Reaching During Virtual Rotation: Context Specific Compensations for Expected Coriolis Forces

2000 ◽  
Vol 83 (6) ◽  
pp. 3230-3240 ◽  
Author(s):  
Joseph V. Cohn ◽  
Paul DiZio ◽  
James R. Lackner
Keyword(s):  
Target Location ◽  
Arm Movements ◽  
Open Loop ◽  
Tactile Feedback ◽  
Body Motion ◽  
Reaching Movements ◽  
Coriolis Forces ◽  
Enclosed Chamber ◽  
Path Curvature ◽  
Context Specific

Subjects who are in an enclosed chamber rotating at constant velocity feel physically stationary but make errors when pointing to targets. Reaching paths and endpoints are deviated in the direction of the transient inertial Coriolis forces generated by their arm movements. By contrast, reaching movements made during natural, voluntary torso rotation seem to be accurate, and subjects are unaware of the Coriolis forces generated by their movements. This pattern suggests that the motor plan for reaching movements uses a representation of body motion to prepare compensations for impending self-generated accelerative loads on the arm. If so, stationary subjects who are experiencing illusory self-rotation should make reaching errors when pointing to a target. These errors should be in the direction opposite the Coriolis accelerations their arm movements would generate if they were actually rotating. To determine whether such compensations exist, we had subjects in four experiments make visually open-loop reaches to targets while they were experiencing compelling illusory self-rotation and displacement induced by rotation of a complex, natural visual scene. The paths and endpoints of their initial reaching movements were significantly displaced leftward during counterclockwise illusory rotary displacement and rightward during clockwise illusory self-displacement. Subjects reached in a curvilinear path to the wrong place. These reaching errors were opposite in direction to the Coriolis forces that would have been generated by their arm movements during actual torso rotation. The magnitude of path curvature and endpoint errors increased as the speed of illusory self-rotation increased. In successive reaches, movement paths became straighter and endpoints more accurate despite the absence of visual error feedback or tactile feedback about target location. When subjects were again presented a stationary scene, their initial reaches were indistinguishable from pre-exposure baseline, indicating a total absence of aftereffects. These experiments demonstrate that the nervous system automatically compensates in a context-specific fashion for the Coriolis forces associated with reaching movements.

Rapid adaptation to Coriolis force perturbations of arm trajectory

1994 ◽  
Vol 72 (1) ◽  
pp. 299-313 ◽  
Author(s):  
J. R. Lackner ◽  
P. Dizio
Keyword(s):  
Coriolis Force ◽  
Opposite Sign ◽  
Tactile Feedback ◽  
Reaching Movements ◽  
Movement Trajectory ◽  
Body Rotation ◽  
Experimental Conditions ◽  
Coriolis Forces ◽  
Partial Restoration ◽  
Movement Trajectories

1. Forward reaching movements made during body rotation generate tangential Coriolis forces that are proportional to the cross product of the angular velocity of rotation and the linear velocity of the arm. Coriolis forces are inertial forces that do not involve mechanical contact. Virtually no constant centrifugal forces will be present in the background when motion of the arm generates transient Coriolis forces if the radius of body rotation is small. 2. We measured the trajectories of arm movements made in darkness to a visual target that was extinguished as movement began. The reaching movements were made prerotation, during rotation at 10 rpm in a fully enclosed rotating room, and postrotation. During testing the subject was seated at the center of the room and pointed radially. Neither visual nor tactile feedback about movement accuracy was present. 3. In experiment 1, subjects reached at a fast or slow rate and their hands made contact with a horizontal surface at the end of the reach. Their initial perrotary movements were highly significantly deviated relative to prerotation in both trajectories and end-points in the direction of the transient Coriolis forces that had been generated during the reaches. Despite the absence of visual and tactile feedback about reaching accuracy, all subjects rapidly regained straight movement trajectories and accurate endpoints. Postrotation, transient errors of opposite sign were present for both trajectories and endpoints. 4. In a second experiment the conditions were identical except that subjects pointed just above the location of the extinguished target so that no surface contact was involved. All subjects showed significant initial perrotation deviations of trajectories and endpoints in the direction of the transient Coriolis forces. With repeated reaches the trajectories, as viewed from above, again became straight, but there was only partial restoration of endpoint accuracy, so that subjects reached in a straight line to the wrong place. Aftereffects of opposite sign were transiently present in the postrotary movements. 5. These observations fail to support current equilibrium point models, both alpha and lambda, of movement control. Such theories would not predict endpoint errors under our experimental conditions, in which the Coriolis force is absent at the beginning and end of a movement. Our results indicate that detailed aspects of movement trajectory are being continuously monitored on the basis of proprioceptive feedback in relation to motor commands. Adaptive compensations can be initiated after one perturbation despite the absence of either visual or tactile feedback about movement trajectory and endpoint error. Moreover, movement trajectory and end-point can be remapped independently.(ABSTRACT TRUNCATED AT 400 WORDS)

Motor adaptation to Coriolis force perturbations of reaching movements: endpoint but not trajectory adaptation transfers to the nonexposed arm

1995 ◽  
Vol 74 (4) ◽  
pp. 1787-1792 ◽  
Author(s):  
P. Dizio ◽  
J. R. Lackner
Keyword(s):  
Muscle Spindle ◽  
Mirror Image ◽  
Tactile Feedback ◽  
Reaching Movements ◽  
Mechanical Contact ◽  
Experimental Conditions ◽  
Coriolis Forces ◽  
Muscle Dynamics ◽  
The Right ◽  
Made In

1. Reaching movements made in a rotating room generate Coriolis forces that are directly proportional to the cross product of the room's angular velocity and the arm's linear velocity. Such Coriolis forces are inertial forces not involving mechanical contact with the arm. 2. We measured the trajectories of arm movements made in darkness to a visual target that was extinguished at the onset of each reach. Prerotation subjects pointed with both the right and left arms in alternating sets of eight movements. During rotation at 10 rpm, the subjects reached only with the right arm. Postrotation, the subjects pointed with the left and right arms, starting with the left, in alternating sets of eight movements. 3. The initial perrotary reaching movements of the right arm were highly deviated both in movement path and endpoint relative to the prerotation reaches of the right arm. With additional movements, subjects rapidly regained straight movement paths and accurate endpoints despite the absence of visual or tactile feedback about reaching accuracy. The initial postrotation reaches of the left arm followed straight paths to the wrong endpoint. The initial postrotation reaches of the right arm had paths with mirror image curvature to the initial perrotation reaches of the right arm but went to the correct endpoint. 4. These observations are inconsistent with current equilibrium point models of movement control. Such theories predict accurate reaches under our experimental conditions. Our observations further show independent implementation of movement and posture, as evidenced by transfer of endpoint adaptation to the nonexposed arm without transfer of path adaptation. Endpoint control may occur at a relatively central stage that represents general constraints such as gravitoinertial force background or egocentric direction relative to both arms, and control of path may occur at a more peripheral stage that represents moments of inertia and muscle dynamics unique to each limb. 5. Endpoint and path adaptation occur despite the absence both of mechanical contact cues about the perturbing force and visual or tactile cues about movement accuracy. These findings point to the importance of muscle spindle signals, monitoring of motor commands, and possibly joint and tendon receptors in a detailed trajectory monitoring process. Muscle spindle primary and secondary afferent signals may differentially influence adaptation of movement shape and endpoint, respectively.

Congenitally Blind Individuals Rapidly Adapt to Coriolis Force Perturbations of Their Reaching Movements

2000 ◽  
Vol 84 (4) ◽  
pp. 2175-2180 ◽  
Author(s):  
Paul DiZio ◽  
James R. Lackner
Keyword(s):  
Visual Feedback ◽  
Target Location ◽  
Mirror Image ◽  
Reaching Movements ◽  
Coriolis Forces ◽  
Rotation Pattern ◽  
Congenitally Blind ◽  
Motor Information ◽  
Blind Individuals ◽  
Straight Ahead

Reaching movements made to visual targets in a rotating room are initially deviated in path and endpoint in the direction of transient Coriolis forces generated by the motion of the arm relative to the rotating environment. With additional reaches, movements become progressively straighter and more accurate. Such adaptation can occur even in the absence of visual feedback about movement progression or terminus. Here we examined whether congenitally blind and sighted subjects without visual feedback would demonstrate adaptation to Coriolis forces when they pointed to a haptically specified target location. Subjects were tested pre-, per-, and postrotation at 10 rpm counterclockwise. Reaching to straight ahead targets prerotation, both groups exhibited slightly curved paths. Per-rotation, both groups showed large initial deviations of movement path and curvature but within 12 reaches on average had returned to prerotation curvature levels and endpoints. Postrotation, both groups showed mirror image patterns of curvature and endpoint to the per-rotation pattern. The groups did not differ significantly on any of the performance measures. These results provide compelling evidence that motor adaptation to Coriolis perturbations can be achieved on the basis of proprioceptive, somatosensory, and motor information in the complete absence of visual experience.

Perisaccadic Mislocalization of Visual Targets by Head-Free Gaze Shifts: Visual or Motor?

2008 ◽  
Vol 100 (4) ◽  
pp. 1848-1867 ◽  
Author(s):  
Sigrid M. C. I. van Wetter ◽  
A. John van Opstal
Keyword(s):  
Target Location ◽  
Saccadic Eye Movements ◽  
Open Loop ◽  
Spatial Updating ◽  
Gaze Shifts ◽  
Gaze Shift ◽  
The Gaze ◽  
Visual Probe ◽  
Saccade Onset ◽  
Saccade Direction

Such perisaccadic mislocalization is maximal in the direction of the saccade and varies systematically with the target-saccade onset delay. We have recently shown that under head-fixed conditions perisaccadic errors do not follow the quantitative predictions of current visuomotor models that explain these mislocalizations in terms of spatial updating. These models all assume sluggish eye-movement feedback and therefore predict that errors should vary systematically with the amplitude and kinematics of the intervening saccade. Instead, we reported that errors depend only weakly on the saccade amplitude. An alternative explanation for the data is that around the saccade the perceived target location undergoes a uniform transient shift in the saccade direction, but that the oculomotor feedback is, on average, accurate. This “ visual shift” hypothesis predicts that errors will also remain insensitive to kinematic variability within much larger head-free gaze shifts. Here we test this prediction by presenting a brief visual probe near the onset of gaze saccades between 40 and 70° amplitude. According to models with inaccurate gaze-motor feedback, the expected perisaccadic errors for such gaze shifts should be as large as 30° and depend heavily on the kinematics of the gaze shift. In contrast, we found that the actual peak errors were similar to those reported for much smaller saccadic eye movements, i.e., on average about 10°, and that neither gaze-shift amplitude nor kinematics plays a systematic role. Our data further corroborate the visual origin of perisaccadic mislocalization under open-loop conditions and strengthen the idea that efferent feedback signals in the gaze-control system are fast and accurate.

The Role of Reafference in Recalibration of Limb Movement Control and Locomotion

1997 ◽  
Vol 7 (4) ◽  
pp. 303-310
Author(s):  
James R. Lackner ◽  
Paul DiZio
Keyword(s):  
Movement Control ◽  
Mirror Image ◽  
The Body ◽  
Head Movements ◽  
Reaching Movements ◽  
Optomotor Response ◽  
Coriolis Forces ◽  
Effects Of Rotation ◽  
Centripetal Forces

The reafference model has frequently been used to explain spatial constancy during eye and head movements. We have found that its basic concepts also form part of the information processing necessary for the control and recalibration of reaching movements. Reaching was studied in a novel force environment–a rotating room that creates centripetal forces of the type that could someday substitute for gravity in space flight, and Coriolis forces which are side effects of rotation. We found that inertial, noncontacting Coriolis forces deviate the path and endpoint of reaching movements, a finding that shows the inadequacy of equilibrium position models of movement control. Repeated movements in the rotating room quickly lead to normal movement patterns and to a failure to perceive the perturbing forces. The first movements made after rotation stops, without Coriolis forces present, show mirror-image deviations and evoke perception of a perturbing force even though none is present. These patterns of sensorimotor control and adaptation can largely be explained on the basis of comparisons of efference copy, reafferent muscle spindle, and cutaneous mechanoreceptor signals. We also describe experiments on human iocomotion using an apparatus similar to that which Mittelstaedt used to study the optomotor response of the Eristalis fly. These results show that the reafference principle relates as well to the perception of the forces acting on and exerted by the body during voluntary locomotion.

Accuracy of Children on an Open-Loop Pointing Task

1978 ◽  
Vol 47 (3_suppl) ◽  
pp. 1079-1082 ◽  
Author(s):  
L. Hay
Keyword(s):  
Open Loop ◽  
Reaching Movements ◽  
Manual Pointing ◽  
Pointing Task ◽  
The Difference ◽  
Passive Movements

The accuracy of active and passive movements was measured in 4-yr.- to 11-yr.-old children and in adults performing a visuo-manual pointing task without seeing their limbs. Accuracy varied according to age and nature of movement. The younger children performed accurate movements. At age 7 the accuracy suddenly decreased while the difference between active and passive movements increased. Between 7 and 11 yr., the active performance improved progressively until attaining an adult-like level, while the passive performance remained unchanged. It is concluded that a change occurs in the manner of controlling reaching movements at age 7.

Modeling of Multibody Flexible Articulated Structures With Mutually Coupled Motions: Part II — Application and Results

1992 ◽  
Author(s):  
Jiechi Xu ◽  
Joseph R. Baumgarten
Keyword(s):  
Experimental Data ◽  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Open Loop ◽  
Body Motion ◽  
Universal Joint ◽  
Open Loop System ◽  
Numerical Examples ◽  
Kinematic Properties ◽  
Good Agreement

Abstract The application of the systematic procedures in the derivation of the equations of motion proposed in Part I of this work is demonstrated and implemented in detail. The equations of motion for each subsystem are derived individually and are assembled under the concept of compatibility between the local kinematic properties of the elastic degrees of freedom of those connected elastic members. The specific structure under consideration is characterized as an open loop system with spherical unconstrained chains being capable of rotating about a Hooke’s or universal joint. The rigid body motion, due to two unknown rotations, and the elastic degrees of freedom are mutually coupled and influence each other. The traditional motion superposition approach is no longer applicable herein. Numerical examples for several cases are presented. These simulations are compared with the experimental data and good agreement is indicated.

scholarly journals Parallel updating and weighting of multiple spatial maps for visual stability during whole body motion

2015 ◽  
Vol 114 (6) ◽  
pp. 3211-3219 ◽  
Author(s):  
J. J. Tramper ◽  
W. P. Medendorp
Keyword(s):  
Reference Frame ◽  
Reference Frames ◽  
Spatial Information ◽  
Target Location ◽  
Visual Space ◽  
Body Motion ◽  
Whole Body ◽  
Spatial Representations ◽  
Integration Model ◽  
The Brain

It is known that the brain uses multiple reference frames to code spatial information, including eye-centered and body-centered frames. When we move our body in space, these internal representations are no longer in register with external space, unless they are actively updated. Whether the brain updates multiple spatial representations in parallel, or whether it restricts its updating mechanisms to a single reference frame from which other representations are constructed, remains an open question. We developed an optimal integration model to simulate the updating of visual space across body motion in multiple or single reference frames. To test this model, we designed an experiment in which participants had to remember the location of a briefly presented target while being translated sideways. The behavioral responses were in agreement with a model that uses a combination of eye- and body-centered representations, weighted according to the reliability in which the target location is stored and updated in each reference frame. Our findings suggest that the brain simultaneously updates multiple spatial representations across body motion. Because both representations are kept in sync, they can be optimally combined to provide a more precise estimate of visual locations in space than based on single-frame updating mechanisms.

Contrasting Neuronal Activity in the Dorsal and Ventral Premotor Areas During Preparation to Reach

2002 ◽  
Vol 87 (2) ◽  
pp. 1123-1128 ◽  
Author(s):  
Eiji Hoshi ◽  
Jun Tanji
Keyword(s):  
Neuronal Activity ◽  
Target Location ◽  
Delay Period ◽  
Reaching Movements ◽  
Target Acquisition ◽  
Trigger Signal ◽  
Arm Reaching ◽  
Motor Set ◽  
Premotor Areas

We compared neuronal activity in the dorsal and ventral premotor areas (PMd and PMv, respectively) when monkeys were preparing to perform arm-reaching movements in a motor-set period before their actual execution. They were required to select one of four possible movements (reaching to a target on the left or right, using either the left or right arm) in accordance with two sets of instruction cues, followed by a delay period, and a subsequent motor-set period. During the motor-set period, the monkeys were required to get ready for a movement-trigger signal to start the arm-reach promptly. We analyzed the activity of 211 PMd and 109 PMv neurons that showed selectivity for the combination of the two instruction cues during the motor-set period. A majority (53%) of PMd neurons exhibited activity significantly tuned to both target location and arm use, and an approximately equal number of PMd neurons showed selectivity to either forthcoming arm use or target location. In contrast, 60% of PMv neurons showed selectivity for target location only and not for arm use. These findings point to preference in the use of neuronal activity in the two areas: preparation for action in the PMd and preparation for target acquisition in the PMv.

Two functionally different synergies during arm reaching movements involving the trunk

1995 ◽  
Vol 73 (5) ◽  
pp. 2120-2122 ◽  
Author(s):  
S. Ma ◽  
A. G. Feldman
Keyword(s):  
Motor Control ◽  
Degrees Of Freedom ◽  
Arm Movements ◽  
The Other ◽  
Reaching Movements ◽  
Positional Error ◽  
Trunk Motion ◽  
Arm Reaching ◽  
Trunk Movements ◽  
The Right

1. To address the problem of the coordination of a redundant number of degrees of freedom in motor control, we analyzed the influence of voluntary trunk movements on the arm endpoint trajectory during reaching. 2. Subjects made fast noncorrected planar movements of the right arm from a near to a far target located in the ipsilateral work space at a 45 degrees angle to the sagittal midline of the trunk. These reaching movements were combined with a forward or a backward sagittal motion of the trunk. 3. The direction, positional error, curvature, and velocity profile of the endpoint trajectory remained invariant regardless of trunk movements. Trunk motion preceded endpoint motion by approximately 175 ms, continued during endpoint movement to the target, and outlasted it by 200 ms. This sequence of trunk and arm movements was observed regardless of the direction of the endpoint trajectory (to or from the far target) or trunk movements (forward or backward). 4. Our data imply that reaching movements result from two control synergies: one coordinates trunk and arm movements leaving the position of the endpoint unchanged, and the other produces interjoint coordination shifting the arm endpoint to the target. The use of functionally different synergies may underlie a solution of the redundancy problem.

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