Dogs are the world's oldest domesticated species, with around 15,000 year since they evolved from the wolf, much of human and dog evolution has been intertwined. But so far we have only been able to guess from behaviour what they might be thinking.

It is widely acknowledged that dogs are smart, and that we have many different methods of communicating between each other. But how does that word or hand signal get converted in the dogs brain into action?

For the first time scientists have used functional magnetic resonance imaging (fMRI) to study the brain function of dogs. The breakthrough required these un anaesthetised dogs to hold their heads still enough while unrestrained, so that the high resolution 3 D scans could be taken of their brains during commands.

THE DOG BRAIN EXPERIMENT METHOD

To create a baseline it was decided to use a simple discrimination task with two human hand signals for initial study.  It was described to use hand signals with primary rewards to provide a linkage with comparable imaging experiments on humans and monkeys.

" The reward-prediction error hypothesis of the dopamine system provides a concrete prediction of activity in the ventral caudate  (section of the brain) of the dog. The task was designed to determine which brain circuits differentially respond to hand signals denoting the presence or absence of a food reward." For the experiments they used two fixed female domestic dogs. One was a mix breed two year old who was adopted from a shelter at age nine months and weighed 12 kg. She had basic training by her owner, The second dog was a three year old 16 kg border collie trained in agility.

THE DOG BRAIN EXPERIMENT

"A hand signal was given that indicated the presence or absence of a food reward that would be received. The left hand up indicated a hot dog reward, while both hands pointing toward each other horizontally indicated no reward. The hand signals were chosen to be easily distinguishable and were maintained for approximately 10 s."

Of course there were training methods to keep the dogs heads very still during the scans. And also calibration of the machines to ensure scan noise was kept to a minimum.

·         For Callie, there were 19 reward trials and 20 no-reward,
·         for McKenzie, 16 reward and 11 no-reward trials

To prevent harm to the dogs they were trained to wear ear muffs and head wraps that reduced the effects of the scanner noise to acceptable levels. They were completely unrestrained and able to leave the machine at any time.

THE DOG BRAIN EXPERIMENT RESULTS

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The right caudate region was found to 'fire' in both dogs under reward hand signals and a NO reward signal resulted in inactivity in this section of the brain.

" The reward prediction error hypothesis of dopamine function suggests that dopamine is released in response to unexpected events that signal future reward.  Thus, it is likely that the caudate signal we observed represents a positive reward prediction to the dog. "

Dopamine is related to pleasure in human and dog brains. It is believed that due to training conditioning that the dog's expectation of a reward (upon the reward signal) released dopamine and activates the part of the brain observed.  Apart from this, they speculated that some component of the brain activity was related to  social reward (the treat being provided by the owner).
It was found that McKenzie the border collie had a much stronger response to the reward hand signals, which could be to do with being rewarded for agility training, and having a strong response to hand signals in general in training.

The observations  of ventral caudate activation are a breakthrough, not only because of the dogs staying still enough to get clear fMRI images, but because each scan took so long and the correlation with hand signals and food reward for each dog was so strong.

CONCLUSION

It is believed that this is the first experiment on dogs with  MRI or fMRI where the dogs are completely awake and unrestrained. Callie was able to stay very still for up to periods of 24 seconds, and  with advances in fMRI technology it may  be possible to gain more detailed brain scans.

Further studies may be able to ascertain what parts of the dog brain are active under other tasks such as when they analyse their owners faces (for emotions) or when they use their gaze to see where owner's are pointing. Experiments may be performed to see  how dogs distinguish humans  - is it by vision or smell? Finding out which parts of the brain fire under given conditions may work out the thought processes that dogs put together.

The complexity in space, timing and intensity of thought within the dogs brain may yet be uncovered so that we can not only train them better, but we may find out what really makes them happy.

Article by Bruce Dwyer. If you wish to use any of this information please use a LINK reference to http://www.dogwalkersmelbourne.com.au

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Reference: Functional MRI in Awake Unrestrained Dogs - Gregory S. Berns  (2012)