Spatial Alignment of Rotational and Static Tilt Responses of Vestibulospinal Neurons in the Cat

1999 ◽  
Vol 82 (2) ◽  
pp. 855-862 ◽  
Author(s):  
S. I. Perlmutter ◽  
Y. Iwamoto ◽  
J. F. Baker ◽  
B. W. Peterson
Keyword(s):  
Horizontal Plane ◽  
Dimensional Space ◽  
Body Position ◽  
Three Dimensional ◽  
Whole Body ◽  
Angular Difference ◽  
Spatial Alignment ◽  
Minimum Sensitivity ◽  
Alert Cats ◽  
Vestibulospinal Neurons

The responses of vestibulospinal neurons to 0.5-Hz, whole-body rotations in three-dimensional space and static tilts of whole-body position were studied in decerebrate and alert cats. The neurons’ spatial properties for earth-vertical rotations were characterized by maximum and minimum sensitivity vectors ( R max and R min) in the cat’s horizontal plane. The orientation of a neuron’s R max was not consistently related to the orientation of its maximum sensitivity vector for static tilts ( T max). The angular difference between R max and T max was widely distributed between 0° and 150°, and R max and T max were aligned (i.e., within 45° of each other) for only 44% (14/32) of the neurons. The alignment of R max and T max was not correlated with the neuron’s sensitivity to earth-horizontal rotations, or to the orientation of R max in the horizontal plane. In addition, the extent to which a neuron exhibited spatiotemporal convergent (STC) behavior in response to vertical rotations was independent of the angular difference between R max and T max. This suggests that the high incidence of STC responses in our sample (56%) reflects not only canal-otolith convergence, but also the presence of static and dynamic otolith inputs with misaligned directionality. The responses of vestibulospinal neurons reflect a complex combination of static and dynamic vestibular inputs that may be required by postural reflexes that vary depending on head, trunk, and limb orientation, or on the frequency of stimulation.

Responses of Neurons in the Nucleus of the Basal Optic Root to Translational and Rotational Flowfields

1999 ◽  
Vol 81 (1) ◽  
pp. 267-276 ◽  
Author(s):  
Douglas R. W. Wylie ◽  
Barrie J. Frost
Keyword(s):  
Optic Flow ◽  
Horizontal Plane ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Vertical Axis ◽  
Mesencephalic Reticular Formation ◽  
Companion Paper ◽  
Direction Selectivity ◽  
Large Field ◽  
Adjacent Area

Wylie, Douglas R. W. and Barrie J. Frost. Responses of Neurons in the nucleus of the basal optic root to translational and rotational flowfields. J. Neurophysiol. 81: 267–276, 1999. The nucleus of the basal optic root (nBOR) receives direct input from the contralateral retina and is the first step in a pathway dedicated to the analysis of optic flowfields resulting from self-motion. Previous studies have shown that most nBOR neurons exhibit direction selectivity in response to large-field stimuli moving in the contralateral hemifield, but a subpopulation of nBOR neurons has binocular receptive fields. In this study, the activity of binocular nBOR neurons was recorded in anesthetized pigeons in response to panoramic translational and rotational optic flow. Translational optic flow was produced by the “translator” projector described in the companion paper, and rotational optic flow was produced by a “planetarium projector” described by Wylie and Frost. The axis of rotation or translation could be positioned to any orientation in three-dimensional space. We recorded from 37 cells, most of which exhibited a strong contralateral dominance. Most of these cells were located in the caudal and dorsal aspects of the nBOR complex and many were localized to the subnucleus nBOR dorsalis. Other units were located outside the boundaries of the nBOR complex in the adjacent area ventralis of Tsai or mesencephalic reticular formation. Six cells responded best to rotational flowfields, whereas 31 responded best to translational flowfields. Of the rotation cells, three preferred rotation about the vertical axis and three preferred horizontal axes. Of the translation cells, 3 responded best to a flowfield simulating downward translation of the bird along a vertical axis, whereas the remaining 28 responded best to flowfields resulting from translation along axes in the horizontal plane. Seventeen of these cells preferred a flowfield resulting from the animal translating backward along an axis oriented ∼45° to the midline, but the best axes of the remaining eleven cells were distributed throughout the horizontal plane with no definitive clustering. These data are compared with the responses of vestibulocerebellar Purkinje cells.

Dissociated Hysteresis of Static Ocular Counterroll in Humans

2006 ◽  
Vol 95 (4) ◽  
pp. 2222-2232 ◽  
Author(s):  
A. Palla ◽  
C. J. Bockisch ◽  
O. Bergamin ◽  
D. Straumann
Keyword(s):  
Second Harmonic ◽  
Human Subjects ◽  
Body Position ◽  
Three Dimensional ◽  
Upright Position ◽  
Whole Body ◽  
Eye Position ◽  
Healthy Human ◽  
Ocular Counterroll ◽  
Head Roll

In stationary head roll positions, the eyes are cyclodivergent. We asked whether this phenomenon can be explained by a static hysteresis that differs between the eyes contra- (CE) and ipsilateral (IE) to head roll. Using a motorized turntable, healthy human subjects ( n = 8) were continuously rotated about the earth-horizontal naso-occipital axis. Starting from the upright position, a total of three full rotations at a constant velocity (2°/s) were completed (acceleration = 0.05°/s2, velocity plateau reached after 40 s). Subjects directed their gaze on a flashing laser dot straight ahead (switched on 20 ms every 2 s). Binocular three-dimensional eye movements were recorded with dual search coils that were modified (wires exiting inferiorly) to minimize torsional artifacts by the eyelids. A sinusoidal function with a first and second harmonic was fitted to torsional eye position as a function of torsional whole body position at constant turntable velocity. The amplitude and phase of the first harmonic differed significantly between the two eyes (paired t-test: P < 0.05): on average, counterroll amplitude of IE was larger [CE: 6.6 ± 1.6° (SD); IE: 8.1 ± 1.7°), whereas CE showed more position lag relative to the turntable (CE: 12.5 ± 10.7°; IE: 5.1 ± 8.7°). We conclude that cyclodivergence observed during static ocular counterroll is mainly a result of hysteresis that depends on whether eyes are contra- or ipsilateral to head roll. Static hysteresis also explains the phenomenon of residual torsion, i.e., an incomplete torsional return of the eyes when the first 360° whole body rotation was completed and subjects were back in upright position (extorsion of CE: 2.0 ± 0.10°; intorsion of IE: 1.4 ± 0.10°). A computer model that includes asymmetric backlash for each eye can explain dissociated torsional hysteresis during quasi-static binocular counterroll. We hypothesize that ocular torsional hysteresis is introduced at the level of the otolith pathways because the direction-dependent torsional position lag of the eyes is related to the head roll position and not the eye position.

A 3D stable trot of a quadruped robot over uneven terrains

2016 ◽  
Vol 231 (3) ◽  
pp. 555-573 ◽  
Author(s):  
Mahdi Khorram ◽  
S Ali A Moosavian
Keyword(s):  
Degrees Of Freedom ◽  
Dimensional Space ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Quadruped Robot ◽  
Legged Robots ◽  
Whole Body ◽  
Main Body ◽  
Stable Gait ◽  
Three Dimensional Space

Legged robots have superior advantages rather than wheeled robots for moving over uneven terrains in the presence of various obstacles. The design of an appropriate path for the main body and legs is an important issue for such robots especially on the uneven terrains. In this paper, the focus is to develop a stable gait for a quadruped robot to trot on uneven terrains. First, a stability condition is developed for a whole-body quadruped robot over uneven terrains based on avoiding the tumbling. By using a simple model, a point with zero moments is calculated in the three-dimensional space. Then, the reference path of this point is determined so that the tumbling moments become zero. The path of the main body will be calculated by using an optimal controller. The main feature of the proposed gait generation framework is that the height of robot can change continuously and stably on uneven terrains. To evaluate the robot stability, the tumbling moments around diagonal lines are calculated and some methods are proposed to reduce these moments to improve the robot stability. The tip of swing foot is also planned to avoid any collision with the environment. The proposed method will be demonstrated using an 18-Degrees of freedom (DOF) quadruped robot in simulation and experimental studies. The experimental setup is a small-size quadruped robot, which is composed of a rectangular plate as its main body with four legs that each one has three active joints with DC servo motors. Obtained results reveal that the robot can trot on uneven terrains stably. Besides, the comparison with the previous methods approves the merits of proposed algorithm on uneven terrains.

scholarly journals Three-dimensional space: locomotory style explains memory differences in rats and hummingbirds

2014 ◽  
Vol 281 (1784) ◽  
pp. 20140301 ◽  
Author(s):  
I. Nuri Flores-Abreu ◽  
T. Andrew Hurly ◽  
James A. Ainge ◽  
Susan D. Healy
Keyword(s):  
Horizontal Plane ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Vertical Component ◽  
Horizontal Component ◽  
Vertical Dimension ◽  
Three Dimensions ◽  
Two Dimensional ◽  
With Memory ◽  
Three Dimensional Space

While most animals live in a three-dimensional world, they move through it to different extents depending on their mode of locomotion: terrestrial animals move vertically less than do swimming and flying animals. As nearly everything we know about how animals learn and remember locations in space comes from two-dimensional experiments in the horizontal plane, here we determined whether the use of three-dimensional space by a terrestrial and a flying animal was correlated with memory for a rewarded location. In the cubic mazes in which we trained and tested rats and hummingbirds, rats moved more vertically than horizontally, whereas hummingbirds moved equally in the three dimensions. Consistent with their movement preferences, rats were more accurate in relocating the horizontal component of a rewarded location than they were in the vertical component. Hummingbirds, however, were more accurate in the vertical dimension than they were in the horizontal, a result that cannot be explained by their use of space. Either as a result of evolution or ontogeny, it appears that birds and rats prioritize horizontal versus vertical components differently when they remember three-dimensional space.

scholarly journals An Analysis of Ocular Counterrolling in Response to Body Positions in Three-Dimensional Space

1992 ◽  
Vol 2 (3) ◽  
pp. 213-220 ◽  
Author(s):  
Urs J. Bucher ◽  
Fred Mast ◽  
Norbert Bischof
Keyword(s):  
Dimensional Space ◽  
Body Position ◽  
Three Dimensional ◽  
Normal Subjects ◽  
Roll Angle ◽  
Otolith Organs ◽  
Lateral Body ◽  
Pitch Direction ◽  
Periodic Characteristic ◽  
Ocular Counterrolling

Four normal subjects underwent ocular counterrolling testing in a tiltable chair. Measurements were taken in 62 different body positions in steps of 30∘ varied rolls and pitches. In each body position the eyes were recorded on video and their roll angle was determined automatically by computer analysis. The ocular counterrolling profile showed a periodic characteristic with maximal amplitude at roll tilts of 60∘. In this study we can clearly show that the eyes’ rolling response is not systematically affected when lateral body tilts are combined with any tilts in the pitch direction. This undoubtedly implies that the ocular counterrolling was mainly stimulated by the subject’s roll angle. As an empirical contribution, this study provides new data specially to be used in modelling and simulating the function of otolith organs.

scholarly journals Visually targeted reaching in horse-head grasshoppers

2012 ◽  
Vol 279 (1743) ◽  
pp. 3697-3705 ◽  
Author(s):  
Jeremy E. Niven ◽  
Swidbert R. Ott ◽  
Stephen M. Rogers
Keyword(s):  
High Speed ◽  
Visual Cues ◽  
Motion Parallax ◽  
Dimensional Space ◽  
Body Position ◽  
Motor Pattern ◽  
Three Dimensional ◽  
Visual Inputs ◽  
Sensorimotor Transformations ◽  
Specific Object

Visually targeted reaching to a specific object is a demanding neuronal task requiring the translation of the location of the object from a two-dimensionsal set of retinotopic coordinates to a motor pattern that guides a limb to that point in three-dimensional space. This sensorimotor transformation has been intensively studied in mammals, but was not previously thought to occur in animals with smaller nervous systems such as insects. We studied horse-head grasshoppers (Orthoptera: Proscopididae) crossing gaps and found that visual inputs are sufficient for them to target their forelimbs to a foothold on the opposite side of the gap. High-speed video analysis showed that these reaches were targeted accurately and directly to footholds at different locations within the visual field through changes in forelimb trajectory and body position, and did not involve stereotyped searching movements. The proscopids estimated distant locations using peering to generate motion parallax, a monocular distance cue, but appeared to use binocular visual cues to estimate the distance of nearby footholds. Following occlusion of regions of binocular overlap, the proscopids resorted to peering to target reaches even to nearby locations. Monocular cues were sufficient for accurate targeting of the ipsilateral but not the contralateral forelimb. Thus, proscopids are capable not only of the sensorimotor transformations necessary for visually targeted reaching with their forelimbs but also of flexibly using different visual cues to target reaches.

scholarly journals Electromechanical Catastrophe

2016 ◽  
Vol 08 (07) ◽  
pp. 1640005 ◽  
Author(s):  
Tongqing Lu ◽  
Sibo Cheng ◽  
Tiefeng Li ◽  
Tiejun Wang ◽  
Zhigang Suo
Keyword(s):  
Nonlinear System ◽  
Horizontal Plane ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Vertical Axis ◽  
Mechanical Force ◽  
The State ◽  
Constant Force ◽  
Constant Voltage ◽  
Three Dimensional Space

A transducer is a system that couples two loads. For example, an electromechanical transducer couples a mechanical force and an electrical voltage. A two-load, nonlinear system can exhibit rich behavior of bifurcation, which can be displayed in a three-dimensional space, with the horizontal plane representing the two loads, and the vertical axis representing the state of the system. In this three-dimensional space, a state of equilibrium at fixed loads corresponds to a point on a surface. The surface is smooth, but its projection to the load plane results in singularities of two types: fold and cusp. Here we identify the fold and cusp for a dielectric elastomer transducer by a combination of experiment and calculation. We conduct two kinds of experiment: electrical actuation under a constant force and mechanical pulling under a constant voltage. The theory and the experiment agree well. The fold and cusp are essential in the design of loading paths to avoid or harness the bifurcation.

scholarly journals Human Visuospatial Updating After Passive Translations in Three-Dimensional Space

2008 ◽  
Vol 99 (4) ◽  
pp. 1799-1809 ◽  
Author(s):  
Eliana M. Klier ◽  
Bernhard J. M. Hess ◽  
Dora E. Angelaki
Keyword(s):  
Dimensional Space ◽  
Three Dimensional ◽  
Motor Command ◽  
Body Motion ◽  
Whole Body ◽  
Fixed Target ◽  
Stable Representation ◽  
Vergence Movement ◽  
The Brain ◽  
Three Dimensional Space

To maintain a stable representation of the visual environment as we move, the brain must update the locations of targets in space using extra-retinal signals. Humans can accurately update after intervening active whole-body translations. But can they also update for passive translations (i.e., without efference copy signals of an outgoing motor command)? We asked six head-fixed subjects to remember the location of a briefly flashed target (five possible targets were located at depths of 23, 33, 43, 63, and 150 cm in front of the cyclopean eye) as they moved 10 cm left, right, up, down, forward, or backward while fixating a head-fixed target at 53 cm. After the movement, the subjects made a saccade to the remembered location of the flash with a combination of version and vergence eye movements. We computed an updating ratio where 0 indicates no updating and 1 indicates perfect updating. For lateral and vertical whole-body motion, where updating performance is judged by the size of the version movement, the updating ratios were similar for leftward and rightward translations, averaging 0.84 ± 0.28 (mean ± SD) as compared with 0.51 ± 0.33 for downward and 1.05 ± 0.50 for upward translations. For forward/backward movements, where updating performance is judged by the size of the vergence movement, the average updating ratio was 1.12 ± 0.45. Updating ratios tended to be larger for far targets than near targets, although both intra- and intersubject variabilities were smallest for near targets. Thus in addition to self-generated movements, extra-retinal signals involving otolith and proprioceptive cues can also be used for spatial constancy.

Three-Dimensional Analysis of the Men‘s 100-m Freestyle during the 1992 Olympic Games

1995 ◽  
Vol 11 (1) ◽  
pp. 103-112 ◽  
Author(s):  
Jane M. Cappaert ◽  
David L. Pease ◽  
John P. Troup
Keyword(s):  
Olympic Games ◽  
Body Position ◽  
Three Dimensional ◽  
Longitudinal Axis ◽  
The Body ◽  
Whole Body ◽  
Swimming Velocity ◽  
Body Roll ◽  
Symmetrical Body ◽  
Stroke Cycle

Twelve male 100-m freestyle swimmers were videotaped during the 1992 Olympic Games. Four cameras, two above water and two below, recorded the same stroke cycle of the swimmer at approximately the 40- to 45-m mark. The whole body and the recovering arms were digitized from the videotapes to recreate a complete stroke cycle. Body position variables and hand reaction forces (Schleihauf, 1979) were calculated. Swimmers were divided into elite and subelite groups based on their swimming velocity and were compared for differences in biomechanical variables. Elites used slightly lower hand forces while maintaining a higher propelling efficiency. Subelites had opposite rotations about the longitudinal axis of the body rather than symmetrical body roll. The elite swimmers were different from subelites in that their pulling patterns were more efficient and their body position was more streamlined. These variables assisted them in achieving faster swimming velocities without requiring higher propulsive forces.

Noncommutative Updating of Perceived Self-Orientation in Three Dimensions

2007 ◽  
Vol 97 (4) ◽  
pp. 2958-2964 ◽  
Author(s):  
Stefan Glasauer ◽  
Thomas Brandt
Keyword(s):  
Vestibular System ◽  
Horizontal Plane ◽  
Three Dimensional ◽  
Vertical Axis ◽  
Three Dimensions ◽  
Whole Body ◽  
The Earth ◽  
Angular Velocities ◽  
Velocity Information ◽  
Final Orientation

After whole body rotations around an earth-vertical axis in darkness, subjects can indicate their orientation in space with respect to their initial orientation reasonably well. This is possible because the brain is able to mathematically integrate self-velocity information provided by the vestibular system to obtain self-orientation, a process called path integration. For rotations around multiple axes, however, computations are more demanding to accurately update self-orientation with respect to space. In such a case, simple integration is no longer sufficient because of the noncommutativity of rotations. We investigated whether such updating is possible after three-dimensional whole body rotations and whether the noncommutativity of three-dimensional rotations is taken into account. The ability of ten subjects to indicate their spatial orientation in the earth-horizontal plane was tested after different rotational paths from upright to supine positions. Initial and final orientations of the subjects were the same in all cases, but the paths taken were different, and so were the angular velocities sensed by the vestibular system. The results show that seven of the ten subjects could consistently indicate their final orientation within the earth-horizontal plane. Thus perceived final orientation was independent of the path taken, i.e., the noncommutativity of rotations was taken into account.

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