Department of Biomedical Engineering, Marquette University, Olin Engineering Center, 303, P.O. Box 1881, Milwaukee, WI, 53201-1881, USA.
Exp Brain Res. 2010 Jul;204(2):239-54. doi: 10.1007/s00221-010-2308-1. Epub 2010 Jun 8.
We examined how proprioceptive contributions to perception of hand path straightness are influenced by visual, motor and attentional sources of performance variability during horizontal planar reaching. Subjects held the handle of a robot that constrained goal-directed movements of the hand to the paths of controlled curvature. Subjects attempted to detect the presence of hand path curvature during both active (subject driven) and passive (robot driven) movements that either required active muscle force production or not. Subjects were less able to discriminate curved from straight paths when actively reaching for a target versus when the robot moved their hand through the same curved paths. This effect was especially evident during robot-driven movements requiring concurrent activation of lengthening but not shortening muscles. Subjects were less likely to report curvature and were more variable in reporting when movements appeared straight in a novel "visual channel" condition previously shown to block adaptive updating of motor commands in response to deviations from a straight-line hand path. Similarly, compromised performance was obtained when subjects simultaneously performed a distracting secondary task (key pressing with the contralateral hand). The effects compounded when these last two treatments were combined. It is concluded that environmental, intrinsic and attentional factors all impact the ability to detect deviations from a rectilinear hand path during goal-directed movement by decreasing proprioceptive contributions to limb state estimation. In contrast, response variability increased only in experimental conditions thought to impose additional attentional demands on the observer. Implications of these results for perception and other sensorimotor behaviors are discussed.
我们研究了在水平平面伸手过程中，视觉、运动和注意力来源的表现变异性如何影响对手路径直线度的感知的本体感受贡献。受试者握住机器人的手柄，该手柄限制了手向受控曲率路径的目标导向运动。受试者试图在主动（受试者驱动）和被动（机器人驱动）运动期间检测到手路径曲率的存在，这两种运动要么需要主动肌肉力量产生，要么不需要。与机器人驱动的运动相比，当受试者主动伸手到达目标时，他们能够更准确地辨别出弯曲的路径与直线路径，而不是当机器人通过相同的弯曲路径移动他们的手时。当机器人驱动的运动需要同时激活伸肌而不是缩短肌肉时，这种效果尤其明显。当运动在一个新的“视觉通道”条件下出现直线路径时，受试者不太可能报告曲率，并且在报告时更具变异性，在该条件下，先前已经证明会阻止根据偏离直线的手路径自适应更新运动命令。同样，当受试者同时执行分心的次要任务（用对侧手按键）时，表现也会受到影响。当这最后两种处理方式结合在一起时，效果会叠加。结论是，环境、内在和注意力因素都会通过降低本体感受对手部状态估计的贡献，从而影响在目标导向运动中对手部路径偏离直线的检测能力。相比之下，仅在被认为对观察者施加额外注意力要求的实验条件下，响应变异性才会增加。这些结果对感知和其他感觉运动行为的意义将进行讨论。
