Il solo guardare diminuisce il dolore e se s’immagina più grande la parte del corpo da cui proviene quella sensazione, allora si avrà una conseguente riduzione del dolore stesso: è la conclusione di una ricerca dell’University College di Londra e dell’Università di Milano-Bicocca.

Per giungere a queste conclusioni, i ricercatori, si sono avvalsi della collaborazione di 18 volontari, ai quali, è stata posta nella mano sinistra una sonda termica, che aumentava gradatamente la temperatura ed un pedale da premere, per segnalare quando questo provocava dolore.

Durante l’esperimento, i ricercatori hanno usato specchi, anche concavi o convessi, facendo o no vedere la mano, normale, ingrandita o più piccola e registrato le temperature alle quali, secondo lo specchio usato o se si visualizzava la mano od un altro oggetto, i volontari sentivano dolore.

I risultati, evidenziavano che il solo visualizzare la mano con la sonda, permetteva di alzare di 3° C, la soglia del dolore, rispetto a chi non la visualizzava e che usando specchi che ingrandivano la mano, si alzava ulteriormente la soglia del dolore.

Usando uno specchio, che ne diminuiva le dimensioni, la soglia del dolore diminuiva arrivando a temperature più basse di, quando si visualizzava la mano a dimensioni normali.

Per Flavia Mancini autore dello studio, pubblicato su Psychological Science, insieme al professor Patrick Haggard, “L’immagine che il cervello mostra del nostro corpo ha una forte correlazione sul livello del dolore. Inoltre il modo stesso in cui il nostro corpo viene rappresentato influenza la percezione del dolore.” – “Ad esempio, quando un bambino va dal medico per un esame del sangue, diciamo loro che farà meno male se non guarda l’ago” – dichiara il professor – “I nostri risultati suggeriscono che dovrebbero guardare il loro braccio, ma cercando di evitare di vedere l’ago, se questo è possibile!”. Leggi l’articolo completo qui http://bbk.ac.uk/psychology/bodylab/docs/maninciEtal-psycholsci-2011.pdf

Visual Distortion of Body Size Modulates Pain Perception, Psychological Science, January 2011, Flavia Mancini1^,2, Matthew R. Longo1^,3, Marjolein P.M. Kammers1 and Patrick Haggard1 Author Affiliations

¹Institute of Cognitive Neuroscience, University College London ²Department of Psychology, University of Milano-Bicocca ³Department of Psychological Sciences, Birkbeck, University of London

Flavia Mancini, Institute of Cognitive Neuroscience, University College London, 17 Queen Square, London WC1N 3AR, United Kingdom E-mail: f.mancini@ucl.ac.uk

Abstract

Pain is a complex subjective experience that is shaped by numerous contextual factors. For example, simply viewing the body reduces the reported intensity of acute physical pain. In this study, we investigated whether this visually induced analgesia is modulated by the visual size of the stimulated body part. We measured contact heat-pain thresholds while participants viewed either their own hand or a neutral object in three size conditions: reduced, actual size, or enlarged. Vision of the body was analgesic, increasing heat-pain thresholds by an average of 3.2 °C. We further found that visual enlargement of the viewed hand enhanced analgesia, whereas visual reduction of the hand decreased analgesia. These results demonstrate that pain perception depends on multisensory representations of the body and that visual distortions of body size modulate sensory components of pain. http://pss.sagepub.com/content/early/2011/02/07/0956797611398496.abstract

Look at your body to reduce pain. Simply looking at your body reduces pain, according to new research by BBSRC-funded scientists from UCL (University College London) and the University of Milano-Bicocca, Italy.

The team has been studying the relationships between sensory experiences – touch or pain, for example – bodily actions such as movement, and how it is that the brain is able to modify actions and sensory processing based on our perception of our own body as distinct from external objects. By understanding the fundamentals of how our brains and bodies integrate in this way, we can appreciate the bioscience that underpins many elements of physical and mental wellbeing.

Published in the journal Psychological Science, this new research shows that viewing your hand reduces the pain experienced when a hot object touches the skin. Furthermore, the level of pain depended on how large the hand looked – the larger the hand the greater the effect of pain reduction.

Flavia Mancini, the first author of the study, said “The image that the brain forms of our own body has a strong effect on the experienced level of pain. Moreover, the way the body is represented influences the level of pain experienced.” During the experiment, 18 participants had a heat probe placed on their left hand. The probe temperature was gradually increased, and participants stopped the heat by pressing a foot pedal as soon as they began to feel pain. The scientists used a set of mirrors to manipulate what the participants saw during the experiment. Participants always looked towards their left hand, but they either saw their own hand, or a wooden object appearing at the hand’s location. The team found that simply viewing the hand reduced pain levels: the pain threshold was about 3°C higher when looking at the hand, compared to when looking at another object. Next, the team used concave and convex mirrors to show the hand as either enlarged or reduced in size. When the hand was seen as enlarged, participants tolerated even greater levels of heat from the probe before reporting pain. When the hand was seen as smaller than its true size, participants reported pain at lower temperatures than when viewing the hand at its normal size. This suggests that the experience of pain arises in parts of the brain that represent the size of the body. The scientists’ ‘visual trick’ may have influenced the brain’s spatial maps of the skin. The results suggest that the processing of pain is closely linked to these brain maps of the skin.

Professor Patrick Haggard said: “Many psychological therapies for pain focus on the painful stimulus, for example by changing expectations, or by teaching distraction techniques. However, thinking beyond the stimulus that causes pain, to the body itself, may have novel therapeutic implications. For example, when a child goes to the doctor for a blood test, we tell them it will hurt less if they don’t look at the needle. Our results suggest that they should look at their arm, but they should try to avoid seeing the needle, if that is possible!” http://www.health.am/ab/more/look-at-your-body-to-reduce-pain/