New York, Nov 19 (IANS): A new technique that makes mouse brains transparent has revealed how the brain responds to cocaine addiction and fear.

The findings could uncover new brain circuits involved in drug response.

"It is apparent that complex behaviours such as addiction are due to connections and cross-talk between different parts of the brain rather than activity in a single area," said Karl Deisseroth from Stanford University in California, US.

In the technique known as CLARITY, brains were infused with a chemical compound called acrylamide which forms a matrix in the cells and preserves their structure along with the DNA and proteins inside them.

The organs were then treated with a detergent that left the cells completely clear and visible.

The team is now planning to engineer mice so that the pathways identified in this research can be activated by a flash of light to see whether this causes the mice to act as if they are fearful or happy.

The team presented the results at the conference of the US National Institute on Drug Abuse in Bethesda, Maryland, recently.