Factors affecting grip force: anatomy, mechanics, and referent configurations

Ambike, Satyajit; Paclet, Florent; Zatsiorsky, Vladimir M.; Latash, Mark L.

doi:10.1007/s00221-014-3838-8

Cited by 56 publications

(65 citation statements)

References 38 publications

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“…We believe that the results are most compatible with the idea of RC-backcoupling (Ambike et al 2014;Zhou et al 2015) described further in this section. Some of the results, however, have no straightforward explanation: They raise more questions than they answer.…”

Section: Discussionsupporting

confidence: 86%

“…Corcos et al 1992). A series of recent observations have suggested that, if body motion toward RC is impossible, RC may drift toward the current actual configuration-a phenomenon addressed as RC-back-coupling (Wilhelm et al 2013;Zhou et al 2014;Ambike et al 2014). The notion of RC-back-coupling has been introduced to account for unintentional drifts of performance in kinetic and kinematic variables observed when subjects, who began an action with the assistance of visual feedback, were instructed to continue to produce the action after the visual feedback was removed.…”

Section: Rc-back-coupling Hypothesis On Unintentional Actionsmentioning

confidence: 97%

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The nature of constant and cyclic force production: unintentional force-drift characteristics

et al. 2015

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We explored unintentional changes in forces during performance of constant and cyclic force-production tasks (F-tasks) after visual feedback removal. Based on earlier studies, we expected all force parameters to drop exponentially with time. We also explored possible role of working memory in the force drop phenomena. Healthy subjects performed constant or cyclic isometric F-tasks with the index finger under visual feedback. The cyclic task was paced by a metronome. Removing visual feedback resulted in a consistent force drop in constant F-tasks and a qualitatively similar drift in the mean force in the cyclic F-task. Both were slow with characteristic times of about 10-20 s. In contrast, force amplitude in the cyclic F-task increased quickly (within 1-2 s). When the subjects were asked to stop producing force for 5 s after the visual feedback disappeared and then resume force production, no downward force drift was seen in constant F-tasks, while in cyclic F-tasks, the drift of the mean force was present and an exaggerated increase in force amplitude was also observed. We conclude that while working memory limitations may influence cyclic F-tasks, their role in determining the force drift in constant F-tasks is limited. The results of both experiments are interpreted within the referent configuration hypothesis supplemented with an idea of unintentional drift of referent coordinates (RC-back-coupling) induced by differences between the referent and actual body configurations.

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Section: Discussionsupporting

confidence: 86%

Section: Rc-back-coupling Hypothesis On Unintentional Actionsmentioning

confidence: 97%

The nature of constant and cyclic force production: unintentional force-drift characteristics

et al. 2015

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“…Another sort of back-coupling has recently been suggested based on observations of unintentional movements in experiments when actual body configuration was kept away from the RC for long time intervals (Ambike et al 2014;Zhou et al 2014b). This process, addressed as RC-back-coupling, is thought to result in a relatively slow drift of RC toward the actual body configuration.…”

mentioning

confidence: 99%

“…In addition to investigating other finger pressing/finger perturbed pairs, we would like to expand our understanding of the hierarchical control of finger actions to other types of perturbations: downward with the inverse piano (the present study used upward perturbations only), as well as more ecological prehension-based ones using another device built in our laboratory, "the expanding handle" (Gao et al 2005;Ambike et al 2014), a handle that can change width (and thereby subjects' grip aperture) during trials. We also hope to investigate more thoroughly the role of visual feedback and the effects of its removal, as well as the effects of varying instructions ("do not interfere" vs. "try to maintain a constant force level") on finger coordination in pressing tasks.…”

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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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“…The wrist contains the following eight bones: the hamate, pisiform, triquetral, capitate, lunate, trapezoid, trapezium, and scaphoid. In total, the hand has 27 bones and 28 muscles [5]. These various bones and muscles enable the hand to perform various functions.…”

Section: Introductionmentioning

confidence: 99%

The Effects of Hand Function on the Angle of Holding a Smartphone

Kim¹,

Kim²

2015

Journal of the Korea Academia-Industrial cooperation Society

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The purpose of the study is to prevent pain and malfunction of the hand by correcting the angle of holding a smartphone. Subjects comprised of 21 healthy students. This research was conducted from April 21 2014 to April 27 2014. The three groups were as follows: first group included 7 students who held the phone at an angle of 90 degrees without a sling, and second group included 7 students who held the smartphone at an angle of 90 degrees with a sling; and the third group included 7 students who held the smartphone at an angle of 120 degrees with a sling. VAS was measured through the Finkelstein Test. Also, pain rating and muscle strength were assessed four times 30 minutes before and after the experiment for one and a half hour with pinch grip, dynamometer, and visual analogue scale. Smartphone was used. In all of the measurements, period showed a significant difference (p<.05) between both sides and a significant difference was not found between the group. In the time × group, pain score and grip strength were significantly different in the right side only (p<.05). According to the results of this experiment, providing support to the hand helps to increase the hand function by reducing the stress.

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Factors affecting grip force: anatomy, mechanics, and referent configurations

Cited by 56 publications

References 38 publications

The nature of constant and cyclic force production: unintentional force-drift characteristics

The nature of constant and cyclic force production: unintentional force-drift characteristics

Stability of multifinger action in different state spaces

The Effects of Hand Function on the Angle of Holding a Smartphone

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