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In an anatomy classroom in 1990, the gathered medical students were instructed to inject an anaesthetised dog with various drugs to study how they affected its heart rate and blood pressure. At the end of the lesson, they were told to euthanise the animal. Reluctantly, Gregory Berns shouldered that responsibility. Today, still haunted by the memory, Berns advocates treating animals in experiments as if they were humans – by acknowledging that they have feelings and experience the world as we do. He has functional MRI scans to make his case.

What made you put dogs in an MRI scanner?

Strangely enough, it started with the 2011 mission that killed Bin Laden. There was a dog on that mission. I thought, if dogs can be trained to jump out of helicopters and work in noisy environments, then we can train them to go in an MRI machine – which sounds like a jackhammer when you are inside it. I wanted to know what dogs were thinking. Is it just about food or do they have any emotions similar to ours? My favourite pet dog had died months earlier. Maybe subconsciously I had wondered if he’d experienced anything similar to the feelings of love that I had for him.

How difficult is it to teach a dog to play along?

It’s actually not that difficult, but I’m saying that with hindsight, having trained almost 100 dogs to do it. First, we created MRI simulators, starting with bits of construction tubing on a table. We built the elements of the head coil that picks up the signals. Once we’d figured out how to make a chin rest that dogs could put their head on to ensure a consistent and stable position, the behaviour itself is easy for the dogs. It’s just lying down and staying. Then it’s a matter of gradually getting them used to the banging noise of the MRI.

What are your ethical guidelines?

They go beyond what’s legally required. We don’t give dogs any sedation or anaesthesia, or restrain them. If they don’t want to be in the scanner, they can get up and leave. Sometimes they do. Self-determination is critical: animals in experiments are rarely given that right.

Why do you study dogs?

Neuroscience has concentrated on just a few species. We know a lot about ourselves, rats and mice, and something about monkeys. But in many ways, dogs are even closer to humans than monkeys, because they are the only other species that truly share our social environment. They can tell us things no other animal can: we are blazing a path in studying the evolution of cross-species sociality.

What do other scientists think about this work?

It’s mixed, but a common criticism is, “you can always design behavioural experiments to learn about the internal state of a dog. You don’t need brain imaging to tell you.”

I don’t agree. Dogs are not like rats or monkeys. In evolving from wolves, dogs’ strategy has been to attach themselves to us, and that’s very effective – just look at all the dogs in the world. So in any behavioural test, pet dogs especially look towards the human to solve the problem for them. That makes it very hard to design good behavioural tests for dogs as you are constantly battling their tendency to look to the human. And people cannot help it: if the dog can see you, it’s all too easy to give subtle signals that the dog will pick up.

What have you seen with MRI scanning that you couldn’t get with a behavioural experiment?

Functional MRI data tells us something about mental states that we can’t get just by looking at outward behaviour. For example, we did an MRI study on 50 dogs in collaboration with a group that trains service dogs – at significant expense – for people with disabilities. The goal was to see if we could predict, based on brain activity alone, whether a dog would be useful for people with disabilities. We found we could.

What did you do to test the dogs?

After training the dogs to lie still in the scanner, we presented them with hand signals, either from their trainer or a stranger, indicating that a food treat was coming or not. The reaction in the brain showed that the animals were responding to the two humans differently. This was particularly evident with activity in the caudate nucleus, the structure in mammal brains that signals anticipation of something important, and the amygdala, which is linked to the level of emotional arousal or anxiety an animal is experiencing.

“If the dogs don’t want to be in the MRI scanner, they can get up and leave”

Dogs that responded strongly in the caudate nucleus regardless of who gave the hand signals were highly likely to have a successful placement. A strong response in the amygdala to the stranger correlated to the dog ultimately failing its service training.

How do you interpret these results in terms of possible mental states?

The dogs were simply lying down, so there was no behaviour to suggest differences in mental states. But the caudate activity suggested that dogs who attached a higher incentive value to the hand signals were the ones who eventually became good service dogs. Perhaps this is a measure of motivation. In contrast, higher amygdala activity in the dogs – perhaps from anxiety or excitement – indicated that they were experiencing arousal without showing it.

How could this approach be better than a behavioural one?

By focusing on internal states, we may be able to detect emotions before they lead to problem behaviours. We could reinforce “good” internal states with praise and play, and decrease “bad” states through calming approaches.

In your book, you say philosopher Thomas Nagel’s 1974 essay, “What is it like to be a bat?”, cast a long shadow over neuroscience. Why?

That essay basically said it doesn’t matter how much you study the brain, you’ll never know what it’s like inside another brain or mind.

He picked bats because they fly and because they echolocate, unlike humans. But that’s no longer true. Now, people put on wingsuits and jump from cliffs. So they know what it’s like to fly and can tell us about the experience. Even the echolocation argument is false, because people can echolocate: we can all tell the dimensions of a room, and whether it has hard or soft surfaces, just by how it sounds.

So what’s your take-home message?

That pretty much all mammals have basically the same sensory experiences, albeit enhanced or degraded in different ways. Denying this allows scientists to do experiments on animals that we wouldn’t do on a person, because we supposedly don’t know what the animal is experiencing. But I think we do know: when we see similar structures and functions in the brains of other animals, they are very likely having similar subjective experiences. It’s easier to ignore their plight if you sweep their sentience under the rug.

This article appeared in print under the headline “I know what your dog is thinking”