Lu Ying, Bilaloglu Seda, Aluru Viswanath, Raghavan Preeti
Center for the Promotion of Research Involving Innovative Statistical Methodology, Steinhardt School of Culture, Education and Human Development, New York University; New York, New York;
Department of Rehabilitation Medicine, New York University School of Medicine, New York, New York; and.
J Neurophysiol. 2015 Jul;114(1):411-8. doi: 10.1152/jn.00065.2015. Epub 2015 Apr 15.
The ability to predict the optimal fingertip forces according to object properties before the object is lifted is known as feedforward control, and it is thought to occur due to the formation of internal representations of the object's properties. The control of fingertip forces to objects of different weights has been studied extensively by using a custom-made grip device instrumented with force sensors. Feedforward control is measured by the rate of change of the vertical (load) force before the object is lifted. However, the precise relationship between the rate of change of load force and object weight and how it varies across healthy individuals in a population is not clearly understood. Using sets of 10 different weights, we have shown that there is a log-linear relationship between the fingertip load force rates and weight among neurologically intact individuals. We found that after one practice lift, as the weight increased, the peak load force rate (PLFR) increased by a fixed percentage, and this proportionality was common among the healthy subjects. However, at any given weight, the level of PLFR varied across individuals and was related to the efficiency of the muscles involved in lifting the object, in this case the wrist and finger extensor muscles. These results quantify feedforward control during grasp and lift among healthy individuals and provide new benchmarks to interpret data from neurologically impaired populations as well as a means to assess the effect of interventions on restoration of feedforward control and its relationship to muscular control.
在物体被提起之前，根据物体属性预测最佳指尖力的能力被称为前馈控制，人们认为这是由于物体属性的内部表征形成所致。通过使用配备力传感器的定制握持装置，对不同重量物体的指尖力控制进行了广泛研究。前馈控制通过物体被提起之前垂直（负载）力的变化率来衡量。然而，负载力变化率与物体重量之间的确切关系以及它在人群中健康个体之间的变化情况尚不清楚。我们使用10组不同重量的物体进行研究，结果表明，在神经功能正常的个体中，指尖负载力变化率与重量之间存在对数线性关系。我们发现，在进行一次练习提起后，随着重量增加，峰值负载力变化率（PLFR）以固定百分比增加，而且这种比例关系在健康受试者中很常见。然而，在任何给定重量下，PLFR水平在个体之间存在差异，并且与提起物体所涉及肌肉（在这种情况下是手腕和手指伸肌）的效率有关。这些结果量化了健康个体在抓握和提起过程中的前馈控制，为解释神经功能受损人群的数据提供了新的基准，同时也为评估干预措施对前馈控制恢复及其与肌肉控制关系的影响提供了一种方法。
