Hypervigilance for innocuous tactile stimuli in patients with fibromyalgia: an experimental approach

Background: Hypervigilance, i.e., excessive attention, is often invoked as a potential explanation for the observation that many individuals with fibromyalgia show a heightened sensitivity to stimulation in various sensory modalities, such as touch and hearing. Compelling evidence for this assumption is, however, lacking. The aim of the present study was to investigate the presence of somatosensory hypervigilance in patients with fibromyalgia. Methods: Fibromyalgia patients (n=41) and a matched control group (n=40) performed a tactile change detection task in which they had to detect whether there was a change between two consecutively presented patterns of tactile stimuli presented to various body locations. The task was performed under two conditions: in the unpredictable condition, tactile changes occurred equally often at all possible body locations; in the predictable condition, the majority of tactile changes occurred at one specific body location. Results: It was hypothesized that the fibromyalgia group would show better tactile change detection in the unpredictable condition and when changes ocurred at unexpected locations in the predictable condition. The results did not support this hypothesis. In neither condition was the fibromyalgia group better than the control group in detecting tactile changes. Conclusions: No evidence was found to support the claim that patients with fibromyalgia display somatosensory hypervigilance. This finding challenges the idea of hypervigilance as a static feature of fibromyalgia and urges for a more dynamic view in which hypervigilance emerges in situations when bodily threat is experienced

The brain's response to pleasant touch: an EEG investigation of tactile caressing

Somatosensation as a proximal sense can have a strong impact on our attitude toward physical objects and other human beings. However, relatively little is known about how hedonic valence of touch is processed at the cortical level. Here we investigated the electrophysiological correlates of affective tactile sensation during caressing of the right forearm with pleasant and unpleasant textile fabrics. We show dissociation between more physically driven differential brain responses to the different fabrics in early somatosensory cortex - the well-known mu-suppression (10-20 Hz) - and a beta-band response (25-30 Hz) in presumably higher-order somatosensory areas in the right hemisphere that correlated well with the subjective valence of tactile caressing. Importantly, when using single trial classification techniques, beta-power significantly distinguished between pleasant and unpleasant stimulation on a single trial basis with high accuracy. Our results therefore suggest a dissociation of the sensory and affective aspects of touch in the somatosensory system and may provide features that may be used for single trial decoding of affective mental states from simple electroencephalographic measurements

Exploring virtual reality object perception following sensory-motor interactions with different visuo-haptic collider properties.

Interacting with the environment often requires the integration of visual and haptic information. Notably, perceiving external objects depends on how our brain binds sensory inputs into a unitary experience. The feedback provided by objects when we interact (through our movements) with them might then influence our perception. In VR, the interaction with an object can be dissociated by the size of the object itself by means of 'colliders' (interactive spaces surrounding the objects). The present study investigates possible after-effects in size discrimination for virtual objects after exposure to a prolonged interaction characterized by visual and haptic incongruencies. A total of 96 participants participated in this virtual reality study. Participants were distributed into four groups, in which they were required to perform a size discrimination task between two cubes before and after 15 min of a visuomotor task involving the interaction with the same virtual cubes. Each group interacted with a different cube where the visual (normal vs. small collider) and the virtual cube's haptic (vibration vs. no vibration) features were manipulated. The quality of interaction (number of touches and trials performed) was used as a dependent variable to investigate the performance in the visuomotor task. To measure bias in size perception, we compared changes in point of subjective equality (PSE) before and after the task in the four groups. The results showed that a small visual collider decreased manipulation performance, regardless of the presence or not of the haptic signal. However, change in PSE was found only in the group exposed to the small visual collider with haptic feedback, leading to increased perception of the cube size. This after-effect was absent in the only visual incongruency condition, suggesting that haptic information and multisensory integration played a crucial role in inducing perceptual changes. The results are discussed considering the recent findings in visual-haptic integration during multisensory information processing in real and virtual environments

Redefining Access: Embracing multimodality, memorability and shared experience in Museums

Disability access to museums, both physical and intellectual, is generally considered a minority issue. Whilst museums and cultural institutions acknowledge the moral and legal importance of equal access to their establishments, there is generally a conflict between the perceived number of potential visitors that will benefit and the cost implications. Set in the context of research on multisensory learning, this article discusses why disability access is, in fact, a majority issue. It discusses two case studies where an “access for all” museological approach has been applied to access to the collections, with differing success. The article considers how an “access for all” approach would potentially enhance learning, long-term memorability and the ‘cultural value’ of a museum experience for all visitors

The meaning of the virtual Midas touch: An ERP study in economic decision making

The Midas touch refers to the altruistic effects of a brief touch. Though these effects have often been replicated, they remain poorly understood. We investigate the psychophysiology of the effect using remotely transmitted, precisely timed, tactile messages in an economic decision-making game called Ultimatum. Participants were more likely to accept offers after receiving a remotely transmitted touch. Furthermore, we found distinct effects of touch on event-related potentials evoked by (a) feedback regarding accepted and rejected offers, (b) decision cues related to proposals, and (c) the haptic and auditory cues themselves. In each case, a late positive effect of touch was observed and related to the P3. Given the role of the P3 in memory-related functions, the results indicate an indirect relationship between touch and generosity that relies on memory. This hypothesis was further tested and confirmed in the positive effects of touch on later proposals

Putting pain out of mind with an ‘out of body’ illusion

Background: Chronic pain is a growing societal concern that warrants scientific investigation, especially given the ineffectiveness of many treatments. Given evidence that pain experience relies on multisensory integration there is interest in using body ownership illusions for reducing acute pain. Aim: In the present study we investigate whether patients’ experience of chronic pain could be reduced by full body illusions (FBIs) that cause participants to dissociate from their own body. Methods: Participants with chronic pain (including sciatica, osteoarthritis, fibromyalgia, muscular pain, IBS, and back pain) viewed their own ‘virtual’ bodies via a video camera and head-mounted display for two minutes. In the ‘back stroking FBI’ their backs were stroked with a stick while they viewed synchronous or asynchronous stroking on the virtual body and in the ‘front stroking FBI’ they were stroked near their collarbone while viewing the stick approach their field of view in a synchronous or asynchronous fashion. Illusion strength and pain intensity were measured with self-report questionnaires. Results: We found that full body illusions were experienced by patients with chronic pain and further, that pain intensity was reduced by an average of 37% after illusion (synchronous) conditions. Conclusion: These findings add support to theories that high-level multisensory body representations can interact with homeostatic regulation and pain perception

Spatial sensorimotor mismatch between the motor command and somatosensory feedback decreases motor cortical excitability. A transcranial magnetic stimulation-virtual reality study.

Effective control of movement predominantly depends on the exchange and integration between sensory feedback received by our body and motor command. However, the precise mechanisms governing the adaptation of the motor system's response to altered somatosensory signals (i.e., discrepancies between an action performed and feedback received) following movement execution remain largely unclear. In order to address these questions, we developed a unique paradigm using virtual reality (VR) technology. This paradigm can induce spatial incongruence between the motor commands executed by a body district (i.e., moving the right hand) and the resulting somatosensory feedback received (i.e., feeling touch on the left ankle). We measured functional sensorimotor plasticity in 17 participants by assessing the effector's motor cortical excitability (right hand) before and after a 10-min VR task. The results revealed a decrease in motor cortical excitability of the movement effector following exposure to a 10-min conflict between the motor output and the somatosensory input, in comparison to the control condition where spatial congruence between the moved body part and the area of the body that received the feedback was maintained. This finding provides valuable insights into the functional plasticity resulting from spatial sensorimotor conflict arising from the discrepancy between the anticipated and received somatosensory feedback following movement execution. The cortical reorganization observed can be attributed to functional plasticity mechanisms within the sensorimotor cortex that are related to establishing a new connection between somatosensory input and motor output, guided by temporal binding and the Hebbian plasticity rule

Tactile Change Blindness Induced by Tactile and Visual Distractors

Change blindness studies have revealed people's inability to detect changes between two consecutively presented scenes when they are separated by a distractor. This failure has been reported within vision, audition, and touch but also crossmodally. In particular, participants' performance in detecting changes in position between two tactile scenes is impaired not only when a tactile mask is introduced between the two to-be-compared displays but also when a visual mask is used instead. Interestingly, with similar procedure, there is no effect of auditory masks on a tactile task or of tactile masks on a visual task (Auvray et al., 2007, 2008; Gallace et al., 2006). Such crossmodal change blindness effect also occurs when participants perform a different task. In a recent experiment, participants had to detect changes in the frequency of presentation of tactile stimuli. The two to-be-compared sequences of three tactile stimuli were presented either at a same or at a different rate. They were presented either consecutively, separated by an empty interval, a tactile, visual, or auditory mask. The visual and tactile masks significantly impaired participants' performance whereas the auditory mask had no effect on performance. These findings are discussed in relation to the crossmodal nature of attention