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O'Kane SH, Chancel M, Ehrsson HH. Hierarchical and dynamic relationships between body part ownership and full-body ownership. Cognition 2024; 246:105697. [PMID: 38364444 DOI: 10.1016/j.cognition.2023.105697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 12/12/2023] [Accepted: 12/13/2023] [Indexed: 02/18/2024]
Abstract
What is the relationship between experiencing individual body parts and the whole body as one's own? We theorised that body part ownership is driven primarily by the perceptual binding of visual and somatosensory signals from specific body parts, whereas full-body ownership depends on a more global binding process based on multisensory information from several body segments. To examine this hypothesis, we used a bodily illusion and asked participants to rate illusory changes in ownership over five different parts of a mannequin's body and the mannequin as a whole, while we manipulated the synchrony or asynchrony of visual and tactile stimuli delivered to three different body parts. We found that body part ownership was driven primarily by local visuotactile synchrony and could be experienced relatively independently of full-body ownership. Full-body ownership depended on the number of synchronously stimulated parts in a nonlinear manner, with the strongest full-body ownership illusion occurring when all parts received synchronous stimulation. Additionally, full-body ownership influenced body part ownership for nonstimulated body parts, and skin conductance responses provided physiological evidence supporting an interaction between body part and full-body ownership. We conclude that body part and full-body ownership correspond to different processes and propose a hierarchical probabilistic model to explain the relationship between part and whole in the context of multisensory awareness of one's own body.
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Affiliation(s)
- Sophie H O'Kane
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
| | - Marie Chancel
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden; Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, LPNC, 38000 Grenoble, France
| | - H Henrik Ehrsson
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
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Castro F, Lenggenhager B, Zeller D, Pellegrino G, D'Alonzo M, Di Pino G. From rubber hands to neuroprosthetics: Neural correlates of embodiment. Neurosci Biobehav Rev 2023; 153:105351. [PMID: 37544389 PMCID: PMC10582798 DOI: 10.1016/j.neubiorev.2023.105351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Revised: 07/10/2023] [Accepted: 08/03/2023] [Indexed: 08/08/2023]
Abstract
Our interaction with the world rests on the knowledge that we are a body in space and time, which can interact with the environment. This awareness is usually referred to as sense of embodiment. For the good part of the past 30 years, the rubber hand illusion (RHI) has been a prime tool to study embodiment in healthy and people with a variety of clinical conditions. In this paper, we provide a critical overview of this research with a focus on the RHI paradigm as a tool to study prothesis embodiment in individuals with amputation. The RHI relies on well-documented multisensory integration mechanisms based on sensory precision, where parietal areas are involved in resolving the visuo-tactile conflict, and premotor areas in updating the conscious bodily representation. This mechanism may be transferable to prosthesis ownership in amputees. We discuss how these results might transfer to technological development of sensorised prostheses, which in turn might progress the acceptability by users.
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Affiliation(s)
- Fabio Castro
- Neurophysiology and Neuroengineering of Human-Technology Interaction Research Unit, Campus Bio-Medico University, via Alvaro del Portillo 5, 00128 Rome, Italy; Institute of Sport, School of Life and Medical Sciences, University of Hertfordshire, Hatfield, United Kingdom
| | - Bigna Lenggenhager
- Department of Psychology, Cognitive Psychology, University of Konstanz, Universitätsstraße 10, 78464 Konstanz, Germany; Department of Psychology, University of Zurich, Binzmuehlestrasse 14, 8050 Zurich, Switzerland
| | - Daniel Zeller
- Department of Neurology, University Hospital Würzburg, Josef-Schneider-Str. 11, 97080 Würzburg, Germany
| | - Giovanni Pellegrino
- Epilepsy program, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Marco D'Alonzo
- Neurophysiology and Neuroengineering of Human-Technology Interaction Research Unit, Campus Bio-Medico University, via Alvaro del Portillo 5, 00128 Rome, Italy.
| | - Giovanni Di Pino
- Neurophysiology and Neuroengineering of Human-Technology Interaction Research Unit, Campus Bio-Medico University, via Alvaro del Portillo 5, 00128 Rome, Italy
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Reader AT, Coppi S, Trifonova VS, Ehrsson HH. No reduction in motor-evoked potential amplitude during the rubber hand illusion. Brain Behav 2023; 13:e3211. [PMID: 37548563 PMCID: PMC10570491 DOI: 10.1002/brb3.3211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 07/03/2023] [Accepted: 07/26/2023] [Indexed: 08/08/2023] Open
Abstract
INTRODUCTION In the rubber hand illusion (RHI), touches are applied to a fake hand at the same time as touches are applied to a participant's real hand that is hidden in a congruent position. Synchronous (but not asynchronous) tactile stimulation of the two hands may induce the sensation that the fake hand is the participant's own. As such, the illusion is commonly used to examine the sense of body ownership. Some studies indicate that in addition to the subjective experience of limb ownership reported by participants, the RHI can also reduce corticospinal excitability (e.g., as reflected in motor-evoked potential [MEP] amplitude) and alter parietal-motor cortical connectivity in passive participants. These findings have been taken to support a link between motor cortical processing and the subjective experience of body ownership. METHODS In this study, we tried to replicate the reduction in MEP amplitude associated with the RHI and uncover the components of the illusion that might explain these changes. As such, we used single-pulse transcranial magnetic stimulation to probe the excitability of the corticospinal motor system as participants experienced the RHI. RESULTS Despite participants reporting the presence of the illusion and showing shifts in perceived real hand position towards the fake limb supporting its elicitation, we did not observe any associated reduction in MEP amplitude. CONCLUSION We conclude that a reduction in MEP amplitude is not a reliable outcome of the RHI and argue that if such effects do occur, they are unlikely to be large or functionally relevant.
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Affiliation(s)
- Arran T. Reader
- Department of PsychologyFaculty of Natural SciencesUniversity of StirlingStirlingUK
- Department of NeuroscienceKarolinska InstitutetStockholmSweden
| | - Sara Coppi
- Department of NeuroscienceKarolinska InstitutetStockholmSweden
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Nishiyama Y, Yamashita C, Nomura S. An illusion of disownership over one's own limb is associated with pain perception. Sci Rep 2023; 13:2801. [PMID: 36859438 PMCID: PMC9977932 DOI: 10.1038/s41598-023-29993-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 02/14/2023] [Indexed: 03/03/2023] Open
Abstract
Viewing one's body and even a fake/virtual body experienced as one's own has been suggested to modulate pain perception. However, what happens to pain perception when one's own body part is felt as not belonging to one? We designed a paradigm to induce an illusory feeling of disownership regarding one's limb, investigating whether the feeling affects pain threshold. Participants observed right-side images of their bodies from a third-person perspective via a head-mounted display in real-time. Following instructions, they moved their left hand while keeping their left elbow behind the upper body, so that the connection of their arm to the torso was not visible (test condition), or in front of it, so they could see the arm being part of them (control condition). Then, pain threshold was tested with a thermal stimulator. We found a significantly higher strength of disownership in the test condition than in the control condition. While there was no pain modulation within and between conditions, disownership ratings negatively correlated with pain-threshold changes, where the participants reporting explicit disownership showed lower pain-threshold changes than the others. The finding suggests that while multisensory disintegration had no modulatory effect, the individual sense of disownership was associated with pain perception.
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Affiliation(s)
- Yuta Nishiyama
- Department of Information and Management Systems Engineering, Nagaoka University of Technology, Niigata, Japan.
| | - Chihiro Yamashita
- grid.260427.50000 0001 0671 2234Department of Information and Management Systems Engineering, Nagaoka University of Technology, Niigata, Japan
| | - Shusaku Nomura
- grid.260427.50000 0001 0671 2234Department of Information and Management Systems Engineering, Nagaoka University of Technology, Niigata, Japan
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Weijs ML, Ho JT, Roel Lesur M, Lenggenhager B. Is this my foot? Experimentally induced disownership in individuals with body integrity dysphoria. Conscious Cogn 2022; 106:103432. [PMID: 36372053 DOI: 10.1016/j.concog.2022.103432] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 09/07/2022] [Accepted: 10/14/2022] [Indexed: 11/12/2022]
Abstract
In body integrity dysphoria (BID), otherwise healthy individuals feel like a part of their physical body does not belong to them despite normal sensorimotor functioning. Theoretical and empirical evidence suggested aweakened integration of the affected body part into higher-order multisensory cortical body networks. Here, we used a multisensory stimulation paradigm in mixed reality to modulate and investigate multisensory processing underlying body (dis)ownership in individuals with BID of the lower limb. In 20 participants with BID, delay perception and body ownership were measured after introducing delays between the visual and tactile information of viewed stroking applied to affected and unaffected body parts. Unlike predicted, delay perception did not differ between the two body parts. However, specifically for the affected limb, ownership was lower and more strongly modulated by delay. These findings might be following the idea of a stronger dependency on online bottom up sensory signals in BID.
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Affiliation(s)
- Marieke L Weijs
- Department of Psychology, University of Zurich, Zurich, Switzerland; Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland.
| | - Jasmine T Ho
- Department of Psychology, University of Zurich, Zurich, Switzerland; Department of Psychiatry, Psychotherapy and Psychosomatics, University of Zurich, Zurich, Switzerland
| | - Marte Roel Lesur
- Department of Psychology, University of Zurich, Zurich, Switzerland; Department of Computer Science and Engineering, Universidad Carlos III de Madrid, Madrid, Spain
| | - Bigna Lenggenhager
- Department of Psychology, University of Zurich, Zurich, Switzerland; Department of Psychology, University of Konstanz, Konstanz, Germany
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Leach WT, Medina J. Understanding components of embodiment: Evidence from the mirror box illusion. Conscious Cogn 2022; 103:103373. [PMID: 35751927 DOI: 10.1016/j.concog.2022.103373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 06/15/2022] [Accepted: 06/16/2022] [Indexed: 11/25/2022]
Abstract
Past studies have examined embodiment in the rubber hand illusion, using principal components analysis (PCA) to identify factors from questionnaire responses during synchronous and asynchronous stroking. To better understand the phenomenology of embodiment, we used PCA in the mirror box illusion to examine performance across conditions that varied in movement synchrony to examine multisensory integration and movement type to vary the amount of multisensory congruence. We found three dissociable components in all conditions: embodiment, deafference and attentiveness. We also examined how these embodiment ratings varied across the four conditions. As hypothesized, embodiment ratings were highest for synchronous movement, with feelings of deafference highest for asynchronous movement. Furthermore, there was a movement by timing interaction, such that sliding resulted in greater differences in synchronous versus asynchronous ratings than tapping. These results suggest that embodiment or deafference can be changed as a function of the amount of multisensory congruence.
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Affiliation(s)
- William T Leach
- Department of Psychological & Brain Sciences, University of Delaware, Newark, DE, USA
| | - Jared Medina
- Department of Psychological & Brain Sciences, University of Delaware, Newark, DE, USA.
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Sebastiano AR, Poles K, Miller LE, Fossataro C, Milano E, Gindri P, Garbarini F. Reach planning with someone else’s hand. Cortex 2022; 153:207-219. [DOI: 10.1016/j.cortex.2022.05.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 03/18/2022] [Accepted: 05/03/2022] [Indexed: 01/08/2023]
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Sustained rubber hand illusion after the end of visuotactile stimulation with a similar time course for the reduction of subjective ownership and proprioceptive drift. Exp Brain Res 2021; 239:3471-3486. [PMID: 34524490 PMCID: PMC8599369 DOI: 10.1007/s00221-021-06211-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 09/01/2021] [Indexed: 11/20/2022]
Abstract
The rubber hand illusion is a perceptual illusion in which participants experience an inanimate rubber hand as their own when they observe this model hand being stroked in synchrony with strokes applied to the person’s real hand, which is hidden. Earlier studies have focused on the factors that determine the elicitation of this illusion, the relative contribution of vision, touch and other sensory modalities involved and the best ways to quantify this perceptual phenomenon. Questionnaires serve to assess the subjective feeling of ownership, whereas proprioceptive drift is a measure of the recalibration of hand position sense towards the rubber hand when the illusion is induced. Proprioceptive drift has been widely used and thought of as an objective measure of the illusion, although the relationship between this measure and the subjective illusion is not fully understood. Here, we examined how long the illusion is maintained after the synchronous visuotactile stimulation stops with the specific aim of clarifying the temporal relationship in the reduction of both subjective ownership and proprioceptive drift. Our results show that both the feeling of ownership and proprioceptive drift are sustained for tens of seconds after visuotactile stroking has ceased. Furthermore, our results indicate that the reduction of proprioceptive drift and the feeling of ownership follow similar time courses in their reduction, suggesting that the two phenomena are temporally correlated. Collectively, these findings help us better understand the relationships of multisensory stimulation, subjective ownership, and proprioceptive drift in the rubber hand illusion.
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Reader AT, Trifonova VS, Ehrsson HH. Little evidence for an effect of the rubber hand illusion on basic movement. Eur J Neurosci 2021; 54:6463-6486. [PMID: 34486767 DOI: 10.1111/ejn.15444] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 08/12/2021] [Accepted: 08/28/2021] [Indexed: 11/30/2022]
Abstract
Body ownership refers to the distinct sensation that our observed body belongs to us, which is believed to stem from multisensory integration. This is commonly shown through the rubber hand illusion (RHI), which induces a sense of ownership over a false limb. Whilst the RHI may interfere with object-directed action and alter motor cortical activity, it is not yet clear whether a sense of ownership over an artificial hand has functional consequences for movement production per se. As such, we performed two motion-tracking experiments (n = 117) to examine the effects of the RHI on the reaction time, acceleration, and velocity of rapid index finger abduction. We observed little convincing evidence that the induction of the RHI altered these kinematic variables. Moreover, the subjective sensations of rubber hand ownership, referral of touch, and agency did not convincingly correlate with kinematic variables, and nor did proprioceptive drift, suggesting that changes in body representation elicited by the RHI may not influence basic movement. Whilst experiment 1 suggested that individuals reporting a greater sensation of the real hand disappearing performed movements with smaller acceleration and velocity following illusion induction, we did not replicate this effect in a second experiment, suggesting that these effects may be small or not particularly robust. Overall, these results indicate that manipulating the conscious experience of body ownership has little impact on basic motor control, at least in the RHI with healthy participants.
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Affiliation(s)
- Arran T Reader
- Department of Psychology, Faculty of Natural Sciences, University of Stirling, Stirling, UK.,Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | | | - H Henrik Ehrsson
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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Seinfeld S, Müller J. Impact of visuomotor feedback on the embodiment of virtual hands detached from the body. Sci Rep 2020; 10:22427. [PMID: 33380732 PMCID: PMC7773737 DOI: 10.1038/s41598-020-79255-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 12/07/2020] [Indexed: 12/13/2022] Open
Abstract
It has been shown that mere observation of body discontinuity leads to diminished body ownership. However, the impact of body discontinuity has mainly been investigated in conditions where participants observe a collocated static virtual body from a first-person perspective. This study explores the influence of body discountinuity on the sense of embodiment, when rich visuomotor correlations between a real and an artificial virtual body are established. In two experiments, we evaluated body ownership and motor performance, when participants interacted in virtual reality either using virtual hands connected or disconnected from a body. We found that even under the presence of congruent visuomotor feedback, mere observation of body discontinuity resulted in diminished embodiment. Contradictory evidence was found in relation to motor performance, where further research is needed to understand the role of visual body discontinuity in motor tasks. Preliminary findings on physiological reactions to a threat were also assessed, indicating that body visual discontinuity does not differently impact threat-related skin conductance responses. The present results are in accordance with past evidence showing that body discontinuity negatively impacts embodiment. However, further research is needed to understand the influence of visuomotor feedback and body morphological congruency on motor performance and threat-related physiological reactions.
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Affiliation(s)
- Sofia Seinfeld
- Chair of Applied Computer Science VIII, Institute of Computer Science, University of Bayreuth, 95447, Bayreuth, Germany.
- Universitat Politècnica de Catalunya, Centre de la Imatge i la Tecnologia Multimèdia (CITM), Barcelona, Spain.
| | - Jörg Müller
- Chair of Applied Computer Science VIII, Institute of Computer Science, University of Bayreuth, 95447, Bayreuth, Germany
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Tacikowski P, Weijs ML, Ehrsson HH. Perception of Our Own Body Influences Self-Concept and Self-Incoherence Impairs Episodic Memory. iScience 2020; 23:101429. [PMID: 32853552 PMCID: PMC7520895 DOI: 10.1016/j.isci.2020.101429] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 07/08/2020] [Accepted: 07/30/2020] [Indexed: 11/21/2022] Open
Abstract
How does our body affect the way we think about our personality? We addressed this question by eliciting the perceptual illusion that pairs of friends swapped bodies with each other. We found that during the illusion, the participants rated their own personality characteristics more similarly to the way they previously rated their friend's personality, and this flexible adjustment of self-concept to the "new" bodily self was related to the strength of illusory ownership of the friend's body. Moreover, a subsequent memory test showed that personality traits rated during the friend-body-swap illusion were generally remembered worse than traits rated during the control conditions; importantly, however, this impairment of episodic recognition memory was reduced for the participants who considerably adjusted their self-concept during the illusory body swapping. These findings demonstrate that our beliefs about own personality are dynamically shaped by the perception of our body and that coherence between the bodily and conceptual self-representations is important for the normal encoding of episodic memories.
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Affiliation(s)
- Pawel Tacikowski
- Karolinska Institutet, Department of Neuroscience, Solnavägen 9, 17165 Stockholm, Sweden
- University of California Los Angeles, Department of Neurosurgery, 300 Stein Plaza Drwy., 90024 Los Angeles, USA
| | - Marieke L. Weijs
- Karolinska Institutet, Department of Neuroscience, Solnavägen 9, 17165 Stockholm, Sweden
- University of Zurich, Department of Psychology, Cognitive Neuropsychology, Binzmühlestrasse 14, 8050 Zurich, Switzerland
| | - H. Henrik Ehrsson
- Karolinska Institutet, Department of Neuroscience, Solnavägen 9, 17165 Stockholm, Sweden
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