Role of eye, head, and shoulder geometry in the planning of accurate arm movements
Role of eye, head, and shoulder geometry in the planning of accurate arm movements
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DOI：
10.1152/jn.00509.2001
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发表时间：
2002-04-01
影响因子：
2.5
通讯作者：
Crawford, JD
中科院分区：
文献类型：
--
作者：
Henriques, DYP;Crawford, JD
眼手协调需要大脑将视觉信息与眼睛、头部和手臂位置的持续变化相结合。这是一个几何上复杂的过程，因为眼睛、头部和肩膀有不同的旋转中心。因此，头部旋转会导致眼睛相对于肩膀发生平移。本研究考察了这种几何形状对在不同方向的指向任务中规划精确手臂运动的影响。当被要求指向一个物体时，受试者将他们的手臂指向从目标到视线的线上。但是当眼睛随着每一个新的头部方向移动时，这条目标线就会发生变化，因此需要一个新的手臂指向方向。我们证实，当注视目标时，受试者确实在闭环指向不同水平头部方向时将指尖与眼睛目标线重新对齐。更重要的是，在完全黑暗的情况下，受试者也表现出这种头部位置依赖的指向反应模式。然而，当凝视不在目标上时，旋转中心的这些平移补偿部分失效。结果，受试者倾向于偏离当前凝视的目标方向；也许可以解释先前报道的将手臂对准视网膜外围目标的错误。这些结果表明，对头部位置信号的了解以及由此产生的眼睛和肩膀旋转中心的相对位移，可以使用眼手协调的开环机制进行整合，但这些转换最好是针对注视点、注视目标运动进行校准。
Eye-hand coordination requires the brain to integrate visual information with the continuous changes in eye, head, and arm positions. This is a geometrically complex process because the eyes, head, and shoulder have different centers of rotation. As a result, head rotation causes the eye to translate with respect to the shoulder. The present study examines the consequences of this geometry for planning accurate arm movements in a pointing task with the head at different orientations. When asked to point at an object, subjects oriented their arm to position the fingertip on the line running from the target to the viewing eye. But this eye-target line shifts when the eyes translate with each new head orientation, thereby requiring a new arm pointing direction. We confirmed that subjects do realign their fingertip with the eye-target line during closed-loop pointing across various horizontal head orientations when gaze is on target. More importantly, subjects also showed this head-position-dependent pattern of pointing responses for the same paradigm performed in complete darkness. However, when gaze was not on target, compensation for these translations in the rotational centers partially broke down. As a result, subjects tended to overshoot the target direction relative to current gaze; perhaps explaining previously reported errors in aiming the arm to retinally peripheral targets. These results suggest that knowledge of head position signals and the resulting relative displacements in the centers of rotation of the eye and shoulder are incorporated using open-loop mechanisms for eye-hand coordination, but these translations are best calibrated for foveated, gaze-on-target movements.