Henningsen H, Ende-Henningsen B, Gordon A M
Department of Neurology, University of Wisconsin, Madison 53705, USA.
Exp Brain Res. 1995;105(2):312-7. doi: 10.1007/BF00240967.
The ability to match the voluntary isometric force output of the right and left index fingers when the contact surfaces differ in shape was examined. Before the experiment, subjects were trained to produce both a "low" force level (50 +/- 25 g) and a "high" force level (200 +/- 50 g) with the right and left index finger, separately. Following the training session, subjects were instructed to match the forces of both fingers simultaneously within the required range (either low or high) so that the forces were perceived to be identical. One of the index fingers pushed against a conical contact pad, while the other pushed against a flat contact pad. Midway through the experiment, the two contact pads were reversed. Subjects consistently produced less force with the finger pressing against the conical pad. This asymmetry could already be seen during the beginning of the ramp increase in force and continued throughout the trial, independent of the target force levels (low or high). These findings suggest tactile afferent information at the finger-tip is important for determining the voluntary force exerted by the finger. It must be properly integrated with other peripheral information as well as with the central motor command, otherwise the perception of force is distorted. Furthermore, the perception of the force produced seemingly is dependent on the extent to which the skin of the fingertip is indented rather than the local pressure exerted at the skin.
研究了在接触表面形状不同时，左右食指匹配自愿等长力输出的能力。在实验前，受试者分别接受训练，用左右食指产生“低”力水平（50±25克）和“高”力水平（200±50克）。训练结束后，受试者被要求在所需范围内（低或高）同时匹配两根手指的力，使力被感知为相同。其中一根食指按压在圆锥形接触垫上，而另一根按压在平坦接触垫上。在实验进行到一半时，两个接触垫互换。受试者用按压圆锥形垫的手指持续产生较小的力。这种不对称在力的斜坡增加开始时就已可见，并在整个试验过程中持续存在，与目标力水平（低或高）无关。这些发现表明，指尖的触觉传入信息对于确定手指施加的自愿力很重要。它必须与其他外周信息以及中枢运动指令进行适当整合，否则力的感知会失真。此外，所产生力的感知似乎取决于指尖皮肤的凹陷程度，而不是施加在皮肤上的局部压力。
