When you say "squirrel" to your canine companion, are they really picturing a bushy-tailed animal, or are they responding to the call based on cues like the tone of voice or the gestures you're using?

We'd be pretty safe to assume the latter, since language isn't known to easily work across species. But, according to a new study, dogs might have at least some understanding of the words we humans are using.

By analysing dogs inside an fMRI scanner measuring brain activity, the research shows different brain patterns in the pooches when they hear words they've heard before, compared with completely new words.

That's not enough to suggest they really are picturing a squirrel when they hear the word, but it points to some kind of recognition happening, based on the word itself.

The research team says it's an important step forward in understanding how dogs process language – particularly because it uses data gathered from the dogs themselves rather than the observations of their owners.

"We know that dogs have the capacity to process at least some aspects of human language since they can learn to follow verbal commands," says one of the team, neuroscientist Gregory Berns from Emory University in Atlanta.

"Previous research, however, suggests dogs may rely on many other cues to follow a verbal command, such as gaze, gestures and even emotional expressions from their owners."

The study used 12 dogs of different breeds, trained by their owners over several months to distinguish between two objects – and to retrieve the right object when its name was said.

Once the dogs showed they could pick out the correct object each time, the researchers moved on to the fMRI scanner experiments.

Owners at the end of the scanner were then asked to say the names of the objects the dogs had learned, as well as gibberish words that they'd never heard before – like  "bobbu" and "bodmick".

Each time, an object was held up: either the objects the dogs had been trained with, or random objects like hats or dolls.

When the results were pulled together, they showed brain activity in the canines increased when novel words and novel objects were said and presented.

The team says that might be because the dogs want to please their owners, and are straining to understand what's being said.

"We expected to see that dogs neurally discriminate between words that they know and words that they don't," says one of the researchers, Ashley Prichard from Emory University.

"What's surprising is that the result is opposite to that of research on humans – people typically show greater neural activation for known words than novel words."

While the increased brain activity was consistent across all the dogs when novel words were spoken, it wasn't happening in the same place. In half the animals it appeared in the parietotemporal cortex, which researchers think might be used for the purpose of distinguishing between commands.

In the other half, the heightened brain activity appeared elsewhere: across the left temporal cortex (in humans, linked to processing audio), the amygdala (handling emotions), the caudate nucleus (learning and motor control), and the thalamus (for relaying motor and sensory signals).

Perhaps that's because of one of the study's limitations, say the researchers – different breeds of dog, each with their own way of figuring commands out.

So we're a long way from knowing for sure what dogs really get from listening to our babble. But it seems they are smart enough to identify at least some of the words being spoken to them.

"Dogs may have varying capacity and motivation for learning and understanding human words," says Berns, "but they appear to have a neural representation for the meaning of words they have been taught, beyond just a low-level Pavlovian response."

The research has been published in Frontiers in Neuroscience.