This is Scientific Americans 60 Second Science.

I'm Karen Hopkins.

Everyone knows what it's like to itch,

and the sensation can drive you mad.

Or if you're Yanggau Sun of the Chinese Academy of Sciences,

it can drive you to explore how the brain tells you it's time to scratch.

Our study is aiming to understand the brain mechanism that promote the each scratching cycle.

Itching can be caused by a number of irritants, from allergic reactions and abrasive textures to bug bites, skin conditions, infections or drugs.

The usual solution is to simply scratch.

But this cycle of itching and scratching, if it continues unabated, can actually damage tissue, like if you scratch yourself raw.

And Sun notes that...

Effective treatment for a chronic age is still lacking.

This is largely due to our limited knowledge about the neural mechanism of each.

Over the past 10 years, scientists have learned a lot about how the itch signal is carried from the skin to the spinal cord.

In contrast, we know very little about how each information is processing the brain and how the brain can dynamically modulate the processing of each.

Sun and his colleagues focus their attention on the peri aqueductile gray, a brain region known

to be involved in handling the closely related sensation of pain.

They started by exposing mice to histamine, or the anti-malarial drug chloroquine, both of which trigger scratching.

And they found that this itch-inducing treatment activates a particular set of neurons within

the peri aqueductile gray, neurons that produce a neurochemical called tach 1.

When the researchers eliminated this set of neurons, scratching was significantly diminished.

And when they activated the neurons, even in the absence of a chemical irritant, the scratching resumed. the Getting these neurons firing makes animals itchy and gets them to scratch.

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