Importance of Cutaneous Feedback in Maintaining a Secure Grip During Manipulation of Hand-Held Objects

2003 ◽  
Vol 89 (2) ◽  
pp. 665-671 ◽  
Author(s):  
Anne-Sophie Augurelle ◽  
Allan M. Smith ◽  
Thierry Lejeune ◽  
Jean-Louis Thonnard
Keyword(s):  
Internal Model ◽  
Grip Force ◽  
Tangential Force ◽  
Safety Margin ◽  
Background Level ◽  
Load Force ◽  
Initial Contact ◽  
Phase Lag ◽  
Cutaneous Sensation ◽  
Hold Period

Previous research has shown that grip and load forces are modulated simultaneously during manipulation of a hand-held object. This close temporal coupling suggested that both forces are controlled by an internal model within the CNS that predicts the changes in tangential force on the fingers. The objective of the present study was to examine how the internal model would compensate for the loss of cutaneous sensation through local anesthesia of the index and thumb. Ten healthy adult subjects (5 men and 5 women aged 20–57 yr) were asked to grasp, lift, and hold stationary, a 250 g object for 20 s. Next, the subjects were asked to perform vertical oscillatory movements over a distance of 20 cm at a rate of 1.0 Hz for 30 s. Eleven trials were performed with intact sensation, and 11 trials after a local ring-block anesthesia of the index and thumb with bupivacain (5 mg/ml). During static holding, loss of cutaneous sensation produced a significant increase in the safety margin. However, the grip force declined significantly over the 20-s static hold period. During oscillatory arm movements, grip and load forces were continuously modulated together in a predictive manner as suggested by Flanagan and Wing. Again, the grip force declined over the 30-s movement, and 7/10 subjects dropped the object at least once. With intact sensation, the object was never dropped; but with the fingers anesthetized, it was dropped on 36% of the trials, and a significant slip occurred on a further 12%. The mean correlation between the grip and load forces for all subjects deteriorated from 0.71 with intact sensation to 0.48 after digital anesthesia. However, a cross-correlation calculated between the grip and load forces indicated that the phase lag was approximately zero both with and without digital anesthesia. Taken together, the data from the present study suggest that cutaneous afferents are required for setting and maintaining the background level of the grip force in addition to their phasic slip-detection function and their role in adapting the grip force/load force ratio to the friction on initial contact with an object. Finally, at a more theoretical level, they correct and maintain an internal model of the physical properties of hand-held objects.

Grip force anticipation of nonlinear, underactuated load force

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.

scholarly journals The Effects of Digital Anesthesia on Force Control Using a Precision Grip

2003 ◽  
Vol 89 (2) ◽  
pp. 672-683 ◽  
Author(s):  
Joël Monzée ◽  
Yves Lamarre ◽  
Allan M. Smith
Keyword(s):  
Internal Model ◽  
Grip Force ◽  
Index Finger ◽  
Precision Grip ◽  
Initial Study ◽  
Cutaneous Sensation ◽  
Surface Textures ◽  
Cutaneous Feedback ◽  
Resistive Forces ◽  
Tonic Excitation

A total of 20 right-handed subjects were asked to perform a grasp-lift-and-hold task using a precision grip. The grasped object was a one-degree-of-freedom manipuladum consisting of a vertically mounted linear motor capable of generating resistive forces to simulate a range of object weights. In the initial study, seven subjects (6 women, 1 man; ages 24–56 yr) were first asked to lift and hold the object stationary for 4 s. The object presented a metal tab with two different surface textures and offered one of four resistive forces (0.5, 1.0, 1.5, and 2.0 N). The lifts were performed both with and without visual feedback. Next, the subjects were asked to perform the same grasping sequence again after ring block anesthesia of the thumb and index finger with mepivacaine. The objective was to determine the degree to which an internal model obtained through prior familiarity might compensate for the loss of cutaneous sensation. In agreement with previous studies, it was found that all subjects applied significantly greater grip force after digital anesthesia, and the coordination between grip and load forces was disrupted. It appears from these data, that the internal model alone is insufficient to completely compensate for the loss of cutaneous sensation. Moreover, the results suggest that the internal model must have either continuous tonic excitation from cutaneous receptors or at least frequent intermittent reiteration to function optimally. A subsequent study performed with 10 additional subjects (9 women, 1 man; ages 24–49 yr) indicated that with unimpaired cutaneous feedback, the grasping and lifting forces were applied together with negligible forces and torques in other directions. In contrast, after digital anesthesia, significant additional linear and torsional forces appeared, particularly in the horizontal and frontal planes. These torques were thought to arise partially from the application of excessive grip force and partially from a misalignment of the two grasping fingers. These torques were further increased by an imbalance in the pressure exerted by the two opposing fingers. Vision of the grasping hand did not significantly correct the finger misalignment after digital anesthesia. Taken together, these results suggest that mechanoreceptors in the fingertips signal the source and direction of pressure applied to the skin. The nervous system uses this information to adjust the fingers and direct the pinch forces optimally for grasping and object manipulation.

Impaired Grip Force Modulation in the Ipsilesional Hand after Unilateral Middle Cerebral Artery Stroke

2005 ◽  
Vol 19 (4) ◽  
pp. 338-349 ◽  
Author(s):  
Barbara M. Quaney ◽  
Subashan Perera ◽  
Rebecca Maletsky ◽  
Carl W. Luchies ◽  
Randolph J. Nudo
Keyword(s):  
Middle Cerebral Artery ◽  
Cerebral Artery ◽  
Cognitive Deficits ◽  
Grip Force ◽  
Precision Grip ◽  
Load Force ◽  
Cutaneous Sensation ◽  
Sensorimotor Processing ◽  
Object Weight ◽  
Stroke Group

Understanding grasping control after stroke is important for relearning motor skills. The authors examined 10 individuals (5 males; 5 females; ages 32-86) with chronic unilateral middle cerebral artery (MCA) stroke (4 right lesions; 6 left lesions) when lifting a novel test object using skilled precision grip with their ipsilesional (“unaffected”) hand compared to healthy controls (n = 14; 6 males; 8 females; ages 19-86). All subjects possessed normal range of motion, cutaneous sensation, and proprioception in the hand tested and had no apraxia or cognitive deficits. Subjects lifted the object 10 times at each object weight (260 g, 500 g, 780 g) using a moderately paced self-selected lifting speed. The normal horizontal (“grip”) force and vertical tangential (“lift”) force were separately measured at the thumb and index finger. Regardless of the object weight or stroke location, the stroke group generated greater grip forces at liftoff of the object (≥ 39%; P ≤ 0.05) and across the dynamic (P ≤ 0.05) and static portions (P ≤ 0.05) of the lifts compared to the healthy group. Peak lift forces were equivalent between groups, suggesting accurate load force information processing occurred. These results warrant further investigation of altered sensorimotor processing or compensatory biomechanical strategies that may lead to inaccurate grip force execution after strokes.

Effects of local and core body temperature on grip force modulation during movement-induced load force fluctuations

2008 ◽  
Vol 103 (1) ◽  
pp. 59-69 ◽  
Author(s):  
Stephen S. Cheung ◽  
Luke F. Reynolds ◽  
Mark A. B. Macdonald ◽  
Constance L. Tweedie ◽  
Robin L. Urquhart ◽  
...  
Keyword(s):  
Body Temperature ◽  
Grip Force ◽  
Core Body Temperature ◽  
Load Force ◽  
Force Fluctuations ◽  
Force Modulation ◽  
Core Body

Variable and intermittent grip force control in response to differing load force dynamics

2018 ◽  
Vol 237 (3) ◽  
pp. 687-703 ◽  
Author(s):  
Francis M. Grover ◽  
Patrick Nalepka ◽  
Paula L. Silva ◽  
Tamara Lorenz ◽  
Michael A. Riley
Keyword(s):  
Force Control ◽  
Grip Force ◽  
Load Force ◽  
Force Dynamics ◽  
Grip Force Control

Wrist Action Affects Precision Grip Force

1997 ◽  
Vol 78 (1) ◽  
pp. 271-280 ◽  
Author(s):  
Mary M. Werremeyer ◽  
Kelly J. Cole
Keyword(s):  
Grip Force ◽  
Precision Grip ◽  
Load Force ◽  
Myoelectric Activity ◽  
Resistive Load ◽  
Wrist Flexion ◽  
Wrist Extension ◽  
Hand Muscles ◽  
Force Pulse ◽  
Grasp Stability

Werremeyer, Mary M. and Kelly J. Cole. Wrist action affects precision grip force. J. Neurophysiol. 78: 271–280, 1997. When moving objects with a precision grip, fingertip forces normal to the object surface (grip force) change in parallel with forces tangential to the object (load force). We investigated whether voluntary wrist actions can affect grip force independent of load force, because the extrinsic finger muscles cross the wrist. Grip force increased with wrist angular speed during wrist motion in the horizontal plane, and was much larger than the increased tangential load at the fingertips or the reaction forces from linear acceleration of the test object. During wrist flexion the index finger muscles in the hand and forearm increased myoelectric activity; during wrist extension this myoelectric activity increased little, or decreased for some subjects. The grip force maxima coincided with wrist acceleration maxima, and grip force remained elevated when subjects held the wrist in extreme flexion or extension. Likewise, during isometric wrist actions the grip force increased even though the fingertip loads remained constant. A grip force “pulse” developed that increased with wrist force rate, followed by a static grip force while the wrist force was sustained. Subjects could not suppress the grip force pulse when provided visual feedback of their grip force. We conclude that the extrinsic hand muscles can be recruited to assist the intended wrist action, yielding higher grip-load ratios than those employed with the wrist at rest. This added drive to hand muscles overcame any loss in muscle force while the extrinsic finger flexors shortened during wrist flexion motion. During wrist extension motion grip force increases apparently occurred from eccentric contraction of the extrinsic finger flexors. The coactivation of hand closing muscles with other wrist muscles also may result in part from a general motor facilitation, because grip force increased during isometric knee extension. However, these increases were related weakly to the knee force. The observed muscle coactivation, from all sources, may contribute to grasp stability. For example, when transporting grasped objects, upper limb accelerations simultaneously produce inertial torques at the wrist that must be resisted, and inertial loads at the fingertips from the object that must be offset by increased grip force. The muscle coactivation described here would cause similarly timed pulses in the wrist force and grip force. However, grip-load coupling from this mechanism would not contribute much to grasp stability when small wrist forces are required, such as for slow movements or when the object's total resistive load is small.

scholarly journals Flexible organization of grip force control during movement frequency scaling

2019 ◽  
Vol 122 (6) ◽  
pp. 2304-2315
Author(s):  
Francis M. Grover ◽  
Sarah M. Schwab ◽  
Paula L. Silva ◽  
Tamara Lorenz ◽  
Michael A. Riley
Keyword(s):  
Force Control ◽  
Grip Force ◽  
Sagittal Plane ◽  
Oscillation Amplitude ◽  
Load Force ◽  
Force Load ◽  
Grip Force Control ◽  
Force Coupling ◽  
Tightly Coupled ◽  
Oscillation Frequencies

The grip force applied to maintain grasp of a handheld object has been typically reported as tightly coupled to the load force exerted by the object as it is actively manipulated, occurring proportionally and consistently in phase with changes in load force. However, continuous grip force-load force coupling breaks down when overall load force levels and oscillation amplitudes are lower (Grover F, Lamb M, Bonnette S, Silva PL, Lorenz T, Riley MA. Exp Brain Res 236: 2531–2544, 2018) or more predictable (Grover FM, Nalepka P, Silva PL, Lorenz T, Riley MA. Exp Brain Res 237: 687–703, 2019). Under these circumstances, grip force is instead only intermittently coupled to load force; continuous coupling is prompted only when load force levels or variations become sufficiently high or unpredictable. The current study investigated the nature of the transition between continuous and intermittent modes of grip force control by scaling the load force level and the oscillation amplitude continuously in time by means of scaling the required frequency of movement oscillations. Participants grasped a cylindrical object between the thumb and forefinger and oscillated their arm about the shoulder in the sagittal plane. Oscillation frequencies were paced with a metronome that scaled through an ascending or descending frequency progression. Due to greater accelerations, faster frequencies produced greater overall load force levels and more pronounced load oscillations. We observed smooth but nonlinear transitions between clear regimes of intermittent and continuous grip force-load force coordination, for both scaling directions, indicating that grip force control can flexibly reorganize as parameters affecting grasp (e.g., variations in load force) change over time. NEW & NOTEWORTHY Grip force (GF) is synchronously coupled to changing load forces (LF) during object manipulation when LF levels are high or unpredictable, but only intermittently coupled to LF during less challenging grasp conditions. This study characterized the nature of transitions between synchronous and intermittent GF-LF coupling, revealing a smooth but nonlinear change in intermittent GF modulation in response to continuous scaling of LF amplitude. Intermittent, “drift-and-act” control may provide an alternative framework for understanding GF-LF coupling.

Some shear facts and pure friction related to roughness discrimination and the cutaneous control of grasping

1994 ◽  
Vol 72 (5) ◽  
pp. 583-590 ◽  
Author(s):  
Allan M. Smith
Keyword(s):  
Surface Texture ◽  
Grip Force ◽  
Shear Forces ◽  
Low Friction ◽  
Cutaneous Sensation ◽  
Tangential Forces ◽  
Roughness Discrimination ◽  
Almost All ◽  
The Brain ◽  
Skin Mechanoreceptors

The question of whether friction contributes to the perception of roughness has been overdebated and underinvestigated. A review of the psychophysical literature suggests that roughness and friction can be subjectively distinguished very effectively, although the same rapidly adapting Meissner corpuscles (RA1s) and slowly adapting Merkel receptors (SA1s) are stimulated by both stimuli. It appears that to achieve the subjective appreciation of roughness, the brain must learn to ignore variations in the speed of movement over the skin, the perpendicular force applied to the receptor surface, and the shear forces tangential to the skin generated by friction. Similarly, the subjective appreciation of slipperiness requires selective attention to tangential forces to the exclusion of speed, perpendicular force, and surface texture. A clearer picture is gradually emerging concerning the detection and appreciation of shear forces from investigations of the grasping and lifting of objects of different surfaces against the force of gravity. Although high shear forces provoke larger responses in almost all skin mechanoreceptors, some neurons in both the sensory and motor cortex discharge more vigorously with smooth textures and lower coefficients of friction. Although populations of such neurons sensitive to smooth surfaces and low friction would be very useful in detecting both potential and real slips, just how the afferent signals are derived remains puzzling.Key words: cutaneous sensation, friction, grip force, roughness, shear force, surface texture.

Coupling of grip force and load force during arm movements with grasped objects

1993 ◽  
Vol 152 (1-2) ◽  
pp. 53-56 ◽  
Author(s):  
J.Randall Flanagan ◽  
James Tresilian ◽  
Alan M. Wing
Keyword(s):  
Grip Force ◽  
Arm Movements ◽  
Load Force

scholarly journals Assessment of Hand Function Through the Coordination of Contact Forces in Manipulation Tasks

2013 ◽  
Vol 36 (1) ◽  
pp. 5-160 ◽  
Author(s):  
Slobodan Jaric ◽  
Mehmet Uygur
Keyword(s):  
Hand Function ◽  
Safety Margin ◽  
Tangential Component ◽  
Contact Forces ◽  
Load Force ◽  
Dominant Hand ◽  
Factors Affecting ◽  
Relative Safety ◽  
Safety Margins ◽  
Mechanical Factors

Exploration of force coordination has been one of the most often used approaches in studies of hand function. When holding and manipulating a hand-held object healthy individuals are typically able to highly coordinate the perpendicular (grip force; GF) with the tangential component of the contact force (load force; LF). The purpose of this review is to present the findings of our recent studies of GF-LF coordination. Regarding the mechanical factors affecting GF-LF coordination, our data suggest that both different hand segments and their particular skin areas could have markedly different friction properties. It also appears that the absolute, rather than relative safety margin (i.e., how much the actual GF exceeds the minimum value that prevents slipping) should be a variable of choice when assessing the applied magnitude of GF. The safety margin could also be lower in static than in free holding tasks. Regarding the involved neural factors, the data suggest that the increased frequency, rather than an increased range of a cyclic LF could have a prominent detrimental effect on the GF-LF coordination. Finally, it appears that the given instructions (e.g., 'to hold' vs. 'to pull') can prominently alter GF-LF coordination in otherwise identical manipulation tasks. Conversely, the effects of handedness could be relatively week showing only slight lagging of GF in the non-dominant, but not in the dominant hand. The presented findings reveal important aspects of hand function as seen through GF-LF coordination. Specifically, the use of specific hand areas for grasping, calculation of particular safety margins, the role of LF frequency (but not of LF range) and the effects of given instructions should be all taken into account when conducting future studies of manipulation tasks, standardizing their procedures and designing routine clinical tests of hand function.

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