McKenzie reacted the same way Callie had. As soon as the buzzing started, she scooted out of the magnet. We did this three, four times, and despite the earmuffs, McKenzie was not having any part of it.
“What do you think we should do?” I asked Mark.
“The problem seems to be the sudden onset,” he said. “The dogs are comfortable in the magnet when it’s quiet, but the scanner starts without warning and scares them.”
I turned to Sinyeob: “Can we start the scan before the dog is in there, and then get her to go in while it’s running?”
He shook his head. “No, the scanner won’t run with nothing inside.”
“Maybe we could mask the transition,” Mark suggested. “I’ll make some noise before the scan starts to distract McKenzie.”
Now on the fifth try, Melissa once again coaxed McKenzie into the MRI. Mark started whooping and hollering at her. Then the shimming began. Maybe it was Mark’s carrying on, or maybe she had finally gotten used to it, but McKenzie stayed put. At least until the klaxon of the localizer began.
She’d been so close.
“Did it complete the shim?”
“Yes,” Sinyeob said, “but she moved before the localizer.” It was almost five o’clock, and we were just about out of time.
“Let’s skip the localizer and go right to the functionals,” I said. “The chin rest should put her head in the same location as Callie’s. We’ll just use the same orientation and field of view that we used on Callie.”
Andrew took up his position at the rear of the scanner and prepared to cue Melissa on peas and hot dogs. Mark started carrying on, making a ruckus to distract McKenzie from the sudden onset of the functional scan. Robert hit the start button.
I fully expected to see McKenzie’s butt start backing out of the magnet. But she didn’t. Mark stopped hollering. Images started appearing on the scanner console. At first, a nose poked into the field of view. Then part of a brain. And a little more. And then it would disappear, only to reemerge a few seconds later.
McKenzie was staying in the scanner. Melissa was putting up hand signals and feeding peas and hot dogs. From outward appearances, McKenzie was doing even better with this part of the scan than Callie had. The images popping up on the screen clearly showed McKenzie’s brain, and they weren’t moving, which meant that she was holding her head perfectly still.
The only problem was that her head was on the edge of the field of view. Even though she wasn’t moving, we were capturing only the front half of her brain. This was a direct consequence of setting the field of view without a localizer image. We’d shot blind and missed by an inch.
I let the functional sequence run for the full five minutes. Even if we wouldn’t be able to use her data this time, it was good training for Melissa and McKenzie. When it was done, I gave them the report.
“The good news is that McKenzie held her head still,” I said. “The bad news is that we got only half her brain.”
“McKenzie’s not too tired,” Melissa said. “We could try again.”
“If you could get her to scoot her head forward an inch,” I said, “that would help.”
Mark, Melissa, I, Sinyeob, Robert, Lisa, and Kristina study the first functional images.
(Bryan Meltz)
Once again, everyone took their positions, and with McKenzie resettled in the magnet, we went through the protocol for what seemed like the hundredth time that day. This time, her head was closer to the center of the field of view. Some images were still clipped, but overall, the run looked very good.
Between Callie and McKenzie, we had exceeded our goal of acquiring a sequence of ten functional images. Even if we had only a partial scan of McKenzie, we had almost one hundred images of both dogs—enough to do a crude analysis of brain activation comparing hand signals for peas and hot dogs.
When we got home, Callie ran right to the kitchen. Even though she had spent the entire afternoon consuming peas and hot dogs, her appetite had not diminished in the slightest. She stood expectantly next to her food bowl. So, where’s my dinner?
Lyra detected the foreign smells of the hospital and sniffed Callie from head to tail. Satisfied that it was still Callie, Lyra wagged her tail and let out a few yippy barks of recognition.
Helen plopped down on the sofa.
“So,” I said, “what did you think?”
“It was pretty cool.”
“Science doesn’t always go the way they teach it at school,” I said. “You never know what will happen.” I paused and continued. “I’m really glad you came today. It was fun having you there.”
Helen nodded her head, and I gave her a hug.
16
A New World
THAT NIGHT, CALLIE CURLED UP in her usual spot on the bed. Exhausted from the day of scanning, she immediately fell into a deep sleep, snoring softly. But I was still too jacked up; for the second night in a row, I didn’t sleep. Images of Callie’s brain danced in my head. But I had no idea what we had actually done. Dog brains were going to be our new world, but we had no map.
It turned out that the dogs’ brains looked nothing like a human’s brain. Apart from the size difference, many of the landmarks that I had become accustomed to seeing in human brains were either absent in the dogs or distorted into unrecognizable shapes. Now that we had dog brain scans, Andrew and I would have to grapple with interpreting all that data.
Dog brains and human brains differ in two important ways: structure and function. Brain structure refers to its shape. You don’t need to be a neuroscientist to see that humans and dogs have brains of different shapes. The brain structure consists of the different parts of the brain and their location relative to one another. This is why neuroscientists refer to prominent parts of the brain as landmarks. Obvious landmarks in all brains include the brainstem and spinal cord, the cerebellum, the ventricles (which make the cerebrospinal fluid), the corpus callosum (which connects the left and right sides of the brain), and a few structures in the basal ganglia—part of MacLean’s reptilian brain.
The dog brain (left) and the human brain (right). (Not to scale.)
(Dog brain image by permission of Thomas Fletcher, University of Minnesota; human brain by Gregory Berns)
But even with these landmarks, the largest part of the brain—the cerebral cortex—is radically different in dogs and humans. Presumably, that is what makes us different from each other.
Imagine comparing a map of the United States to a map of France. What can you deduce about these countries from looking at their maps? There is an obvious difference in size, but that doesn’t say much. Based on the arrangement of roads, the maps would give you a sense of where hubs of activity lie. Many roads lead to Paris, and you might correctly conclude that Paris is a key center in France. You would also notice important port cities like Marseille and Bordeaux and guess that these cities are centers of trade. In comparison, there is no obvious center of activity in the United States, but the road map would give you much of the same kind of information. The Northeast Corridor, from Washington, DC, to New York, immediately stands out, and you would be correct in assuming that this region is a critical center of government and economic activity. Similarly, coastal cities like Boston, Houston, Los Angeles, and San Francisco would stand out as centers of trade.