Load and Grip Force Coordination in Static Bimanual Manipulation Tasks in Multiple Sclerosis

Marwaha, Rahul; Hall, Susan J.; Knight, Christopher A.; Jarić, Slobodan

doi:10.1123/mcj.10.2.160

Cited by 33 publications

(36 citation statements)

References 35 publications

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“…Regarding task performance, a deterioration of task performance in MS patients was noticed in all three tasks. This finding is in line with our previous results (Jaric, Knight, Collins, & Marwaha, 2005;Marwaha, Hall, Knight, & Jaric, 2006) and generally suggests that the ability to exert an accurate pattern of external forces could be one of the first signs of functional impairment of the hands associated with the progress of the disease.Force coordination was assessed through G/L ratio, force coupling, and G modulation. When compared with healthy controls, MS patients showed a higher G/L ratio in all three tasks This result is in line with findings obtained from other neural pathologies (see the introduction for details) and suggests that, in addition to inaccurate L pattern, an elevated G/L ratio could also be an early sign of hand function impairment in MS.…”

supporting

confidence: 82%

“…We hypothesized that even the mildly involved patients will demonstrate impaired task performance and decreased force coordination when compared with healthy controls. When compared with our previous study, performed on a similar group of MS patients (Marwaha, Hall, Knight, & Jaric, 2006), the present one has been extended from purely static to both static and dynamic tasks. Specifically, we expected that the hypothesized differences would be more prominent in the tasks performed bimanually rather than unimanually, as well as in the tasks in which visual feedback is available.…”

Section: Nih Public Accessmentioning

confidence: 97%

“…The clinical symptoms of MS are highly variable depending on the site and extent of CNS involvement. However, one of the common and important clinical features is impaired hand function caused by deterioration of hand dexterity (Feys, Duportail, Kos, Van Asch, & Ketelaer, 2002).In our recent study we tested mildly involved MS patients (EDSS 1.5−4) in a variety of bimanual static tasks, looking for disease-specific aspects of impairment of hand function (Marwaha, Hall, Knight, & Jaric, 2006). When compared with healthy controls, the patients revealed an elevated G/L ratio and lower task performance regarding the accuracy of the instructed L profile, although both the coupling of G and L and modulation of G were preserved.…”

mentioning

confidence: 99%

“…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). In general, the higher correlation coefficients were interpreted as higher coordination of G and L. In line with a number of previous studies, the modulation of G with respect to changes in L has been interpreted as an index of force coordination (Flanagan, Tresilian, & Wing, 1993;Jaric, Collins, Marwaha, & Russell, 2006;Zatsiorsky, Gao, & Latash, 2005).…”

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confidence: 99%

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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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supporting

confidence: 82%

Section: Nih Public Accessmentioning

confidence: 97%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Impaired Object Manipulation in Mildly Involved Individuals with Multiple Sclerosis

Krishnan¹,

Freitas²,

Jarić³

2008

Motor Control

Self Cite

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“…Other studies also demonstrated that precision grip force control capacity became degraded with advancing age [10,15,16]. Patients with some neurological disorders also experience difficulties in precise adjustments of the grip force to the task demands [9,11,[17][18][19][20][21][22][23]. For instance, patients with cerebral stroke have deficits in sensory input and therefore demonstrated an exaggerated grip force compared to normal control [41].…”

Section: Introductionmentioning

confidence: 99%

Similar Motion of a Hand-held Object may Trigger Nonsimilar Grip Force Adjustments

Gao¹,

Latash

Zatsiorsky

2007

Journal of Hand Therapy

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The tight coupling between load (L) and grip (G) forces during voluntary manipulation of a handheld object is well established. The current study is to examine grip-load force coupling when motion of the hand with an object was either self-generated (voluntary) or externally generated. Subjects performed similar cyclic movements of different loads at various frequencies with three types of manipulation: (a) voluntary oscillation, (b) oscillating the right arm via the pulley system by the left leg (self-driven oscillation), (c) oscillating the arm via the pulley system by another person (otherdriven oscillation). During the self-generated movements: (a) the grip forces were larger and (b) gripload force modulation was more pronounced than in the externally generated movements. The G-L adjustments are not completely determined by the mechanics of object motion; non-mechanical factors related to movement performance, for instance perceptual factors, may affect the G-L coupling. Potentially the results of study can be used to provide hand therapists with another way for administering the Rapid Exchange Gripping Test.

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Force coordination in static manipulation tasks: effects of the change in direction and handedness

2007

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A number of studies have demonstrated high coordination of the hand grip force (GF; normal component of force acting at the digits-object contact area) and load force (LF; tangential component) in a variety of manipulation tasks. The aim of the study was to explore the mainly neglected effect of the change in LF direction and the effect of handedness on GF and LF coordination in bimanual manipulation task. Subjects (N = 14) exerted a bimanual sinusoidal LF pattern against externally fixed handles in trials that gradually changed from unidirectional (LF exerted only in one direction) to fully bidirectional (equal LF peaks in two opposite directions). Despite the gradual change of LF, unidirectional trials demonstrated high indices of force coordination, while in all bidirectional trials, no matter how low and brief LF exertion was in the opposite direction, all indices of GF and LF coordination deteriorated to a considerably lower level. The non-dominant hand demonstrated both a higher directional accuracy of exerting LF and higher GF modulation than the dominant one. We concluded that manipulation tasks performed in a single and two alternating directions may be based on partly distinctive neural control mechanisms, as well as that a switching of muscle synergies required in bidirectional tasks could play a role in the observed phenomenon. Regarding the effect of hand dominance, the recorded advantage of the non-dominant hand could be considered as an addition to the current views of the non-dominant arm/hemisphere specialization in controlling limb position.

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Load and Grip Force Coordination in Static Bimanual Manipulation Tasks in Multiple Sclerosis

Cited by 33 publications

References 35 publications

Impaired Object Manipulation in Mildly Involved Individuals with Multiple Sclerosis

Impaired Object Manipulation in Mildly Involved Individuals with Multiple Sclerosis

Similar Motion of a Hand-held Object may Trigger Nonsimilar Grip Force Adjustments

Force coordination in static manipulation tasks: effects of the change in direction and handedness

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