The rubber hand illusion is a fallible method to study ownership of prosthetic limbs

AbstractEnabling sensory feedback in limb prostheses can reverse a damaged body image caused by amputation. The rubber hand illusion (RHI) is a popular paradigm to study ownership of artificial limbs and potentially useful to assess sensory feedback strategies. We investigated the RHI as means to induce ownership of a prosthetic hand by providing congruent visual and tactile stimuli. We elicited tactile sensations via electric stimulation of severed afferent nerve fibres in four participants with transhumeral amputation. Contrary to our expectations, they failed to experience the RHI. The sensations we elicited via nerve stimulation resemble tapping as opposed to stroking, as in the original RHI. We therefore investigated the effect of tapping versus stroking in 30 able-bodied subjects. We found that either tactile modality equally induced ownership in two-thirds of the subjects. Failure to induce the RHI in the intact hand of our participants with amputation later confirmed that they form part of the RHI-immune population. Conversely, these participants use neuromusculoskeletal prostheses with neural sensory feedback in their daily lives and reported said prostheses as part of their body. Our findings suggest that people immune to the RHI can nevertheless experience ownership over prosthetic limbs when used in daily life and accentuates a significant limitation of the RHI paradigm.

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Self-body recognition through a mirror: Easing spatial-consistency requirements for rubber hand illusion

10.1101/691634 ◽

2019 ◽

Author(s):

Hikaru Hasegawa ◽

Shogo Okamoto ◽

Ken Ito ◽

Masayuki Hara ◽

Noriaki Kanayama ◽

...

Keyword(s):

Visual Cues ◽

Mirror Image ◽

Rubber Hand Illusion ◽

Body Ownership ◽

Rubber Hand ◽

Subjective Evaluations ◽

Spatial Consistency ◽

Tactile Stimuli ◽

Significant Difference ◽

Body Recognition

AbstractTypical experiments to induce the rubber hand illusion (RHI) require experimental participants to gaze at a fake hand while tactile stimuli are provided to both the fake and hidden actual hands in a synchronous manner. However, under such conditions, postural and apparent disagreement between a seen fake hand and hidden actual hand prevents illusory body ownership. Provided that humans recognize mirror images as copies of the real world in spite of their spatial uncertainties or incongruence, the sensory disagreement may be accepted in RHI settings if using a mirror to show a fake hand. The present study performed two experiments to reveal how self-body recognition of a fake hand feature via mirror affects the RHI. These experiments were conducted in an RHI environment involving voluntary hand movements to investigate not only body ownership but also agency. The first experiment (Experiment 1) examined whether illusory ownership of a fake hand seen in a mirror could be induced. Then, we examined whether the RHI using a mirror image allows disagreement in orientation between the rubber and actual hands (Experiment 2). Subjective evaluations using a RHI questionnaire demonstrated that evoked embodiment of the rubber hand was stronger in the presence of a mirror than in the absence of it (Experiment 1) and that participants experienced the RHI even if the actual and rubber hands were incongruent in terms of orientation (45 °; Experiment 2). No significant difference was found in the change of perceived finger location (proprioceptive drift) between these experiments. These findings suggest that the use of a mirror masks subtle spatial incongruency or degrades the contribution of visual cues for spatial recognition and facilitates multisensory integration for bodily illusions.

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The rubber hand illusion and the tactile Simon effect

Seeing and Perceiving ◽

10.1163/187847612x648161 ◽

2012 ◽

Vol 25 (0) ◽

pp. 187

Author(s):

Michael Iannacone ◽

Jared Medina

Keyword(s):

Simon Effect ◽

Body Schema ◽

Reaction Times ◽

The Body ◽

Rubber Hand Illusion ◽

Hand Position ◽

Rubber Hand ◽

Tactile Stimuli ◽

Experimental Block ◽

Four Blocks

We examined the effects of the rubber hand illusion on representing tactile stimuli using the Simon effect. In a tactile Simon effect task, participants are instructed to make intensity judgments (using foot pedal responses) to tactile stimuli presented to the hands. Participants are faster when the tactile stimulus and response foot are on the same versus opposite side of the body, regardless of whether the limbs are crossed or uncrossed. Furthermore, participants are faster overall when the hands are crossed versus uncrossed. In this study, participants engaged in a tactile Simon effect experiment with rubber hands positioned directly above the participants’ hidden hands, and with real and rubber hands stroked before each experimental block. Each participant was tested in four blocks, manipulating real and rubber hand position (crossed or uncrossed). First, we found that participants responded faster with real or rubber hands crossed, demonstrating that crossing the hands (real or rubber) can hasten tactile intensity judgments. Furthermore, on trials when the rubber hands were crossed, high ownership ratings for the rubber hand were significantly correlated with faster reaction times. Finally, we found a significantly more robust Simon effect when the rubber hands (but not real hands) were crossed. We discuss these findings with reference to how integration of rubber hands into the body schema influences how we represent the location of tactile stimuli.

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Neural Network Underlying Recovery from Disowned Bodily States Induced by the Rubber Hand Illusion

Neural Plasticity ◽

10.1155/2016/8307175 ◽

2016 ◽

Vol 2016 ◽

pp. 1-9 ◽

Cited By ~ 2

Author(s):

In-Seon Lee ◽

Younbyoung Chae

Keyword(s):

Effective Connectivity ◽

Premotor Cortex ◽

Visual Stimuli ◽

Brain Regions ◽

Causal Modeling ◽

Rubber Hand Illusion ◽

Body Ownership ◽

Rubber Hand ◽

Tactile Stimuli ◽

Bodily States

We used functional magnetic resonance imaging to investigate how causal influences between brain regions during the rubber hand illusion (RHI) are modulated by tactile and visual stimuli. We applied needle rotations during the RHI in two different ways: one was with the real hand (reinstantiation by tactile stimuli, R-TS) and the other was with the rubber hand (reinstantiation by visual stimuli, R-VS). We used dynamic causal modeling to investigate interactions among four relevant brain regions: the ventral premotor cortex (PMv), the intraparietal sulcus (IPS), the secondary somatosensory cortex (SII), and the lateral occipitotemporal cortex (LOC). The tactile aspects of needle rotations changed the effective connectivity by directly influencing activity in the SII, whereas visual aspects of needle rotation changed the effective connectivity by influencing both the SII and the LOC. The endogenous connectivity parameters between the IPS and the PMv were reduced significantly in the R-TS condition. The modulatory parameters between the IPS and the PMv were enhanced significantly in the R-TS condition. The connectivity patterns driven by disowned bodily states could be differentially modulated by tactile and visual afferent inputs. Effective connectivity between the parietal and frontal multimodal areas may play important roles in the reinstantiation of body ownership.

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