Body and gaze centered coding of touch locations during a dynamic task

2012 ◽  
Vol 25 (0) ◽  
pp. 195
Author(s):  
Lisa M. Pritchett ◽  
Michael J. Carnevale ◽  
Laurence R. Harris
Keyword(s):  
Reference Frame ◽  
Opposite Direction ◽  
Head Position ◽  
Head Orientation ◽  
Computer Screen ◽  
Dynamic Conditions ◽  
Dynamic Task ◽  
Visual Scale ◽  
The Subject

We have previously reported that head position affects the perceived location of touch differently depending on the dynamics of the task the subject is involved in. When touch was delivered and responses were made with head rotated touch location shifted in the opposite direction to the head position, consistent with body-centered coding. When touch was delivered with head rotated but response was made with head centered touch shifted in the same direction as the head, consistent with gaze-centered coding. Here we tested whether moving the head in-between touch and response would modulate the effects of head position on touch location. Each trial consisted of three periods, in the first arrows and LEDs guided the subject to a randomly chosen head orientation (90° left, right, or center) and a vibration stimulus was delivered. Next, they were either guided to turn their head or to remain in the same location. In the final period they again were guided to turn or to remain in the same location before reporting the perceived location of the touch on a visual scale using a mouse and computer screen. Reported touch location was shifted in the opposite direction of head orientation during touch presentation regardless of the orientation during response or whether a movement was made before the response. The size of the effect was much reduced compared to our previous results. These results are consistent with touch location being coded in both a gaze centered and body centered reference frame during dynamic conditions.

scholarly journals A New Horizontal Plane of the Head

2018 ◽  
Vol 6 (5) ◽  
pp. 767-771 ◽  
Author(s):  
Ehab El Kattan ◽  
Mohamed El Kattan ◽  
Omnia A. Elhiny
Keyword(s):  
Soft Tissue ◽  
Horizontal Plane ◽  
Head Position ◽  
The Other ◽  
Reference Plane ◽  
Head Orientation ◽  
Mean Values ◽  
The Subject ◽  
Frankfurt Horizontal ◽  
Frankfort Horizontal Plane

AIM: This study aimed to attempt to introduce a new extracranial horizontal plane of the head (K plane that extends from SN to SAE bilaterally) that could act as a substitute to the Frankfurt horizontal intracranial reference plane; both clinically and radiographically.MATERIAL AND METHODS: The new K plane depended on three points of the head. The first was the soft tissue nasion (NS) on the interpupillary line when the subject looked forward at a distant point at eye level. The other two points were the superior attachments of the ears (SAE).RESULTS: The student “t” test comparing mean values of K/V and FH/V was not significant; -0.21.  The coefficient of correlation between different variables was highly positively significant (r = 0.98 with probability = 0.001).CONCLUSION: Within the limitations of this prospective study, the new K plane was found to be both reliable and reproducible. It can be used as a reliable reference plane instead of Frankfort horizontal plane both clinically and radiographically; as it is an accurate tool for head orientation in the natural head position.

scholarly journals Cartesian Control of Sit-to-Stand Motion Using Head Position Feedback

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Samina Rafique ◽  
M. Najam-ul-Islam ◽  
M. Shafique ◽  
A. Mahmood
Keyword(s):  
Well Being ◽  
Human Motion ◽  
Head Position ◽  
Head Orientation ◽  
Motor Execution ◽  
Modeling Framework ◽  
Task Control ◽  
Low Level ◽  
Sit To Stand ◽  
High Level

Sit-to-stand (STS) motion is an indicator of an individual’s physical independence and well-being. Determination of various variables that contribute to the execution and control of STS motion is an active area of research. In this study, we evaluate the clinical hypothesis that besides numerous other factors, the central nervous system (CNS) controls STS motion by tracking a prelearned head position trajectory. Motivated by the evidence for a task-oriented encoding of motion by the CNS, we adopt a robotic approach for the synthesis of STS motion and propose this scheme as a solution to this hypothesis. We propose an analytical biomechanical human CNS modeling framework where the head position trajectory defines the high-level task control variable. The motion control is divided into low-level task generation and motor execution phases. We model CNS as STS controller and its Estimator subsystem plans joint trajectories to perform the low-level task. The motor execution is done through the Cartesian controller subsystem that generates torque commands to the joints. We do extensive motion and force capture experiments on human subjects to validate our analytical modeling scheme. We first scale our biomechanical model to match the anthropometry of the subjects. We do dynamic motion reconstruction through the control of simulated custom human CNS models to follow the captured head position trajectories in real time. We perform kinematic and kinetic analyses and comparison of experimental and simulated motions. For head position trajectories, root mean square (RMS) errors are 0.0118 m in horizontal and 0.0315 m in vertical directions. Errors in angle estimates are 0.55 rad, 0.93 rad, 0.59 rad, and 0.0442 rad for ankle, knee, hip, and head orientation, respectively. RMS error of ground reaction force (GRF) is 50.26 N, and the correlation between ground reaction torque and the support moment is 0.72. Low errors in our results validate (1) the reliability of motion/force capture methods and anthropometric technique for customization of human models and (2) high-level task control framework and human CNS modeling as a solution to the hypothesis. Accurate modeling and detailed understanding of human motion can have significant scope in the fields of rehabilitation, humanoid robotics, and virtual characters’ motion planning based on high-level task control schemes.

scholarly journals Transformation of vestibular signals for the decisions of hand choice during whole body motion

2019 ◽  
Vol 121 (6) ◽  
pp. 2392-2400 ◽  
Author(s):  
Romy S. Bakker ◽  
Luc P. J. Selen ◽  
W. Pieter Medendorp
Keyword(s):  
Reference Frame ◽  
Early Stage ◽  
Hand Preference ◽  
The Body ◽  
Body Motion ◽  
Whole Body ◽  
Head Orientation ◽  
Inertial Acceleration ◽  
Reach Planning ◽  
The Brain

In daily life, we frequently reach toward objects while our body is in motion. We have recently shown that body accelerations influence the decision of which hand to use for the reach, possibly by modulating the body-centered computations of the expected reach costs. However, head orientation relative to the body was not manipulated, and hence it remains unclear whether vestibular signals contribute in their head-based sensory frame or in a transformed body-centered reference frame to these cost calculations. To test this, subjects performed a preferential reaching task to targets at various directions while they were sinusoidally translated along the lateral body axis, with their head either aligned with the body (straight ahead) or rotated 18° to the left. As a measure of hand preference, we determined the target direction that resulted in equiprobable right/left-hand choices. Results show that head orientation affects this balanced target angle when the body is stationary but does not further modulate hand preference when the body is in motion. Furthermore, reaction and movement times were larger for reaches to the balanced target angle, resembling a competitive selection process, and were modulated by head orientation when the body was stationary. During body translation, reaction and movement times depended on the phase of the motion, but this phase-dependent modulation had no interaction with head orientation. We conclude that the brain transforms vestibular signals to body-centered coordinates at the early stage of reach planning, when the decision of hand choice is computed. NEW & NOTEWORTHY The brain takes inertial acceleration into account in computing the anticipated biomechanical costs that guide hand selection during whole body motion. Whereas these costs are defined in a body-centered, muscle-based reference frame, the otoliths detect the inertial acceleration in head-centered coordinates. By systematically manipulating head position relative to the body, we show that the brain transforms otolith signals into body-centered coordinates at an early stage of reach planning, i.e., before the decision of hand choice is computed.

scholarly journals The morphology of Trypanosoma simiæ , sp. nov

1912 ◽  
Vol 85 (581) ◽  
pp. 477-481 ◽  
Keyword(s):  
Opposite Direction ◽  
Guinea Pigs ◽  
Short Distance ◽  
Average Duration ◽  
Glossina Morsitans ◽  
Single Cage ◽  
White Rats ◽  
Future Paper ◽  
The Subject

This species of trypanosome, which does not seem to have been described before, is remarkable in that it attacks only such widely different animals as the monkey and the goat. Oxen, baboons, dogs, guinea-pigs, and white rats appear to be immune. The rapidity with which it kills monkeys is very striking. In a series of 19 the average duration of life after the trypanosomes were first seen in the blood was only 2·9 days. Its action on animals, its reservoir, its carrier, and cultivation, have not been fully worked out, and will form the subject of a future paper. In regard to its carrier, it may be stated that in this district it is Glossina morsitans , and that scarcely a single cage of flies is brought to Kasu Hill from the neighbouring “fly-country” but is found to be infected with this trypanosome. A. Living, Unstained . Trypanosoma simiœ shows active translatory movements when alive: some individuals pass completely across the field of the microscope. Apparently the usual mode of progression is flagellum first, but occasionally an individual can be seen to move a short distance in the opposite direction.

Effect of Head Orientation on the Diagnostic Sensitivity of Posturography in Patients with Compensated Unilateral Lesions

1992 ◽  
Vol 106 (4) ◽  
pp. 355-362 ◽  
Author(s):  
Kamran Barin ◽  
Curtis M. Seitz ◽  
D. Bradley Welling
Keyword(s):  
Postural Sway ◽  
Head Position ◽  
Diagnostic Sensitivity ◽  
Test Sequence ◽  
Order Effects ◽  
Head Orientation ◽  
Additional Information ◽  
Head Extension ◽  
The Difference ◽  
Unilateral Vestibulopathy

Patients with compensated unilateral vestibular lesions often have no detectable abnormality on conventional posturography. The purpose of this study was to determine whether a change in head orientation could improve the diagnostic sensitivity of the test for these patients. Twenty-four patients with known unilateral vestibulopathy and twenty-four normal controls were tested on the EqulTest apparatus in four head positions: head centered, head tilted right, head tilted left, and head extended. The sensory organization test was performed for each head position, using a single trial for each sensory condition. The test sequence was randomized to account for simple order effects. The subject's equilibrium was quantified by a performance index and a composite score of all sensory conditions was calculated for each head position. Patients with unilateral vestibulopathy had more postural sway with the head tilted contralateral to the side of lesion. The difference between the mean composite scores for ipsilateral and contralateral head tilts was statistically significant ( p < 0.05). When individual trials were compared, equilibrium scores were significantly different only for sensory conditions that required vestibular input. Head extension increased postural sway in both patients and controls. Equilibrium scores were significantly different for all sensory conditions in which the support was sway-referenced. We suggest that the results of head extension in patients are similar to those found in normal individuals. However, equilibrium scores for right-left head flits are sensitive to the side of lesion and can provide additional information for patients with unilateral vestibulopathy.

scholarly journals Human head orientation and eye visibility as indicators of attention for goats (Capra hircus)

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3073 ◽  
Author(s):  
Christian Nawroth ◽  
Alan G. McElligott
Keyword(s):  
Food Reward ◽  
Human Head ◽  
Capra Hircus ◽  
Head Orientation ◽  
Choice Behaviour ◽  
Test Arena ◽  
The Third ◽  
Probe Test ◽  
The Subject

Animals domesticated for working closely with humans (e.g. dogs) have been shown to be remarkable in adjusting their behaviour to human attentional stance. However, there is little evidence for this form of information perception in species domesticated for production rather than companionship. We tested domestic ungulates (goats) for their ability to differentiate attentional states of humans. In the first experiment, we investigated the effect of body and head orientation of one human experimenter on approach behaviour by goats. Test subjects (N = 24) significantly changed their behaviour when the experimenter turned its back to the subjects, but did not take into account head orientation alone. In the second experiment, goats (N = 24) could choose to approach one of two experimenters, while only one was paying attention to them. Goats preferred to approach humans that oriented their body and head towards the subject, whereas head orientation alone had no effect on choice behaviour. In the third experiment, goats (N = 32) were transferred to a separate test arena and were rewarded for approaching two experimenters providing a food reward during training trials. In subsequent probe test trials, goats had to choose between the two experimenters differing in their attentional states. Like in Experiments 1 and 2, goats did not show a preference for the attentive person when the inattentive person turned her head away from the subject. In this last experiment, goats preferred to approach the attentive person compared to a person who closed their eyes or covered the whole face with a blind. However, goats showed no preference when one person covered only the eyes. Our results show that animals bred for production rather than companionship show differences in their approach and choice behaviour depending on human attentive state. However, our results contrast with previous findings regarding the use of the head orientation to attribute attention and show the importance of cross-validating results.

scholarly journals The Use of Egocentric and Allocentric Reference Frames in Static and Dynamic Conditions in Humans

2020 ◽  
pp. 787-801
Author(s):  
S MORARESKU ◽  
K VLCEK
Keyword(s):  
Reference Frame ◽  
Reference Frames ◽  
Spatial Navigation ◽  
Three Dimensional ◽  
Neural Correlates ◽  
Two Dimensional ◽  
Spatial Coding ◽  
Dynamic Conditions ◽  
Spatial Reference Frames ◽  
Static Conditions

The dissociation between egocentric and allocentric reference frames is well established. Spatial coding relative to oneself has been associated with a brain network distinct from spatial coding using a cognitive map independently of the actual position. These differences were, however, revealed by a variety of tasks from both static conditions, using a series of images, and dynamic conditions, using movements through space. We aimed to clarify how these paradigms correspond to each other concerning the neural correlates of the use of egocentric and allocentric reference frames. We review here studies of allocentric and egocentric judgments used in static two- and three-dimensional tasks and compare their results with the findings from spatial navigation studies. We argue that neural correlates of allocentric coding in static conditions but using complex three-dimensional scenes and involving spatial memory of participants resemble those in spatial navigation studies, while allocentric representations in two-dimensional tasks are connected with other perceptual and attentional processes. In contrast, the brain networks associated with the egocentric reference frame in static two-dimensional and three-dimensional tasks and spatial navigation tasks are, with some limitations, more similar. Our review demonstrates the heterogeneity of experimental designs focused on spatial reference frames. At the same time, it indicates similarities in brain activation during reference frame use despite this heterogeneity.

Gravity-Specific Adaptation of the Angular Vestibuloocular Reflex: Dependence on Head Orientation With Regard to Gravity

2003 ◽  
Vol 89 (1) ◽  
pp. 571-586 ◽  
Author(s):  
Sergei B. Yakushin ◽  
Theodore Raphan ◽  
Bernard Cohen
Keyword(s):  
Head Tilt ◽  
Vertical Axis ◽  
Continuous Functions ◽  
Head Position ◽  
Head Orientation ◽  
Vestibuloocular Reflex ◽  
Specific Adaptation ◽  
Gain Adaptation ◽  
Bias Level ◽  
Single State

The gain of the vertical angular vestibuloocular reflex (aVOR) was adaptively altered by visual-vestibular mismatch during rotation about an interaural axis, using steps of velocity in three head orientations: upright, left-side down, and right-side down. Gains were decreased by rotating the animal and visual surround in the same direction and increased by visual and surround rotation in opposite directions. Gains were adapted in one head position (single-state adaptation) or decreased with one side down and increased with the other side down (dual-state adaptation). Animals were tested in darkness using sinusoidal rotation at 0.5 Hz about an interaural axis that was tilted from horizontal to vertical. They were also sinusoidally oscillated from 0.5 to 4 Hz about a spatial vertical axis in static tilt positions from yaw to pitch. After both single- and dual-state adaptation, gain changes were maximal when the monkeys were in the position in which the gain had been adapted, and the gain changes progressively declined as the head was tilted away from that position. We call this gravity-specific aVOR gain adaptation. The spatial distribution of the specific aVOR gain changes could be represented by a cosine function that was superimposed on a bias level, which we called gravity-independent gain adaptation. Maximal gravity-specific gain changes were produced by 2–4 h of adaptation for both single- and dual-state adaptations, and changes in gain were similar at all test frequencies. When adapted while upright, the magnitude and distribution of the gravity-specific adaptation was comparable to that when animals were adapted in side-down positions. Single-state adaptation also produced gain changes that were independent of head position re gravity particularly in association with gain reduction. There was no bias after dual-state adaptation. With this difference, fits to data obtained by altering the gain in separate sessions predicted the modulations in gain obtained from dual-state adaptations. These data show that the vertical aVOR gain changes dependent on head position with regard to gravity are continuous functions of head tilt, whose spatial phase depends on the position in which the gain was adapted. From their different characteristics, it is likely that gravity-specific and gravity-independent adaptive changes in gain are produced by separate neural processes. These data demonstrate that head orientation to gravity plays an important role in both orienting and tuning the gain of the vertical aVOR.

Cooperation and Altruism

2001 ◽  
Author(s):  
David Sloan Wilson
Keyword(s):  
Natural Selection ◽  
Evolutionary Theory ◽  
Opposite Direction ◽  
Social Adaptation ◽  
Herbivore Damage ◽  
Individual Level ◽  
Cryptic Coloration ◽  
The Subject ◽  
The Individual ◽  
Shed Light

People have always been fascinated by cooperation and altruism in animals, in part to shed light on our own propensity or reluctance to help others. Darwin’s theory added a certain urgency to the subject because the principle of “nature red in tooth and claw” superficially seems to deny the possibility of altruism and cooperation altogether. Some evolutionary biologists have accepted and even reveled in this vision of nature, giving rise to statements such as “the economy of nature is competitive from beginning to end . . . scratch an ‘altruist’ and watch a hypocrite bleed”. Others have gone so far in the opposite direction as to proclaim the entire earth a unit that cooperatively regulates its own atmosphere (Lovelock 1979). The truth is somewhere between these two extremes; cooperation and altruism can evolve but only if special conditions are met. As might be expected from the polarized views outlined above, achieving this middle ground has been a difficult process. Science is often portrayed as a heroic march to the truth, but in this case, it is more like the Three Stooges trying to move a piano. I don’t mean to underestimate the progress that been made—the piano has been moved—but we need to appreciate the twists, turns, and reversals in addition to the final location. To see why cooperation and altruism pose a problem for evolutionary theory, consider the evolution of a nonsocial adaptation, such as cryptic coloration. Imagine a population of moths that vary in the degree to which they match their background. Every generation, the most conspicuous moths are detected and eaten by predators while the most cryptic moths survive and reproduce. If offspring resemble their parents, then the average moth will become more cryptic with every generation. Anyone who has beheld a moth that looks exactly like a leaf, right down to the veins and simulated herbivore damage, cannot fail to be impressed by the power of natural selection to evolve breathtaking adaptations at the individual level. Now consider the same process for a social adaptation, such as members of a group warning each other about approaching predators.

Vertical nystagmus in normal subjects: Effects of head position, nicotine and scopolamine

2000 ◽  
Vol 10 (6) ◽  
pp. 291-300
Author(s):  
J.I. Kim ◽  
J.T. Somers ◽  
J.S. Stahl ◽  
R. Bhidayasiri ◽  
R.J. Leigh
Keyword(s):  
Nicotine Patch ◽  
Head Rotation ◽  
Normal Subjects ◽  
Head Position ◽  
Slow Phase ◽  
Head Orientation ◽  
Slow Phase Velocity ◽  
Gaze Stability ◽  
Normal Humans ◽  
Vertical Nystagmus

We measured gaze stability in darkness of four normal humans using the search coil technique. Subjects were tested first with their heads erect, and then with their heads positioned 180 degrees upside-down. In each position, subjects held their head stationary for one minute, and then actively performed pitch rotations for 20 sec. All subjects showed sustained chin-beating nystagmus in the upside-down position. Each subject showed a significant increase of slow-phase velocity directed towards their brow after 40 sec in the inverted versus erect position. Pitch head rotation had little effect on subsequent nystagmus, except for transient reversal in one subject. The sustained changes of vertical eye drifts induced by 180 deg change of head position suggest that otolithic factors may contribute to vertical nystagmus in normals. The subjects were retested after wearing a nicotine patch for 2 hours. In three subjects, nicotine induced brow-beating nystagmus; adopting a head-hanging position increased this nystagmus in two subjects. In a third session, subjects were tested after wearing a scopolamine patch for 2 hours; results were generally similar to the control condition. We conclude that normal subjects may show chin-beating (“downbeating”) nystagmus in a head-hanging position in darkness, reflecting a normal, physiological change in otolithic inputs brought about by the head orientation.

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