Does slippage influence the EEG response to load force variations during object manipulation?

Hand Interactions in Rapid Grip Force Adjustments Are Independent of Object Dynamics

Journal of Neurophysiology ◽

10.1152/jn.90593.2008 ◽

2008 ◽

Vol 100 (5) ◽

pp. 2738-2745 ◽

Cited By ~ 20

Author(s):

Olivier White ◽

Noreen Dowling ◽

R. Martyn Bracewell ◽

Jörn Diedrichsen

Keyword(s):

Grip Force ◽

Object Manipulation ◽

Load Force ◽

Single Object ◽

Stereo Display ◽

Force Increase ◽

Robotic Devices ◽

The Moment ◽

Pure Measurement ◽

Object Dynamics

Object manipulation requires rapid increase in grip force to prevent slippage when the load force of the object suddenly increases. Previous experiments have shown that grip force reactions interact between the hands when holding a single object. Here we test whether this interaction is modulated by the object dynamics experienced before the perturbation of the load force. We hypothesized that coupling of grip forces should be stronger when holding a single object than when holding separate objects. We measured the grip force reactions elicited by unpredictable load perturbations when participants were instructed to hold one single or two separate objects. We simulated these objects both visually and dynamically using a virtual environment consisting of two robotic devices and a calibrated stereo display. In contrast to previous studies, the load forces arising from a single object could be uncoupled at the moment of perturbation, allowing for a pure measurement of grip force coupling. Participants increased grip forces rapidly (onset ∼70 ms) in response to perturbations. Grip force increases were stronger when the load force on the other hand also increased. No such coupling was present in the reaction of the arms to the load force increase. Surprisingly, however, the grip force interaction did not depend on the nature of the manipulated object. These results show fast obligatory coupling of bimanual grip force responses. Although this coupling may play a functional role for providing stability in bimanual object manipulation, it seems to constitute a relatively hard-wired modulation of a reflex.

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Grip force anticipation of nonlinear, underactuated load force

Journal of Neurophysiology ◽

10.1152/jn.00616.2020 ◽

2021 ◽

Author(s):

Francis M. Grover ◽

Christopher Riehm ◽

Paula L. Silva ◽

Tamara Lorenz ◽

Michael A. Riley

Keyword(s):

Force Control ◽

Internal Model ◽

Grip Force ◽

Object Manipulation ◽

Load Force ◽

Complex Object ◽

Active Object ◽

Grip Force Control ◽

Motor Commands ◽

Model Approach

Feedforward internal model-based control enabled by efference copies of motor commands is the prevailing theoretical account of motor anticipation. Grip force control during object manipulation-a paradigmatic example of motor anticipation-is a key line of evidence for that account. However, the internal model approach has not addressed the computational challenges faced by the act of manipulating mechanically complex objects with nonlinear, underactuated degrees of freedom. These objects exhibit complex and unpredictable load force dynamics which cannot be encoded by efference copies of underlying motor commands, leading to the prediction from the perspective of an efference copy-enabled feedforward control scheme that grip force should either lag or fail to coordinate with changes in load force. In contrast to that prediction, we found evidence for strong, precise, anticipatory grip force control during manipulations of a complex object. The results are therefore inconsistent with the internal forward model approach and suggest that efference copies of motor commands are not necessary to enable anticipatory control during active object manipulation.

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Proximal arm kinematics affect grip force-load force coordination

Journal of Neurophysiology ◽

10.1152/jn.00227.2015 ◽

2015 ◽

Vol 114 (4) ◽

pp. 2265-2277 ◽

Cited By ~ 1

Author(s):

Billy C. Vermillion ◽

Peter S. Lum ◽

Sang Wook Lee

Keyword(s):

Force Control ◽

Muscle Activation ◽

Grip Force ◽

Object Manipulation ◽

Load Force ◽

Hand Muscles ◽

Grip Force Control ◽

Arm Kinematics ◽

Force Ratio ◽

The Impact

During object manipulation, grip force is coordinated with load force, which is primarily determined by object kinematics. Proximal arm kinematics may affect grip force control, as proximal segment motion could affect control of distal hand muscles via biomechanical and/or neural pathways. The aim of this study was to investigate the impact of proximal kinematics on grip force modulation during object manipulation. Fifteen subjects performed three vertical lifting tasks that involved distinct proximal kinematics (elbow/shoulder), but resulted in similar end-point (hand) trajectories. While temporal coordination of grip and load forces remained similar across the tasks, proximal kinematics significantly affected the grip force-to-load force ratio ( P = 0.042), intrinsic finger muscle activation ( P = 0.045), and flexor-extensor ratio ( P < 0.001). Biomechanical coupling between extrinsic hand muscles and the elbow joint cannot fully explain the observed changes, as task-related changes in intrinsic hand muscle activation were greater than in extrinsic hand muscles. Rather, between-task variation in grip force (highest during task 3) appears to contrast to that in shoulder joint velocity/acceleration (lowest during task 3). These results suggest that complex neural coupling between the distal and proximal upper extremity musculature may affect grip force control during movements, also indicated by task-related changes in intermuscular coherence of muscle pairs, including intrinsic finger muscles. Furthermore, examination of the fingertip force showed that the human motor system may attempt to reduce variability in task-relevant motor output (grip force-to-load force ratio), while allowing larger fluctuations in output less relevant to task goal (shear force-to-grip force ratio).

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Grip and load force control and coordination in object manipulation during a night of sleep deprivation

Sleep and Biological Rhythms ◽

10.1111/sbr.12102 ◽

2014 ◽

Vol 13 (2) ◽

pp. 163-171 ◽

Cited By ~ 1

Author(s):

Sabrina Tiago Pedão ◽

Stefane Aline Aguiar ◽

Bianca Pinto Cunha ◽

Paulo Barbosa de Freitas

Keyword(s):

Sleep Deprivation ◽

Force Control ◽

Object Manipulation ◽

Load Force

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Fast-adapting mechanoreceptors are important for force control in precision grip but not for sensorimotor memory

Journal of Neurophysiology ◽

10.1152/jn.00195.2016 ◽

2016 ◽

Vol 115 (6) ◽

pp. 3156-3161 ◽

Cited By ~ 4

Author(s):

Susanna B. Park ◽

Marco Davare ◽

Marika Falla ◽

William R. Kennedy ◽

Mona M. Selim ◽

...

Keyword(s):

Force Control ◽

Precision Grip ◽

Object Manipulation ◽

Load Force ◽

Type I ◽

Tactile Sensitivity ◽

Latex Gloves ◽

Variable Weight ◽

Sensorimotor Memory ◽

Force Scaling

Sensory feedback from cutaneous mechanoreceptors in the fingertips is important in effective object manipulation, allowing appropriate scaling of grip and load forces during precision grip. However, the role of mechanoreceptor subtypes in these tasks remains incompletely understood. To address this issue, psychophysical tasks that may specifically assess function of type I fast-adapting (FAI) and slowly adapting (SAI) mechanoreceptors were used with object manipulation experiments to examine the regulation of grip force control in an experimental model of graded reduction in tactile sensitivity (healthy volunteers wearing 2 layers of latex gloves). With gloves, tactile sensitivity decreased significantly from 1.9 ± 0.4 to 12.3 ± 2.2 μm in the Bumps task assessing function of FAI afferents but not in a grating orientation task assessing SAI afferents (1.6 ± 0.1 to 1.8 ± 0.2 mm). Six axis force/torque sensors measured peak grip (PGF) and load (PLF) forces generated by the fingertips during a grip-lift task. With gloves there was a significant increase of PGF (14 ± 6%), PLF (17 ± 5%), and grip and load force rates (26 ± 8%, 20 ± 8%). A variable-weight series task was used to examine sensorimotor memory. There was a 20% increase in PGF when the lift of a light object was preceded by a heavy relative to a light object. This relationship was not significantly altered when lifting with gloves, suggesting that the addition of gloves did not change sensorimotor memory effects. We conclude that FAI fibers may be important for the online force scaling but not for the buildup of a sensorimotor memory.

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