Flanagan J R, Wing A M
Department of Psychology, Queen's University, Kingston, Ontario, Canada, K7L 3N6.
J Neurosci. 1997 Feb 15;17(4):1519-28. doi: 10.1523/JNEUROSCI.17-04-01519.1997.
We investigated the issue of whether or not the CNS makes use of an internal model of the motor apparatus in planning and controlling arm movements. In particular, we tested the ability of subjects to predict different hand-held loads by examining grip force adjustments used to stabilize the load in the hand during arm movements. Subjects grasped a manipulandum using a precision grip with the tips of the thumb and index finger on either side. The grip force (normal to the contact surfaces) and the load force (tangential to the surfaces) were measured, along with the trajectory of the hand. The manipulandum was attached to two servo-controlled linear motors used to create inertial and viscous loads as well as a composite load, including inertial, viscous, and elastic components. The form of the hand trajectory was independent of load for some subjects but varied systematically across load conditions in others. Nevertheless, under all load conditions and in all subjects, grip force was modulated in parallel with, and thus anticipated, fluctuations in load force despite the marked variation in the form of the load function. This indicates that the CNS is able to predict the load force and the kinematics of hand movement on which the load depends. We suggest this prediction is based on an internal model of the motor apparatus and external load and is used to determine the grip forces required to stabilize the load.
我们研究了中枢神经系统（CNS）在计划和控制手臂运动时是否利用运动装置的内部模型这一问题。具体而言，我们通过检查在手臂运动过程中用于稳定手中负载的握力调整，测试了受试者预测不同手持负载的能力。受试者用拇指和食指指尖采用精确抓握方式抓住一个操作手柄。测量了握力（垂直于接触面）和负载力（切于表面）以及手的轨迹。操作手柄连接到两个伺服控制的线性电机上，用于产生惯性和粘性负载以及一个复合负载，该复合负载包括惯性、粘性和弹性成分。对于一些受试者，手轨迹的形式与负载无关，但在其他受试者中，其在不同负载条件下会有系统地变化。然而，在所有负载条件下以及所有受试者中，尽管负载函数的形式有显著变化，但握力与负载力的波动平行调制，因此是对负载力波动的预期。这表明中枢神经系统能够预测负载力以及负载所依赖的手部运动的运动学。我们认为这种预测基于运动装置和外部负载的内部模型，并用于确定稳定负载所需的握力。
