TY - JOUR
T1 - Quantifying feed forward control
T2 - A linear scaling model for fingertip forces and object weight
AU - Lu, Ying
AU - Bilaloglu, Seda
AU - Aluru, Viswanath
AU - Raghavan, Preeti
N1 - Publisher Copyright:
© 2015 the American Physiological Society
PY - 2015/7/1
Y1 - 2015/7/1
N2 - The ability to predict the optimal fingertip forces according to object properties before the object is lifted is known as feed forward 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. Feed forward 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 feed forward 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 feed forward control and its relationship to muscular control.
AB - The ability to predict the optimal fingertip forces according to object properties before the object is lifted is known as feed forward 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. Feed forward 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 feed forward 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 feed forward control and its relationship to muscular control.
KW - Electromyography
KW - Feed forward and feedback control
KW - Motor control and learning
KW - Precision grasp
KW - Sensorimotor adaptation
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U2 - 10.1152/jn.00065.2015
DO - 10.1152/jn.00065.2015
M3 - Article
C2 - 25878151
AN - SCOPUS:84937419028
SN - 0022-3077
VL - 114
SP - 411
EP - 418
JO - Journal of neurophysiology
JF - Journal of neurophysiology
IS - 1
M1 - A30
ER -