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Researchers have captured exactly what taking cocaine does to the flow of blood in the brain.

They created a laser-based method of measuring how cocaine disrupts blood flow in the brains of mice.

It shows for the first time how drug abuse affects the brain.

A side-by-side comparison of blood flow in a healthy mouse brain vs. a mouse brain exposed to cocaine. The image on the left (a) shows the mouse brain blood vessels before cocaine. The image on the right (b) shows the blood vessels after, revealing that many of the vessels are now darker, which signifies lower blood flow.

The breakthrough could help doctors and researchers better understand how drug abuse affects the brain, which may aid in improving brain-cancer surgery and tissue engineering, and lead to better treatment options for recovering drug addicts.

It was developed by a team of researchers from Stony Brook University in New York, USA and the U.S. National Institutes of Health, was published today in The Optical Society's open-access journal. 

The resulting images are the first of their kind that directly and clearly document such effects, according to co-author Yingtian Pan, associate professor in the Department of Biomedical Engineering at Stony Brook University. 

'We show that quantitative flow imaging can provide a lot of useful physiological and functional information that we haven't had access to before,' he said.

Drugs such as cocaine can cause aneurysm-like bleeding and strokes, but the exact details of what happens to the brain's blood vessels have remained elusive—partly because current imaging tools are limited in what they can see, Pan says. 

But using their new and improved methods, the team was able to observe exactly how cocaine affects the tiny blood vessels in a mouse's brain. 

The researchers were, for the first time, able to identify cocaine-induced microischemia, when blood flow is shut down—a precursor to a stroke.

The images reveal that after 30 days of chronic cocaine injection or even after just repeated acute injection of cocaine, there's a dramatic drop in blood flow speed. 

The researchers were, for the first time, able to identify cocaine-induced microischemia, when blood flow is shut down—a precursor to a stroke.

Researchers including Pan and his colleagues have developed another method called optical coherence Doppler tomography (ODT). In this technique, laser light hits the moving blood cells and bounces back. 

By measuring the shift in the reflected light's frequency—the same Doppler effect that causes the rise or fall of a siren's pitch as it moves toward or away from you—researchers can determine how fast the blood is flowing.

It turns out that ODT offers a wide field of view at high resolution. 'To my knowledge, this is a unique technology that can do both,' Pan said.  

ODT can only see down to 1-1.5 millimeters below the surface, so the method is limited to smaller animals if researchers want to probe into deeper parts of the brain. 

But, Pan says, it would still be useful when the brain's exposed in the operating room, to help surgeons operate on tumors, for example.