Finger inter-dependence: Linking the kinetic and kinematic variables

Kim, Sun Wook; Shim, Jae Kun; Zatsiorsky, Vladimir M.; Latash, Mark L.

doi:10.1016/j.humov.2007.08.005

Cited by 40 publications

(31 citation statements)

References 37 publications

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“…These studies focused on involuntary force production or on finger movement in the non-instructed fingers. In terms of force, it has been shown that enslaving is present for each finger and is largest for the neighboring finger [2, 16]. The cause of the enslaving effect in force tasks is thought to be primarily neural, because in these static tasks relatively minimal movement occurs.…”

Section: Introductionmentioning

confidence: 99%

Variable and Asymmetric Range of Enslaving: Fingers Can Act Independently over Small Range of Flexion

Noort

Beek

Kraan³

et al. 2016

PLoS ONE

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The variability in the numerous tasks in which we use our hands is very large. However, independent movement control of individual fingers is limited. To assess the extent of finger independency during full-range finger flexion including all finger joints, we studied enslaving (movement in non-instructed fingers) and range of independent finger movement through the whole finger flexion trajectory in single and multi-finger movement tasks. Thirteen young healthy subjects performed single- and multi-finger movement tasks under two conditions: active flexion through the full range of movement with all fingers free to move and active flexion while the non-instructed finger(s) were restrained. Finger kinematics were measured using inertial sensors (PowerGlove), to assess enslaving and range of independent finger movement. Although all fingers showed enslaving movement to some extent, highest enslaving was found in adjacent fingers. Enslaving effects in ring and little finger were increased with movement of additional, non-adjacent fingers. The middle finger was the only finger affected by restriction in movement of non-instructed fingers. Each finger showed a range of independent movement before the non-instructed fingers started to move, which was largest for the index finger. The start of enslaving was asymmetrical for adjacent fingers. Little finger enslaving movement was affected by multi-finger movement. We conclude that no finger can move independently through the full range of finger flexion, although some degree of full independence is present for smaller movements. This range of independent movement is asymmetric and variable between fingers and between subjects. The presented results provide insight into the role of finger independency for different types of tasks and populations.

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Section: Introductionmentioning

confidence: 99%

Variable and Asymmetric Range of Enslaving: Fingers Can Act Independently over Small Range of Flexion

Noort

Beek

Kraan³

et al. 2016

PLoS ONE

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“…This term reflects unintentional movement of (force production by) a finger when another finger of the hand moves (produces force) intentionally (Kilbreath and Gandevia; Li et al 1998;Zatsiorsky et al 2000;Kim et al 2008). Enslaving results from a variety of factors including multidigit extrinsic hand muscles, connective tissue links between fingers, and overlapping cortical representations (reviewed in Schieber and Santello 2004;Zatsiorsky and Latash 2008).…”

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confidence: 99%

Stability of multifinger action in different state spaces

Reschechtko

Zatsiorsky

Latash

2014

Journal of Neurophysiology

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Reschechtko S, Zatsiorsky VM, Latash ML. Stability of multifinger action in different state spaces. J Neurophysiol 112: 3209-3218, 2014. First published September 24, 2014 doi:10.1152/jn.00395.2014.-We investigated stability of action by a multifinger system with three methods: analysis of intertrial variance, application of transient perturbations, and analysis of the system's motion in different state spaces. The "inverse piano" device was used to apply transient (lifting-andlowering) perturbations to individual fingers during single-and twofinger accurate force production tasks. In each trial, the perturbation was applied either to a finger explicitly involved in the task or one that was not. We hypothesized that, in one-finger tasks, task-specific stability would be observed in the redundant space of finger forces but not in the nonredundant space of finger modes (commands to explicitly involved fingers). In two-finger tasks, we expected that perturbations applied to a nontask finger would not contribute to task-specific stability in mode space. In contrast to our expectations, analyses in both force and mode spaces showed lower stability in directions that did not change total force output compared with directions that did cause changes in total force. In addition, the transient perturbations led to a significant increase in the enslaving index. We consider these results within a theoretical scheme of control with referent body configurations organized hierarchically, using multiple few-to-many mappings organized in a synergic way. The observed volatility of enslaving, greater equifinality of total force compared with elemental variables, and large magnitude of motor equivalent motion in both force and mode spaces provide support for the concept of task-specific stability of performance and the existence of multiple neural loops, which ensure this stability. redundancy; abundance; synergy; referent configuration; uncontrolled manifold hypothesis; equifinality; enslaving ONE OF THE FUNDAMENTAL PROBLEMS of motor control is that of redundancy (Bernstein 1967): at any level of description of the system involved in movement production, the number of elements (and of their output variables, elemental variables) is higher than the number of constraints associated with typical motor tasks. Recently, the problem of motor redundancy has been revisited in the context of the principle of motor abundance (Gelfand and Latash 1998;Latash 2012). This approach posits a way for the central nervous system (CNS) to take advantage of all of the elemental variables at its disposal to ensure stability of movement, rather than requiring the CNS to achieve a single, optimal solution by eliminating redundant degrees of freedom. Thus the principle of abundance avoids requiring computational, and physiologically unfeasible, control schemes, which involve explicit instruction to all body structures involved in a given action.A theoretical scheme has been developed, which unites the principle of abundance with the idea of hierarchical...

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“…In this study, the nail, the bone, and the textured surface are considered as linearly elastic for both calculus [7,14]. Epidermis and dermis, and subcutaneous tissues are assumed to be viscoelastic damping material [4,10,12,21,23]. The elastic material parameters for the different tissues are reported in Table 2.…”

Section: Fe Modelsmentioning

confidence: 99%