Core Sackler members Jamie Ward, Hugo Crtichley and Anil Seth along with colleague Henning Holle at the University of Hull have identified the regions of the brain responsible for ‘contagious’ itching – and discovered why some people are more prone to it than others. The project aimed to understand why some people are particularly vulnerable to itchiness when they see others scratching. Healthy volunteers filled in personality questionnaires and then underwent Functional Magnetic Resonance Imaging (fMRI) scans while being shown short videos of people either tapping or scratching parts of their arms and chest.
The paper entitled The Neural Basis of Contagious Itch and Why Some People are more Prone to it, was published on the 12th November 2012 in the journal PNAS, and showed that, while contagious itch is experienced by most – around two-thirds of those involved in the study actually scratched themselves while watching the video – the people who experience more negative emotions are more susceptible than others. We also correlated the volunteers' tendency to scratch with activity in several brain regions previously identified as part of the 'itch matrix.' Additionally, we found that the activity noted in three specific regions of the brain could be linked to subjective ratings of itchiness. Our results help people suffering from chronic itching sensations where there is no underlying dermatological cause. More generally, they point to interesting relationships between how we perceive our own body and how we perceive the world. Jamie Ward is now taking this work further to explore the neural basis of vicarious pain.
The PNAS paper recieved a large amount of media coverage; here are some selected quotes from lead researcher Henning Holle:
“Almost everyone has felt that urge to scratch when watching someone else, but no-one has ever really known why.
“It had previously been thought that empathy was responsible. But we found that neuroticism - a measure of the tendency to experience negative emotions - was positively linked to contagious itch.
“Highly neurotic people are known to be highly emotionally reactive and vulnerable to stress. We found that participants with higher neuroticism scores are also the ones that are more easily ‘infected’ by contagious itch.
“Our observed link between activity in prefrontal cortex and neuroticism might reflect that the emotionally more stable participants, with low neuroticism scores, are less susceptible to contagious itch, because they are better at suppressing the irrelevant itch sensation arising from observing someone scratch themselves.”
People:
Reference:
Holle, H., Warne, K., Seth, A. K., Critchley, H. D., & Ward, J. (2012). The neural basis of contagious itch and why some people are more prone to it. Proceedings of the National Academy of Science, USAMedia Coverage:
http://www.bbc.co.uk/news/health-20445805
http://blogs.nature.com/soapboxscience/2012/11/21/socially-contagious-itching
http://bodyodd.nbcnews.com/_news/2012/11/12/15115633-itchiness-is-contagious-just-like-yawning?lite
http://www.huffingtonpost.co.uk/2012/11/22/health-scratching-contagious-study_n_2174902.html