Dog brains divide language tasks: as in humans, meaning and intonation interpreted separately.
Dogs process speech much like people do. Meaningful words like "good boy" activate the left side of a dog's brain regardless of tone of voice; a region on the right side responds to intonation, scientists report in the Sept. 2 Science.
Similarly, humans process the meanings of words in the left hemisphere of the brain and interpret intonation in the right hemisphere. That lets people sort out words that convey meaning from random sounds that don't. It has been unclear whether language abilities were a prerequisite for that division of brain labor, says neuroscientist Attila Andics of Eotvos Lorand University in Budapest.
Dogs are ideal subjects for understanding speech processing because of their close connection to humans, Andics says. "Humans use words towards dogs in their everyday, normal communication, and dogs pay attention to this speech in a way that cats and hamsters don't," he adds.
Andics and colleagues trained dogs to lie still for functional MRI scans, which can reveal when and where the brain responds to a specific cue. The dogs heard recordings of a trainer saying either meaningful praise words like "well done," or neutral words like "such" or "yet," either in an enthusiastic or neutral tone.
Dogs had increased activity in the left sides of their brains in response to meaningful words but not neutral ones. The area on the right side reacted to intonation regardless of the words' meaning.
When the dogs heard praising words in an enthusiastic tone, neural circuits associated with reward became more active. It turns out an excited "Good dog!" might have the same effect as giving a dog a treat. Praise words or enthusiastic intonation alone didn't have the same effect.
Humans stand out from other animals in their ability to use language--that is, to rearrange sequences of sounds to convey different meanings. But the findings suggest that the ability to hear these arbitrary sequences and link them to meaning isn't a uniquely human ability.
"I love these results, as they point to how well domestication has shaped dogs to use and track the very same cues that we use to make sense of what other people are saying," says Laurie Santos, a cognitive psychologist at Yale University.
Humans and dogs have been companions for only about 30,000 years. That's too short for lateralized speech processing to evolve, Andics thinks. He suspects that some older underlying neural mechanism for processing meaningful sounds is present in other animals, too.
Caption: By training dogs to undergo functional MRI brain scans, researchers learned that dogs and humans parse speech in similar ways.
Please note: Illustration(s) are not available due to copyright restrictions.
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|Title Annotation:||LIFE & EVOLUTION|
|Date:||Oct 1, 2016|
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