How Dogs Love Us: A Neuroscientist and His Adopted Dog Decode the Canine Brain (17 page)

Callie would be in the scanner, holding her head still and watching me. So many things could be going on in her brain there might not be a way to interpret the fMRI measurements. Even if we trained the dogs on a hand signal, we would still need something to compare their brain responses to. Ideally, the comparison condition would be almost the same as the thing of interest. You want to keep everything
the same in both conditions except for the one thing that is being varied in the experiment.

To measure the response to a hand signal, we needed another hand signal as a comparison condition. This way, everything would be the same—holding still, watching the handler and even the handler’s movements. We would vary the
meaning
of the signals.

“How about another hand signal,” I suggested, “which means something else?”

“Like what?” Andrew asked.

“A different type of food,” I said. “Something the dogs don’t like as much as hot dogs.”

“Like what?” Lisa asked. “Sheriff likes everything.”

It was a fine line. We wouldn’t want the dogs to eat something nasty. We needed something that they would eat but not like as much as hot dogs. Dogs are mostly carnivores. It seemed logical that they wouldn’t value a vegetable as much as a piece of meat.

“How about peas?”

Everyone nodded as they envisioned how this would work. I held up my left hand in a “stop” gesture.

“Suppose this means ‘hot dog.’ ” I thought briefly about holding up my right hand for “pea,” but as we didn’t know the extent to which dogs distinguished left and right, this seemed like a bad idea. Instead, I held both hands flat in front of my chest, pointing toward each other. “And suppose this means ‘pea’?”

Mark nodded.

“Those signals should be easily distinguishable to a dog.”

The rest of the team agreed.

It was decided. The first canine fMRI experiment would be “Peas versus Hot Dogs.”

Over the next week, Andrew and I formalized the design of the experiment, which is in some ways like writing a screenplay. Every detail
has to be planned in advance. The lab walls became our storyboard. We needed to decide how many times we would give peas and hot dogs and the order of their presentation. Dogs are very good at learning sequences of things, so we wouldn’t want to simply alternate between peas and hot dogs. If we did, the dogs would know that as soon as they got a pea, the hot dog would be coming next, and there would be no need to pay attention to the hand signals. To prevent this, the order would have to be random.

The most important detail, though, would be the timing of the experiment. Each repetition would have four elements. First, the dog would place her head in the chin rest. Because of the associated movement, this would cause artifacts on the scan being acquired at that moment. We would need to wait at least two seconds for the next scan to begin. Once the dog was settled in the chin rest and enough time had passed for the artifacts to decay, we would proceed to the second element, the hand signal.

Melissa and I would be giving the signals to our dogs, and all of our attention would be focused on Callie and McKenzie. It would be too much for us to randomly decide on the fly which hand signal to give, so Andrew would be standing next to us with a pregenerated list of the order of signals. He would hold up one finger for hot dogs and two for peas. The handler, facing the dog in the scanner, would then give the corresponding hand signal. Timing was critical.

We knew that the fMRI response would not be instantaneous. The blood vessels surrounding the neurons take a few seconds to dilate, peaking after six seconds and returning to baseline twenty seconds after that. This profile is called the
hemodynamic response function
, or HRF, and it is a bugaboo of fMRI experiments. The lag in response meant that the dogs would have to hold perfectly still for the time it took the HRF to peak and decay. This delay period was the third element. Ideally, the dog would hold still for twenty seconds. But I
would settle for ten, which would be enough time to capture at least the peak of the HRF.

Mark and Andrew and I debated whether we should just flash the hand signal for a second and then wait ten seconds before giving the reward. The alternative would be to hold up the hand signal for the entire waiting period. In the end, we opted for the latter. If we flashed the signal briefly, we wouldn’t know whether the dogs were paying attention to the appearance of the hand signal or its removal. Both could be salient. To make sure that they paid attention to the signal’s appearance, it seemed prudent to keep our hands up until we gave them the treat, which was the fourth element and the end of each sequence.

This would be easy for the hot dog repetitions. Left hand up for the signal, and then deliver the hot dog with the right hand. The pea repetitions, though, required both hands as part of the signal. This meant that the pea would have to be palmed in the right hand.

To make sure we were smooth on scan day, Melissa and I practiced all the elements over and over again. The dogs might pick up subtle changes in our body language, but there wasn’t much we could do about it other than practice.

At home, Callie and I continued working with the mockup. She was so used to it, even with the scanner noise at 95 decibels, that she was starting to get bored with the routine. She liked the hot dogs, but once inside the head coil, it was all business. No tail wagging anymore. Just a look that said,
I’m here waiting for my treats.
The day before scan day, we practiced for barely ten minutes. No sense in wearing her out.

Callie was ready. If she knew what was about to happen, she gave no sign.

I, on the other hand, could barely contain myself. We had made a
lot of progress since the dress rehearsal. The redesign of the chin rest, the modification of the scan parameters, and the choreography of the experiment were all positive developments. But still, there was a lot riding on this. Tomorrow, we would know for sure whether the Dog Project would work.

Helen had been eagerly waiting for Dog Day too. She had made an earnest attempt to improve her study habits, making flash cards and going through them diligently. The night before scan day, I kissed her good night.

“Dad,” she asked, “am I going with you to work tomorrow?”

“Yes,” I said. “I’m very proud of how hard you’ve been working. I know science is a hard class. Tomorrow you’ll see how much fun science can be.”

She smiled and gave me a hug.

There was no sleep for me that night. I lay in bed wide awake. Callie was curled up between Kat and me. I rested a hand on Callie’s smooth fur and immediately felt the calming effect of her chest rising up and down slowly. Newton had had the same calming effect, augmented by his soft snoring.

With nothing to do but let my imagination spin away, Edward Jenner popped into my head. In 1796, Jenner invented the smallpox vaccine. He had made the astute observation that women who milked cows were immune to smallpox. Jenner suspected that the blisters the milkmaids acquired from a similar disease, cowpox, contained a substance that could provide immunity to other people. Jenner tested his theory on James Phipps, the eight-year-old son of his gardener. After inoculating James with pus from a milkmaid, Jenner exposed him to the real smallpox virus. James didn’t get sick. Thanks to Jenner, the world is now rid of smallpox.

What Jenner did, though, could never be done today. He took an outrageous risk. If he had been wrong, the boy would have contracted smallpox and would probably have died. Perhaps the gardener had
no choice in the matter, but I still admire Jenner for having the courage to test his theory on a member of his own household. If today’s biomedical researchers were required to test their theories first on people they know, there would be a lot less crap making it into the scientific archives.

Callie was a part of our family. And I was about to pull a Jenner on her. I had no qualms about going into the MRI myself. I routinely volunteered for the lab’s experiments. But Callie wasn’t human. There was much we didn’t know about dogs. Mark had told me stories about dogs that had found their way home after being lost hundreds of miles away. How did they do that? Maybe they were like pigeons and had some primitive magnetic sense in their brains. Would the MRI blind Callie’s sense of direction?

We were about to venture into unknown territory. People would question what we were doing. Some might view this as animal torture, even though we had elevated the dogs’ rights to those of humans.

There was no other way. It had to be family.

15

Dog Day Afternoon

T
HE NEXT MORNING
,
HELEN HELPED
me load up the car. I couldn’t tell if she was more excited about seeing the experiment or playing hooky from school. It didn’t matter. It was great to have her along.

I’d prepared a checklist to make sure we didn’t forget anything: earmuffs, chin rest, hot dogs, peas, nylon collars and leashes with the metal removed to be MRI-safe, and plastic steps. We tried to be discreet about it, but as soon as Callie saw the chin rest, she started pogo-sticking in excitement. She followed us to the garage door and wiggled between my legs to run to the car.

The three of us arrived at the lab just before noon, and it was already packed. Since this might never happen again, we also had a photographer come to document everything. To make sure we were in compliance with the IACUC protocol and to look out for the welfare of the dogs, we had requested a veterinary technician. I had no idea who would be sent and what he or she would think about the Dog Project, but any concerns I’d had instantly disappeared when Rebeccah Hunter introduced herself. Rebeccah was young and enthusiastic
and, most important, a dog person. Callie ran over to her and jumped up to lick her face. As any dog person knows, this is a crucial test in evaluating someone’s character. Do they back away in disgust or do they lean into the doggie kiss?

Rebeccah being greeted by McKenzie.
(Bryan Meltz)

Rebeccah not only leaned in, she knelt down to Callie’s level and cooed, “Oh, what a good girl!” Callie planted one right on her lips.

I didn’t know it yet, but Rebeccah’s rapport with the dogs would be crucial in just a few hours.

Mark and Melissa soon arrived with McKenzie, and we let the dogs run around the lab to burn off nervous energy. They zoomed from person to person, making sure everyone got a good sniffing. Callie’s tail never stopped wagging. Even when lying on the floor, her tail would begin thwack-thwacking whenever someone approached
her. After ten minutes of playtime, both dogs had settled down. For what was about to happen, we wanted the dogs as calm as possible. Being a little tired would help them hold still in the MRI.

Sinyeob, I, Andrew, and Callie ponder the MRI.
(Bryan Meltz)

We swapped the dogs’ collars for nylon ones. I had replaced the standard metal D-rings and clips on these leashes with plastic equivalents. Everyone did a double-check for metal in their pockets, like keys and cell phones, and for credit cards that would be erased if they got too close to the magnet. Normally, we would do the metal check in the control room at the scanner, but in order to avoid parading the dogs through the halls of the hospital, we would be entering the MRI room directly from outside through a side door. We needed to make sure everyone who was going to be in the room was MRI-safe.

At the scanner, we were greeted by Robert Smith, the tech who would run the MRI and who had been there for Callie’s dress rehearsal, and Sinyeob Ahn, a magnetic resonance physicist from China who would tweak scanner settings for us on the fly. They both smiled when they
saw Callie and McKenzie, but I could tell neither of them thought this would actually work.

I heaved shut the vaultlike doors to the magnet room, creating a seal impenetrable by any form of electricity or radio waves. With the room secured and the doors locked, we let the dogs off-leash. Callie, of course, had been here before and knew that crumbs of food could be found on the floor of the control room. She gave only a passing glance at the magnet as she went off in search of something to eat. McKenzie gave the MRI her best border collie stare. Despite the susurrations of the cryogen pump, McKenzie soon realized that the magnet was not alive and could not be herded.