scholarly journals Are reaching and grasping effector-independent? Similarities and differences in reaching and grasping kinematics between the hand and foot

2021 ◽  
Author(s):  
Yuqi Liu ◽  
James Caracoglia ◽  
Sriparna Sen ◽  
Ella Striem-Amit
Keyword(s):  
Peak Velocity ◽  
Object Size ◽  
Body Parts ◽  
Acceleration Phase ◽  
Grip Aperture ◽  
Deceleration Phase ◽  
Neural Representations ◽  
Maximum Grip Aperture ◽  
Similarities And Differences ◽  
Maximum Grip

While reaching and grasping are highly prevalent manual actions, neuroimaging studies provide evidence that their neural representations may be shared between different body parts, i.e. effectors. If these actions are guided by effector-independent mechanisms, similar kinematics should be observed when the action is performed by the hand or by a cortically remote and less experienced effector, such as the foot. We tested this hypothesis with two characteristic components of action: the initial ballistic stage of reaching, and the preshaping of the digits during grasping based on object size. We examined if these kinematic features reflect effector-independent mechanisms by asking participants to reach toward and to grasp objects of different widths with their hand and foot. First, during both reaching and grasping, the velocity profile up to peak velocity matched between the hand and the foot, indicating a shared ballistic acceleration phase. Secondly, maximum grip aperture and time of maximum grip aperture of grasping increased with object size for both effectors, indicating encoding of object size during transport. Differences between the hand and foot were found in the deceleration phase and time of maximum grip aperture, likely due to biomechanical differences and the participants' inexperience with foot actions. These findings provide evidence for effector-independent visuomotor mechanisms of reaching and grasping that generalize across body parts.

scholarly journals Prehension and Perception of Size in Left Visual Neglect

2002 ◽  
Vol 13 (1-2) ◽  
pp. 3-15 ◽  
Author(s):  
R. D. McIntosh ◽  
C. L. Pritchard ◽  
H. C. Dijkerman ◽  
A. D. Milner ◽  
R. C. Roberts
Keyword(s):  
Right Hemisphere ◽  
Visual Neglect ◽  
Grip Aperture ◽  
Estimation Task ◽  
Deceleration Phase ◽  
Maximum Grip Aperture ◽  
Patient Groups ◽  
Visual Size ◽  
Null Finding ◽  
Maximum Grip

Right hemisphere damaged patients with and without left visual neglect, and age-matched controls had objects of various sizes presented within left or right body hemispace. Subjects were asked to estimate the objects’ sizes or to reach out and grasp them, in order to assess visual size processing in perceptual-experiential and action-based contexts respectively. No impairments of size processing were detected in the prehension performance of the neglect patients but a generalised slowing of movement was observed, associated with an extended deceleration phase. Additionally both patient groups reached maximum grip aperture relatively later in the movement than did controls. For the estimation task it was predicted that the left visual neglect group would systematically underestimate the sizes of objects presented within left hemispace but no such abnormalities were observed. Possible reasons for this unexpected null finding are discussed.

On the Relation Between Object Shape and Grasping Kinematics

2004 ◽  
Vol 91 (6) ◽  
pp. 2598-2606 ◽  
Author(s):  
Raymond H. Cuijpers ◽  
Jeroen B. J. Smeets ◽  
Eli Brenner
Keyword(s):  
Principal Axis ◽  
Grip Aperture ◽  
Object Shape ◽  
Hand Orientation ◽  
Principal Axes ◽  
Movement Distance ◽  
Maximum Grip Aperture ◽  
The Many ◽  
Elliptical Cylinders ◽  
Maximum Grip

Despite the many studies on the visual control of grasping, little is known about how and when small variations in shape affect grasping kinematics. In the present study we asked subjects to grasp elliptical cylinders that were placed 30 and 60 cm in front of them. The cylinders' aspect ratio was varied systematically between 0.4 and 1.6, and their orientation was varied in steps of 30°. Subjects picked up all noncircular cylinders with a hand orientation that approximately coincided with one of the principal axes. The probability of selecting a given principal axis was the highest when its orientation was equal to the preferred orientation for picking up a circular cylinder at the same location. The maximum grip aperture was scaled to the length of the selected principal axis, but the maximum grip aperture was also larger when the length of the axis orthogonal to the grip axis was longer than that of the grip axis. The correlation between the grip aperture— or the hand orientation—at a given instant, and its final value, increased monotonically with the traversed distance. The final hand orientation could already be inferred from its value after 30% of the movement distance with a reliability that explains 50% of the variance. For the final grip aperture, this was only so after 80% of the movement distance. The results indicate that the perceived shape of the cylinder is used for selecting appropriate grasping locations before or early in the movement and that the grip aperture and orientation are gradually attuned to these locations during the movement.

The influence of object height on maximum grip aperture in empirical and modeled data.

2014 ◽  
Vol 40 (2) ◽  
pp. 889-896 ◽  
Author(s):  
Svenja Borchers ◽  
Rebekka Verheij ◽  
Jeroen B. J. Smeets ◽  
Marc Himmelbach
Keyword(s):  
Grip Aperture ◽  
Maximum Grip Aperture ◽  
Maximum Grip

The influence of target object shape on maximum grip aperture in human grasping movements

2014 ◽  
Vol 232 (11) ◽  
pp. 3569-3578 ◽  
Author(s):  
Rebekka Verheij ◽  
Eli Brenner ◽  
Jeroen B. J. Smeets
Keyword(s):  
Target Object ◽  
Grip Aperture ◽  
Object Shape ◽  
Maximum Grip Aperture ◽  
Maximum Grip

scholarly journals Is Grasping Impaired in Hemispatial Neglect?

2002 ◽  
Vol 13 (1-2) ◽  
pp. 17-28 ◽  
Author(s):  
Monika Harvey ◽  
Stephen R. Jackson ◽  
Roger Newport ◽  
Tanja Krämer ◽  
D. Llewlyn Morris ◽  
...  
Keyword(s):  
Right Hemisphere ◽  
Target Object ◽  
Cerebral Stroke ◽  
Hemispatial Neglect ◽  
Grip Aperture ◽  
Maximum Grip Aperture ◽  
Path Curvature ◽  
The Right ◽  
Path Deviation ◽  
Maximum Grip

Patients with right unilateral cerebral stroke, four of which showed acute hemispatial neglect, and healthy aged-matched controls were tested for their ability to grasp objects located in either right or left space at near or far distances. Reaches were performed either in free vision or without visual feedback from the hand or target object. It was found that the patient group showed normal grasp kinematics with respect to maximum grip aperture, grip orientation, and the time taken to reach the maximum grip aperture. Analysis of hand path curvature showed that control subjects produced straighter right hand reaches when vision was available compared to when it was not. The right hemisphere lesioned patients, however, showed similar levels of curvature in each of these conditions. No behavioural differences, though, could be found between right hemisphere lesioned patients with or without hemispatial neglect on either grasp parameters, path deviation or temporal kinematics.

scholarly journals Some illusions are more inconsistent than others

2019 ◽  
Author(s):  
Jeroen B. J. Smeets ◽  
Eli Brenner
Keyword(s):  
Motion Aftereffect ◽  
Apparent Size ◽  
Ebbinghaus Illusion ◽  
Reach To Grasp ◽  
Grip Aperture ◽  
Maximum Grip Aperture ◽  
Pencil And Paper ◽  
Maximum Grip

Illusions are characterized by inconsistencies. For instance, in the motion aftereffect, we see motion without an equivalent change in position. We used a simple pencil-and-paper experiment to determine whether illusions that influence an object’s apparent size give rise to equivalent changes in apparent positions along the object’s outline. We found different results for two equally strong size illusions. The Ebbinghaus illusion affected perceived positions in a way that was consistent with its influence on perceived size, but a modified diagonal illusion did not affect perceived positions. This difference between the illusions might explain why there are so many conflicting reports about the effects of size illusions on the maximum grip aperture during reach-to-grasp movements.

Representation of hand position prior to movement and motor variability

1995 ◽  
Vol 73 (2) ◽  
pp. 262-272 ◽  
Author(s):  
Michel Desmurget ◽  
Yves Rossetti ◽  
Claude Prablanc ◽  
Marc Jeannerod ◽  
George E. Stelmach
Keyword(s):  
Peak Velocity ◽  
Human Subjects ◽  
Hand Position ◽  
Feedback Process ◽  
Significant Modification ◽  
Movement Kinematics ◽  
Acceleration Phase ◽  
Movement Onset ◽  
Motor Variability ◽  
Deceleration Phase

Pointing accurary of six human subjects was measured in two blocked conditions where the hand was either never visible (T: target only) or only visible in static position prior to movement onset (H+T: hand + target). It was shown in condition H+T that, viewing the hand prior to movement greatly decreased end-point variability compared with condition T. This effect was associated with a significant modification of the movement kinematics: the H+T condition induced a shortened acceleration phase with a corresponding lengthened deceleration phase, compared with the T condition. These results led us to the hypothesis that viewing the hand prior to movement onset allowed a decrease of pointing variability through a feedback process. This hypothesis was further tested by turning the target off during the deceleration phase of the movement at half peak velocity. It was shown that turning the target off had no effect upon the T condition but induced a significant increase of pointing variability in the H+T condition. This result suggests that vision of the static hand enhances the proprioceptive localization of the limb and allows for a better visual to kinesthesic feedback.Key words: proprioception, vision, motor control, pointing, feedback, human.

scholarly journals A Wind-Storage Combined Frequency Regulation Control Strategy Based on Improved Torque Limit Control

2021 ◽  
Vol 13 (7) ◽  
pp. 3765
Author(s):  
Benxi Hu ◽  
Fei Tang ◽  
Dichen Liu ◽  
Yu Li ◽  
Xiaoqing Wei
Keyword(s):  
Control Strategy ◽  
Storage System ◽  
Energy Storage System ◽  
Frequency Regulation ◽  
Small Scale ◽  
Acceleration Phase ◽  
Deceleration Phase ◽  
Combined Control ◽  
Inertial Response ◽  
Battery Energy

The doubly-fed induction generator (DFIG) uses the rotor’s kinetic energy to provide inertial response for the power system. On this basis, this paper proposes an improved torque limit control (ITLC) strategy for the purpose of exploiting the potential of DFIGs’ inertial response. It includes the deceleration phase and acceleration phase. To shorten the recovery time of the rotor speed and avoid the second frequency drop (SFD), a small-scale battery energy storage system (BESS) is utilized by the wind-storage combined control strategy. During the acceleration phase of DFIG, the BESS adaptively adjusts its output according to its state of charge (SOC) and the real-time output of the DFIG. The simulation results prove that the system frequency response can be significantly improved through ITLC and the wind-storage combined control under different wind speeds and different wind power penetration rates.

scholarly journals A conceptual model of cyclical glacier flow in overdeepenings

2014 ◽  
Vol 8 (4) ◽  
pp. 4463-4495 ◽  
Author(s):  
J. B. Turrin ◽  
R. R. Forster
Keyword(s):  
Conceptual Model ◽  
The Other ◽  
Acceleration Phase ◽  
Alaska Range ◽  
Deceleration Phase ◽  
Surface Slopes ◽  
Glacier Dynamics ◽  
Major Tributary ◽  
Cyclical Behavior ◽  
Glacier Flow

Abstract. A nearly four-decade, satellite-based velocity survey of the largest glaciers in the Alaska Range, Chugach Mountains, and the Wrangell Mountains of southern Alaska, spanning the early- to mid-1970s through the 2000s, reveals nine pulsing glaciers: Capps, Copper, Eldridge, Kahiltna, Matanuska, Nabesna, Nizina, Ruth, and Sanford glaciers. The pulses increase velocity by up to 2449% (Capps Glacier) or as little as 77% (Nabesna Glacier), with velocity increases for the other glaciers in the range of 100–250%. The pulses may last from between six years (Copper Glacier) to 12 years (Nizina Glacier) and consist of a multi-year acceleration phase followed by a multi-year deceleration phase during which significant portions of each glacier move en masse. The segments of each glacier affected by the pulses may be anywhere from 14 km (Sanford Glacier) to 36 km (Nabesna Glacier) in length and occur where the glaciers are either laterally constricted or joined by a major tributary, and the surface slopes at these locations are very shallow, 1–2°, suggesting the pulses occur where the glaciers are overdeepened. A conceptual model to explain the cyclical behavior of these pulsing glaciers is presented that incorporates the effects of glaciohydraulic supercooling, glacier dynamics, surface ablation, and subglacial sediment erosion, deposition, and deformation in overdeepenings.

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