Coordinated isometric muscle commands adequately and erroneously programmed for the weight during lifting task with precision grip

Johansson, Roland S.; Westling, G.

doi:10.1007/bf00247522

Cited by 566 publications

(492 citation statements)

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“…its frictional properties and weight. During erroneous programming, somatosensory signals may cause compensatory actions and update various parameters of the internal model (Johansson and Westling 1984b, 1988. The present study indicates that similar principles also may apply during further manipulative actions superimposed on the basic grip.…”

Section: Discussionmentioning

confidence: 51%

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Programmed and triggered actions to rapid load changes during precision grip

1988

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Summary.A test object (grip apparatus) was held at its upper part using a precision grip. Small balls were dropped into a target cup at the bottom of the apparatus. The grip force, the load force (vertical lifting force) and the vertical movement were measured. Electromyographic activity (e.m.g.) was recorded from four antagonist pairs of hand/arm muscles primarily influencing the grip force or the load force. The balls were dropped either by the subject during a bimanual task, or unexpectedly by the experimenter. When the subject dropped the ball, preparatory actions occurred before the rapid increase in the vertical load caused by the impact. These actions appeared ca. 150 ms prior to the impact and involved a grip force increase and a lifting movement of the grip apparatus. The e.m.g, activity increased in all eight of the hand and arm muscles, indicating a general stiffening of the hand/arm system prior to the impact. Furthermore, the preparatory actions were programmed adequately for the size of the load force step at the impact, i.e. an adequate safety margin to prevent slips was preserved during the critical period of the impact. Thus, variations in this step caused by changes in (i) the weight of ball, (ii) the weight of the grip apparatus and (iii) the length of the drop were adequately taken into account during the programming of these actions. In addition, the frictional condition between the skin and the grip surface was also taken into account. The relevant sensory information apparently was obtained during the handling of the ball and the grip apparatus prior to the drop. There were also task-related automatic muscle responses triggered by the impact.These responses, which also served to stiffen the hand/arm system, were most pronounced during unexpected load changes, but they appeared too late to prevent slips. However, if no overall slip occurred, Offprint requests to: R.S. Johansson (address see above) the triggered responses were functional in the sense that they helped to quickly restore the safety margin and the vertical position of the object.

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Section: Discussionmentioning

confidence: 51%

“…processor with rise and decay time constants of 1 ms and 3 ms, respectively. For further details concerning the actions of the muscles during the present lifting task and the recording procedures, see Johansson and Westling 1988.…”

Section: Preparatory Actions In Isolation While the Subject Dropped Tmentioning

confidence: 99%

Programmed and triggered actions to rapid load changes during precision grip

1988

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“…Here, we showed that these alterations of movement kinematics succeeded in blurring the observer's sensitivity in predicting object weight by observing reaching-to-grasp and lifting movements. Importantly, accidental alterations of movement kinematics to adapt to unexpected object weight (Johansson and Westling 1988) could be detected and used by the observers to predict the actual object weight in the deceived condition, as no difference in the observers' predictions of truthful and deceived actions was found. In particular, the kinematic analysis showed that, while movement duration, wrist flexion and GA could not help to make a distinction between truthful and deceived actions, the index finger was more flexed (and the FDI more contracted) during the lifting of an object that was expected to be heavier as compared to the corresponding truthful actions.…”

Section: Deceptive Intentions But Not Kinematic Adaptations Fool the mentioning

confidence: 99%

“…In this deceived condition, the actor aims to provide truthful cues to the observer but receives fooling information about the object weight, thus being forced to alter the movement kinematics to adapt to the unexpected object weight. Importantly, since representation of action kinematics in the observer's motor system is thought to mirror the muscle-specific motor role, we compared the modulation of the cortico-spinal excitability (CSE) in one hand and one forearm muscle that differently contribute to the postural adjustments required by unexpected objects' weight (Johansson and Westling 1988;Tidoni et al 2013). Additionally, given a possible role of emphatic abilities in shaping motor resonance (Gallese 2003), we measured participants' level of trait empathy.…”

Section: Introductionmentioning

confidence: 99%

Dissociated Representations of Deceptive Intentions and Kinematic Adaptations in the Observer's Motor System

et al. 2016

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Previous studies showed that observing deceptive actions modulates the activity of the observer's motor system. However, it is unclear whether this modulation reflects the coding of deceptive intentions or the mapping of the kinematic adaptations required to attain deceptive actions. Here, we used single-pulse transcranial magnetic stimulation to measure cortico-spinal excitability (CSE) from hand and forearm muscles while participants predicted the weight of cubes lifted by actors who received truthful information on the object weight and provided 1) truthful (truthful actions) or 2) deceptive (deceptive actions) cues to the observers or 3) who received fooling information and were asked to provide truthful cues (deceived actions). This way, we independently manipulated actor's intentions and kinematic adaptations. We found that, as compared to truthful action observation, CSE increased during observation of deceptive actions, but decreased during observation of deceived actions. Importantly, while the CSE enhancement in response to deceptive intentions lacked muscle specificity, perceiving kinematic alterations in the deceived condition affected CSE only for the hand muscle involved in kinematic adaptations to unexpected object weight. This suggests that actor's intentions and movement kinematics may be coded by the observer's motor system at different hierarchical levels of action representation.

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“…The rate of increase of grip force and the final grip force depend on the object's weight and its surface texture. Anticipatory increases in grip force can also be observed when subjects see a ball being dropped into a cup that they are supporting (Johansson and Westling 1988). The change in grip force anticipates the increase in load force that will result from contact between ball and cup and guards against slippage.…”

Section: Introductionmentioning

confidence: 99%

Modulation of grip force with load force during point-to-point arm movements

1993

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Abstract. In this paper, we examine grip forces and load forces during point-to-point arm movements with objects grasped with a precision grip. We demonstrate that grip force is finely modulated with load force. Variations in load force arise from inertial forces related to movement; grip force rises as the load force increases and falls as load force decreases. The same finding is observed in vertical and horizontal movements performed at various rates. In vertical movements, maximum grip force coincides in time with maximum load force. The maxima occur early in upward and later in downward movements. In horizontal movements, where peaks in load force are observed during both the acceleratory and deceleratory phases, grip force rises at the beginning of the movement and remains high until the end. The results suggest that when moving an object with the hand the programming of grip force is an integral part of the planning process.

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Coordinated isometric muscle commands adequately and erroneously programmed for the weight during lifting task with precision grip

Cited by 566 publications

References 20 publications

Programmed and triggered actions to rapid load changes during precision grip

Programmed and triggered actions to rapid load changes during precision grip

Dissociated Representations of Deceptive Intentions and Kinematic Adaptations in the Observer's Motor System

Modulation of grip force with load force during point-to-point arm movements

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