Human parietal "reach region" primarily encodes intrinsic visual direction, not extrinsic movement direction, in a visual-motor dissociation task
Human parietal "reach region" primarily encodes intrinsic visual direction, not extrinsic movement direction, in a visual-motor dissociation task
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DOI：
10.1093/cercor/bhl137
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发表时间：
2007-10-01
期刊：
影响因子：
3.7
通讯作者：
Crawford, J. Douglas
中科院分区：
文献类型：
--
作者：
Fernandez-Ruiz, Juan;Goltz, Herbert C.;Crawford, J. Douglas
后顶叶皮层 (PPC) 参与以凝视为中心的坐标中的视觉空间行为的规划，包括触及运动。目前尚不清楚这些表示是否编码视网膜坐标中的视觉目标，或相对于凝视的移动方向。在这里，通过将内在视网膜刺激与外在运动方向分离，我们表明 PPC 使用视觉代码。使用延迟指向和事件相关的功能磁共振成像，我们识别了一组 PPC 区域，其活动在地形上（对侧）与计划运动的方向相关。然后，我们通过使受试者适应光学左/右反转棱镜来切换正常的视觉-运动空间关系。使用棱镜，与运动相关的 PPC 地形发生逆转，仍然与视网膜图像相关。因此，值得注意的是，每个半球的 PPC 区域现在对计划的同侧指向运动的反应更多。其他非 PPC 地区则表现出相反的世界固定模式或电机固定模式。这些发现表明，PPC 主要编码的不是运动命令，而是视觉坐标中的运动目标。
Posterior parietal cortex (PPC) participates in the planning of visuospatial behaviors, including reach movements, in gaze-centered coordinates. It is not known if these representations encode the visual goal in retinal coordinates, or the movement direction relative to gaze. Here, by dissociating the intrinsic retinal stimulus from the extrinsic direction of movement, we show that PPC employs a visual code. Using delayed pointing and event-related functional magnetic resonance imaging, we identified a cluster of PPC regions whose activity was topographically (contralaterally) related to the direction of the planned movement. We then switched the normal visual-motor spatial relationship by adapting subjects to optical left/right reversing prisms. With prisms, movement-related PPC topography reversed, remaining tied to the retinal image. Thus, remarkably, the PPC region in each hemisphere now responded more for planned ipsilateral pointing movements. Other non-PPC regions showed the opposite world- or motor-fixed pattern. These findings suggest that PPC primarily encodes not motor commands but movement goals in visual coordinates.