Changes In Body Orientation Research Articles

Long-lasting pure topographical disorientation due to heading disorientation following left retrosplenial infarction: A report of two cases

Topographical disorientation is linked to lesions in the right hemisphere and typically resolves within a few months post-stroke. Persistent topographical disorientation is uncommon and frequently accompanied by impairments in visual memory, complicating the analysis of the underlying mechanisms. Herein, we report two cases of sustained pure topographical disorientation following cerebral hemorrhages in the left retrosplenial region. The patients exhibited disorientation in both familiar and unfamiliar settings, attributable to heading disorientation, a deficit in determining the directional relationship between one’s current position and a target location or external frames. The patients struggled with reconstructing large-scale spatial frameworks and integrating new egocentric and allocentric perspectives upon changes in body orientation. There were no landmark agnosia, egocentric disorientation, or anterograde disorientation. Although mild verbal memory deficits were observed, no other cognitive impairments, including visual memory deficits, were detected. Our findings imply that lesions confined to the left retrosplenial region can induce enduring heading disorientation and suggest a significant role for this area in processing and integrating spatial information necessary for large-scale navigation. Clarifying the features of topographical disorientation will significantly impact the therapeutic approaches, enhancing the quality of life for affected patients by restoring their independence and mobility.

Biomechanics of Insect Flight Stability and Perturbation Response.

Insects must fly in highly variable natural environments filled with gusts, vortices, and other transient aerodynamic phenomena that challenge flight stability. Furthermore, the aerodynamic forces that support insect flight are produced from rapidly oscillating wings of time-varying orientation and configuration. The instantaneous flight forces produced by these wings are large relative to the average forces supporting body weight. The magnitude of these forces and their time-varying direction add another challenge to flight stability, because even proportionally small asymmetries in timing or magnitude between the left and right wings may be sufficient to produce large changes in body orientation. However, these same large-magnitude oscillating forces also offer an opportunity for unexpected flight stability through nonlinear interactions between body orientation, body oscillation in response to time-varying inertial and aerodynamic forces, and the oscillating wings themselves. Understanding the emergent stability properties of flying insects is a crucial step toward understanding the requirements for evolution of flapping flight and decoding the role of sensory feedback in flight control. Here, we provide a brief review of insect flight stability, with some emphasis on stability effects brought about by oscillating wings, and present some preliminary experimental data probing some aspects of flight stability in free-flying insects.

Saccades and pivoting during positive mechanotaxis in larval zebrafish.

Many animals are drawn to prominent sensory cues. Larval zebrafish consistently show attraction to minute water motions (mWMs). This positive mechanotaxis involves scanning-like eye movements (EMs) and changes in body orientation (pivoting), which likely enhance sensory detection. Video analysis shows that EMs increase during mWMs and negatively correlate with locomotion. Both the strength of mWMs and rearing conditions influence EM frequency, with alterations occurring after mWM offset. Additionally, EMs often accompany pivoting. The quantitative data presented here will aid in further exploring the neural bases of visual responses and positive mechanotaxis.

Postural adjustments to self-triggered perturbations under conditions of changes in body orientation

We studied anticipatory and compensatory postural adjustments (APAs and CPAs) associated with self-triggered postural perturbations in conditions with changes in the initial body orientation. In particular, we were testing hypotheses on adjustments in the reciprocal and coactivation commands, role of proximal vs. distal muscles, and correlations between changes in indices of APAs and CPAs. Healthy young participants stood on a board with full support or reduced support area and held a standard load in the extended arms. They released the load in a self-paced manned with a standard small-amplitude arm movement. Electromyograms of 12 muscles were recorded and used to compute reciprocal and coactivation indices between three muscle pairs on both sides of the body. The subject’s body was oriented toward one of three targets: straight ahead, 60° to the left, and 60° to the right. Body orientation has stronger effects on proximal muscle pairs compared to distal muscles. It led to more consistent changes in the reciprocal command compared to the coactivation command. Indices of APAs and CPAs showed positive correlations across conditions. We conclude that the earlier suggested hierarchical relations between the reciprocal and coactivation command could be task-specific. Predominance of negative or positive correlations between APA and CPA indices could also be task-specific.

Three-dimensional unsupervised probabilistic pose reconstruction (3D-UPPER) for freely moving animals

A key step in understanding animal behaviour relies in the ability to quantify poses and movements. Methods to track body landmarks in 2D have made great progress over the last few years but accurate 3D reconstruction of freely moving animals still represents a challenge. To address this challenge here we develop the 3D-UPPER algorithm, which is fully automated, requires no a priori knowledge of the properties of the body and can also be applied to 2D data. We find that 3D-UPPER reduces by >10 fold the error in 3D reconstruction of mouse body during freely moving behaviour compared with the traditional triangulation of 2D data. To achieve that, 3D-UPPER performs an unsupervised estimation of a Statistical Shape Model (SSM) and uses this model to constrain the viable 3D coordinates. We show, by using simulated data, that our SSM estimator is robust even in datasets containing up to 50% of poses with outliers and/or missing data. In simulated and real data SSM estimation converges rapidly, capturing behaviourally relevant changes in body shape associated with exploratory behaviours (e.g. with rearing and changes in body orientation). Altogether 3D-UPPER represents a simple tool to minimise errors in 3D reconstruction while capturing meaningful behavioural parameters.

Tilt in Place Microscopy: a Simple, Low-Cost Solution to Image Neural Responses to Body Rotations.

Animals use information about gravity and other destabilizing forces to balance and navigate through their environment. Measuring how brains respond to these forces requires considerable technical knowledge and/or financial resources. We present a simple alternative-Tilt In Place Microscopy (TIPM), a low-cost and noninvasive way to measure neural activity following rapid changes in body orientation. Here, we used TIPM to study vestibulospinal neurons in larval zebrafish during and immediately after roll tilts. Vestibulospinal neurons responded with reliable increases in activity that varied as a function of ipsilateral tilt amplitude. TIPM differentiated tonic (i.e., sustained tilt) from phasic responses, revealing coarse topography of stimulus sensitivity in the lateral vestibular nucleus. Neuronal variability across repeated sessions was minor relative to trial-to-trial variability, allowing us to use TIPM for longitudinal studies of the same neurons across two developmental time points. There, we observed global increases in response strength and systematic changes in the neural representation of stimulus direction. Our data extend classical characterization of the body tilt representation by vestibulospinal neurons and establish the utility of TIPM to study the neural basis of balance, especially in developing animals.SIGNIFICANCE STATEMENT Vestibular sensation influences everything from navigation to interoception. Here, we detail a straightforward, validated, and nearly universal approach to image how the nervous system senses and responds to body tilts. We use our new method to replicate and expand on past findings of tilt sensing by a conserved population of spinal-projecting vestibular neurons. The simplicity and broad compatibility of our approach will democratize the study of the response of the brain to destabilization, particularly across development.

Modeling Players' Scanning Activity in Football.

The purpose of this study was to develop and test models of scanning activity in football. Gibson's ecological approach of visual perception and exploratory activity provided the theoretical framework for the models. The video-based data analysis consisted of 17 selected matches and 239 players of the Union of European Football Associations (UEFA) U17 and U19 European Championship 2018 and the UEFA U17 and U21 European Championship 2019. The results showed a positive relation between scanning frequency and successful passes, as well as changes in body orientation. Scanning frequency was also related to a player's appearances in national teams and to opponent pressure. Opponent pressure had a large effect on pass result and the player's body orientation. Previous research on the relation between scanning frequency and performance was extended by several contextual predictors. Future research should focus on gaining a deeper understanding of the relation between scanning frequency and further contextual variables related to scanning.

Beyond the Kármán gait: knifefish swimming in periodic and irregular vortex streets.

Neotropical freshwater fishes such as knifefishes are commonly faced with navigating intense and highly unsteady streams. However, our knowledge on locomotion in apteronotids comes from laminar flows, where the ribbon fin dominates over the pectoral fins or body bending. Here, we studied the 3D kinematics and swimming control of seven black ghost knifefish (Apteronotus albifrons) moving in laminar flows (flow speed U∞≈1-5 BL s-1) and in periodic vortex streets (U∞≈2-4 BL s-1). Two different cylinders (∼2 and ∼3 cm diameter) were used to generate the latter. Additionally, fish were exposed to an irregular wake produced by a free oscillating cylinder (∼2 cm diameter; U∞≈2 BL s-1). In laminar flows, knifefish mainly used their ribbon fin, with wave frequency, speed and acceleration increasing with U∞. In contrast, knifefish swimming behind a fixed cylinder increased the use of pectoral fins, which resulted in changes in body orientation that mimicked steady backward swimming. Meanwhile, individuals behind the oscillating cylinder presented a combination of body bending and ribbon and pectoral fin movements that counteract the out-of-phase yaw oscillations induced by the irregular shedding of vortices. We corroborated passive out-of-phase oscillations by placing a printed knifefish model just downstream of the moving cylinder, but when placed one cylinder diameter downstream, the model oscillated in phase. Thus, the wake left behind an oscillating body is more challenging than a periodic vortex shedding for an animal located downstream, which may have consequences on inter- and intra-specific interactions.

Physiological responses to gravity in an insect

Gravity is one of the most ubiquitous environmental effects on living systems: Cellular and organismal responses to gravity are of central importance to understanding the physiological function of organisms, especially eukaryotes. Gravity has been demonstrated to have strong effects on the closed cardiovascular systems of terrestrial vertebrates, with rapidly responding neural reflexes ensuring proper blood flow despite changes in posture. Invertebrates possess open circulatory systems, which could provide fewer mechanisms to restrict gravity effects on blood flow, suggesting that these species also experience effects of gravity on blood pressure and distribution. However, whether gravity affects the open circulatory systems of invertebrates is unknown, partly due to technical measurement issues associated with small body size. Here we used X-ray imaging, radio-tracing of hemolymph, and micropressure measurements in the American grasshopper, Schistocerca americana, to assess responses to body orientation. Our results show that during changes in body orientation, gravity causes large changes in blood and air distribution, and that body position affects ventilation rate. Remarkably, we also found that insects show similar heart rate responses to body position as vertebrates, and contrasting with the classic understanding of open circulatory systems, have flexible valving systems between thorax and abdomen that can separate pressures. Gravitational effects on invertebrate cardiovascular and respiratory systems are likely to be widely distributed among invertebrates and to have broad influence on morphological and physiological evolution.

Bioarchaeological Evidence for Social Maturation in the Mortuary Ritual of Ipiutak and Tigara Hunter-Gatherers: Lifespan Perspectives on the Emergence of Personhood at Point Hope, Alaska

Identity is a concept that shifts over the lifespan in association with relational interactions. This study documents and interprets the cultural systems influencing shifts in identity during maturation in hunter-gatherers from Point Hope, Alaska through archaeological mortuary practices. Grave goods, body position, body orientation, and burial depth (underground versus surface) were recorded for Ipiutak (1500–1100 BP) and Tigara (800–400 BP) cultures. Age was estimated using tooth formation. No age differences in burial depth were found, likely reflecting environmental constraints. Changes in body orientation, body position, and grave-good allocation were found between three and four years with another increase in grave-good allocation after age six. A larger age range of individuals without grave goods was found at Tigara. Changes in bodily orientation and position likely reflect beliefs surrounding the soul. The initial presence of animal implements may represent gifting of amulets, while increases in these items at later ages indicate continued maturation. Differences in the age ranges of individuals without animal implements between the two sites may reflect stronger delineations of social prestige at Ipiutak. These findings hint at the complex relational pathways associated with the formation of identity in prehistoric hunter-gatherer communities.

Influence of graviceptor stimulation initiated by off-vertical axis rotation on ventilation.

What is the central question of this study? It is known that respiration is affected by graviceptors, but it remains unclear to what extent labyrinthine and non-labyrinthine graviceptors are involved in this process. What is the main finding and its importance? Our results suggest that the modulation of respiration is not a result of a simple reflex arc, but that it involves a higher integration of different types of receptors with variable contributions of either type of graviceptor among subjects. It has been suggested that the otolith system is involved in the physiological response to changes in body orientation with respect to gravity. In studies on animals, an otolith-respiratory reflex has been observed, but data on humans are scarce and inconclusive, mainly because pure otolithic stimulation is difficult to produce in humans. To assess the otolithic-respiratory reflex in humans, we used an off-vertical axis rotation (OVAR) that produces periodic and pure stimulation of graviceptors. The inspiratory flow was measured during earth vertical axis rotation (EVAR, control conditions) and OVAR in 21 subjects. To distinguish the effects of the labyrinthine and non-labyrinthine graviceptors on ventilation, these measurements were repeated with two different static head positions: head turned leftward and rightward in yaw. The velocity of rotation was individually selected to match spontaneous breathing rate (mean 11.4cyclesmin-1 , 0.19Hz). Average ventilatory flow was higher in OVAR than in EVAR, as was tidal volume. In OVAR, the transition between inspiration and expiration occurred mainly in the forward pitch position. The phase of this transition in most subjects was driven mostly by the body position rather than by the head position, suggesting that respiratory modifications during OVAR mainly involved non-labyrinthine receptors. However, the study demonstrated a high intersubject variability both in the ability of OVAR to synchronize breathing and in the influence of labyrinthine stimulation. We conclude that the respiratory response to changes in orientation of the body with respect to the vertical involves labyrinthine and non-labyrinthine stimulation, with the gain of each signal varying individually.

Thermoregulatory behavior and orientation preference in bearded dragons

The regulation of body temperature is a critical function for animals. Although reliant on ambient temperature as a heat source, reptiles, and especially lizards, make use of multiple voluntary and involuntary behaviors to thermoregulate, including postural changes in body orientation, either toward or away from solar sources of heat. This thermal orientation may also result from a thermoregulatory drive to maintain precise control over cranial temperatures or a rostrally-driven sensory bias. The purpose of this work was to examine thermal orientation behavior in adult and neonatal bearded dragons (Pogona vitticeps), to ascertain its prevalence across different life stages within a laboratory situation and its interaction with behavioral thermoregulation. Both adult and neonatal bearded dragons were placed in a thermal gradient and allowed to voluntarily select temperatures for up to 8h to observe the presence and development of a thermoregulatory orientation preference. Both adult and neonatal dragons displayed a non-random orientation, preferring to face toward a heat source while achieving mean thermal preferences of ~ 33–34°C. Specifically, adult dragons were more likely to face a heat source when at cooler ambient temperatures and less likely at warmer temperatures, suggesting that orientation behavior counter-balances local selected temperatures but contributes to their thermoregulatory response. Neonates were also more likely to select cooler temperatures when facing a heat source, but required more experience before this orientation behavior emerged. Combined, these results demonstrate the importance of orientation to behavioral thermoregulation in multiple life stages of bearded dragons.

Multimodal quotation: Role shift practices in spoken narratives

This study investigates how speakers of American English use multimodal articulation when quoting characters in personal narratives. We use the concept of role shift, adapted from signed languages, where it refers to a device used to represent one or more characters with one or more bodily articulators, to describe multimodal role shift practices. In a regression analysis, four bodily articulators were found to predict the impression of a role shift: character intonation, character facial expressions, character viewpoint gestures, and changes in body orientation; gaze was not a significant predictor. Most of the 704 quotes in our data are accompanied by activation of two or three articulators (55.3%) and very few (2.6%) occur without any of the articulators we have annotated. The extent of multimodal articulation depends on the type of quoted utterance: quotations of actual, witnessed speech events tend to garner fewer articulators than constructed (‘fictive interaction’) quotations. These findings demonstrate that speakers, like signers, use a range of bodily articulators when they take on another's role in quotation and thus underpin the importance of investigating the systematic use of the visual modality in quotation and, more generally, in ordinary interaction.

Effect of body position on vocal tract acoustics: Acoustic pharyngometry and vowel formants

The anatomic basis and articulatory features of speech production are often studied with imaging studies that are typically acquired in the supine body position. It is important to determine if changes in body orientation to the gravitational field alter vocal tract dimensions and speech acoustics. The purpose of this study was to assess the effect of body position (upright versus supine) on (1) oral and pharyngeal measurements derived from acoustic pharyngometry and (2) acoustic measurements of fundamental frequency (F0) and the first four formant frequencies (F1-F4) for the quadrilateral point vowels. Data were obtained for 27 male and female participants, aged 17 to 35 yrs. Acoustic pharyngometry showed a statistically significant effect of body position on volumetric measurements, with smaller values in the supine than upright position, but no changes in length measurements. Acoustic analyses of vowels showed significantly larger values in the supine than upright position for the variables of F0, F3, and the Euclidean distance from the centroid to each corner vowel in the F1-F2-F3 space. Changes in body position affected measurements of vocal tract volume but not length. Body position also affected the aforementioned acoustic variables, but the main vowel formants were preserved.

The Function of the Alula in Avian Flight

The alula is a small structure located at the joint between the hand-wing and arm-wing of birds and is known to be used in slow flight with high angles of attack such as landing. It is assumed to function similarly to a leading-edge slat that increases lift and delays stall. However, in spite of its universal presence in flying birds and the wide acceptance of stall delay as its main function, how the alula delays the stall and aids the flight of birds remains unclear. Here, we investigated the function of alula on the aerodynamic performance of avian wings based on data from flight tasks and wind-tunnel experiments. With the alula, the birds performed steeper descending flights with greater changes in body orientation. Force measurements revealed that the alula increases the lift and often delays the stall. Digital particle image velocimetry showed that these effects are caused by the streamwise vortex, formed at the tip of the alula, that induces strong downwash and suppresses the flow separation over the wing surface. This is the first experimental evidence that the alula functions as a vortex generator that increases the lift force and enhances manoeuvrability in flights at high angles of attack.

Munch's SCREAM: A spontaneous movement by zebrafish larvae featuring strong abduction of both pectoral fins often associated with a sudden bend

Stereotyped movement of paired pectoral fins in zebrafish larvae could be considered a simple model with which to investigate the neural basis of behavior. Using a high-speed camera, we explored the repertoire of pectoral fin movements by naturally behaving larvae at 5–6 days post-fertilization. Previously, two types of fin movements were characterized in association with locomotion: ‘CRAWLing,’ an alternating fin movement associated with slow swimming, and ‘TUCKing,’ the adduction of both fins associated with fast swimming. We here describe a third mode of fin movement, which we call ‘Munch's SCREAM’, in which both pectoral fins were flipped anteriorly so that they reached the skin on the sides of the head, thus covering the otic vesicles. This behavior occurred spontaneously and was often associated with a slight regression or a sudden bending and change in body orientation. It could be also induced effectively in the agarose-embedded larvae by tactile stimulation on the skin around the eye and nose, some of which are associated with struggling, in which waves of bending propagate from the tail to the head. Larvae can still CRAWL and perform the SCREAM even when their forebrain and midbrain have been removed, suggesting that the neural circuits involved in the SCREAM are present in the hindbrain and/or spinal cord.

Mechanisms for acute corneal hydrops and perforation.

Acute corneal hydrops (ACH) and perforation in corneal thinning diseases are the consequences of exposure to distending intraocular pressure (IOP) forces that are in excess of corneal resistance to them. Apart from thinning, resistance to these forces may be reduced by disease-related tissue changes, such as corneal scarring, which could lower resistance to IOP. Eye rubbing trauma has sometimes been found to be associated with ACH and perforation. This association is not surprising given that the combination of rubbing-related mechanical tissue trauma and the associated increased distending stress of higher IOP seem likely to increase the risk of complications. Many cases of ACH and perforation are described as spontaneous, but this classification may be the consequence of not considering the multiple potential mechanisms for IOP elevation such as coughing, sneezing, nose blowing, and sneeze suppression in addition to those related to eye rubbing/wiping/massaging/touching as well as changes in body orientation, strenuous exercise, and wearing swimming goggles for example. Classification of ACH or perforation as spontaneous may lead patients to assume that nothing can be done to avoid these complications. Patients with corneal thinning diseases who are counseled regarding the potential precipitating mechanisms for IOP elevation will have the opportunity of reducing exposure to them and the risk of the associated complications. In addition, when ACH or perforation occur, faster resolution of edema and wound healing may depend on reducing potentially exacerbating exposures to mechanisms for IOP elevation.

Is spinal excitability of the triceps surae mainly affected by muscle activity or body position?

The aim of this study was to determine how muscle activity and body orientation contribute to the triceps surae spinal transmission modulation, when moving from a sitting to a standing position. Maximal Hoffmann-reflex (Hmax) and motor potential (Mmax) were evoked in the soleus (SOL), medial and lateral gastrocnemius in 10 male subjects and in three conditions, passive sitting, active sitting and upright standing, with the same SOL activity in active sitting and upright standing. Moreover volitional wave (V) was evoked in the two active conditions (i.e., active sitting and upright standing). The results showed that SOL Hmax/Mmax was lower in active sitting than in passive sitting, while for the gastrocnemii it was not significantly altered. For the three plantar flexors, Hmax/Mmax was lower in upright standing than in active sitting, whereas V/Mmax was not modulated. SOL H-reflex is therefore affected by the increase in muscle activity and change in body orientation, while, in the gastrocnemii, it was only affected by a change in posture. In conclusion, passing from a sitting to a standing position affects the Hmax/Mmax of the whole triceps surae, but the mechanisms responsible for this change differ among the synergist muscles. The V/Mmax does not change when upright stance is assumed. This means that the increased inhibitory activity in orthostatic position is compensated by an increased excitatory inflow to the α-motoneurons of central and/or peripheral origin.

Joint kinematics and kinetics of overground accelerated running versus running on an accelerated treadmill

Literature shows that running on an accelerated motorized treadmill is mechanically different from accelerated running overground. Overground, the subject has to enlarge the net anterior-posterior force impulse proportional to acceleration in order to overcome linear whole body inertia, whereas on a treadmill, this force impulse remains zero, regardless of belt acceleration. Therefore, it can be expected that changes in kinematics and joint kinetics of the human body also are proportional to acceleration overground, whereas no changes according to belt acceleration are expected on a treadmill. This study documents kinematics and joint kinetics of accelerated running overground and running on an accelerated motorized treadmill belt for 10 young healthy subjects. When accelerating overground, ground reaction forces are characterized by less braking and more propulsion, generating a more forward-oriented ground reaction force vector and a more forwardly inclined body compared with steady-state running. This change in body orientation as such is partly responsible for the changed force direction. Besides this, more pronounced hip and knee flexion at initial contact, a larger hip extension velocity, smaller knee flexion velocity and smaller initial plantarflexion velocity are associated with less braking. A larger knee extension and plantarflexion velocity result in larger propulsion. Altogether, during stance, joint moments are not significantly influenced by acceleration overground. Therefore, we suggest that the overall behaviour of the musculoskeletal system (in terms of kinematics and joint moments) during acceleration at a certain speed remains essentially identical to steady-state running at the same speed, yet acting in a different orientation. However, because acceleration implies extra mechanical work to increase the running speed, muscular effort done (in terms of power output) must be larger. This is confirmed by larger joint power generation at the level of the hip and lower power absorption at the knee as the result of subtle differences in joint velocity. On a treadmill, ground reaction forces are not influenced by acceleration and, compared with overground, virtually no kinesiological adaptations to an accelerating belt are observed. Consequently, adaptations to acceleration during running differ from treadmill to overground and should be studied in the condition of interest.

Dynamic transformation of vestibular signals for orientation

The same pattern of vestibular afferent feedback may signify a loss of balance or a change in body orientation, depending upon the initial head posture. To resolve this ambiguity and generate an appropriate motor response, the CNS must transform vestibular information from a head-centred reference frame into relevant motor coordinates. But what if the reference frame is continuously moving? Here, we ask if this neural transformation process is continuously updated during a voluntary change in head posture. Galvanic vestibular stimulation (GVS) was used to induce a sensation of head roll motion in blindfolded subjects marching on the spot. When head orientation was fixed, this caused unconscious turning behaviour that was maximal during neck flexion, minimal with the head level and reversed direction with neck extension. Subjects were then asked to produce a continuous voluntary change in head pitch, while GVS was applied. As the neck moved from full flexion into extension, turn velocity was continuously modulated and even reversed direction, reflecting the pattern observed during the head-fixed condition. Hence, an identical vestibular input resulted in motor output which was dynamically modulated by changes in head pitch. However, response magnitude was significantly reduced, suggesting possible suppression of vestibular input during voluntary head movement. Nevertheless, these results show that the CNS continuously reinterprets vestibular exafference to account for ongoing voluntary changes in head posture. This may explain why the head can be moved freely without losing the sense of balance and orientation.