A technique called CLARITY makes mouse brains transparent so scientists can see how the whole brain reacts to cocaine addiction and fear. Results could provide answers regarding brain circuitry and drug response.
CLARITY infuses the brain with acrylamide, forming a connective substance in the cells while preserving their structure, DNA and proteins, according to Scientific American. The cells are then treated with a detergent that dissolves dense fats.
Neuroscientists Li Ye and Karl Deisseroth from Stanford University in California created mice that would make a fluorescent protein in their neurons. The mice were then grouped and trained to associate a certain box with painful shocks to their feet or a dose of cocaine, according to Scientific American.
Once the mice were conditioned, the neuroscientists injected them with a drug that activated the fluorescent proteins before putting them in the box for one hour.
The brains of the mice were then removed, treated with CLARITY and imaged. Three-dimensional models were made that showed what parts of the brain lit up when the mice were either afraid (because they expected shocks) or waiting for cocaine, according to Scientific American.
Deisseroth said that the experiment shows how addiction affects the entire brain and not just a single area. Ye said the next step is to breed mice so the pathways previously active by a drug injection could be activated by a flash of light, in order for researchers to see if the mice would act fearful or happy.
