Finger interaction during maximal radial and ulnar deviation efforts: experimental data and linear neural network modeling

The purpose of this study was to characterize finger interactions during radial/ulnar deviation, including interactions with flexion movements. Subjects performed single-finger and multi-finger maximal voluntary contraction (MVC), and maximal forces and various indices of interaction among the fingers were quantified. MVCs in radial/ulnar deviation were 50–80% as strong as in flexion. Along with the ‘master’ fingers (i.e., those explicitly instructed to produce force), substantial force production was also observed in ‘slave’ fingers (i.e., those not explicitly instructed to produce force), a phenomenon termed: force ‘enslaving’. In addition, a drop in MVC during multi-finger tasks as compared to single finger tasks (force ‘deficit’) was also observed. A previously unreported phenomenon that we term: ‘preferred direction enslaving’ was also apparent; both master and slave fingers produced force in the instructed direction with a non-zero perpendicular component. Due to the architectural separation of the involved muscles, preferred direction enslaving provides strong evidence that enslaving results from neural rather than biomechanical factors. A final new phenomenon: ‘negative deficit’, or force ‘facilitation’ was observed in 46.4% of the trials in 21 out of 23 subjects during multi-finger lateral efforts and was further demonstrative of extensive interconnection among neurons serving hand muscles. The data were modeled with high accuracy (∼4% mean square error) using a linear neural network with motor ‘commands’ as inputs and finger forces as outputs. The proposed network, equivalent to linear regression, can be used to determine the extent to which finger forces are influenced by peripheral constraints during functional prehensile activities.

[1]  M. Latash,et al.  Prehension synergies: trial-to-trial variability and hierarchical organization of stable performance , 2003, Experimental Brain Research.

[2]  Thomas H. Christophel,et al.  Coupling between wrist flexion-extension and radial-ulnar deviation. , 2005, Clinical biomechanics.

[3]  Vladimir M. Zatsiorsky,et al.  Coordinated force production in multi-finger tasks: finger interaction and neural network modeling , 1998, Biological Cybernetics.

[4]  D. Sinclair,et al.  The range and power of ulnar and radial deviation of the fingers. , 1970, Journal of anatomy.

[5]  Zong-Ming Li,et al.  Dependence of Finger Flexion Force on the Posture of the Nonperforming Fingers During Key Pressing Tasks , 2002, Journal of motor behavior.

[6]  Nirmal K. Bose,et al.  Anatomically and experimentally based neural networks modeling force coordination in static multi-finger tasks , 2002, Neurocomputing.

[7]  Marc H Schieber,et al.  Hand function: peripheral and central constraints on performance. , 2004, Journal of applied physiology.

[8]  Fan Gao,et al.  The principle of superposition in human prehension , 2004, Robotica.

[9]  Roland S Johansson,et al.  Dynamic use of tactile afferent signals in control of dexterous manipulation. , 2002, Advances in experimental medicine and biology.

[10]  Teresa L Brininger,et al.  Motion enslaving among multiple fingers of the human hand. , 2004, Motor control.

[11]  Karl M. Newell,et al.  Motor redundancy during maximal voluntary contraction in four-finger tasks , 1998, Experimental Brain Research.

[12]  S. Gandevia,et al.  Limited independent flexion of the thumb and fingers in human subjects. , 1994, The Journal of physiology.

[13]  Fan Gao,et al.  Inter-finger Connection Matrices , 2004, International Conference on Computational Science.

[14]  T Ohtsuki,et al.  Decrease in grip strength induced by simultaneous bilateral exertion with reference to finger strength. , 1981, Ergonomics.

[15]  M H Schieber,et al.  Quantifying the Independence of Human Finger Movements: Comparisons of Digits, Hands, and Movement Frequencies , 2000, The Journal of Neuroscience.

[16]  T. Ohtsuki.  Inhibition of individual fingers during grip strength exertion. , 1981, Ergonomics.

[17]  Fan Gao,et al.  Matrix analyses of interaction among fingers in static force production tasks , 2003, Biological Cybernetics.

[18]  Gregor Schöner,et al.  A mode hypothesis for finger interaction during multi-finger force-production tasks , 2003, Biological Cybernetics.

[19]  L. Cohen,et al.  Kinematically specific interhemispheric inhibition operating in the process of generation of a voluntary movement. , 2005, Cerebral cortex.

[20]  M. Latash,et al.  Approaches to analysis of handwriting as a task of coordinating a redundant motor system. , 2003, Human movement science.