Rotation axes of the head during positioning, head shaking, and locomotion.
Rotation axes of the head during positioning, head shaking, and locomotion.
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DOI：
10.1152/jn.00764.2007
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发表时间：
2007-11
影响因子：
2.5
通讯作者：
M. Kunin;Y. Osaki;B. Cohen;T. Raphan
中科院分区：
文献类型：
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作者：
M. Kunin;Y. Osaki;B. Cohen;T. Raphan
静态头部方向遵循唐德斯定律，并假定为受菲克万向节约束的旋转。头部摆动可以是自愿的，也可以是在自然运动过程中产生的。自由摆动的旋转轴或运动过程中是否受到相同万向架的约束是未知的，也是本研究的主题。头部定位用Optotrak(Northern Digital)监测。人类受试者戴着针孔护目镜观察视觉目标，以实现眼睛以轨道为中心的静态头部位置。在跑步机上，通过计算头部摆动和以1.5m/S速度运动时的速度矢量，确定俯仰和偏航的增量旋转轴。静态磁头定向可以通过使第二次旋转的轴旋转第一次旋转的角度的分数k而不进行第三次旋转的菲克万向节的推广来描述。我们已经将其指定为k-万向节系统。俯仰和偏航振动的增量旋转轴是俯仰的函数，而不是偏航头部位置的函数。头部摆动的轴心点接近耳间连线的中点。然而，在运动过程中，轴点要低得多。K-万向节模型的实现很好地解释了这些发现，k-万向节模型有一个旋转轴叠加在菲克-万向节系统上。在生理上，这可以通过头部摆动时头部与齿状突和枕髁的界面来实现，在运动中下部脊柱对俯仰的贡献。
Static head orientations obey Donders' law and are postulated to be rotations constrained by a Fick gimbal. Head oscillations can be voluntary or generated during natural locomotion. Whether the rotation axes of the voluntary oscillations or during locomotion are constrained by the same gimbal is unknown and is the subject of this study. Head orientation was monitored with an Optotrak (Northern Digital). Human subjects viewed visual targets wearing pin-hole goggles to achieve static head positions with the eyes centered in the orbit. Incremental rotation axes were determined for pitch and yaw by computing the velocity vectors during head oscillation and during locomotion at 1.5 m/s on a treadmill. Static head orientation could be described by a generalization of the Fick gimbal by having the axis of the second rotation rotate by a fraction, k, of the angle of the first rotation without a third rotation. We have designated this as a k-gimbal system. Incremental rotation axes for both pitch and yaw oscillations were functions of the pitch but not the yaw head positions. The pivot point for head oscillations was close to the midpoint of the interaural line. During locomotion, however, the pivot point was considerably lower. These findings are well explained by an implementation of the k-gimbal model, which has a rotation axis superimposed on a Fick-gimbal system. This could be realized physiologically by the head interface with the dens and occipital condyles during head oscillation with a contribution of the lower spine to pitch during locomotion.