The bodily boundaries in amputees may seem to be more malleable than in non-amputees, given the propensity for a phantom limb to embody a mirror-reflected hand. However, in the present investigation, in which phantom-limb illusions within body space are induced and manipulated, we found that perceiving phantom sensations and illusory embodiment does not require amputation. Surprisingly, in the present modified rubber-hand illusion, we found that simultaneous stroking or stimulation of the participant's target hand was not necessary to induce illusions of embodiment and corresponding perceptual illusions. We tested this upper-limb paradigm in fourteen upper-limb amputees and twenty-six controls (including fourteen lower-limb amputees). We propose a model for embodiment of a rubber or real hand passively observed in a mirror. In this model, passive observation of the hand in the mirror triggers body representations (body image and body schema), most likely through activation of the posterior parietal cortex and temporo-parietal junction. Activity in these regions heightens awareness of peripersonal space and increases tactile sensitivity, and may subsequently enhance perception of illusory touch and embodiment. Furthermore, sense of embodiment may be more apparent to the participant when the hand is threatened; however, embodiment may even be strengthened when the motor system is engaged, evoking motor schemata to support the more easily induced perceptual embodiment via body image.
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http://dx.doi.org/10.1068/p6519 | DOI Listing |
Neuroimage
October 2024
Sensory-Motor Laboratory (SeMoLa), Jules-Gonin Eye Hospital/Fondation Asile des Aveugles, Department of Ophthalmology/University of Lausanne, Lausanne, Switzerland. Electronic address:
Based on visuo-tactile stimulation, the rubber hand illusion induces a sense of ownership for a dummy hand. Manipulating the visibility of the dummy hand during the stimulation influences cognitive aspects of the illusion, suggesting that the related brain activity may be influenced too. To test this, we analyzed brain activity (fMRI), subjective ratings, and skin conductance from 45 neurotypical participants undergoing a modified rubber hand illusion protocol where we manipulated the visibility (high, medium, and low) of a virtual hand, not the brush (virtual hand illusion; VHI).
View Article and Find Full Text PDFFront Neurosci
September 2023
Department of Biomedical Engineering, Faculty of Engineering, Lund University, Lund, Sweden.
Tactile feedback plays a vital role in inducing ownership and improving motor control of prosthetic hands. However, commercially available prosthetic hands typically do not provide tactile feedback and because of that the prosthetic user must rely on visual input to adjust the grip. The classical rubber hand illusion (RHI) where a brush is stroking the rubber hand, and the user's hidden hand synchronously can induce ownership of a rubber hand.
View Article and Find Full Text PDFSci Rep
September 2023
Department of Physical Medicine and Rehabilitation, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8575, Japan.
The sense of body ownership, the feeling that one's body belongs to oneself, is a crucial subjective conscious experience of one's body. Recent methodological advances regarding crossmodal illusions have provided novel insights into how multisensory interactions shape human perception and cognition, underpinning conscious experience, particularly alteration of body ownership. Moreover, in post-stroke rehabilitation, encouraging the use of the paretic limb in daily life is considered vital, as a settled sense of ownership and attentional engagement toward the paralyzed body part may promote increased frequency of its use and prevent learned nonuse.
View Article and Find Full Text PDFSci Rep
May 2023
Department of Psychology, University of Virginia, Charlottesville, Virginia, USA.
It is widely accepted that the representation of the body is not fixed and immutable, but rather flexible and constantly updated based on a continuous stream of multisensory information. This mechanism can be very useful to adapt to several situations, but it would not be adaptive if the body representation was too malleable or if it wasn't capable of restoring its integrity after a transient modification. Here we used the Rubber Hand Illusion (RHI) to investigate how quickly the body representation can be modified.
View Article and Find Full Text PDFJ Exp Psychol Hum Percept Perform
June 2021
Brain, Body, and Self Laboratory.
A controversial and unresolved issue in cognitive neuroscience is whether humans can experience supernumerary limbs as part of their own body. Some previous experiments have claimed that it is possible to elicit supernumerary hand illusions based on modified versions of the rubber hand illusion. However, other studies have provided conflicting results that suggest that only one rubber hand can be perceived as one's own.
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