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

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 αDFA of the vertical shear force Fx (F 3,239 = 6.814, p < 0.001) and αDCCA of Fx (χ 2 = 16.440, p < 0.001). No significant difference was observed in αDFA or αDCCA 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.

[1]  R. Johansson,et al.  Responses of mechanoreceptive afferent units in the glabrous skin of the human hand to sinusoidal skin displacements , 1982, Brain Research.

[2]  R. Johansson,et al.  Responses in glabrous skin mechanoreceptors during precision grip in humans , 2004, Experimental Brain Research.

[3]  Stefan Glasauer,et al.  How predictive is grip force control in the complete absence of somatosensory feedback? , 2004, Brain : a journal of neurology.

[4]  D M Wolpert,et al.  Predicting the Consequences of Our Own Actions: The Role of Sensorimotor Context Estimation , 1998, The Journal of Neuroscience.

[5]  J. Randall Flanagan,et al.  Coding and use of tactile signals from the fingertips in object manipulation tasks , 2009, Nature Reviews Neuroscience.

[6]  R. Johansson,et al.  Properties of cutaneous mechanoreceptors in the human hand related to touch sensation. , 1984, Human neurobiology.

[7]  R. Johansson,et al.  Encoding of Direction of Fingertip Forces by Human Tactile Afferents , 2001, The Journal of Neuroscience.

[8]  Marco Santello,et al.  Effects of carpal tunnel syndrome on adaptation of multi-digit forces to object texture , 2012, Clinical Neurophysiology.

[9]  C. D. Mote,et al.  A structural model of the forced compression of the fingertip pulp. , 1998, Journal of biomechanics.

[10]  K. J. Cole,et al.  The effects of graded compression of the median nerve in the carpal canal on grip force , 2002, Experimental Brain Research.

[11]  K. Newell,et al.  Children's coordination of force output in a pinch grip task. , 2002, Developmental psychobiology.

[12]  H. Stanley,et al.  Quantification of scaling exponents and crossover phenomena in nonstationary heartbeat time series. , 1995, Chaos.

[13]  Thomas J Armstrong,et al.  Friction coefficients in a longitudinal direction between the finger pad and selected materials for different normal forces and curvatures , 2009, Ergonomics.

[14]  J. Bell-Krotoski,et al.  The repeatability of testing with Semmes-Weinstein monofilaments. , 1987, The Journal of hand surgery.

[15]  Anatol G. Feldman,et al.  Threshold position control of arm movement with anticipatory increase in grip force , 2007, Experimental Brain Research.

[16]  R. Johansson,et al.  Detection of tactile stimuli. Thresholds of afferent units related to psychophysical thresholds in the human hand. , 1979, The Journal of physiology.

[17]  Ke Li,et al.  Cross recurrence quantification analysis of precision grip following peripheral median nerve block , 2013, Journal of NeuroEngineering and Rehabilitation.

[18]  H. Stanley,et al.  Detrended cross-correlation analysis: a new method for analyzing two nonstationary time series. , 2007, Physical review letters.

[19]  K. Newell,et al.  Visual information gain and the regulation of constant force levels , 2008, Experimental Brain Research.

[20]  Karl M Newell,et al.  Task goals and change in dynamical degrees of freedom with motor learning. , 2003, Journal of experimental psychology. Human perception and performance.

[21]  M. Schieber,et al.  Sensorimotor Control of Grasping : Physiology and Pathophysiology STROKE , 2008 .

[22]  Miles C. Bowman,et al.  Control strategies in object manipulation tasks , 2006, Current Opinion in Neurobiology.

[23]  Dominic Thewlis,et al.  Coordination of digit force variability during dominant and non-dominant sustained precision pinch , 2015, Experimental Brain Research.

[24]  H Kinoshita.  Effect of gloves on prehensile forces during lifting and holding tasks. , 1999, Ergonomics.

[25]  S Glasauer,et al.  The effects of digital anaesthesia on predictive grip force adjustments during vertical movements of a grasped object , 2001, The European journal of neuroscience.

[26]  Peter J. Evans,et al.  Carpal tunnel syndrome impairs sustained precision pinch performance , 2015, Clinical Neurophysiology.

[27]  R. Johansson,et al.  Regional differences and interindividual variability in sensitivity to vibration in the glabrous skin of the human hand , 1984, Brain Research.

[28]  Michael A. Riley,et al.  Feedback about isometric force production yields more random variations , 2012, Neuroscience Letters.

[29]  Ke Li,et al.  Removal of visual feedback lowers structural variability of inter-digit force coordination during sustained precision pinch , 2013, Neuroscience Letters.

[30]  A. Landi.  Human Hand Function , 2007 .