Corbetta M, Miezin F M, Shulman G L, Petersen S E
Department of Neurology and Neurological Surgery, Washington University School of Medicine, St. Louis, Missouri 63110.
J Neurosci. 1993 Mar;13(3):1202-26. doi: 10.1523/JNEUROSCI.13-03-01202.1993.
Positron emission tomography (PET) was used to identify the neural systems involved in shifting spatial attention to visual stimuli in the left or right visual field along foveofugal or foveocentric directions. Psychophysical evidence indicated that stimuli at validly cued locations were responded to faster than stimuli at invalidly cued locations. Reaction times to invalid probes were faster when they were presented in the same than in the opposite direction of an ongoing attention movement. PET evidence indicated that superior parietal and superior frontal cortex were more active when attention was shifted to peripheral locations than when maintained at the center of gaze. Both regions encoded the visual field and not the direction of an attention shift. In the right superior parietal lobe, two distinct responses were localized for attention to left and right visual field. Finally, the superior parietal region was active when peripheral locations were selected on the basis of cognitive or sensory cues independent of the execution of an overt response. The frontal region was active only when responses were made to stimuli at selected peripheral locations. These findings indicate that parietal and frontal regions control different aspects of spatial selection. The functional asymmetry in superior parietal cortex may be relevant for the pathophysiology of unilateral neglect.
正电子发射断层扫描（PET）被用于识别在沿离中央凹或向中央凹方向将空间注意力转移到左或右视野的视觉刺激时所涉及的神经系统。心理物理学证据表明，有效提示位置的刺激比无效提示位置的刺激反应更快。当无效探测在与正在进行的注意力移动相同而非相反方向呈现时，对其的反应时间更快。PET证据表明，当注意力转移到周边位置时，顶上叶和额上回比保持在注视中心时更活跃。这两个区域编码的是视野而非注意力转移的方向。在右侧顶上叶，针对对左视野和右视野的注意力定位了两种不同的反应。最后，当基于认知或感觉线索选择周边位置而不依赖于明显反应的执行时，顶上叶区域活跃。只有当对所选周边位置的刺激做出反应时，额叶区域才活跃。这些发现表明，顶叶和额叶区域控制空间选择的不同方面。顶上叶皮质的功能不对称可能与单侧忽视的病理生理学有关。
