organization of SC to direct visual stimulation using a wedge of flickering dots (eccentricity 19¿, azimuthal width 144¿) that slowly rotated (24-s period) around the fixation mark. To measure the retinotopy of covert attention, we used a full-field flickering (4-Hz) grating (1 cpd) stimulus at 60% contrast. Subjects were cued to perform a difficult contrast decrement-discrimination task within a region (eccentricity 19¿, azimuthal width 90¿) that slowly rotated (24-s period) in azimuth around fixation. High-resolution fMRI (1.3 mm cubic voxels) data were acquired (3 s/volume) on 8 slices within SC (orientation perpendicular to the neuraxis) using a 3 shot spiral sequence and a TE of 45 ms. These data were then aligned to a high-resolution (0.6-mm voxels) T1-weighted reference volume. The SC was segmented in this volume so that the surface of the SC could be computationally flattened, and to permit computation of a depth map for laminar analysis