Bove Marco, Courtine Gregoire, Schieppati Marco
Department of Experimental Medicine, Section of Human Physiology, University of Genoa, I-16132 Genoa, Italy.
J Neurophysiol. 2002 Nov;88(5):2232-41. doi: 10.1152/jn.00198.2002.
Unilateral long-lasting vibration was applied to the sternomastoid muscle to assess the influence of asymmetric neck proprioceptive input on body orientation during stepping-in-place. Blindfolded subjects performed 3 sequences of 3 trials, each lasting 60 s: control, vibration applied during stepping (VDS), and vibration applied before stepping (VBS). VDS caused clear-cut whole body rotation toward the side opposite to vibration. The body rotated around a vertical axis placed at about arm's length from the body. The rotation did not begin immediately on switching on the vibrator. The delay varied from subject to subject from a few seconds to about 10 s. Once initiated, the angular velocity of rotation was remarkably constant (about 1 degrees /s). In VBS, at the beginning of stepping, subjects rotated for a while as if their neck were still vibrated. At a variable delay, the direction of rotation reversed, and the effects were opposite to those observed during VDS. Under no condition did head rotation, head roll, or lateral body tilt accompany rotation. The results confirm and extend the notion that the neck proprioceptive input plays a major role in body orientation during locomotion. The body rotation does not seem to depend on the same mechanisms that modify the erect posture; rather, the asymmetric neck input would seem to modify the egocentric body-centered coordinate system.
对胸锁乳突肌施加单侧持续振动，以评估原地踏步过程中不对称颈部本体感觉输入对身体定向的影响。蒙眼受试者进行3组，每组3次试验，每次持续60秒：对照组、踏步时施加振动（VDS）以及踏步前施加振动（VBS）。VDS导致身体明显向与振动相反的一侧旋转。身体围绕一条与身体相距约一臂长的垂直轴旋转。旋转并非在开启振动器后立即开始。延迟时间因人而异，从几秒到约10秒不等。一旦开始旋转，旋转角速度相当恒定（约1度/秒）。在VBS中，踏步开始时，受试者会旋转一会儿，就好像他们的颈部仍在振动一样。在可变的延迟后，旋转方向反转，其效果与VDS期间观察到的相反。在任何情况下，旋转过程中都不会伴随头部转动、头部侧倾或身体侧向倾斜。结果证实并扩展了这样一种观点，即颈部本体感觉输入在运动过程中的身体定向中起主要作用。身体旋转似乎不依赖于改变直立姿势的相同机制；相反，不对称的颈部输入似乎会改变以自我为中心的身体坐标系。
