title: Effects of Tactile Sensitivity on Structural Variability of Digit Forces during Stable Precision Grip.
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 αDFAof the vertical shear forceFx(F3,239= 6.814,p< 0.001) and αDCCAofFx(χ2= 16.440,p< 0.001). No significant difference was observed in αDFAor αDCCAof 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.
authors.affiliation: Laboratory of Motor Control and Rehabilitation, Institute of Biomedical Engineering, School of Control Science and Engineering, Shandong University, Jinan, China.
authors.forename: Ke
authors.identifier: 0000-0002-8660-0116
authors.initials: K
authors.lastname: Li
authors.affiliation: Department of Geriatrics, Qilu Hospital, Shandong University, Jinan, China.
authors.forename: Na
authors.initials: N
authors.lastname: Wei
authors.affiliation: Department of Physical Medicine and Rehabilitation, Qilu Hospital, Shandong University, Jinan, China.
authors.forename: Shouwei
authors.identifier: 0000-0002-5399-9044
authors.initials: S
authors.lastname: Yue
mesh_terms: D000328:Adult; D056228:Feedback, Sensory / Q000502:physiology*; D005260:Female; D005385:Fingers / Q000502:physiology*; D018737:Hand Strength; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D020959:Polyethylene / Q000737:chemistry; D011597:Psychomotor Performance / Q000502:physiology*; D033081:Shear Strength; D013314:Stress, Mechanical; D014110:Touch; D055815:Young Adult
chemical_list: D020959:Polyethylene