Removal of visual feedback lowers structural variability of inter-digit force coordination during sustained precision pinch

• Published in: Neuroscience letters Vol. 545; pp. 1 - 5
• Main Authors: Li, Ke, Marquardt, Tamara L., Li, Zong-Ming
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier Ireland Ltd 17.06.2013
• Subjects: Adult; Detrended cross-correlation analysis (DCCA); Detrended fluctuation analysis (DFA); Feedback, Sensory - physiology; Female; Fingers - physiology; Force variability; Hand Strength - physiology; Humans; Male; Muscle Contraction - physiology; Muscle, Skeletal - physiology; Postural Balance - physiology; Psychomotor Performance - physiology; Sustained pinch; Visual feedback; Detrended cross-correlation analysis (DCCA); Sustained pinch; Force variability; Visual feedback; Detrended fluctuation analysis (DFA)
• ISSN: 0304-3940; 1872-7972; 1872-7972
• DOI: 10.1016/j.neulet.2013.04.011

•Each digit produced force with simplified structure after removing visual feedback.•Without visual feedback, force correlation showed reduced structural variability.•Removal of visual feedback lowered variability of inter-digit force coordination. This study examined the effects of visual feedback on inter-digit force coordination during a precision pinch. Sixteen healthy, right-handed subjects were instructed to pinch an instrumented apparatus for 1min with a stable force output. Visual feedback was provided for the first 30s and withdrawn for the second 30s. Detrended fluctuation analysis (DFA) and detrended cross-correlation analysis (DCCA) methods were used to quantify the time-dependent structures of each digit's force and of the force correlation between the digits. After removing visual feedback, the DFA scaling exponent, αDFA, increased from 1.10±0.12 to 1.29±0.13 for the thumb and from 0.95±0.08 to 1.33±0.13 for the index finger (F1,95=372.47, p<0.001); the DCCA scaling exponent, αDCCA, increased from 1.00±0.08 to 1.33±0.13 (t95=20.33, p<0.001). Structural changes were observed beginning with the first 5s epoch after the removal of visual feedback. The results provide evidence that removing visual feedback lowers the structural variability of inter-digit force coordination. This change is reflected in the high-level control strategy, resulting in the two digits being more tightly coupled under somatosensory feedback without visual inputs.