scholarly journals The illusion of having a large virtual body biases action-specific perception in patients with mild cognitive impairment

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hokyoung Ryu ◽  
Kyoungwon Seo
Keyword(s):  
Large Body ◽  
The Body ◽  
Body Ownership ◽  
Immersive Virtual Reality ◽  
Healthy Controls ◽  
Discriminative Power ◽  
Virtual Reality Environment ◽  
Healthy Older Adults ◽  
Action Capability ◽  
Neurological Patients

AbstractThe illusion of having a large body makes us perceive objects as smaller than they really are. This action-specific perception effect occurs because we perceive the property of an object (i.e., size) differently according to our unique action capability (i.e., the affordance of body size). Although the body-ownership illusion contributing to this action-specific perception has been studied, its effects remain unclear in neurological patients. We examined the action-specific perception impairments of MCI patients by means of body-ownership illusion in a non-immersive virtual reality environment. Twenty healthy young adults, 21 healthy older adults, and 15 MCI patients were recruited. We assessed their “original-body action-specific perception” and “enlarged-body action-specific perception” using the original and enlarged sizes of their virtual bodies, respectively. The MCI patients’ original-body action-specific perception was no different than that of the healthy controls (p = 0.679). However, the enlarged-body action-specific perception of the MCI patients was significantly biased (p < 0.001). The inclusion of the enlarged-body action-specific perception provides additional discriminative power for early diagnosis of MCI (89.3% accuracy, 75.0% sensitivity, 100.0% specificity, and 87.5% balanced accuracy).

Chaos in body–vortex interactions

2010 ◽  
Vol 466 (2119) ◽  
pp. 1871-1891 ◽  
Author(s):  
Johan Roenby ◽  
Hassan Aref
Keyword(s):  
Body Shape ◽  
Mass Density ◽  
Relative Equilibrium ◽  
Large Body ◽  
Point Vortex ◽  
Cylindrical Body ◽  
The Body ◽  
Body Motion ◽  
Single Vortex ◽  
Vortex Interactions

The model of body–vortex interactions, where the fluid flow is planar, ideal and unbounded, and the vortex is a point vortex, is studied. The body may have a constant circulation around it. The governing equations for the general case of a freely moving body of arbitrary shape and mass density and an arbitrary number of point vortices are presented. The case of a body and a single vortex is then investigated numerically in detail. In this paper, the body is a homogeneous, elliptical cylinder. For large body–vortex separations, the system behaves much like a vortex pair regardless of body shape. The case of a circle is integrable. As the body is made slightly elliptic, a chaotic region grows from an unstable relative equilibrium of the circle-vortex case. The case of a cylindrical body of any shape moving in fluid otherwise at rest is also integrable. A second transition to chaos arises from the limit between rocking and tumbling motion of the body known in this case. In both instances, the chaos may be detected both in the body motion and in the vortex motion. The effect of increasing body mass at a fixed body shape is to damp the chaos.

scholarly journals Kinematic of the Position and Orientation Synchronization of the Posture of a n DoF Upper-Limb Exoskeleton with a Virtual Object in an Immersive Virtual Reality Environment

Electronics ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1069
Author(s):  
Deyby Huamanchahua ◽  
Adriana Vargas-Martinez ◽  
Ricardo Ramirez-Mendoza
Keyword(s):  
Virtual Reality ◽  
Upper Limb ◽  
Human Performance ◽  
Early Stage ◽  
Inverse Kinematic ◽  
Virtual Object ◽  
Immersive Virtual Reality ◽  
Virtual Reality Environment ◽  
Upper Limb Exoskeleton ◽  
Position And Orientation

Exoskeletons are an external structural mechanism with joints and links that work in tandem with the user, which increases, reinforces, or restores human performance. Virtual Reality can be used to produce environments, in which the intensity of practice and feedback on performance can be manipulated to provide tailored motor training. Will it be possible to combine both technologies and have them synchronized to reach better performance? This paper consists of the kinematics analysis for the position and orientation synchronization between an n DoF upper-limb exoskeleton pose and a projected object in an immersive virtual reality environment using a VR headset. To achieve this goal, the exoskeletal mechanism is analyzed using Euler angles and the Pieper technique to obtain the equations that lead to its orientation, forward, and inverse kinematic models. This paper extends the author’s previous work by using an early stage upper-limb exoskeleton prototype for the synchronization process.

scholarly journals Experiential ownership and body ownership are different phenomena

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Caleb Liang ◽  
Wen-Hsiang Lin ◽  
Tai-Yuan Chang ◽  
Chi-Hong Chen ◽  
Chen-Wei Wu ◽  
...  
Keyword(s):  
Conscious Experience ◽  
Distinct Type ◽  
Body Part ◽  
The Body ◽  
Body Ownership ◽  
Rubber Hand ◽  
Person Perspective ◽  
The One ◽  
First Time ◽  
Full Body

AbstractBody ownership concerns what it is like to feel a body part or a full body as mine, and has become a prominent area of study. We propose that there is a closely related type of bodily self-consciousness largely neglected by researchers—experiential ownership. It refers to the sense that I am the one who is having a conscious experience. Are body ownership and experiential ownership actually the same phenomenon or are they genuinely different? In our experiments, the participant watched a rubber hand or someone else’s body from the first-person perspective and was touched either synchronously or asynchronously. The main findings: (1) The sense of body ownership was hindered in the asynchronous conditions of both the body-part and the full-body experiments. However, a strong sense of experiential ownership was observed in those conditions. (2) We found the opposite when the participants’ responses were measured after tactile stimulations had ceased for 5 s. In the synchronous conditions of another set of body-part and full-body experiments, only experiential ownership was blocked but not body ownership. These results demonstrate for the first time the double dissociation between body ownership and experiential ownership. Experiential ownership is indeed a distinct type of bodily self-consciousness.

scholarly journals Increased plasticity of the bodily self in eating disorders

2011 ◽  
Vol 42 (4) ◽  
pp. 819-828 ◽  
Author(s):  
E. Eshkevari ◽  
E. Rieger ◽  
M. R. Longo ◽  
P. Haggard ◽  
J. Treasure
Keyword(s):  
Eating Disorders ◽  
Visual Processing ◽  
Subjective Experience ◽  
Emotional Dysregulation ◽  
The Body ◽  
Self Report ◽  
Healthy Controls ◽  
Drive For Thinness ◽  
Maintenance Factors ◽  
Self Objectification

BackgroundThe rubber hand illusion (RHI) has been widely used to investigate the bodily self in healthy individuals. The aim of the present study was to extend the use of the RHI to examine the bodily self in eating disorders (EDs).MethodThe RHI and self-report measures of ED psychopathology [the Eating Disorder Inventory – 3 (EDI-3) subscales of Drive for Thinness, Bulimia, Body Dissatisfaction, Interoceptive Deficits, and Emotional Dysregulation; the 21-item Depression, Anxiety and Stress Scale (DASS-21); and the Self-Objectification Questionnaire (SOQ)] were administered to 78 individuals with an ED and 61 healthy controls.ResultsIndividuals with an ED experienced the RHI significantly more strongly than healthy controls on both perceptual (i.e. proprioceptive drift) and subjective (i.e. self-report questionnaire) measures. Furthermore, both the subjective experience of the RHI and associated proprioceptive biases were correlated with ED psychopathology. Approximately 23% of the variance for embodiment of the fake hand was accounted for by ED psychopathology, with interoceptive deficits and self-objectification significant predictors of embodiment.ConclusionsThese results indicate that the bodily self is more plastic in people with an ED. These findings may shed light on both aetiological and maintenance factors involved in EDs, particularly visual processing of the body, interoceptive deficits, and self-objectification.

scholarly journals Perception of visual-tactile asynchrony, bodily perceptual aberrations, and bodily illusions in schizophrenia

2020 ◽  
Author(s):  
Regine Zopf
Keyword(s):  
The Body ◽  
Detection Sensitivity ◽  
Body Ownership ◽  
Body Perception ◽  
Rubber Hand ◽  
Bodily Experiences ◽  
Asynchrony Detection ◽  
Body Perceptions ◽  
Proprioceptive Drift ◽  
Insight Into

Body perception can be dramatically altered in individuals with schizophrenia resulting in experiences of undefined bodily boundaries, loss of body ownership, and size changes for parts of the body. These individuals may also be more susceptible to the rubber hand illusion (RHI: an illusion of body perception that can also be induced in neurotypical populations), but the findings are mixed. Furthermore, the perception of timing information about multisensory stimuli, which is thought to be fundamental for body perception, has been reported to be altered in schizophrenia. We tested here whether altered perception of the temporal relationship between visual and tactile signals in schizophrenia can predict self-reported perceptual aberrations and RHI susceptibility (indexed by both illusion self-ratings and a more objective proprioceptive-drift measure). We found that the sensitivity to detect temporal asynchronies is reduced in schizophrenia and this predicts bodily perceptual symptoms. In contrast, we found no evidence for a direct relationship between asynchrony detection sensitivity and RHI susceptibility. Instead, our findings suggest that experiencing more bodily perceptual symptoms increases the likelihood of endorsing unusual bodily experiences, resulting in higher RHI self-ratings but not higher proprioceptive-drift scores. Overall, our findings provide evidence for both direct and indirect links between temporal and body perception and thus new insight into the mechanisms that may underlie unusual body perceptions in schizophrenia.

scholarly journals Aflatoxins in body fluids and food of Nigeria children with protein-energy malnutrition

2012 ◽  
Vol 12 (53) ◽  
pp. 6553-6566
Author(s):  
GC Onyemelukwe ◽  
◽  
D Ogoina ◽  
GE Ibiam ◽  
GH Ogbadu
Keyword(s):  
Protein Energy Malnutrition ◽  
Cross Sectional Study ◽  
Body Fluids ◽  
The Body ◽  
Healthy Controls ◽  
Cross Sectional ◽  
Detection Rates ◽  
Nigerian Children ◽  
Protein Energy ◽  
Patient Groups

Aflatoxins are natural contaminants of food crops implicated in the pathogenesis of various human diseases. This study aimed to determine the associations between aflatoxins and protein- energy malnutrition ( PEM) by measurements of aflatoxins in serum, urine and food on plate of Nigerian children with PEM. A cross - sectional study was undertaken in 3 agro - ecological regions of Nigeria (Guinea savannah, Sudan savannah and Rain forest), where aflatoxins B1 , B2, G1, G2, M1, and M2 were measured in sera, urine and food on plate of 79 children with PEM (kwashiorkor n=36, marasmic kwashiorkor n=29 and marasmus n=13) and 33 healthy controls, matched for age and sex. Among healthy controls, aflatoxin detection rates were higher in the Guinea Savannah (72.2%) than in the Sudan Savannah (53.8%), albeit statistically insignificant. In relation to nutritional groups, the rates of detection of aflatoxins were higher in marasmic kwashiorkor (93.1%) and kwashiorkor patients (88.9%) , compared to marasmus (76.9%) and controls (63.6%, p=0.013). The rates of detection of B1 aflatoxin followed a similar trend viz. marasmic kwashiorkor (82.4%), kwashiorkor (69.4%), marasmus (53.8%) and controls (42.4%, p=0.007). Of all types of aflatoxins detected in serum, M2 had the highest rates of detection in all patient groups and controls. The median concentrations of aflatoxins detected in sera of each PEM group were significantly higher than those of controls, but comparisons between PEM groups were not statistically significant. The frequency and concentration of aflatoxins detected in urine and food of PEM groups and controls were not statistically different. However, controls had the lowest serum / urine aflatoxin ratio as well as lowest median aflatoxins concentrations in their food as compared to PEM patient s. In conclusion, aflatoxins are commonly detected in the body fluids and food of Nigerian children , but more frequently and at higher concentrations in children with PEM , possibly due to decreased excretion or increased exposure. Future prospective studies are desirable to determine if aflatoxins contribute to the pathogenesis of all types of PEM and not necessarily kwashiorkor alone.

scholarly journals New records of ring nematodes, Bakernema enormese n. sp. and Criconema (Nothocriconemella) graminicola Loof, Wouts & Yeates, 1997 (Nematoda: Criconematidae) from natural forests of Vietnam

2019 ◽  
Vol 41 (3) ◽  
Author(s):  
Nguyen Ngoc Chau
Keyword(s):  
New Species ◽  
Body Size ◽  
New Records ◽  
Large Body ◽  
Lateral View ◽  
The Body ◽  
Natural Forests ◽  
Large Body Size ◽  
Stylet Length ◽  
North Vietnam

Bakernema enormese sp. n., collected from rhizosphere of forest wood trees in Muong Phang, Dien Bien Province (north Vietnam) is described and illustrated. The new species is characterized by large body size and stylet. In general, this new species is close to two existing species of the same genus, B. inaequale and B. dauniense by cuticle structure in transparent membranous projections which appear in lateral view as spine-like structures on each annulus. These structure arranged into several rows along the body. In morphology, the new species differs from B. inaequale and B. dauniense  by body and stylet length, i.e. 609–842 µm and 143.5–150 µm vs. 391–578 µm and 59–74 µm for B. inaequale and vs. 391–461 µm and 65–74 µm for B. dauniense. In addition, new species can be distinguished from B. inaequale by the longer membranous projection, 8–12 vs. 6–10 µm and vagina shape, curved vs. sigmoid. From B. dauniense, the new species differs by the much longer membranous projection, 8–12 vs. 1.4–2.2 µm and less number annules between vulva and tail end (RV), 3–4 vs. 7.8 annules. The presence of Criconema (Nothocriconemella) graminicola Loof, Wouts & Yeates, in Vietnam with morphometrics, illustrators and remarks given.

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