caa a22 4500 445354232 CHVBK 20180317142854.0 cr unu---uuuuu 170323e20110201xx s 000 0 eng 10.1007/s00221-010-2492-z doi (NATIONALLICENCE)springer-10.1007/s00221-010-2492-z Multi-finger interaction during involuntary and voluntary single finger force changes [Elektronische Daten] [J. Martin, V. Zatsiorsky, M. Latash] Two types of finger interaction are characterized by positive co-variation (enslaving) or negative co-variation (error compensation) of finger forces. Enslaving reflects mechanical and neural connections among fingers, while error compensation results from synergic control of fingers to stabilize their net output. Involuntary and voluntary force changes by a finger were used to explore these patterns. We hypothesized that synergic mechanisms will dominate during involuntary force changes, while enslaving will dominate during voluntary finger force changes. Subjects pressed with all four fingers to match a target force that was 10% of their maximum voluntary contraction (MVC). One of the fingers was unexpectedly raised 5.0mm at a speed of 30.0mm/s. During finger raising the subject was instructed "not to intervene voluntarily”. After the finger was passively lifted and a new steady-state achieved, subjects pressed down with the lifted finger, producing a pulse of force voluntarily. The data were analyzed in terms of finger forces and finger modes (hypothetical commands to fingers reflecting their intended involvement). The target finger showed an increase in force during both phases. In the involuntary phase, the target finger force changes ranged between 10.71±1.89% MVC (I-finger) and 16.60±2.26% MVC (L-finger). Generally, non-target fingers displayed a force decrease with a maximum amplitude of −1.49±0.43% MVC (L-finger). Thus, during the involuntary phase, error compensation was observed—non-lifted fingers showed a decrease in force (as well as in mode magnitude). During the voluntary phase, enslaving was observed—non-target fingers showed an increase in force and only minor changes in mode magnitude. The average change in force of non-target fingers ranged from 21.83±4.47% MVC for R-finger (M-finger task) to 0.71±1.10% MVC for L-finger (I-finger task). The average change in mode of non-target fingers was between −7.34±19.27% MVC for R-finger (L-finger task) and 7.10±1.38% MVC for M-finger (I-finger task). We discuss a range of factors affecting force changes, from purely mechanical effects of finger passive lifting to neural synergic adjustments of commands to individual fingers. The data fit a recently suggested scheme that merges the equilibrium-point hypothesis (control with referent configurations) with the idea of hierarchical synergic control of multi-element systems. Springer-Verlag, 2010 Synergy nationallicence Hand nationallicence Force nationallicence Enslaving nationallicence Equilibrium-point hypothesis nationallicence Martin J. Department of Kinesiology, The Pennsylvania State University, 16802, University Park, PA, USA aut Zatsiorsky V. Department of Kinesiology, The Pennsylvania State University, 16802, University Park, PA, USA aut Latash M. Department of Kinesiology, The Pennsylvania State University, 16802, University Park, PA, USA aut Experimental Brain Research Springer-Verlag 208/3(2011-02-01), 423-435 0014-4819 208:3<423 2011 208 221 https://doi.org/10.1007/s00221-010-2492-z text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00221-010-2492-z text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Martin J. Department of Kinesiology, The Pennsylvania State University, 16802, University Park, PA, USA aut NATIONALLICENCE 700 1- Zatsiorsky V. Department of Kinesiology, The Pennsylvania State University, 16802, University Park, PA, USA aut NATIONALLICENCE 700 1- Latash M. Department of Kinesiology, The Pennsylvania State University, 16802, University Park, PA, USA aut NATIONALLICENCE 773 0- Experimental Brain Research Springer-Verlag 208/3(2011-02-01), 423-435 0014-4819 208:3<423 2011 208 221 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer