Modulation of pain threshold by virtual body ownership

Background Appropriate sensorimotor correlations can result in the illusion of ownership of exogenous body parts. Nevertheless, whether and how the illusion of owning a new body part affects human perception, and in particular pain detection, is still poorly investigated. Recent findings have shown that seeing one’s own body is analgesic, but it is not known whether this effect is transferable to newly embodied, but exogenous, body parts. In recent years, results from our laboratory have demonstrated that a virtual body can be felt as one’s own, provided realistic multisensory correlations. Methods The current work aimed at investigating the impact of virtual body ownership on pain threshold. An immersive virtual environment allowed a first-person perspective of a virtual body that replaced the own. Passive movement of the index finger congruent with the movement of the virtual index finger was used in the “synchronous” condition to induce ownership of the virtual arm. The pain threshold was tested by thermal stimulation under four conditions: 1) synchronous movements of the real and virtual fingers, 2) asynchronous movements, 3) seeing a virtual object instead of an arm, and 4) not seeing any limb in real world. Results Our results show that, independently of attentional and stimulus adaptation processes, the ownership of a virtual arm per se can significantly increase the thermal pain threshold. Conclusions This finding may be relevant for the development and improvement of digital solutions for rehabilitation and pain treatment

Virtual Reality as a Vehicle to Empower Motor-Cognitive Neurorehabilitation.

In this paper, we advocate the combination of four key ingredients that we believe are necessary to design long-lasting effective treatments for neurorehabilitation: (i) motor-cognitive training, (ii) evidence-based neuroscience principles, in particular those related to body perception, (iii) motivational games, and (iv) empowerment techniques. Then, we propose virtual reality (VR) as the appropriate medium to encompass all the requirements mentioned above. VR is arguably one of the most suitable technologies for neurorehabilitation able to integrate evidence-based neurorehabilitation techniques and neuroscience principles into motivating training approaches that promote self-management by empowering patients to own their recovery process. We discuss the advantages and challenges of such an approach on several exemplary applications and outline directions for future developments. We strongly believe that the combination of positive psychology and positive technology mediated by VR-based interventions can heavily impact the rehabilitation outcomes of motor-cognitive functions along all the stages of the rehabilitation path

Systematic Implementation of Implicit Regularization for Multi-Loop Feynman Diagrams

Implicit Regularization (IReg) is a candidate to become an invariant framework in momentum space to perform Feynman diagram calculations to arbitrary loop order. In this work we present a systematic implementation of our method that automatically displays the terms to be subtracted by Bogoliubov's recursion formula. Therefore, we achieve a twofold objective: we show that the IReg program respects unitarity, locality and Lorentz invariance and we show that our method is consistent since we are able to display the divergent content of a multi-loop amplitude in a well defined set of basic divergent integrals in one loop momentum only which is the essence of IReg. Moreover, we conjecture that momentum routing invariance in the loops, which has been shown to be connected with gauge symmetry, is a fundamental symmetry of any Feynman diagram in a renormalizable quantum field theory

Enhanced expression of the voltage-dependent anion channel 1 (VDAC1) in Alzheimer's disease transgenic mice: an insight into the pathogenic effects of amyloid-β

The mitochondrial voltage-dependent anion channel 1 (VDAC1) is involved in the release of apoptotic proteins with possible relevance in Alzheimer's disease (AD) neuropathology. Through proteomic analysis followed by Western blotting and immunohistochemical techniques, we have found that VDAC1 is overexpressed in the hippocampus from amyloidogenic AD transgenic mice models. VDAC1 was also overexpressed in postmortem brain tissue from AD patients at an advanced stage of the disease. Interestingly, amyloid-β (Aβ) soluble oligomers were able to induce upregulation of VDAC1 in a human neuroblastoma cell line, further supporting a correlation between Aβ levels and VDAC1 expression. In hippocampal extracts from transgenic mice, a significant increase was observed in the levels of VDAC1 phosphorylated at an epitope that is susceptible to phosphorylation by glycogen synthase kinase-3β, whose activity was also increased. The levels of hexokinase I (HXKI), which interacts with VDAC1 and affects its function, were decreased in mitochondrial samples from AD models. Since phospho-VDAC and reduced HXKI levels favors a VDAC1 conformational state more prone to the release proapoptotic factors, regulation of the function of this channel may be a promising therapeutic approach to combat AD

Is my hand connected to my body? The impact of body continuity and arm alignment on the virtual hand illusion

When a rubber hand is placed on a table top in a plausible position as if part of a person"s body, and is stroked synchronously with the person"s corresponding hidden real hand, an illusion of ownership over the rubber hand can occur (Botvinick and Cohen 1998). A similar result has been found with respect to a virtual hand portrayed in a virtual environment, a virtual hand illusion (Slater et al. 2008). The conditions under which these illusions occur have been the subject of considerable study. Here we exploited the flexibility of virtual reality to examine four contributory factors: visuo-tactile synchrony while stroking the virtual and the real arms, body continuity, alignment between the real and virtual arms, and the distance between them. We carried out three experiments on a total of 32 participants where these factors were varied. The results show that the subjective illusion of ownership over the virtual arm and the time to evoke this illusion are highly dependent on synchronous visuo-tactile stimulation and on connectivity of the virtual arm with the rest of the virtual body. The alignment between the real and virtual arms and the distance between these were less important. It was found that proprioceptive drift was not a sensitive measure of the illusion, but was only related to the distance between the real and virtual arms

Obtención de Chalconas, Catalizada por Óxidos Mixtos de Al-Mg Modificadas con Metales Básicos

Los hidróxidos de doble capa son materiales pertenecientes a las arcillas aniónicas. Dichas arcillas pueden ser modificadas con determinados metales de manera de impartirles carácter básico para ser utilizadas en reacciones de química fina. En este trabajo se presenta el estudio realizado a los hidróxidos de doble capa incorporados por el método de coprecipitación, con metales como el Zn, Ni, La y Ce. Dichos materiales presentaron buena estructura, área superficial y alta basicidad. En cuanto a la actividad catalítica, se estudió la reacción de condensación para la obtención de chalconas, obteniéndose conversiones por encima de 80% con altas selectividades y pureza del producto deseado

Owning an overweight or underweight body: distinguishing the physical, experienced and virtual body

Our bodies are the most intimately familiar objects we encounter in our perceptual environment. Virtual reality provides a unique method to allow us to experience having a very different body from our own, thereby providing a valuable method to explore the plasticity of body representation. In this paper, we show that women can experience ownership over a whole virtual body that is considerably smaller or larger than their physical body. In order to gain a better understanding of the mechanisms underlying body ownership, we use an embodiment questionnaire, and introduce two new behavioral response measures: an affordance estimation task (indirect measure of body size) and a body size estimation task (direct measure of body size). Interestingly, after viewing the virtual body from first person perspective, both the affordance and the body size estimation tasks indicate a change in the perception of the size of the participant’s experienced body. The change is biased by the size of the virtual body (overweight or underweight). Another novel aspect of our study is that we distinguish between the physical, experienced and virtual bodies, by asking participants to provide affordance and body size estimations for each of the three bodies separately. This methodological point is important for virtual reality experiments investigating body ownership of a virtual body, because it offers a better understanding of which cues (e.g. visual, proprioceptive, memory, or a combination thereof) influence body perception, and whether the impact of these cues can vary between different setups