Coordination of hand grip and load forces in uni- and bidirectional static force production tasks

Jarić, Slobodan; Russell, Elizabeth M.; Collins, Jeffrey J.; Marwaha, Rahul

doi:10.1016/j.neulet.2005.01.086

Cited by 38 publications

(37 citation statements)

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“…In the ramp-and-hold task (the ramp phase) and oscillation task, the coupling of G and L was assessed by calculating the maximum cross-correlation coefficients between the time series of G and L (Flanagan & Tresilian, 1994;Marwaha, Hall, Knight, & Jaric, 2006). However, similar to the findings of previous studies (Jaric, Collins, Marwaha, & Russell, 2006;Jaric, Russell, Collins, & Marwaha, 2005), the time lags appeared to be exceptionally small and inconsistent for all three tasks, demonstrating no significant effects even at the level of p < .1. Therefore, the maximum correlation coefficients alone were taken for further analysis (see Marwaha, Hall, Knight, & Jaric, 2006, for a similar approach).…”

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confidence: 68%

Impaired Object Manipulation in Mildly Involved Individuals with Multiple Sclerosis

Krishnan¹,

Freitas²,

Jarić³

2008

Motor Control

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We investigated hand function in mildly involved Multiple Sclerosis (MS) patients (N = 16; EDSS 1−5, 9-hole peg test 14−32 s) during static and dynamic manipulation tasks using an instrumented device. When compared with healthy controls (N = 16), the patients revealed impaired task performance regarding their ability to exert prescribed patterns of load force (L; force acting tangentially at the digits-object surface). Regarding the coordination of grip force (G; normal component) and L, the data only revealed elevated G/L ratio, although both the G and L coupling (maximum correlation coefficients and the time lags between them), and G modulation (gain and offset of G with respect to L) remained comparable in the two groups. Finally, most of the data suggested no MS-specific effects of switching from uni-to bimanual tasks, from available visual feedback to deprived feedback conditions. We conclude that the deterioration in the ability for precise control of external forces and overgripping could precede the decoupling of G and L and decreased G modulation in early phases of the disease. The results also suggest that the applied methodology could be sensitive enough to detect mild levels of impairment of hand function in MS and, possibly, other neurological diseases.Keywords hand function; grip; load; force coordination; coupling; task performanceThe main hand function is to grasp and manipulate objects and external supports. This function is essential for everyday life, and, consequently, an impaired hand function (e.g., associated with neurological diseases or injuries) could be an important obstacle to living an independent life. When an externally fixed (e.g., a handle providing external support) or a free-moving object (a cup of coffee, or a tool) is held with the opposing tips of the thumb and fingers, a load force (L) is applied tangentially to the surfaces in contact to move the object or exert a reaction force. The slippage of the object is countered by friction force originating from grip force (G) acting normally to the surface. A consistent finding throughout the literature has been that the changes in G and L appear to be highly coordinated. This coordination is based not only on an ability of the neural controlling mechanisms to assess the skin-object friction coefficient and, based on it, apply a relatively low safety margin [i.e., G slightly higher than necessary to prevent slippage; (Johansson & Westling, 1984)], but also to modulate G in parallel with L without any considerable time delays between them [i.e., using anticipatory mechanisms (Flanagan & Wing, 1995. The result appears to be a stable and relatively low grip-toload (G/L) ratio (Johansson, 1998), high coupling of G and L (as assessed by both high correlation coefficient and virtually no time lags between them [Blakemore, Goodbody, & Wolpert, 1998;Flanagan & Tresilian, 1994]), and a high level of modulation of G with respect to changes in L [i.e., high gain and low offset assessed through the slope and intercept, respectively, o...

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confidence: 68%

Impaired Object Manipulation in Mildly Involved Individuals with Multiple Sclerosis

Krishnan¹,

Freitas²,

Jarić³

2008

Motor Control

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“…For self-produced load perturbations, as they appear while moving handheld objects, grip forces are modulated in parallel and synchronous to load-force changes. Anticipatory feedforward control of grip forces is a necessary prerequisite to these abilities (Flanagan and Johansson 2002;Jaric et al 2005;Johansson et al 1992a,b;Wing 1996). Based on these and other findings, the theoretical concept of internal forward models has been postulated, which accounts for the causal relationship between actions and their consequences (Kawato et al 2003;Miall and Wolpert 1996;Wolpert et al 1998).…”

Section: Introductionmentioning

confidence: 99%

Influences of Load Characteristics on Impaired Control of Grip Forces in Patients With Cerebellar Damage

Brandauer

Timmann

Häusler

et al. 2010

Journal of Neurophysiology

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“…The obtained effect of direction was also in line with previous studies performed on either free movements or isometric actions. In particular, switching from uni-to bidirectional production of L was associated with a deteriorated coordination of G and L reflected in increased G/L ratio, decreased correlation coefficients between G and L, and a decreased modulation of G revealed in both a low gain and high offset [6,10]. Therefore, the remaining part of the discussion will be focused on the main finding of our study related to the effect of grasp on the G and L coordination.…”

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“…NIH-PA Author Manuscript NIH-PA Author Manuscript the slippage but also keeps a stable grip-to-load (G/L) ratio [2,8,10,11,[20][21][22]. Based on these observations, it has been concluded that the coordination of G and L is controlled by predictive, feed-forward mechanisms [11].…”

Section: Nih-pa Author Manuscriptmentioning

confidence: 99%

Elaborate force coordination of precision grip could be generalized to bimanual grasping techniques

Freitas

Krishnan

Jarić

2007

Neuroscience Letters

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Exceptional coordination of grip (G; the normal force that prevents slippage of the grasped object) and load force (L; the tangential force originating from the object's weight and inertia) has been interpreted as a part of evidence that both the anatomy and neural control of human hands have been predominantly designed for manipulation tasks. In the present study, we tested the hypothesis that the precision grasp (uses only the tips of fingers and the thumb of one hand) provides better indices of G and L coordination in static manipulation tasks than two bimanual grasps (palm-palm and fingers-thumb; both using opposing segments of two hands). However, in addition to a subtle difference in relative timing of G and L between the precision and two bimanual grasps, we only found that the fingers-thumb grasp is characterized with higher G/L ratio and somewhat higher modulation of G than not only the precision, but also the bimanual palm-palm grasp. However, all remaining data including the correlation coefficients between G and L demonstrated no difference among three evaluated grasping techniques. Therefore, we concluded that the elaborate G and L coordination associated with uni-manual grasps could be partly generalized to a variety of manipulation tasks including those based on bimanual grasping techniques. Taking into account the importance of manipulation tasks in both everyday life and clinical practice, future studies should extend the present research to both other grasping techniques and dynamic manipulation conditions. KeywordsHuman; movement control; isometric; oscillatory; manipulation; bimanual To hold and manipulate an object we have to grasp it and apply a grip force to achieve the manipulation goals and prevent slippage. During the hand-object interaction, a number of the object's properties and ongoing movement related events should be taken into account, such as the size, shape and weight of the object, inertial load caused by acceleration, or the coefficient of friction acting at the contact surface. The final result is an elaborate coordination of the grip force (G) with respect to the load force (L) tending to cause slippage. For example, G is accurately adjusted to friction acting at the contact surfaces and only slightly exceeds the minimal value required to prevent slippage [6,11]. Changes in L caused either by inertial forces acting due to the acceleration of the hand-held object or by exertion of L against an externally fixed object are associated with a high and simultaneous modulation of G that not only prevents Address for correspondence: Dr. Slobodan Jaric Human Performance Lab University of Delaware 547 S. College Av. Newark, DE 19716 E-mail: jaric@udel.edu Phone: +1-302-8316174 Fax: +1-302-8313693 Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof...

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Coordination of hand grip and load forces in uni- and bidirectional static force production tasks

Cited by 38 publications

References 19 publications

Impaired Object Manipulation in Mildly Involved Individuals with Multiple Sclerosis

Impaired Object Manipulation in Mildly Involved Individuals with Multiple Sclerosis

Influences of Load Characteristics on Impaired Control of Grip Forces in Patients With Cerebellar Damage

Elaborate force coordination of precision grip could be generalized to bimanual grasping techniques

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