Alstermark B, Lundberg A, Pettersson L G, Tantisira B, Walkowska M
Department of Physiology, University of Göteborg, Sweden.
Exp Brain Res. 1993;94(2):279-86. doi: 10.1007/BF00230297.
Trajectory formation of unrestrained forelimb target-reaching was investigated in six cats. A Selspot-like recording system was used for three-dimensional recording of the position of the wrist every 3 ms with the aid of two cameras detecting infrared light emitted from diodes taped to the wrist. These measurements allowed reconstruction of movement paths in the horizontal and sagittal planes and velocity profiles in the direction of the cartesian x, y and z co-ordinates. Horizontal movement paths were smoothly curved, segmented or almost linear. Sagittal movement paths were sigmoid. The net velocity profile was usually bell-shaped with longer deceleration than acceleration, but for some slow movements the velocity profile had a plateau. When the net velocity profile was bell-shaped, the averaged sagittal movement paths and normalized x (protraction) and z (lifting) velocity profiles were virtually superimposable for fast and slow movements: thus, movement speed was changed by parallel scaling of protraction and lifting. Comparison of movement paths and velocity profiles amongst the different cats revealed considerable differences. The x profile was unimodal in one cat and double peaked in five cats: the second component was pronounced in two cats and small in the other three. The z profile was unimodal and, except for one cat, it had later onset and summit than the first component of the x profile. In contrast to the interindividual differences, there was a high degree of intraindividual constancy over 6-12 months. It is postulated that the interindividual variability depends on chance differences established early during learning of the task and that the imprinted pattern remains, resulting in intra-individual constancy.
研究了6只猫无约束前肢目标指向的轨迹形成。使用了一种类似Selspot的记录系统，借助两台检测贴在手腕上的二极管发出的红外光的摄像机，每3毫秒对腕部位置进行三维记录。这些测量使得能够重建水平和矢状面内的运动路径以及笛卡尔x、y和z坐标方向上的速度剖面。水平运动路径呈平滑曲线、分段或几乎呈直线状。矢状运动路径呈S形。净速度剖面通常呈钟形，减速时间比加速时间长，但对于一些缓慢运动，速度剖面有一个平台期。当净速度剖面呈钟形时，快速和缓慢运动的平均矢状运动路径以及归一化的x（前伸）和z（抬起）速度剖面实际上是可叠加的：因此，运动速度通过前伸和抬起的平行缩放而改变。不同猫之间运动路径和速度剖面的比较显示出相当大的差异。x剖面在一只猫中是单峰的，在五只猫中是双峰的：第二个成分在两只猫中明显，在另外三只猫中较小。z剖面是单峰的，除了一只猫外，它的起始和峰值比x剖面的第一个成分晚。与个体间差异相反，在6至12个月内个体内具有高度的稳定性。据推测，个体间的变异性取决于任务学习早期建立的偶然差异，并且印记模式得以保留，从而导致个体内的稳定性。
