Scent can be used as stimuli with dogs in fMRI machines - and it can tell us a lot about their cogni
The first example of dogs in fMRI machines was demonstrated by the Center for Neuropolicy at Emory University in Atlanta, Georgia in 2013. If you have never been in an MRI, they are very noisy (but won’t hurt you), and this can be scary to animals! Monkeys and rats need to be paralyzed or immobilized in order to participate. However, thanks to our amazing partnership with dogs, we are able to train them using positive reinforcement to lay in the fMRI machine, and even train them to be less frightened or desensitized to the noise in the scanner.
Due to our bonds with dogs, there is a level of trust that allows the dogs to be trained to enter into a circumstance they would typically be afraid, with no fear at all. This is an exciting advancement in dog science – but also could tell us tons about mammalian cognition in general, all without animal cruelty. As a fellow dog lover, I am sure you are excited about the possibility of this cruelty-free interspecies science partnership! The same researchers that discovered dogs can be trained to enter the MRI later investigated how we can use scent to better understand reward pathways in dogs. The dogs entered the fMRI, then were presented with five scents: self, familiar human, strange human, familiar dog, and strange dog. When the dogs smelled these different scents, one area of their brain was activated at different levels depending on stimuli: the caudate nucleus, considered to be a reward center in the brain. The caudate nucleus was activated most when the dog smelled the scent of a familiar human, indicating the dog recognized the scent as more rewarding than the others. This is likely due to the rewarding nature of human-canine bonds, and your dog’s cognitive understanding that familiar humans (moms, dads, siblings) are more rewarding than strangers or even other dogs. Read more about dogs in the scanner & this study specifically through the link in our bio! You won’t regret it.
You might be wondering how the dogs were able to be trained – it sounds complicated! But, it really just comes down to correctly rewarding behaviors as they become closer and closer to what you want – called shaping. The experimenters constructed a pseudo-scanner using foam and other materials, and would slowly train the dogs to enter it, and to stay there for the necessary time. Recordings of the scanner noise were also played for the dogs, first at a very low level, then slowly bringing the sound up to the level of the scanner. This is called desensitization, and it helps the dog become more comfortable with the noise. Once the dogs were fully trained to comfortably enter the pseudo-scanner with noise, they moved on to the real scanner! Since it is so similar to the training apparatus, the dogs were comfortable completing the experimental sessions.
This study tells us important things about canine social cognition that couldn’t be confirmed before. For example, that dogs find familiar humans to be more rewarding than conspecifics. This is likely due to a combination of genetic and experiential factors which have wired the dog’s brains to understand that familiar humans mean treats, fun, and lots of love.
Reference: Berns, G., Brooks, A. M., Spivak, M. (2015). Scent of the familiar: An fMRI study of canine brain responses to familiar and unfamiliar human and dog odors. Behavioural Processes, 110, 37-46. http://dx.doi.org/10.1016/j.beproc.2014.02.011