What are these rodents thinking? Thanks to the RatCAP we may be closer to finding out.
Scientists are able to peer into the minds of fully awake, moving animals, thanks to the development of a miniature brain scanning device.
Normally for a brain scan to work, the subject has to be immobile within the scanner. This isn’t such a problem for humans, who can be told to lie still, but when scientists perform brain scans on laboratory animals, the animals must be anaesthetised or restrained.
As a result, much of our knowledge of how the brain works when animals or humans are moving around (that is, most of the time) is based on extrapolation and conjecture.
The new scanner, developed by scientists at Brookhaven National Laboratory in the US, weighs only 250 grams and contains built in motion stabilisers. It is therefore ‘worn’ quite easily by laboratory rats.
The ‘RatCAP’, as the device is named, is presented together with results from the first experiments to use it, in the April edition of Nature Methods.
Those first studies imply that our understanding of how neurotransmitters – the chemicals that brain cells use to communicate with each other – influence behaviour might require some modification.
The Brookhaven scientists looked at how levels of the neurotransmitter dopamine changed with the rodents’ behaviour. They found that as the rats became more active, their dopamine levels decreased.
As Dr Daniela Schulz, the lead author of the paper, explained: “This is perhaps a counterintuitive result because behavioural activation is typically associated with an increase in dopamine release. So [the RatCAP] provides data which may challenge traditional paradigms and ultimately improve our understanding of the dopamine system.”
Rats’ brains are, of course, very different from humans’ brains. Nonetheless, similar future studies using the RatCAP may have implications for medicine. Disturbance of the dopamine system is thought to play a key role in addiction and a number of mental health conditions, particularly schizophrenia and depression.
The RatCAP is in fact a miniature Positron Emission Tomography (PET) scanner. PET scanning has applications in human medicine, particularly as a diagnostic tool in oncology and neurology, but is used sparingly as it requires a radioactive substance to be introduced into the body.
Schulz, D., Southekal, S., Junnarkar, S., Pratte, J., Purschke, M., Stoll, S., Ravindranath, B., Maramraju, S., Krishnamoorthy, S., Henn, F., O’Connor, P., Woody, C., Schlyer, D., & Vaska, P. (2011). Simultaneous assessment of rodent behavior and neurochemistry using a miniature positron emission tomograph Nature Methods DOI: 10.1038/nmeth.1582
Image: Tatiana Bulyonkova (Flickr)
Other Elements articles in which you might be interested:
Good post. The result about dopamine is very counterintuitive but interesting.