Until now, imaging a brain during activity was impossible. The common technique in research labs has been anesthetizing a rat and then using Positron Emission Tomography, or PET, scans. But now researchers from Brookhaven National Laboratory have created a PET head cover that allows them to study a rat's brain as it navigates a maze or enjoys a hunk of cheese.
The Rat Conscious Animal PET, or the RatCAP, is a donut-shaped cover that fits on a rat's head. It weighs only 250 grams and is further designed to not interfere with rat movement by containing a set of springs and motion stabilizers. After a rat is injected with a radioactive molecule, a tracer that emits gamma rays that the PET can detect, they are set free on the wheel or maze or whatever lab task the researchers have in mind.
In initial studies with the RatCAP, the researchers used a tracer that showed the levels of dopamine in the brain during different levels of activity. The brain levels of dopamine, a chemical involved in movement, memory and reward-response reactions, were previously thought to increase with activity. Surprisingly though, the more active the rats in caps were, the less of the chemical that showed up in the scan.
The RatCAP will especially intrigue neurologists who typically only study behavior and can now combine their work with precise brain imaging, or scientists concerned only with the chemicals and molecular processes in the brain who can extend their work to behavior. In the video below, Brookhaven scientist Paul Vaska explains more about work.