MRI study may help explain how pups understand human communication
By training pooches to lie absolutely still in a brain scanner, scientists have begun revealing the mysterious inner workings of the canine brain. Like their human companions, dogs use certain parts of their brains to detect voices, researchers report in the March 3 Current Biology.
What’s more, dog brains, like people’s, react to emotional cues. A playful yip, pleading whine and aggressive bark elicit varying levels of activity in a certain brain region. Human laughs or cries have similar effects on dogs’ brains, functional magnetic resonance imaging shows. The results might help explain how dogs sense their owners’ emotions.
“Dogs are really good at tuning into their owners’ feelings,” says study coauthor Attila Andics of MTA-ELTE Comparative Ethology Research Group in Budapest. But until this study, he adds, “we just had no idea what goes on in their brain.”
Andics and colleagues trained six border collies and five golden retrievers to lie still inside an fMRI scanner for more than six minutes at a time (the data were useless if a dog moved more than three millimeters). The dogs actually enjoyed their tedious job. “You should just see how these dogs love to go to the scanner,” Andics says. “They just cannot wait to be the next one.”
During the scan, the dogs listened to a recording of people crying, laughing and shouting (no speech was included) and dogs barking angrily, whining and yipping playfully. When dogs heard canine vocalizations, regions in the front part of the primary auditory cortex, a swath of neural tissue in the middle of the brain that helps detect sound, became active. These regions are analogous to brain locales in humans that respond to human voices, the team found by playing the same recording for 22 people undergoing fMRI scans.
In both dogs and people, other brain regions near the primary auditory cortex were more active when hearing happier noises, regardless of whether the voice belonged to a dog or a person. Laughing and joyful barks elicited greater responses than crying and growling, for instance.
Neuroscientist and psychologist Pascal Belin of the University of Glasgow in Scotland cautions that those areas may respond to acoustical differences in the sounds, not the emotion itself. Nonetheless, the new results are plausible to anyone with a pooch. “Without even doing science, if you own a dog, you clearly see that a dog is able to recognize your identity and your emotional state,” Belin says.
The human-dog comparison also revealed an interesting difference: The vast majority of sound-responsive areas in the human brain react more strongly to human voices than to sounds from the environment, such as a thunderstorm, a ringing phone or a car horn. In dogs, almost half of the analogous areas respond more strongly to nonvocal environmental sounds. That finding highlights how sensitive the human brain is to voices, Andics says.
It would be fascinating to scan the brains of other animals such as wolves or cats, Andics says, but coaxing those animals to lie still for an fMRI scan is a long shot. He and his colleagues plan on running more experiments to see how the dog brain handles smells, sights and speech.
A. Andics et al. Voice-sensitive regions in the dog and human brain are revealed by comparative fMRI. Current Biology. Vol. 24, March 3, 2014, p. 1. doi: 10.1016/j.cub.2014.01.058.
B. Bower. Dog sniffs out grammar. Science News Online, May 21, 2013.