Anatomically plausible illusory posture affects mental rotation of body parts (original) (raw)
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Virtual hand illusion induced by visuomotor correlations
PloS one, 2010
Background: Our body schema gives the subjective impression of being highly stable. However, a number of easily-evoked illusions illustrate its remarkable malleability. In the rubber-hand illusion, illusory ownership of a rubber-hand is evoked by synchronous visual and tactile stimulation on a visible rubber arm and on the hidden real arm. Ownership is concurrent with a proprioceptive illusion of displacement of the arm position towards the fake arm. We have previously shown that this illusion of ownership plus the proprioceptive displacement also occurs towards a virtual 3D projection of an arm when the appropriate synchronous visuotactile stimulation is provided. Our objective here was to explore whether these illusions (ownership and proprioceptive displacement) can be induced by only synchronous visuomotor stimulation, in the absence of tactile stimulation.
Rubber Hand Illusion: Evidence for a multisensory integration of proprioception
Avances en Psicología Latinoamericana, 2017
This review seeks to describe a multisensory integration hypothesis for proprioception through the description of different Rubber Hand Illusion (rhi) experimental settings. rhi is a paradigm created in 1998 to explore the relation between visual and tactile sensory systems. The task involves a synchronous stroking, using a paintbrush, of one of a subject's hands occluded from his vision, and a prosthetic rubber hand located in front of the subject. Instructed to look at the rubber hand, the subject starts to feel as if the rubber hand is his own hand after approximately half a minute, which is to say that the illusion produces a feeling of ownership of the rubber hand. Additional research over the last 15 years has widely explored these results, illustrating the dynamic functions of the brain and body sensory systems, as well as shedding light on the bases of amputee rehabilitation and different types of paresthesia. The review is structured around three topics: (1) the definition, limits, and scope of rhi; (2) the physiological and neurocognitive evidence backing rhi; and (3) the use of action based rhi experimental settings. The paper concludes that rhi is a salient example of a neuroscientific trend towards an integrated account of body, brain, and perceptual space. The discovery of the illusion has also provided an alternative context for the study of proprioception and related brain dynamics in normal subjects.
Cognitive Neuroscience, 2011
The rubber hand illusion is one reliable way to experimentally manipulate the experience of body ownership. However, debate continues about the necessary and sufficient conditions eliciting the illusion. We measured proprioceptive drift and the subjective experience (via questionnaire) while manipulating two variables that have been suggested to affect the intensity of the illusion. First, the rubber hand was positioned either in a posturally congruent position, or rotated by 180 . Second, either the anatomically same rubber hand was used, or an anatomically incongruent one. We found in two independent experiments that a rubber hand rotated by 180 leads to increased proprioceptive drift during synchronous visuo-tactile stroking, although it does not lead to feelings of ownership (as measured by questionnaire). This dissociation between drift and ownership suggests that proprioceptive drift is not necessarily a valid proxy for the illusion when using hands rotated by 180 .
Experimental Brain Research
Recent evidence suggests that imagined auditory and visual sensory stimuli can be integrated with real sensory information from a different sensory modality to change the perception of external events via cross-modal multisensory integration mechanisms. Here, we explored whether imagined voluntary movements can integrate visual and proprioceptive cues to change how we perceive our own limbs in space. Participants viewed a robotic hand wearing a glove repetitively moving its right index finger up and down at a frequency of 1 Hz, while they imagined executing the corresponding movements synchronously or asynchronously (kinesthetic-motor imagery); electromyography (EMG) from the participants’ right index flexor muscle confirmed that the participants kept their hand relaxed while imagining the movements. The questionnaire results revealed that the synchronously imagined movements elicited illusory ownership and a sense of agency over the moving robotic hand—the moving rubber hand illusi...
Rubber Hand Illusion survives Ventral Premotor area inhibition: A rTMS study
Neuropsychologia, 2018
The sense of body ownership is a fundamental feature that refers to the ability to recognize our body as our own, allowing us to interact properly with the outside world. Usually, it is explored by means of the Rubber Hand Illusion (RHI) during which a dummy hand is incorporated in the mental representation of one's own body throughout a multisensory (visuo-tactile) integration mechanism. Particular attention has been paid to the neurofunctional counterparts of this mechanism highlighting the pivotal role of an occipito-parieto-frontal network involving the Ventral Premotor area (PMv). To date, the specific role of the PMv in generating the sense of ownership is still unknown. In this study, we aimed at exploring the role of PMv in generating and experiencing the RHI. Off-line repetitive Transcranial Magnetic Stimulation (rTMS) was applied to a group of 24 healthy participants whilst changes in proprioceptive judgment and self-reported illusion sensations were collected and analysed separately. The PMv was not directly implicated in generating the sense of ownership. Indeed, its inhibition affected the explicit detection of the visuo-tactile congruence without interfering with the illusion experience itself. We hypothesized that the conscious visuo-tactile congruence detection may be independent from the conscious illusion experience. Also, our results support the view that the RHI grounds on a complex interaction between bottom-up and top-down processes, as the visuo-tactile integration per se may be not sufficient to trigger the subjective illusion.
The Rubber Hand Illusion: body ownership and spatial updating do not go hand in hand
PLoS ONE
In the Rubber Hand Illusion, the feeling of ownership of a rubber hand displaced from a participant's real occluded hand is evoked by synchronously stroking both hands with paintbrushes. A change of perceived finger location towards the rubber hand (proprioceptive drift) has been reported to correlate with this illusion. To measure the time course of proprioceptive drift during the Rubber Hand Illusion, we regularly interrupted stroking (performed by robot arms) to measure perceived finger location. Measurements were made by projecting a probe dot into the field of view (using a semi-transparent mirror) and asking participants if the dot is to the left or to the right of their invisible hand (Experiment 1) or to adjust the position of the dot to that of their invisible hand (Experiment 2). We varied both the measurement frequency (every 10 s, 40 s, 120 s) and the mode of stroking (synchronous, asynchronous, just vision). Surprisingly, with frequent measurements, proprioceptive drift occurs not only in the synchronous stroking condition but also in the two control conditions (asynchronous stroking, just vision). Proprioceptive drift in the synchronous stroking condition is never higher than in the just vision condition. Only continuous exposure to asynchronous stroking prevents proprioceptive drift and thus replicates the differences in drift reported in the literature. By contrast, complementary subjective ratings (questionnaire) show that the feeling of ownership requires synchronous stroking and is not present in the asynchronous stroking condition. Thus, subjective ratings and drift are dissociated. We conclude that different mechanisms of multisensory integration are responsible for proprioceptive drift and the feeling of ownership. Proprioceptive drift relies on visuoproprioceptive integration alone, a process that is inhibited by asynchronous stroking, the most common control condition in Rubber Hand Illusion experiments. This dissociation implies that conclusions about feelings of ownership cannot be drawn from measuring proprioceptive drift alone.
Journal of Neurophysiology, 2019
The rubber hand illusion (RHI) paradigm experimentally produces an illusion of rubber hand ownership and arm shift by simultaneously stroking a rubber hand in view and a participant's visually occluded hand. It involves visual, tactile, and proprioceptive multisensory integration and activates multisensory areas in the brain, including the posterior parietal cortex (PPC). Multisensory inputs are transformed into outputs for motor control in association areas such as PPC. A behavioral study reported decreased motor performance after RHI. However, it remains unclear whether RHI modifies the interactions between sensory and motor systems and between PPC and the primary motor cortex (M1). We used transcranial magnetic stimulation (TMS) and examined the functional connections from the primary somatosensory and association cortices to M1 and from PPC to M1 during RHI. In experiment 1, short-latency afferent inhibition (SAI) and long-latency afferent inhibition (LAI) were measured before and immediately after a synchronous (RHI) or an asynchronous (control) condition. In experiment 2, PPC-M1 interaction was measured using two coils. We found that SAI and LAI were reduced in the synchronous condition compared with baseline, suggesting that RHI decreased somatosensory processing in the primary sensory and the association cortices projecting to M1. We also found that greater inhibitory PPC-M1 interaction was associated with stronger RHI assessed by questionnaire. Our findings suggest that RHI modulates both the early and late stages of processing of tactile afferent, which leads to altered M1 excitability by reducing the gain of somatosensory afferents to resolve conflicts among multisensory inputs. NEW & NOTEWORTHY Perception of one's own body parts involves integrating different sensory information and is important for motor control. We found decreased effects of cutaneous stimulation on motor cortical excitability during rubber hand illusion (RHI), which may reflect decreased gain of tactile input to resolve multisensory conflicts. RHI strength correlated with the degree of inhibitory posterior parietal cortex-motor cortex interaction, indicating that parietal-motor connection is involved in resolving sensory conflicts and body ownership during RHI. multisensory integration; posterior parietal cortex; rubber hand illusion; short-and long-latency afferent inhibition; transcranial magnetic stimulation
PLOS ONE, 2019
The rubber hand illusion describes a phenomenon in which participants experience a rubber hand as being part of their body by the synchronous application of visuotactile stimulation to the real and the artificial limb. In the recently introduced robotic hand illusion (RobHI), a robotic hand is incorporated into one's body representation due to the integration of synchronous visuomotor information. However, there are no setups so far that combine visuotactile and visuomotor feedback, which is expected to unravel mechanisms that cannot be detected in experimental designs applying this information in isolation. We developed a robotic hand, controlled by a sensor glove and equipped with pressure sensors, and varied systematically and separately the synchrony for motor feedback (MF) and tactile feedback (TF). In Experiment 1, we implemented a ball-grasping task and assessed the perceived proprioceptive drift of one's own hand as a behavioral measure of the spatial calibration of body coordinates as well as explicit embodiment experiences by a questionnaire. Results revealed significant main effects of both MF and TF for proprioceptive drift data, but we only observed main effects for MF on perceived embodiment. Furthermore, for the proprioceptive drift we found that synchronous feedback in one factor compensates for asynchronous feedback in the other. In Experiment 2, including a new sample of naïve participants, we further explored this finding by adding unimodal conditions, in which we manipulated the presence or absence of MF and/or TF. These findings replicated the results from Experiment 1 and we further found evidence for a supper-additive multisensory effect on spatial body representation caused by the presence of both factors. Results on conscious body perception were less consistent across both experiments. The findings indicate that sensory and motor input equally contribute to the representation of spatial body coordinates which for their part are subject to multisensory enhancing effects. The results outline the potential of
Neuroscience letters, 2012
Ownership for body parts depends on multisensory integration of visual, tactile and proprioceptive signals. In a previous study, we demonstrated that vestibular signals also contribute to ownership for body parts, since vestibular stimulation increased illusory ownership for a rubber hand. However, it remained an open question whether the vestibular information acts on the visual or on the tactile input. Here, we used a non-visual variant of the rubber hand illusion, manipulating the synchrony between tactile signals from the participant's left and right hand. The results revealed a strong illusory ownership through self-reports (questionnaires) and proprioceptive drift measures. Interestingly, however, there was no influence of vestibular stimulation on illusory ownership and the proprioceptive drift. The present data suggest that vestibular signals do not interfere with the tactile-proprioceptive mechanisms underlying ownership for body parts when visual feedback from the body surface is absent.
The rubber hand illusion in action
Neuropsychologia, 2009
In the well-known rubber hand illusion (RHI), watching a rubber hand being stroked while one's own unseen hand is synchronously stroked, induces a relocation of the sensed position of one's own hand towards the rubber hand . Rubber hands 'feel' touch that eyes see. Nature, 391(6669), 756]. As one has lost the veridical location of one's hand, one should not be able to correctly guide one's hand movements. An accurate representation of the location of body parts is indeed a necessary pre-requisite for any correct motor command . How the brain represents the body: Insights from neurophysiology and psychology. In D. Gopher, & A. Koriat (Eds.), Attention and performance XVII-Cognitive regulation of performance interaction of theory and application (pp. 136-157)]. However, it has not yet been investigated whether action is indeed affected by the proprioceptive drift towards the rubber hand, nor has the resistance of visual capture in the RHI to new proprioceptive information been assessed. In the present two kinematic experiments, we show for the first time that action resists the RHI and that the RHI resists action. In other words, we show a dissociation between illusion-insensitive ballistic motor responses and illusion-sensitive perceptual bodily judgments. Moreover, the stimulated hand was judged closer to the rubber hand for the perceptual responses, even after active movements. This challenges the view that any proprioceptive update through active movement of the stimulated hand erases the illusion. These results expand the knowledge about representations of the body in the healthy brain, and are in line with the currently most used dissociation between two types of body representations so far mainly based on neuropsychological patients . Knowing where and knowing how to get there. In J. Paillard (Ed.), Brain and space (pp. 461-481); Paillard, J. (1999). Body schema and body image: A double dissociation in deafferented patients. In G. N. Gantchev, S. Mori, & J.Massion (Eds.), Motor control, today and tomorrow (pp. 197-214)].