Gaze displacement and inter-segmental coordination during large whole body voluntary rotations
Gaze displacement and inter-segmental coordination during large whole body voluntary rotations
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DOI：
10.1007/s00221-008-1627-y
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发表时间：
2009-03-01
影响因子：
2
通讯作者：
Bronstein, Adolfo
中科院分区：
文献类型：
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作者：
Anastasopoulos, Dimitri;Ziavra, Nausica;Bronstein, Adolfo
研究了 10 名人类受试者 (Ss) 在自愿重新定向至偏心率高达 180A 度的照明目标期间的视轴位移和偏航平面中的多节段（眼到脚）协调。我们还研究了目标位置的知识如何改变运动模式。偏心目标（出站试验）会在大约 10 分钟的延迟时间内引发眼睛、头部、躯干和脚部的运动。分别为 0.5、0.6、0.7 和 1.1 秒。对目标位置的了解（返回试验）减少了脚和躯干（但不是眼睛和头部）的延迟，因此眼睛、头部和躯干的移动更加整体。在大多数试验中，最初的注视移动未达到目标，并且超过 50% 的视角被前庭眼球震颤快相和头空间位移之和覆盖，直到目标固定。这表明在大的注视移动期间，前庭眼反射在目标获取中的“反代偿”作用是突出的。在一些可预测的试验中，Ss 通过一次大的注视移动来获取目标，从而将目标获取时间缩短了 200 毫秒以上。在这些实验中，注视速度（躯干在空间+头在躯干+眼睛在轨道）在长达 500 毫秒的持续时间内通常保持相当恒定，这表明注视速度是一个受控参数。这种模式发生在躯干动员期间，因此眼睛速度与头部在空间中而不是头部在躯干上的速度共同变化。脚的旋转是固定的并且具有恒定的频率，这表明它们是由运动模式发生器产生的。然而，对目标位置的了解减少了足部延迟，表明局部和脊髓上机制相互作用以实现足部控制。我们建议单个控制器负责多个身体部分的耦合以及视线转移期间的视线速度控制。
Displacements of the visual axis and multi-segmental (eye-to-foot) coordination in the yaw plane were studied in ten human subjects (Ss) during voluntary reorientations to illuminated targets of eccentricities up to 180A degrees. We also investigated how knowledge of target location modifies the movement pattern. Eccentric targets (outbound trials) elicited eye, head, trunk and foot movements at latencies ca. 0.5, 0.6, 0.7 and 1.1 s, respectively. Knowledge of target location (return trials) reduced latencies for foot and trunk (but not eye and head) thus eye, head and trunk moved more en bloc. In most trials, the initial gaze shift fell short of the target and more than 50% of the visual angle was covered by the sum of vestibular nystagmic fast phases and head-in-space displacement, until target fixation. This indicates that during large gaze shifts the 'anticompensatory' role of the vestibulo-ocular reflex in target acquisition is prominent. During some predictable trials Ss acquired targets with a single large gaze shift, shortening target acquisition time by more than 200 ms. In these, gaze velocity (trunk-in-space + head-on-trunk + eye-in-orbit) remained often fairly constant for durations of up to 500 ms, suggesting that gaze velocity is a controlled parameter. Such pattern occurred during trunk mobilization, thus eye velocity co-varied with head-in-space rather than head-on-trunk velocity. Foot rotations were stereotyped and of constant frequency, suggesting they are generated by locomotor pattern generators. However, knowledge of target location reduced foot latencies indicating that local and supraspinal mechanisms interact for foot control. We propose that a single controller is responsible for the coupling of the multiple body segments and gaze velocity control during gaze shifts.