Department of Psychology, Brain Imaging Center, University of California, Santa Barbara, Santa Barbara, CA 93106, USA.
Neuron. 2010 Nov 18;68(4):776-88. doi: 10.1016/j.neuron.2010.11.002.
Current models of sensorimotor transformations emphasize the dominant role of gaze-centered representations for reach planning in the posterior parietal cortex (PPC). Here we exploit fMRI repetition suppression to test whether the sensory modality of a target determines the reference frame used to define the motor goal in the PPC and premotor cortex. We show that when targets are defined visually, the anterior precuneus selectively encodes the motor goal in gaze-centered coordinates, whereas the parieto-occipital junction, Brodman Area 5 (BA 5), and PMd use a mixed gaze- and body-centered representation. In contrast, when targets are defined by unseen proprioceptive cues, activity in these areas switches to represent the motor goal predominantly in body-centered coordinates. These results support computational models arguing for flexibility in reference frames for action according to sensory context. Critically, they provide neuroanatomical evidence that flexibility is achieved by exploiting a multiplicity of reference frames that can be expressed within individual areas.
目前的感觉运动转换模型强调了在后顶叶皮层（PPC）中，注视中心的代表对于伸手规划的主导作用。在这里，我们利用 fMRI 重复抑制来测试目标的感觉模态是否决定了在 PPC 和前运动皮层中定义运动目标的参考框架。我们表明，当目标通过视觉定义时，前扣带皮层选择性地以注视中心坐标编码运动目标，而顶枕交界处、布罗德曼区 5（BA5）和 PMd 则使用混合的注视和身体中心表示。相比之下，当目标通过未被感知的本体感受线索定义时，这些区域的活动会切换到主要以身体中心坐标表示运动目标。这些结果支持了计算模型的观点，即根据感觉环境，行动的参考框架具有灵活性。至关重要的是，它们提供了神经解剖学证据，证明通过利用可以在单个区域内表达的多种参考框架来实现灵活性。
