Medical Research Council - London Institute of Medical Sciences

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Itchy and Scratchy
13 March 2014

Itchy and Scratchy

We all know how hard it is to resist scratching an itch. This natural response is part of a cycle; when you feel an itch, the sudden need to scratch can be strong. Scratching then leads to relief and to feelings of pleasure. Pictured are brain maps from functional magnetic resonance imaging (fMRI) showing the parts involved during the itch-scratch cycle. Cowhage – a hairy plant – was used to irritate the skin (activating the red-orange areas) and make the subjects scratch (activating the yellow areas). The results show that during scratching more areas of the brain are linked to pleasure, rather than relief. While relief-associated areas are known to be involved in the reward circuit, they were deactivated during scratching. Nevertheless, a feeling of reward was evoked by the drop in the intensity of the itch and the pleasure that arose from scratching – two mechanisms working together to neutralise the itch.

Written by Katie Panteli

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