Rescaling perceptual hand maps by visual-tactile recalibration.

After concurrent visual and tactile stimuli have been presented repeatedly with a spatial offset, unisensory tactile stimuli, too, are perceived with a spatial bias towards the previously presented visual stimuli. This so-called visual-tactile ventriloquism aftereffect reflects crossmodal recalibration. As touch is intrinsically linked to body parts, we asked here whether recalibration occurs at the level of individual stimuli or at a higher, integrated, map-like level.

Prevalence of Phantom Phenomena in Congenital and Early-Life Amputees.

Phantom limb pain (PLP) is a common consequence of the amputation of a limb. Persons with congenital limb absence (congenital amputees) or an acquired limb amputation at an early age seem to rarely experience PLP. However, the number of available studies and their sample sizes are low.

Illusory tactile movement crosses arms and legs and is coded in external space.

Humans often misjudge where on the body a touch occurred. Theoretical accounts have ascribed such misperceptions to local interactions in peripheral and primary somatosensory neurons, positing that spatial-perceptual mechanisms adhere to limb boundaries and skin layout. Yet, perception often reflects integration of sensory signals with prior experience.

The Prevalence and Characteristics of Phantom Limb Pain and Non-Painful Phantom Phenomena in a Nationwide Survey of 3,374 Unilateral Limb Amputees.

The experience of phantom limb pain (PLP) is a common consequence of limb amputation, resulting in severe impairments of the affected person. Previous studies have shown that several factors such as age at or site of amputation are associated with the emergence and maintenance of PLP. In this cross-sectional study we assessed the presence of several phantom phenomena including PLP and other amputation-related information in a sample of 3,374 unilateral upper and lower limb amputees.

Phantom limb pain after unilateral arm amputation is associated with decreased heat pain thresholds in the face.

Background: The mechanisms underlying chronic phantom limb pain (PLP) are complex and insufficiently understood. Altered sensory thresholds are often associated with chronic pain but quantitative sensory testing (QST) in PLP has so far been inconclusive due to large methodological variation between studies and small sample sizes.

Methods: In this study, we applied QST in 37 unilateral upper-limb amputees (23 with and 14 without PLP) and 19 healthy controls.

Relationship of prosthesis ownership and phantom limb pain: results of a survey in 2383 limb amputees.

Phantom limb pain (PLP) accounts for a significant reduction in quality of life and is difficult to treat. Prosthesis use has been shown to negatively covary with PLP. Recent research on body perception in amputees suggest that prosthesis ownership, defined as the extent to which a prosthesis is experienced as being part of the body rather than an artificial device foreign to the body, might interact with PLP.

Assessment of cortical reorganization and preserved function in phantom limb pain: a methodological perspective.

Phantom limb pain (PLP) has been associated with reorganization in primary somatosensory cortex (S1) and preserved S1 function. Here we examined if methodological differences in the assessment of cortical representations might explain these findings. We used functional magnetic resonance imaging during a virtual reality movement task, analogous to the classical mirror box task, in twenty amputees with and without PLP and twenty matched healthy controls.

Brain-behaviour correlates of habitual motivation in chronic back pain.

Chronic pain may sap the motivation for positive events and stimuli. This may lead to a negative behavioural cycle reducing the establishment of appetitive habitual engagement. One potential mechanism for this might be biased learning.

Online sensory feedback during active search improves tactile localization.

Natural motor behavior is usually refined by ongoing sensory input in closed feedback loops. Research has suggested that humans make systematic errors when localizing touch on the skin, and that perceptual body representations underlying these behaviors are distorted. However, experimental procedures usually prevent participants from touching the target limb, interrupting the natural action-perception loop.

What does "moderate pain" mean? Subgroups holding different conceptions of rating scales evaluate experimental pain differently.

Background: Pain ratings are almost ubiquitous in pain assessment, but their variability is high. Low correlations of continuous/numerical rating scales with categorical scales suggest that individuals associate different sensations with the same number on a scale, jeopardizing the interpretation of statistical results. We analysed individual conceptions of rating scales and whether these conceptions can be utilized in the analysis of ratings of experimental stimuli in pain-free healthy individuals and people with reoccurring/persistent pain.

Synchronous Stimulation With Light and Heat Induces Body Ownership and Reduces Pain Perception.

In this study, we investigated whether illusionary body ownership over artificial hands and non-corporeal objects modulates pain perception. Previous research has yielded to mixed results, but has separated painful stimulation used to test pain perception from the stimulation that was used to induce the illusion. Here, we used a variant of the rubber hand illusion (RHI) paradigm and induced the illusion directly via a combination of visual and painful stimuli.

The rubber hand universe: On the impact of methodological differences in the rubber hand illusion.

The rubber hand illusion (RHI) is a widely applied paradigm to investigate changes in body representations. Extensive scientific interest has produced a great variability in the observed results and many contradictory findings have been reported. Taking into account the numerous variations in the experimental implementation of the RHI, many of these contradictive findings can be reconciled, but to date a thorough analysis of the methodological differences between RHI studies is lacking.

Volumetric brain correlates of approach-avoidance behavior and their relation to chronic back pain.

Avoiding any harm, such as painful experiences, is an important ability for our physical and mental health. This avoidance behavior might be overactive under chronic pain, and the cortical and subcortical brain volumetry, which also often changes in chronic pain states, might be a significant correlate of this behavior. In the present study, we thus investigated the association between volumetric brain differences using 3 T structural magnetic resonance imaging and pain- versus pleasure-related approach-avoidance behavior using an Approach Avoidance Task in the laboratory in chronic back pain (N = 42; mean age: 51.

The rubber hand illusion induced by visual-thermal stimulation.

In the rubber hand illusion (RHI), synchronous touch of a real hand and an artificial hand leads to the feeling of the artificial hand belonging to one's own body. This study examined whether the RHI can be induced using visual-thermal instead of visual-tactile stimulus patterns and to which extent the congruency between temperature and colour of the visual stimulus influences the RHI. In a within-subject design, we presented cold vs.

Psychological Factors Associated with Phantom Limb Pain: A Review of Recent Findings.

Phantom limb pain (PLP) is a common phenomenon occurring after the amputation of a limb and can be accompanied by serious suffering. Psychological factors have been shown to play an important role in other types of chronic pain, where they are pivotal in the acquisition and maintenance of pain symptoms. For PLP, however, the interaction between pain and psychological variables is less well documented.

Perceptual drifts of real and artificial limbs in the rubber hand illusion.

In the rubber hand illusion (RHI), transient embodiment of an artificial hand is induced. An often-used indicator for this effect is the "proprioceptive drift", a localization bias of the real hand towards the artificial hand. This measure suggests that the real hand is attracted by the artificial hand.

Do mirror glasses have the same effect on brain activity as a mirror box? Evidence from a functional magnetic resonance imaging study with healthy subjects.

Since its original proposal, mirror therapy has been established as a successful neurorehabilitative intervention in several neurological disorders to recover motor function or to relieve pain. Mirror therapy seems to operate by reactivating the contralesional representation of the non-mirrored limb in primary motor- and somatosensory cortex. However, mirror boxes have some limitations which prompted the use of additional mirror visual feedback devices.

Post-amputation pain is associated with the recall of an impaired body representation in dreams-results from a nation-wide survey on limb amputees.

The experience of post-amputation pain such as phantom limb pain (PLP) and residual limb pain (RLP), is a common consequence of limb amputation, and its presence has negative effects on a person's well-being. The continuity hypothesis of dreams suggests that the presence of such aversive experiences in the waking state should be reflected in dream content, with the recalled body representation reflecting a cognitive proxy of negative impact. In the present study, we epidemiologically assessed the presence of post-amputation pain and other amputation-related information as well as recalled body representation in dreams in a sample of 3,234 unilateral limb amputees.

Illusion-related brain activations: a new virtual reality mirror box system for use during functional magnetic resonance imaging.

Extended viewing of movements of one's intact limb in a mirror as well as motor imagery have been shown to decrease pain in persons with phantom limb pain or complex regional pain syndrome and to increase the movement ability in hemiparesis following stroke. In addition, mirrored movements differentially activate sensorimotor cortex in amputees with and without phantom limb pain. However, using a so-called mirror box has technical limitations, some of which can be overcome by virtual reality applications.

The rubber hand illusion depends on a congruent mapping between real and artificial fingers.

The rubber hand illusion (RHI), in which a visible artificial hand is touched (or moves) synchronously with the participant's unseen own hand, indicates that body representations can undergo rapid changes. While several constraints for this illusion have been described, some reports highlight a remarkable flexibility of body representations, even contradicting a priori assumptions regarding body appearance and anatomy (e.g.

The importance of synchrony and temporal order of visual and tactile input for illusory limb ownership experiences - an FMRI study applying virtual reality.

In the so-called rubber hand illusion, synchronous visuotactile stimulation of a visible rubber hand together with one's own hidden hand elicits ownership experiences for the artificial limb. Recently, advanced virtual reality setups were developed to induce a virtual hand illusion (VHI). Here, we present functional imaging data from a sample of 25 healthy participants using a new device to induce the VHI in the environment of a magnetic resonance imaging (MRI) system.

An augmented reality home-training system based on the mirror training and imagery approach.

Mirror training and movement imagery have been demonstrated to be effective in treating several clinical conditions, such as phantom limb pain, stroke-induced hemiparesis, and complex regional pain syndrome. This article presents an augmented reality home-training system based on the mirror and imagery treatment approaches for hand training. A head-mounted display equipped with cameras captures one hand held in front of the body, mirrors this hand, and displays it in real time in a set of four different training tasks: (1) flexing fingers in a predefined sequence, (2) moving the hand into a posture fitting into a silhouette template, (3) driving a "Snake" video game with the index finger, and (4) grasping and moving a virtual ball.