Vestibular contribution to the planning of reach trajectories
Vestibular contribution to the planning of reach trajectories
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DOI：
10.1007/s00221-007-0997-x
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发表时间：
2007-09-01
影响因子：
2
通讯作者：
Haslwanter, Thomas
中科院分区：
文献类型：
--
作者：
Bockisch, Christopher J.;Haslwanter, Thomas
在同时旋转的同时触及物体会在手臂上产生科里奥利力和离心惯性力，这需要补偿动作来保持精度。我们研究了神经系统是否使用头部旋转的前庭信号来预测惯性力。人类受试者在黑暗中到达33厘米远的记忆目标。受试者是静止的，但经历了强烈的前庭旋转信号。我们通过以360度/秒的速度旋转受试者2分钟然后停止来实现这一点，并且受试者在“旋转后”期间到达，此时前庭系统将减速解释为相反方向的旋转。在没有旋转刺激的对照试验中，手臂轨迹是直的。在前庭刺激的情况下，轨迹曲率在前庭刺激的方向上平均增加3cm（例如，右下角为右下角刺激）。前庭诱导的曲率迅速恢复正常，平均时间常数为6秒。随着前庭刺激的减少，运动也变得更长，并恢复到正常长度，平均时间常数为5.6 s。在第二个实验中，我们比较了惯用手和非惯用手的伸手行为，发现它们同样受到前庭刺激的影响。如果神经系统基于前庭信号预期并试图抵消科里奥利力的存在，则到达曲率处于预期方向。同样，较短的距离可能是因为神经系统试图补偿预期的离心力。由于前庭刺激也会改变目标的感知位置，前庭信号可能会影响感觉运动通路的所有阶段，将所需的伸手目标转化为特定的运动单位神经支配。
Reaching for an object while simultaneously rotating induces Coriolis and centrifugal inertial forces on the arm that require compensatory actions to maintain accuracy. We investigated whether the nervous system uses vestibular signals of head rotation to predict inertial forces. Human subjects reached in darkness to a remembered target 33 cm distant. Subjects were stationary, but experienced a strong vestibular rotation signal. We achieved this by rotating subjects at 360 degrees/s in yaw for 2 min and then stopping, and subjects reached during the 'post-rotary' period when the deceleration is interpreted by the vestibular system as a rotation in the opposite direction. Arm trajectories were straight in control trials without a rotary stimulus. With vestibular stimulation, trajectory curvature increased an average of 3 cm in the direction of the vestibular stimulation (e.g., to the right for a rightward yaw stimulus). Vestibular-induced curvature returned rapidly to normal, with an average time constant of 6 s. Movements also became longer as the vestibular stimulus diminished, and returned towards normal length with an average time constant of 5.6 s. In a second experiment we compared reaching with preferred and non-preferred hands, and found that they were similarly affected by vestibular stimulation. The reach curvatures were in the expected direction if the nervous system anticipated and attempted to counteract the presence of Coriolis forces based on the vestibular signals. Similarly, the shorter reaches may have occurred because the nervous system was attempting to compensate for an expected centrifugal force. Since vestibular stimulation also alters the perceived location of targets, vestibular signals probably influence all stages of the sensorimotor pathway transforming the desired goal of a reach into specific motor-unit innervation.