Hand-held tools with complex kinematics are efficiently incorporated into movement planning and online control

2012 ◽  
Vol 108 (7) ◽  
pp. 1954-1964 ◽  
Author(s):  
Lee A. Baugh ◽  
Erica Hoe ◽  
J. Randall Flanagan
Keyword(s):  
Online Control ◽  
Movement Planning ◽  
Control Mechanisms ◽  
Movement Initiation ◽  
Reaching Movement ◽  
Hand Motion ◽  
Reversal Condition ◽  
End Point ◽  
Point Motion ◽  
Time Required

Certain hand-held tools alter the mapping between hand motion and motion of the tool end point that must be controlled in order to perform a task. For example, when using a pool cue, the motion of the cue tip is reversed relative to the hand. Previous studies have shown that the time required to initiate a reaching movement (Fernandez-Ruiz J, Wong W, Armstrong IT, Flanagan JR. Behav Brain Res 219: 8–14, 2011), or correct an ongoing reaching movement (Gritsenko V, Kalaska JF. J Neurophysiol 104: 3084–3104, 2010), is prolonged when the mapping between hand motion and motion of a cursor controlled by the hand is reversed. Here we show that these time costs can be significantly reduced when the reversal is instantiated by a virtual hand-held tool. Participants grasped the near end of a virtual tool, consisting of a rod connecting two circles, and moved the end point to displayed targets. In the reversal condition, the rod translated through, and rotated about, a pivot point such that there was a left-right reversal between hand and end point motion. In the nonreversal control, the tool translated with the hand. As expected, when only the two circles were presented, movement initiation and correction times were much longer in the reversal condition. However, when full vision of the tool was provided, the reaction time cost was almost eliminated. These results indicate that tools with complex kinematics can be efficiently incorporated into sensorimotor control mechanisms used in movement planning and online control.

scholarly journals THE EFFECTS ON BIOLOGICAL MATERIALS OF FREEZING AND DRYING BY VACUUM SUBLIMATION

1954 ◽  
Vol 100 (1) ◽  
pp. 81-88 ◽  
Author(s):  
Donald Greiff ◽  
Henry Pinkerton
Keyword(s):  
Influenza Virus ◽  
Biological Materials ◽  
Continuous Operation ◽  
Virus Suspension ◽  
Vacuum Sublimation ◽  
End Point ◽  
Different Temperatures ◽  
Time Required

A vacuum sublimation apparatus is described which will permit, (a) the removal of water from virus suspensions at temperatures ranging down to –80°C., (b) continuous operation with a minimum of attention from the investigator, (c) sealing off of samples at operating pressures (10–5 mm. Hg), (d) simultaneous lyophilization of aliquot samples at different temperatures, (e) isolation of a portion of the apparatus without disturbing the remainder of the system, and (f) determination of the end-point of sublimation without disturbing the samples. The time required for drying 0.1 ml. of influenza virus suspension was shown to increase markedly with decrease of temperature, 8 days being required for dehydration at –80°C. in contrast to 2 days at –30°C. and 1 day at 0°C.

scholarly journals Passive sensorimotor stimulation triggers long lasting alpha-band fluctuations in visual perception

2018 ◽  
Vol 119 (2) ◽  
pp. 380-388 ◽  
Author(s):  
Alice Tomassini ◽  
Alessandro D’Ausilio
Keyword(s):  
Visual Perception ◽  
Median Nerve ◽  
Movement Planning ◽  
Sensorimotor System ◽  
Alpha Power ◽  
Alpha Band ◽  
Movement Initiation ◽  
Visual Contrast ◽  
Sensorimotor Processes ◽  
Stimulation Of

Movement planning and execution rely on the anticipation and online control of the incoming sensory input. Evidence suggests that sensorimotor processes may synchronize visual rhythmic activity in preparation of action performance. Indeed, we recently reported periodic fluctuations of visual contrast sensitivity that are time-locked to the onset of an intended movement of the arm. However, the origin of the observed visual modulations has so far remained unclear because of the endogenous (and thus temporally undetermined) activation of the sensorimotor system that is associated with voluntary movement initiation. In this study, we activated the sensorimotor circuitry involved in the hand control in an exogenous and controlled way by means of peripheral stimulation of the median nerve and characterized the spectrotemporal dynamics of the ensuing visual perception. The stimulation of the median nerve triggers robust and long-lasting (∼1 s) alpha-band oscillations in visual perception, whose strength is temporally modulated in a way that is consistent with the changes in alpha power described at the neurophysiological level after sensorimotor stimulation. These findings provide evidence in support of a causal role of the sensorimotor system in modulating oscillatory activity in visual areas with consequences for visual perception. NEW & NOTEWORTHY This study shows that the peripheral activation of the somatomotor hand system triggers long-lasting alpha periodicity in visual perception. This demonstrates that not only the endogenous sensorimotor processes involved in movement preparation but also the passive stimulation of the sensorimotor system can synchronize visual activity. The present work suggests that oscillation-based mechanisms may subserve core (task independent) sensorimotor integration functions.

The Staining of Nervous Elements by the Bodian Method

1962 ◽  
Vol s3-103 (63) ◽  
pp. 297-310
Author(s):  
TERRY WILLIAMS
Keyword(s):  
Smooth Muscle ◽  
Paraffin Sections ◽  
Nerve Fibres ◽  
End Point ◽  
Pilot Trials ◽  
Initial Ph ◽  
Muscle Nerve ◽  
Impregnation Time ◽  
Time Required

In paraffin sections of tissues containing much smooth muscle, nerve-fibres are difficult to demonstrate by silver techniques. In pilot trials Bodian's activated protargol technique proved most promising for stomach sections. From a fixed Bodian-type schedule, the effects of variation in pH, time, and temperature of impregnation were studied separately and together. These experiments provided means of determining optimal levels for some of the variables in the process. The impregnation time required for optimal staining varies according to the temperature and initial pH. Stirring, or agitation of the slides, at intervals of a few hours has been found to be a valuable aid to even staining, and if this has been done it is possible to use the stage of clearing of the fluid as an end-point indicator.

Experimentally Confirmed Mathematical Model for Human Control of a Non-Rigid Object

2004 ◽  
Vol 91 (3) ◽  
pp. 1158-1170 ◽  
Author(s):  
Jonathan B. Dingwell ◽  
Christopher D. Mah ◽  
Ferdinando A. Mussa-Ivaldi
Keyword(s):  
Mathematical Model ◽  
Human Subjects ◽  
Movement Planning ◽  
Relative Speed ◽  
Rigid Object ◽  
Hand Motion ◽  
Human Control ◽  
Rigid Objects ◽  
Minimum Jerk ◽  
Neuroscience Research

Determining the principles used to plan and execute movements is a fundamental question in neuroscience research. When humans reach to a target with their hand, they exhibit stereotypical movements that closely follow an optimally smooth trajectory. Even when faced with various perceptual or mechanical perturbations, subjects readily adapt their motor output to preserve this stereotypical trajectory. When humans manipulate non-rigid objects, however, they must control the movements of the object as well as the hand. Such tasks impose a fundamentally different control problem than that of moving one's arm alone. Here, we developed a mathematical model for transporting a mass-on-a-spring to a target in an optimally smooth way. We demonstrate that the well-known “minimum-jerk” model for smooth reaching movements cannot accomplish this task. Our model extends the concept of smoothness to allow for the control of non-rigid objects. Although our model makes some predictions that are similar to minimum jerk, it predicts distinctly different optimal trajectories in several specific cases. In particular, when the relative speed of the movement becomes fast enough or when the object stiffness becomes small enough, the model predicts that subjects will transition from a uni-phasic hand motion to a bi-phasic hand motion. We directly tested these predictions in human subjects. Our subjects adopted trajectories that were well-predicted by our model, including all of the predicted transitions between uni- and bi-phasic hand motions. These findings suggest that smoothness of motion is a general principle of movement planning that extends beyond the control of hand trajectories.

Using Passive End-Point Motion Constraints to Calibrate Robot Manipulators

1993 ◽  
Vol 115 (3) ◽  
pp. 560-566 ◽  
Author(s):  
M. R. Driels
Keyword(s):  
Robot Manipulator ◽  
Measurement Noise ◽  
Joint Angles ◽  
Kinematic Parameters ◽  
Motion Constraints ◽  
End Point ◽  
Ball Bar ◽  
Point Motion ◽  
Six Degree Of Freedom ◽  
Ancillary Equipment

The concept of using a method to constrain the endpoint of a serial linkage (such as a robot manipulator) in order to identify the kinematic parameters is appealing, since it no longer becomes necessary to use ancillary equipment to measure the pose, partial or otherwise. This means that the joint angles obtained from the manipulator and knowledge of the type of constraint, are all that is needed to perform the calibration. This concept is applied to the calibration of a six-degree-of-freedom manipulator by connecting its end point to a table by means of a ball bar. The kinematic equations of the manipulator and constraint are developed, and then used to simulate the calibration process in order to determine whether the noise level present in the measurements disrupts the convergence of the process, the effect of measurement noise on the accuracy of identification and the number of experimental observations needed. The acquisition of experimental data is then described, and the results of the identification are discussed. It is concluded that for certain types of kinematic structures, this method of calibration is particularly attractive since it is rapid, simple to perform, and requires very little precision equipment.

scholarly journals The duration of reaching movement is longer than predicted by minimum variance

2016 ◽  
Vol 116 (5) ◽  
pp. 2342-2345 ◽  
Author(s):  
Chunji Wang ◽  
Yupeng Xiao ◽  
Etienne Burdet ◽  
James Gordon ◽  
Nicolas Schweighofer
Keyword(s):  
Minimum Variance ◽  
Reaching Movements ◽  
Movement Duration ◽  
Slow Movement ◽  
Reaching Movement ◽  
End Point ◽  
Parsimonious Explanation ◽  
Arm Reaching ◽  
The Central Nervous System ◽  
Duration Condition

Whether the central nervous system minimizes variability or effort in planning arm movements can be tested by measuring the preferred movement duration and end-point variability. Here we conducted an experiment in which subjects performed arm reaching movements without visual feedback in fast-, medium-, slow-, and preferred-duration conditions. Results show that 1) total end-point variance was smallest in the medium-duration condition and 2) subjects preferred to carry out movements that were slower than this medium-duration condition. A parsimonious explanation for the overall pattern of end-point errors across fast, medium, preferred, and slow movement durations is that movements are planned to minimize effort as well as end-point error due to both signal-dependent and constant noise.

scholarly journals Online modification of goal-directed control in human reaching movements

2021 ◽  
Author(s):  
Antoine De Comite ◽  
Frédéric Crevecoeur ◽  
Philippe Lefèvre
Keyword(s):  
Control Strategies ◽  
Control Policy ◽  
Visual Display ◽  
Surface Emg ◽  
Movement Planning ◽  
Reaching Movements ◽  
Reaching Movement ◽  
Flexible Control ◽  
Task Goal ◽  
Sudden Appearance

Humans are able to perform very sophisticated reaching movements in a myriad of contexts based on flexible control strategies influenced by the task goal and environmental constraints such as obstacles. However, it remains unknown whether these control strategies can be adjusted online. The objective of this study was to determine whether the factors which determine control strategies during planning also modify the execution of an ongoing movement following sudden changes in task demand. More precisely, we investigated whether, and at which latency, feedback responses to perturbation loads followed the change in the structure of the goal target or environment. We changed the target width (square or rectangle) to alter the task redundancy, or the presence of obstacles to induce different constraints on the reach path, and assessed based on surface EMG recordings when the change in visual display altered the feedback response to mechanical perturbations. Task-related EMG responses were detected within 150 ms of a change in target shape. Considering visuomotor delays of ~ 100 ms, these results suggest that it takes 50 ms to change control policy within a trial. An additional 30 ms delay was observed when the change in context involved sudden appearance or disappearance of obstacles. Overall, our results demonstrate that the control policy within a reaching movement is not static: contextual factors which influence movement planning also influence movement execution at surprisingly short latencies. Moreover, the additional 30 ms associated with obstacles suggest that these two types of changes may be mediated via distinct processes.

scholarly journals Prior Knowledge of Target Direction and Intended Movement Selection Improves Indirect Reaching Movement Decoding

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Hongbao Li ◽  
Yaoyao Hao ◽  
Shaomin Zhang ◽  
Yiwen Wang ◽  
Weidong Chen ◽  
...  
Keyword(s):  
Prior Knowledge ◽  
Premotor Cortex ◽  
Movement Planning ◽  
Avoidance Task ◽  
Movement Trajectory ◽  
Reaching Movement ◽  
Target Direction ◽  
Neural Activities ◽  
Direction Information ◽  
Movement Selection

Objective.Previous studies have demonstrated that target direction information presented by the dorsal premotor cortex (PMd) during movement planning could be incorporated into neural decoder for achieving better decoding performance. It is still unknown whether the neural decoder combined with only target direction could work in more complex tasks where obstacles impeded direct reaching paths.Methods.In this study, spike activities were collected from the PMd of two monkeys when performing a delayed obstacle-avoidance task. We examined how target direction and intended movement selection were encoded in neuron population activities of the PMd during movement planning. The decoding performances of movement trajectory were compared for three neural decoders with no prior knowledge, or only target direction, or both target direction and intended movement selection integrated into a mixture of trajectory model (MTM).Results.We found that not only target direction but also intended movement selection was presented in neural activities of the PMd during movement planning. It was further confirmed by quantitative analysis. Combined with prior knowledge, the trajectory decoder achieved the best performance among three decoders.Conclusion.Recruiting prior knowledge about target direction and intended movement selection extracted from the PMd could enhance the decoding performance of hand trajectory in indirect reaching movement.

Effect of visuomotor-map uncertainty on visuomotor adaptation

2012 ◽  
Vol 107 (6) ◽  
pp. 1576-1585 ◽  
Author(s):  
Naoki Saijo ◽  
Hiroaki Gomi
Keyword(s):  
Feedback Control ◽  
Probe Trial ◽  
Visual Target ◽  
Hand Movement ◽  
Visuomotor Adaptation ◽  
Proprioceptive Feedback ◽  
Visuomotor Rotation ◽  
Feedback Controls ◽  
Reaching Movement ◽  
End Point

Vision and proprioception contribute to generating hand movement. If a conflict between the visual and proprioceptive feedback of hand position is given, reaching movement is disturbed initially but recovers after training. Although previous studies have predominantly investigated the adaptive change in the motor output, it is unclear whether the contributions of visual and proprioceptive feedback controls to the reaching movement are modified by visuomotor adaptation. To investigate this, we focused on the change in proprioceptive feedback control associated with visuomotor adaptation. After the adaptation to gradually introduce visuomotor rotation, the hand reached the shifted position of the visual target to move the cursor to the visual target correctly. When the cursor feedback was occasionally eliminated (probe trial), the end point of the hand movement was biased in the visual-target direction, while the movement was initiated in the adapted direction, suggesting the incomplete adaptation of proprioceptive feedback control. Moreover, after the learning of uncertain visuomotor rotation, in which the rotation angle was randomly fluctuated on a trial-by-trial basis, the end-point bias in the probe trial increased, but the initial movement direction was not affected, suggesting a reduction in the adaptation level of proprioceptive feedback control. These results suggest that the change in the relative contribution of visual and proprioceptive feedback controls to the reaching movement in response to the visuomotor-map uncertainty is involved in visuomotor adaptation, whereas feedforward control might adapt in a manner different from that of the feedback control.

Sign in / Sign up

Export Citation Format

Share Document