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
THE 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.