Department of Kinesiology, The Pennsylvania State University, PA, USA.
Neuroscience. 2009 Dec 1;164(2):597-610. doi: 10.1016/j.neuroscience.2009.07.057. Epub 2009 Aug 6.
Multi-sensory integration studies have shown that combining heterogeneous signals can optimize motor performance by reducing errors inherent to any single modality. However, it has also been suggested that errors could arise from erroneous transformations between heterogeneous coordinate systems. Here we investigated the effect of visuo-proprioceptive integration on the control of multi-joint arm movements by manipulating target modality. When the target was visual, movement control required the integration of visual target signals with proprioceptive signals about limb configuration. In contrast, when the target was the unseen fingertip, movement control relied solely on proprioceptive signals since visual feedback of hand position was precluded. We hypothesized that a faulty integration of visual target signals with proprioceptive arm signals would result in a less accurate planning of visually-targeted movements with respect to proprioceptively-targeted movements. Different inter-joint coordinations patterns were tested by varying starting hand position. Results showed larger initial trajectory deviations from target direction for visually-targeted movements involving substantial shoulder and elbow motions. Inverse dynamic analysis revealed that these deviations were associated with less efficient intersegmental coordination. The control of visually-targeted movements thus appeared sub-optimal compared to proprioceptively-targeted movements when considering theoretical models of motor planning assuming kinematic or dynamic optimizations. Additional experiments further highlighted the effect of target position, and visual feedback of starting hand position, on motor planning for proprioceptively- and visually-targeted movements. Our findings suggest that the integration of heterogeneous sensory signals related to hand and target positions introduces errors in motor planning.
多感觉整合研究表明，通过减少任何单一模态固有的误差，组合异质信号可以优化运动表现。然而，也有人认为，误差可能来自异质坐标系之间的错误转换。在这里，我们通过操纵目标模态来研究视动整合对多关节手臂运动控制的影响。当目标是视觉时，运动控制需要将视觉目标信号与关于肢体构型的本体感觉信号整合。相比之下，当目标是看不见的指尖时，运动控制仅依赖于本体感觉信号，因为手位置的视觉反馈被排除在外。我们假设视觉目标信号与本体感觉臂信号的错误整合会导致视觉目标运动相对于本体感觉目标运动的规划不准确。通过改变起始手位置测试不同的关节间协调模式。结果表明，对于涉及大量肩部和肘部运动的视觉目标运动，初始轨迹偏离目标方向的偏差较大。逆动力学分析表明，这些偏差与节段间协调效率较低有关。与基于运动规划的理论模型（假设运动学或动力学优化）相比，当考虑到视觉目标运动时，控制看起来不如本体感觉目标运动优化。额外的实验进一步强调了目标位置和起始手位置的视觉反馈对本体感觉和视觉目标运动的运动规划的影响。我们的发现表明，与手和目标位置相关的异质感觉信号的整合会在运动规划中引入误差。
