Schlicht Erik J, Schrater Paul R
Department of Psychology, Univ. of Minnesota, N218 Elliott Hall, 75 East River Rd., Minneapolis, MN 55455, USA.
J Neurophysiol. 2007 Jun;97(6):4203-14. doi: 10.1152/jn.00160.2007. Epub 2007 Apr 4.
Humans build representations of objects and their locations by integrating imperfect information from multiple perceptual modalities (e.g., visual, haptic). Because sensory information is specified in different frames of reference (i.e., eye- and body-centered), it must be remapped into a common coordinate frame before integration and storage in memory. Such transformations require an understanding of body articulation, which is estimated through noisy sensory data. Consequently, target information acquires additional coordinate transformation uncertainty (CTU) during remapping because of errors in joint angle sensing. As a result, CTU creates differences in the reliability of target information depending on the reference frame used for storage. This paper explores whether the brain represents and compensates for CTU when making grasping movements. To address this question, we varied eye position in the head, while participants reached to grasp a spatially fixed object, both when the object was in view and when it was occluded. Varying eye position changes CTU between eye and head, producing additional uncertainty in remapped information away from forward view. The results showed that people adjust their maximum grip aperture to compensate both for changes in visual information and for changes in CTU when the target is occluded. Moreover, the amount of compensation is predicted by a Bayesian model for location inference that uses eye-centered storage.
人类通过整合来自多种感知模态（如视觉、触觉）的不完美信息来构建物体及其位置的表征。由于感官信息是在不同的参考系（即以眼睛为中心和以身体为中心）中指定的，在整合并存储到记忆中之前，它必须重新映射到一个共同的坐标框架中。这种转换需要对身体关节活动有所了解，而这是通过有噪声的感官数据来估计的。因此，由于关节角度传感中的误差，目标信息在重新映射期间会获得额外的坐标转换不确定性（CTU）。结果，CTU会根据用于存储的参考系在目标信息的可靠性上产生差异。本文探讨了大脑在进行抓握动作时是否会表征并补偿CTU这种情况。为了解决这个问题，我们改变了头部中的眼睛位置，同时让参与者在物体可见和被遮挡时伸手去抓握一个空间位置固定的物体。改变眼睛位置会改变眼睛和头部之间的CTU，在偏离正视方向的重新映射信息中产生额外的不确定性。结果表明，当目标被遮挡时，人们会调整他们的最大握距，以补偿视觉信息的变化以及CTU的变化。此外，补偿量由一个使用以眼睛为中心存储的位置推断贝叶斯模型预测。
