Medendorp W Pieter, Goltz Herbert C, Vilis Tutis
Nijmegen Institute for Cognition and Information, Radboud University Nijmegen, NL-6500 HE, Nijmegen, The Netherlands.
J Neurophysiol. 2006 Mar;95(3):1645-55. doi: 10.1152/jn.00905.2005. Epub 2005 Nov 16.
We used functional magnetic resonance imaging (fMRI) to investigate the role of the human posterior parietal cortex (PPC) in storing target locations for delayed double-step saccades. To do so, we exploited the laterality of a subregion of PPC that preferentially responds to the memory of a target location presented in the contralateral visual field. Using an event-related design, we tracked fMRI signal changes in this region while subjects remembered the locations of two sequentially flashed targets, presented in either the same or different visual hemifields, and then saccaded to them in sequence. After presentation of the first target, the fMRI signal was always related to the side of the visual field in which it had been presented. When the second target was added, the cortical activity depended on the respective locations of both targets but was still significantly selective for the target of the first saccade. We conclude that this region within the human posterior parietal cortex not only acts as spatial storage center by retaining target locations for subsequent saccades but is also involved in selecting the target for the first intended saccade.
我们使用功能磁共振成像（fMRI）来研究人类后顶叶皮层（PPC）在存储延迟双步扫视目标位置中的作用。为此，我们利用了PPC一个子区域的偏侧性，该子区域优先对呈现于对侧视野的目标位置记忆做出反应。采用事件相关设计，我们在受试者记住两个依次闪现的目标（呈现于同侧或不同侧视野）的位置，然后依次向其进行扫视时，追踪该区域的fMRI信号变化。在呈现第一个目标后，fMRI信号总是与呈现该目标的视野一侧相关。当添加第二个目标时，皮层活动取决于两个目标各自的位置，但对第一个扫视目标仍具有显著的选择性。我们得出结论，人类后顶叶皮层内的这一区域不仅通过保留目标位置以供后续扫视而充当空间存储中心，还参与选择第一个预期扫视的目标。
