Like our human studies, the Dog Project would qualify as minimal risk. So we simply copied a consent form that we had used in one of our previous fMRI studies of children. Wherever the words your child appeared, we replaced them with your dog.

That left the dog itself. Since a dog can’t sign a form, how would we detect the canine equivalent of assent? With a child, assent is usually determined by asking the child. If he is old enough, he can sign a document of assent, which is a child-friendly version of the consent form. But if he is too young to understand or to express himself, the researcher must rely on his behavior. For example, if a mother signs up for a research project with her infant and the baby shows obvious signs of distress, like inconsolable crying, the researcher should interpret this as a sign that the baby doesn’t want to participate, and the experiment should be stopped.

We could do the same thing with dogs and treat them like infant research subjects. If they showed any signs of not wanting to participate, we would stop the experiment. The simplest way to do this would be to dispense with restraints. If a dog didn’t want to be in the MRI scanner anymore, he could simply get out. Same as a human.

Never mind that all previous animal research treated animals as property. Elevating the rights of a dog to that of a human child made both ethical and scientific sense. It was the right thing to do and it would result in better-quality data too. If the dog didn’t want to be in the scanner, the data would be useless anyway. And if he were strapped down, we might not even know that he didn’t want to be there.

With the ethics squared away, it was time to go back to the IACUC with our proposal. The committee was happy with the consent form and pleased that Sarah Putney had helped draft the language. That left just a lineup of university administrators ready to say no.

First up was risk management. The sole purpose of this department is to minimize the chance of anything bad happening. The risk management department looks at research starting with the worst-case scenario. What is the most catastrophic thing that could happen, how would that damage the university’s reputation, and what would it cost the university to defend itself in court?

Although we said “dog,” I think risk management heard “Cujo,” after Stephen King’s fictional rabid Saint Bernard. Worst-case scenario: dog escapes, runs amok on campus, bites student, student gets rabies and dies. Because we would not be scanning at Yerkes, the dogs would have to be under control at all times, particularly when they were being transported to the MRI scanner at the Emory University Hospital. Fortunately, the MRI room had a door leading directly to the outside of the building. We could walk the dogs right up to the door without having to go through crowded corridors. Risk management liked that. It minimized the chance of inadvertent human contact. On the inside, there were three doors between the MRI room and the rest of the hospital, so there was no chance a dog was going to escape once inside the scanner room.

Next up was employee health. Working with animals created an occupational hazard. What if somebody on the research team was allergic to dogs? Could the dogs leave dander in the MRI that would cause a reaction in someone who went in the scanner afterward? The solution to the first question was for all members of the lab to certify that they were not allergic to dogs. Most of the team had dogs, so this wasn’t a problem. To deal with the dog dander, we would dispose of the linens and wipe down the scanner with disinfectant.

The only remaining hurdle was the biosafety office. The biosafety officer was also concerned about rabies. She suggested that the research team receive preventive rabies vaccinations. Never mind that there have been no cases of human rabies in the United States resulting from a domestic dog bite in the last decade. Because all the volunteer dogs in our study would have proof of vaccination, the chances of contracting rabies from them would be essentially zero. The risks from the vaccine were far greater. The preventive rabies vaccination requires three shots over a month, and 50 to 75 percent of people receiving it get mild to moderate side effects, including headaches, nausea, dizziness, abdominal pain, and fever. No thanks. After being confronted with this data from the CDC, the biosafety office backed down and agreed that the risks from vaccination were greater than the risks of contracting rabies from a domestic dog.

With the final administrative hurdle cleared, the army of lawyers signed off on the Dog Project. We received approval to initially study up to ten dogs. If things went well, we could seek approval for more dogs after that.

Now we just had to find some subjects.

8

The Simulator

WITH THE ISSUE OF where to scan the dogs out of the way, we could turn our attention to acclimating the dogs to the MRI. This meant that we would have to build an MRI simulator.

The entire project hinged on a dog’s ability to hold its head still while in the scanner. But training a dog to hold its head still was going to be the easy part. Doing it in an MRI was a different story. The interior of the MRI scanner is six feet long and less than two feet in diameter. Many people don’t like being stuck in a coffin-sized tube. Fortunately, dogs aren’t like humans, and many breeds actually like to be in small spaces. Callie, being of the terrier family, had no such fears and loved to tunnel under ivy and into holes. Even so, all the dogs that were going to participate in the study would need to be trained to go into a tube of the exact dimensions of the MRI. Once they were acclimated to the tube, they would then have to be trained to put their head into the head coil. The coil, which is nicknamed the “birdcage” because of the resemblance, is even smaller than the MRI tube. The dog would need to shimmy its body and head into the center of the birdcage.

The second, more difficult aspect of the MRI was the noise. MRIs are loud. When performing a functional scan, the MRI sounds like a machine gun. At nearly 100 decibels, being in an MRI is like standing next to a leaf blower. Although not terribly painful for humans, dogs have more sensitive hearing, and we worried about damaging their ears. Also, many dogs are just plain afraid of loud noises. It would do no good to scan the brain of an anxious, frightened dog. Not only would we need to find dogs with a calm temperament, we would still need to get them used to the noise. The simulator had to mimic this key aspect of the MRI procedure.

It is commonly believed that dogs have more sensitive hearing than humans. But how much more? At the low end, humans can hear frequencies of about 8 Hz, which sounds like a very deep vibration. The high end is limited to about 20,000 Hz. This range tends to shrink with age, with the high frequencies being lost to ear damage from loud noises over the years. Most human speech is in the 300 to 3,000 Hz range. The first investigation of dogs’ hearing was done in the 1940s. But because sound-generation technology was limited at the time, the scientists couldn’t generate very high frequencies, and they couldn’t determine the dogs’ upper frequency range. It wasn’t until the 1980s that technology could reliably generate high-frequency tones. In the 1990s, an even more sophisticated technique was developed. This technique measures electrical responses in the part of the dog’s brain that responds to sound. These brainstem auditory evoked responses, or BAERs, are also used in humans. Today, most scientists agree that dogs can hear tones up to about 60,000 Hz, well beyond the human range.