Alterations in transport path differentially affect temporal and spatial movement parameters

Alberts, Jay L.; M, Saling; Stelmach, George E.

doi:10.1007/s00221-002-1005-0

Cited by 30 publications

(29 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, each subject produced a relatively constant closure distance across trials in relation to the total transport distance for each speed condition. Such stability in aperture closure distance in comparison to the aperture opening distance was in agreement with other previous studies (Alberts et al 2000(Alberts et al , 2002Rand and Stelmach 2005;Rand et al 2004;Stelmach 1998, 2001). However, across the range of speed conditions the closure distance changed (Fig.…”

Section: Aperture Closure Distancesupporting

confidence: 93%

“…These distances were calculated as a cumulative resultant trajectory length between two positions of the wrist IRED. It should be noted that the end of the arm transport was simultaneous to the target touch in this study, which is slightly earlier than the time defined in many other studies (the end of grasp, Alberts et al 2002;Castiello et al 2000;Paulignan et al 1991a), because the fingers continued to close after the target touch. Forward displacement of the wrist IRED was observed from the target touch to the completion of the grasp, most often for the faster speed conditions.…”

Section: Discussionmentioning

confidence: 59%

“…It may be possible that the aperture closure distance could be altered, if a much greater range of transport speed were examined. Similar to our previous studies (Alberts et al 2000(Alberts et al , 2002Rand et al 2004;Saling et al 1998;Stelmach 1998, 2001), the current study examines whether transport-grasp coordination is better formulated in terms of spatial or in terms of temporal characteristics of the movement by comparing the extent of invariance in those characteristics with regard to transport speed and distance. For this purpose, in this study we expanded the range of speed manipulations from that previously tested and examined how the aperture closure distance varied across that range.…”

Section: Introductionmentioning

confidence: 77%

“…It was shown that the distance traveled by the wrist after maximum aperture (aperture closure distance) was relatively invariant, even though the distance traveled by the wrist prior to maximum aperture varied under different task constraints. This was observed in experiments that employed different target sizes and target distances (Alberts et al 2000;Stelmach 1998, 2001), different involvements of body segments Stelmach 1998, 2001), a forearm rotation during the reach (Rand and Stelmach 2005), different conditions for obstacle avoidance (Alberts et al 2002;Saling et al 1998), and with or without mechanical perturbations applied on the reaching arm . These findings were interpreted as evidence that the onset of aperture closure is controlled by spatial information regarding the hand location relative to the object, and hence the transport and grasp components are coordinated primarily in the spatial domain.…”

Section: Introductionmentioning

confidence: 86%

“…More specifically, the grip aperture is modulated based on the distance between the hand and the object. Recent studies from our laboratory support this view by demonstrating an invariant nature of the hand location relative to the object where the aperture begins to close (Alberts et al 2000(Alberts et al , 2002Rand and Stelmach 2005;Saling et al 1998;Stelmach 1998, 2001). It was shown that the distance traveled by the wrist after maximum aperture (aperture closure distance) was relatively invariant, even though the distance traveled by the wrist prior to maximum aperture varied under different task constraints.…”

Section: Introductionmentioning

confidence: 86%

See 4 more Smart Citations

Effect of speed manipulation on the control of aperture closure during reach-to-grasp movements

2006

Self Cite

View full text Add to dashboard Cite

This study investigates coordination between hand transport and grasp movement components by examining a hypothesis that the hand location, relative to the object, in which aperture closure is initiated remains relatively constant under a wide range of transport speed. Subjects made reach-tograsp movements to a dowel under four speed conditions: slow, comfortable, fast but comfortable, and maximum (i.e., as fast as possible). The distance traveled by the wrist after aperture reached its maximum (aperture closure distance) increased with an increase of transport speed across the speed conditions. This finding rejected the hypothesis and suggests that the speed of hand transport is taken into account in aperture closure initiation. Within each speed condition, however, the closure distance exhibited relatively small variability across trials, even though the total distance traveled by the wrist during the entire transport movement varied from trial to trial. The observed stability in aperture closure distance across trials implies that the hand distance to the object plays an important role in the control law governing the initiation of aperture closure. Further analysis showed that the aperture closure distance depended on the amplitude of peak aperture as well as hand velocity and acceleration. To clarify the form of the above control law, we analyzed four different mathematical models, in which a decision to initiate grasp closure is made as soon as a specific movement parameter (wrist distance to target or transport time) crosses a threshold that is either a constant value or a function of the above-mentioned other movement-related parameters. Statistical analysis performed across all movement conditions revealed that the control law model (according to which grasp initiation is made when hand distance to target becomes less than a certain linear function of aperture amplitude, hand velocity, and hand acceleration) produced significantly smaller residual errors than the other three models. The findings support the notion that transport-grasp coordination and grasp initiation is based predominantly on spatial characteristics of the arm movement, rather than movement timing.

show abstract

Section: Aperture Closure Distancesupporting

confidence: 93%

Section: Discussionmentioning

confidence: 59%

Section: Introductionmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 86%

See 3 more Smart Citations

Effect of speed manipulation on the control of aperture closure during reach-to-grasp movements

2006

Self Cite

View full text Add to dashboard Cite

show abstract

Principles of Motor Recovery After Neurological Injury Based on a Motor Control Theory

Levin

2016

Advances in Experimental Medicine and Biology

View full text Add to dashboard Cite

Problems of neurological rehabilitation are considered based on two levels of the International Classification of Functioning (ICF)-Body Structures and Function level and Activity level-and modulating factors related to the individual and the environment. Specifically, at the Body Structures and Function level, problems addressed include spasticity, muscle weakness, disordered muscle activation patterns and disruptions in coordinated movement. At the Activity level, deficits in multi-joint and multi-segment upper limb reaching movements are reviewed. We address how physiologically well established principles in the control of actions, Threshold Control and Referent Control as outlined in the Equilibrium-Point theory can help advance the understanding of underlying deficits that may limit recovery at each level.

show abstract

Adaptation of reach-to-grasp movement in response to force perturbations

Rand

Shimansky

Stelmach

et al. 2004

Experimental Brain Research

View full text Add to dashboard Cite

This study examined how reach-to-grasp movements are modified during adaptation to external force perturbations applied on the arm during reach. Specifically, we examined whether the organization of these movements was dependent upon the condition under which the perturbation was applied. In response to an auditory signal, all subjects were asked to reach for a vertical dowel, grasp it between the index finger and thumb, and lift it a short distance off the table. The subjects were instructed to do the task as fast as possible. The perturbation was an elastic load acting on the wrist at an angle of 105 deg lateral to the reaching direction. The condition was modified by changing the predictability with which the perturbation was applied in a given trial. After recording unperturbed control trials, perturbations were applied first on successive trials (predictable perturbations) and then were applied randomly (unpredictable perturbations). In the early predictable perturbation trials, reach path length became longer and reaching duration increased. As more predictable perturbations were applied, the reach path length gradually decreased and became similar to that of control trials. Reaching duration also decreased gradually as the subjects adapted by exerting force against the perturbation. In addition, the amplitude of peak grip aperture during arm transport initially increased in response to repeated perturbations. During the course of learning, it reached its maximum and thereafter slightly decreased. However, it did not return to the normal level. The subjects also adapted to the unpredictable perturbations through changes in both arm transport and grasping components, indicating that they can compensate even when the occurrence of the perturbation cannot be predicted during the inter-trial interval. Throughout random perturbation trials, large grip aperture values were observed, suggesting that a conservative aperture level is set regardless of whether the reaching arm is perturbed or not. In addition, the results of the predictable perturbations showed that the time from movement onset to the onset of grip aperture closure changed as adaptation occurred. However, the spatial location where the onset of finger closure occurred showed minimum changes with perturbation. These data suggest that the onset of finger closure is dependent upon distance to target rather than the temporal relationship of the grasp relative to the transport phase of the movement.

show abstract

Alterations in transport path differentially affect temporal and spatial movement parameters

Cited by 30 publications

References 17 publications

Effect of speed manipulation on the control of aperture closure during reach-to-grasp movements

Effect of speed manipulation on the control of aperture closure during reach-to-grasp movements

Principles of Motor Recovery After Neurological Injury Based on a Motor Control Theory

Adaptation of reach-to-grasp movement in response to force perturbations

Contact Info

Product

Resources

About