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BioMed Research International
Volume 2016 (2016), Article ID 8314561, 7 pages
http://dx.doi.org/10.1155/2016/8314561
Research Article

Effects of Tactile Sensitivity on Structural Variability of Digit Forces during Stable Precision Grip

1Laboratory of Motor Control and Rehabilitation, Institute of Biomedical Engineering, School of Control Science and Engineering, Shandong University, Jinan, China
2Department of Geriatrics, Qilu Hospital, Shandong University, Jinan, China
3Department of Physical Medicine and Rehabilitation, Qilu Hospital, Shandong University, Jinan, China

Received 1 April 2016; Revised 23 June 2016; Accepted 25 July 2016

Academic Editor: Jacob J. Sosnoff

Copyright © 2016 Ke Li et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This study investigated the effects of fingertip tactile sensitivity on the structural variability of thumb and index finger forces during stable precision grip. Thirty right-handed healthy subjects participated in the experiment. Transient perturbation of tactile afferents was achieved by wrapping up the distal pads of the thumb or index finger with transparent polyethylene films. The time-dependent structure of each digit force and the variability of interdigit force correlation were examined by detrended fluctuation analysis (DFA) and detrended cross-correlation analysis (DCCA), respectively. Results showed that the tactile sensitivity affected of the vertical shear force ( = 6.814, ) and of ( = 16.440, ). No significant difference was observed in or of the normal forces produced by the thumb or index finger. These results suggested that with blurred tactile sensory inputs the central nervous system might decrease the vertical shear force flexibility and increase the interdigit shear force coupling in order to guarantee a stable grip control of an object against gravity. This study shed light on the feedback and feed-forward strategies involved in digit force control and the role of SA-II afferent fibers in regulation of vertical shear force variability for precision grip.