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May 07, 2012

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Pet scan indeed: Scientists map brain activity in man’s best friend

May 7, 2012
Courtesy of Carol Clark / Emory University
and World Science staff

When your dog gazes up at you ador­ing­ly, what does it see? A best friend? A pack lead­er? A can open­er?

Many dog lo­vers make in­fer­ences about how their pets feel about them, but no one has cap­tured im­ages of ac­tu­al ca­nine thought pro­cesses – un­til now.

Re­search­ers at Em­o­ry Uni­vers­ity in At­lan­ta, Ga. have de­vel­oped a meth­od to scan the brains of alert dogs to ex­plore the minds of the old­est spe­cies do­mes­ti­cat­ed by hu­mans. The tech­nique uses func­tion­al Mag­net­ic Res­o­nance Im­ag­ing or fMRI, a scan­ning tech­nol­o­gy tool that is al­so un­lock­ing se­crets of the hu­man brain.

Callie trains in a scan­ner mock-up. (Cour­tesy of Em­ory U.)

A guiding prin­ci­ple in de­vel­op­ing the tech­nique to scan dogs was that “we wanted them to be un­re­strained and go in­to the scan­ner will­ing­ly,” said Greg­o­ry Berns, di­rec­tor of the Em­o­ry Cen­ter for Neu­ro­pol­icy and lead re­search­er on dog proj­ect.

That worked out af­ter some train­ing, he added.

“It was amaz­ing to see the first brain im­ages of a fully awake, un­re­strained dog,” he said. “As far as we know, no one has been able to do this pre­vi­ously. We hope this opens up a whole new door for un­der­stand­ing ca­nine cog­ni­tion and inter-spe­cies com­mu­nica­t­ion. We want to un­der­stand the dog-hu­man rela­t­ion­ship, from the dog’s per­spec­tive.”

The re­search jour­nal PLoS One has pub­lished the re­sults of the first ex­pe­ri­ments, show­ing how the brains of dogs re­acted to hand sig­nals giv­en by their own­ers.

Two dogs are in­volved in a first phase of the proj­ect. Cal­lie is a two-year-old feist, or south­ern squirrel-hunting dog. Berns adopt­ed her at nine months from a shel­ter. Mc­Ken­zie is a three-year-old bor­der col­lie, who was al­ready well-trained in agil­ity com­pe­ti­tions by her own­er, Me­lis­sa Cate. Both pooches were trained over sev­er­al months to walk in­to an fMRI scan­ner and hold com­pletely still while re­search­ers meas­ured their neu­ral ac­ti­vity.

The re­search­ers aim to de­code dogs’ men­tal pro­cesses by re­cord­ing which ar­eas of their brains are ac­tivated by var­i­ous stim­u­li. Ul­ti­mate­ly, they hope to delve in­to ques­tions like: Do dogs have em­pa­thy? Do they know when their own­ers are hap­py or sad? How much lan­guage do they really un­der­stand?

In a first ex­pe­ri­ment, the dogs were trained to re­spond to hand sig­nals. One sig­nal meant the dog would re­ceive a hot dog treat, and an­oth­er sig­nal meant it would not re­ceive one. The brain’s cau­date re­gion, as­so­ci­at­ed with re­wards in hu­mans, showed ac­tiva­t­ion in both dogs when they saw the treat sig­nal, but not the other one, the scient­ists said. “These re­sults in­di­cate that dogs pay very close at­ten­tion to hu­man sig­nals,” Berns re­marked. “And these sig­nals may have a di­rect line to the dog’s re­ward sys­tem.”

Berns is a neu­ro­e­con­om­ist, who nor­mally uses fMRI tech­nol­o­gy to study how the hu­man mind works. His hu­man brain-imaging stud­ies have looked at ever­ything from why teens en­gage in risky be­hav­ior to how adults de­cide to fol­low, or break, rules.

Dog lo­vers may not need con­vinc­ing on the mer­its of re­searchi­ng the minds of our ca­nine com­pan­ions. “To the skep­tics out there, and the cat peo­ple, I would say that dogs are the first do­mes­ti­cat­ed spe­cies, go­ing back at least 10,000 years, and by some es­ti­mates 30,000 years,” Berns says. “The dog’s brain rep­re­sents some­thing spe­cial about how hu­mans and an­i­mals came to­geth­er. It’s pos­si­ble that dogs have even af­fect­ed hu­man ev­o­lu­tion. Peo­ple who took dogs in­to their homes and vil­lages may have had cer­tain ad­van­tages. As much as we made dogs, I think dogs probably made some part of us, too.”

Berns said he got the idea for the proj­ect about a year ago, when he heard that a U.S. Na­vy dog had been on the SEAL team that killed Osama bin Lad­en. 

“I was amazed when I saw the pic­tures of what mil­i­tary dogs can do,” Berns says. “I realized that if dogs can be trained to jump out of he­li­copters and air­planes, we could cer­tainly train them to go in­to an fMRI to see what they’re think­ing.” 

The dogs were trained to wear ear­muffs, to pro­tect them from the noise of the scan­ner. They were al­so taught to hold their heads per­fectly still on a chi­n rest dur­ing the scan­ning pro­cess, to pre­vent blur­ring of the im­ages.

“We know the dogs are hap­py by their body lan­guage,” said Mark Spi­vak, a pro­fes­sion­al train­er in­volved in the proj­ect. Cal­lie, in par­tic­u­lar, seems to rev­el in the at­ten­tion, he added. “She en­ters the scan­ner on her own, with­out a com­mand, some­times when it’s not her turn,” he said.

* * *

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When your dog gazes up at you adoringly, what does it see? A best friend? A pack leader? A can opener? Many dog lovers make inferences about how their pets feel about them, but no one has captured images of actual canine thought processes – until now. Researchers at Emory University in Atlanta, Ga. have developed a method to scan the brains of alert dogs to explore the minds of the oldest domesticated species. The technique uses functional Magnetic Resonance Imaging or fMRI, a scanning technology tool that is also unlocking secrets of the human brain. A key principle in developing the technique to scan dogs was that “we wanted them to be unrestrained and go into the scanner willingly,” which worked out after some training, said Gregory Berns, director of the Emory Center for Neuropolicy and lead researcher on dog project “It was amazing to see the first brain images of a fully awake, unrestrained dog,” he added. “As far as we know, no one has been able to do this previously. We hope this opens up a whole new door for understanding canine cognition and inter-species communication. We want to understand the dog-human relationship, from the dog’s perspective.” The research journal PLoS One has published the results of the first experiments, showing how the brains of dogs reacted to hand signals given by their owners. Two dogs are involved in a first phase of the project. Callie is a two-year-old feist, or southern squirrel-hunting dog. Berns adopted her at nine months from a shelter. McKenzie is a three-year-old border collie, who was already well-trained in agility competition by her owner, Melissa Cate. Both pooches were trained over several months to walk into an fMRI scanner and hold completely still while researchers measured their neural activity. The researchers aim to decode dogs’ mental processes by recording which areas of their brains are activated by various stimuli. Ultimately, they hope to delve into questions like: Do dogs have empathy? Do they know when their owners are happy or sad? How much language do they really understand? In a first experiment, the dogs were trained to respond to hand signals. One signal meant the dog would receive a hot dog treat, and another signal meant it would not receive one. The caudate region of the brain, associated with rewards in humans, showed activation in both dogs when they saw the signal for the treat, but not for the no-treat signal. “These results indicate that dogs pay very close attention to human signals,” Berns says. “And these signals may have a direct line to the dog’s reward system.” Berns is a neuroeconomist, who normally uses fMRI technology to study how the human mind works. His human brain-imaging studies have looked at everything from why teens engage in risky behavior to how adults decide to follow, or break, established rules of society. Dog lovers may not need convincing on the merits of researching the minds of our canine companions. “To the skeptics out there, and the cat people, I would say that dogs are the first domesticated species, going back at least 10,000 years, and by some estimates 30,000 years,” Berns says. “The dog’s brain represents something special about how humans and animals came together. It’s possible that dogs have even affected human evolution. People who took dogs into their homes and villages may have had certain advantages. As much as we made dogs, I think dogs probably made some part of us, too.” Berns said he got the idea for the project about a year ago, when he heard that a U.S. Navy dog had been on the team that killed Osama bin Laden. “I was amazed when I saw the pictures of what military dogs can do,” Berns says. “I realized that if dogs can be trained to jump out of helicopters and airplanes, we could certainly train them to go into an fMRI to see what they’re thinking.” The dogs were trained to wear earmuffs, to protect them from the noise of the scanner. They were also taught to hold their heads perfectly still on a chin rest during the scanning process, to prevent blurring of the images. “We know the dogs are happy by their body language,” says Mark Spivak, a professional trainer involved in the project. Callie, in particular, seems to revel in the attention, he added. “She enters the scanner on her own, without a command, sometimes when it’s not her turn,” he said.