scholarly journals The role of self-touch in somatosensory and body representation disorders after stroke

2011 ◽  
Vol 366 (1581) ◽  
pp. 3142-3152 ◽  
Author(s):  
H. E. van Stralen ◽  
M. J. E. van Zandvoort ◽  
H. C. Dijkerman
Keyword(s):  
Body Representation ◽  
The Body ◽  
Body Ownership ◽  
Structural Representation ◽  
Bodily Experience ◽  
Left Hand ◽  
Patient Reported ◽  
Haptic Object ◽  
Tactile Detection

Somatosensory impairments occur in about half of the cases of stroke. These impairments range from primary deficits in tactile detection and the perception of features, to higher order impairments in haptic object recognition and bodily experience. In this paper, we review the influence of active- and self-touch on somatosensory impairments after stroke. Studies have shown that self-touch improves tactile detection in patients with primary tactile deficits. A small number of studies concerned with the effect of self-touch on bodily experience in healthy individuals have demonstrated that self-touch influences the structural representation of one's own body. In order to better understand the effect of self-touch on body representations, we present an informal study of a stroke patient with somatoparaphrenia and misoplegia. The role of self-touch on body ownership was investigated by asking the patient to stroke the impaired left hand and foreign hands. The patient reported ownership and a change in affect over all presented hands through self-touch. The time it took to accomplish ownership varied, based on the resemblance of the foreign hand to the patient's own hand. Our findings suggest that self-touch can modulate impairments in body ownership and affect, perhaps by helping to reinstate the representation of the body.

The Role of Hand Size in the Fake-Hand Illusion Paradigm

Perception ◽  
10.1068/p5853 ◽  
2007 ◽  
Vol 36 (10) ◽  
pp. 1547-1554 ◽  
Author(s):  
Francesco Pavani ◽  
Massimiliano Zampini
Keyword(s):  
Body Image ◽  
Body Schema ◽  
Body Representation ◽  
The Body ◽  
Video Image ◽  
Body Parts ◽  
Statistical Correlations ◽  
Hand Size ◽  
Visible Hand

When a hand (either real or fake) is stimulated in synchrony with our own hand concealed from view, the felt position of our own hand can be biased toward the location of the seen hand. This intriguing phenomenon relies on the brain's ability to detect statistical correlations in the multisensory inputs (ie visual, tactile, and proprioceptive), but it is also modulated by the pre-existing representation of one's own body. Nonetheless, researchers appear to have accepted the assumption that the size of the seen hand does not matter for this illusion to occur. Here we used a real-time video image of the participant's own hand to elicit the illusion, but we varied the hand size in the video image so that the seen hand was either reduced, veridical, or enlarged in comparison to the participant's own hand. The results showed that visible-hand size modulated the illusion, which was present for veridical and enlarged images of the hand, but absent when the visible hand was reduced. These findings indicate that very specific aspects of our own body image (ie hand size) can constrain the multisensory modulation of the body schema highlighted by the fake-hand illusion paradigm. In addition, they suggest an asymmetric tendency to acknowledge enlarged (but not reduced) images of body parts within our body representation.

scholarly journals tDCS Modulation of Visually Induced Analgesia

2012 ◽  
Vol 24 (12) ◽  
pp. 2419-2427 ◽  
Author(s):  
Flavia Mancini ◽  
Nadia Bolognini ◽  
Patrick Haggard ◽  
Giuseppe Vallar
Keyword(s):  
Visual Cortex ◽  
Pain Perception ◽  
Occipital Cortex ◽  
Body Representation ◽  
The Body ◽  
Left Hand ◽  
Analgesic Effects ◽  
Extrastriate Visual Cortex ◽  
Multisensory Interactions ◽  
The Right

Multisensory interactions can produce analgesic effects. In particular, viewing one's own body reduces pain levels, perhaps because of changes in connectivity between visual areas specialized for body representation, and sensory areas underlying pain perception. We tested the causal role of the extrastriate visual cortex in triggering visually induced analgesia by modulating the excitability of this region with transcranial direct current stimulation (tDCS). Anodal, cathodal, or sham tDCS (2 mA, 10 min) was administered to 24 healthy participants over the right occipital or over the centro-parietal areas thought to be involved in the sensory processing of pain. Participants were required to rate the intensity of painful electrical stimuli while viewing either their left hand or an object occluding the left hand, both before and immediately after tDCS. We found that the analgesic effect of viewing the body was enhanced selectively by anodal stimulation of the occipital cortex. The effect was specific for the polarity and the site of stimulation. The present results indicate that visually induced analgesia may depend on neural signals from the extrastriate visual cortex.

scholarly journals The Effect of a Virtual-Reality Full-Body Illusion on Body Representation in Obesity

2019 ◽  
Vol 8 (9) ◽  
pp. 1330 ◽  
Author(s):  
Scarpina ◽  
Serino ◽  
Keizer ◽  
Chirico ◽  
Scacchi ◽  
...  
Keyword(s):  
Body Size ◽  
Body Representation ◽  
The Body ◽  
Healthy Weight ◽  
Size Estimation ◽  
Estimation Task ◽  
Bodily Experience ◽  
Body Representations ◽  
Body Size Estimation ◽  
Full Body

Background. The effective illusory ownership over an artificial body in modulating body representations in healthy and eating disorders population has been repeatedly reported in recent literature. In this study, we extended this research in the field of obesity: specifically, we investigated whether ownership over a virtual body with a skinny abdomen might be successfully experienced by participants affected by obesity. Methods. Fifteen participants with obesity and fifteen healthy-weight participants took part at this study in which the VR-Full-Body Illusion was adopted. The strength of illusion was investigated through the traditional Embodiment Questionnaire, while changes in bodily experience were measured through a body size estimation task. Results. Participants with obesity as well as healthy-weight participants reported to experience the illusion. About the body size estimation task, both groups reported changes only in the estimation of the abdomen’s circumference after the experimental condition, in absence of any another difference. Discussion. Participants with obesity reported to experience the illusion over a skinny avatar, but the modulation of the bodily experience seems controversial. Future lines of research exploiting this technique for modulating body representations in obesity, specifically in terms of potential therapeutic use, were discussed.

The role of the right parietal lobe in anorexia nervosa

2009 ◽  
Vol 40 (9) ◽  
pp. 1531-1539 ◽  
Author(s):  
D. Nico ◽  
E. Daprati ◽  
N. Nighoghossian ◽  
E. Carrier ◽  
J.-R. Duhamel ◽  
...  
Keyword(s):  
Anorexia Nervosa ◽  
Healthy Volunteers ◽  
Parietal Lobe ◽  
Body Schema ◽  
Body Representation ◽  
The Body ◽  
Subjective Perception ◽  
Body Boundary ◽  
The Right

BackgroundPatients with anorexia nervosa (AN) overestimate their size despite being severely underweight. Whether this misperception echoes an underlying emotional disturbance or also reflects a genuine body-representation deficit is debatable. Current measures inquire directly about subjective perception of body image, thus distinguishing poorly between top-down effects of emotions/attitudes towards the body and disturbances due to proprioceptive disorders/distorted body schema. Disorders of body representation also emerge following damage to the right parietal lobe. The possibility that parietal dysfunction might contribute to AN is suspected, based on the demonstrated association of spatial impairments, comparable to those found after parietal lesion, with this syndrome.MethodWe used a behavioral task to compare body knowledge in severe anorexics (n=8), healthy volunteers (n=11) and stroke patients with focal damage to the left/right parietal lobe (n=4). We applied a psychophysical procedure based on the perception, in the dark, of an approaching visual stimulus that was turned off before reaching the observer. Participants had to predict whether the stimulus would have hit/missed their body, had it continued its linear motion.ResultsHealthy volunteers and left parietal patients estimated body boundaries very close to the real ones. Conversely, anorexics and right parietal patients underestimated eccentricity of their left body boundary.ConclusionsThese findings are in line with the role the parietal cortex plays in developing and maintaining body representation, and support the possibility for a neuropsychological component in the pathogenesis of anorexia, offering alternative approaches to treatment of the disorder.

scholarly journals What do participants expect to experience in the rubber hand illusion?

2021 ◽  
Author(s):  
Arran T Reader
Keyword(s):  
Subjective Experience ◽  
The Body ◽  
Rubber Hand Illusion ◽  
Body Ownership ◽  
Rubber Hand ◽  
Demand Characteristics ◽  
Open Questions ◽  
Synchronous Condition ◽  
Subjective Reports

The sense of body ownership (the feeling that the body belongs to the self) is commonly believed to arise through multisensory integration. This is famously shown in the rubber hand illusion (RHI), where touches applied synchronously to a false hand and to the participant’s real hand (which is hidden from view) can induce a sensation of ownership over the fake one. Asynchronous touches weaken the illusion, and are typically used as a control condition. Subjective experience during the illusion is measured using a questionnaire, with some statements designed to capture illusory sensation and others designed as controls. However, recent work by Lush (2020, Collabra: Psychology) claimed that participants may have different levels of expectation for questionnaire items in the synchronous condition compared to the asynchronous condition, and for the illusion-related items compared to the control items. This may mean that the classic RHI questionnaire is poorly controlled for demand characteristics. As such, Lush (2020) suggested that subjective reports in the RHI may reflect compliance or even the generation of experience to meet expectations (‘phenomenological control’), rather than multisensory processes underlying the sense of body ownership. In the current work a conceptual replication of Lush (2020) was performed with an improved experimental design. Participants were presented with a video of the RHI procedure and reported the sensations they would expect to experience, both in open questions and by rating questionnaire items. In keeping with Lush (2020), participants had greater expectations for illusion statements in the synchronous condition compared to the asynchronous condition, and for illusion statements compared to control statements. However, there was also evidence that some expectations may be driven by exposure to the questionnaire items rather than exposure to the illusion procedure. The role of pre-illusion expectations and expectations driven by questionnaire exposure in the RHI require further examination.

Cross-referenced body and action for the unified self: empirical, developmental, and clinical perspectives

2021 ◽  
pp. 194-209 ◽  
Author(s):  
Shu Imaizumi ◽  
Tomohisa Asai ◽  
Michiko Miyazaki
Keyword(s):  
Body Representation ◽  
Body Part ◽  
The Body ◽  
The Self ◽  
Sense Of Agency ◽  
Phantom Limb ◽  
Body Ownership ◽  
Motor Rehabilitation ◽  
Self Recognition ◽  
The Brain

This chapter discusses how the self emerges in the brain through the body and bodily actions. In terms of minimal selfhood, self-representation has two aspects: sense of body ownership and sense of agency over action. In the rubber hand illusion paradigm, multisensory and sensorimotor signals induce illusory ownership over a fake hand. Studies in healthy adults suggest a cross-referenced relationship between body and action as a mechanism of the self-representation. Specifically, one’s own hand can spontaneously move towards the fake hand due to illusory ownership, suggesting a body-to-action relationship. In contrast, an object which is moving synchronously with one’s hand can entail a sense of body ownership as well as a sense of agency, suggesting an action-to-body relationship. The chapter also discusses developmental and clinical perspectives. Immature self-recognition and body part localization in children suggest a prerequisite of representations of the self and body. Although such representations can deteriorate due to damage to the body and brain, amputees can incorporate phantom limb and prosthesis into their body representation through visuo-motor rehabilitation, regaining senses of ownership and agency over these limbs once again. The chapter proposes generation-loss-regeneration dynamism in self-representation originating from the cross-referenced body and action.

scholarly journals Mr Fantastic Meets The Invisible Man: An Illusion of Invisible Finger Stretching

Perception ◽  
2019 ◽  
Vol 48 (2) ◽  
pp. 185-188 ◽  
Author(s):  
Ailish Byrne ◽  
Catherine Preston
Keyword(s):  
Visual Stimuli ◽  
Empty Space ◽  
The Body ◽  
Body Ownership ◽  
Top Down ◽  
Invisible Man ◽  
Bodily Experience ◽  
The Real ◽  
Body Appearance ◽  
The Invisible

Our brain continually integrates bottom-up sensory signals to create a coherent experience of the body. This bodily experience is also constrained by top-down knowledge of body appearance. However, the extent of these constraints has been challenged. Here, we explore top-down limits on body ownership with the invisible finger stretching illusion, in which synchronous visuotactile stimulation applied to the real fingers and an area of empty space elicits the illusion of owning elongating fingers. The results demonstrate that it is possible to experience stretchy fingers like Mr Fantastic without visual stimuli of a fake hand, even if we do not actually feel invisible like The Invisible Man.

scholarly journals Is Right Angular Gyrus Involved in the Metric Component of the Mental Body Representation in Touch and Vision? A tDCS Study

2021 ◽  
Vol 11 (3) ◽  
pp. 284
Author(s):  
Grazia Fernanda Spitoni ◽  
Giorgio Pireddu ◽  
Valerio Zanellati ◽  
Beatrice Dionisi ◽  
Gaspare Galati ◽  
...  
Keyword(s):  
Discrimination Task ◽  
Sensory Modality ◽  
Body Representation ◽  
The Body ◽  
Angular Gyrus ◽  
Visual Modality ◽  
Order Function ◽  
The Right ◽  
Sense Of Touch

Several studies have found in the sense of touch a good sensory modality by which to study body representation. Here, we address the “metric component of body representation”, a specific function developed to process the discrimination of tactile distances on the body. The literature suggests the involvement of the right angular gyrus (rAG) in processing the tactile metricity on the body. The question of this study is the following: is the rAG also responsible for the visual metric component of body representation? We used tDCS (anodal and sham) in 20 subjects who were administered an on-body distance discrimination task with both tactile and visual stimuli. They were also asked to perform the same task in a near-body condition. The results allow us to confirm the role of rAG in the estimation of tactile distances. Further, we also showed that rAG might be involved in the discrimination of distances on the body not only in tactile but also in visual modality. Finally, based on the significant effects of anodal stimulation even in a near-body visual discrimination task, we proposed a higher-order function of the AG in terms of a supramodal comparator of quantities.

scholarly journals Theorizing Pentecostal Experiences Among Church of God (Cleveland, TN) Adolescents

2020 ◽  
Vol 4 (2) ◽  
Author(s):  
Christopher D Fraley
Keyword(s):  
Religious Experience ◽  
The Body ◽  
Church Of God ◽  
Ethnographic Research ◽  
Emotional Intensity ◽  
Bodily Experience ◽  
Speaking In Tongues ◽  
Positive Experiences ◽  
The Church

This article describes and theorizes the liturgical contexts in which adolescents have Pentecostal experiences such as “speaking in tongues” and being “slain in the Spirit.” It is based on ethnographic research done at a Pentecostal church affiliated with the Church of God (Cleveland, TN).  I begin by offering a snapshot of modern Pentecostalism in order to demonstrate the framework that informed the context of the current study. Then I describe six factors of the liturgy that facilitate Pentecostal experience in adolescents: the language of encounter with God, the use of music to build emotional intensity, the prominent role of the body, the participatory nature of worship, the call for salvation, and the alter call as culmination of the liturgy.  My analysis reveals that adolescents are more likely to have positive experiences if they have been educated in a Christian environment, had a prayer partner, have experienced a sense of distance from God, have accepted a biblicist approach to Scripture, and have a common bodily experience. I argue that Pentecostal experiences are ultimately beneficial and that a thorough analysis of their underlying factors is essential towards the construction of healthier forms of religious experience. 

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