Humans, monkeys share brain bond

London :Humans and monkeys share the brain region involved in recognising the basic structure of language, according to a new study that could help better understand language impairment in stroke or dementia patients.

Researchers led by Ben Wilson and Chris Petkov of Newcastle University in UK used an imaging technique to explore the brain activity in humans and monkeys.

They identified the evolutionary origins of cognitive functions in the brain that underpin language and allow us to evaluate orderliness in sequences of sounds.

This new knowledge will help our understanding of how we learn – and lose – language such as in aphasia after a stroke or in dementia, researchers said.

Scanning the brains of humans and macaque monkeys, the research team identified the area at the front of the brain which recognises when sequences of sounds occur in a legal order or in an unexpected, illegal order.

“We used a ‘made up’ language first developed to study infants, which our lab has shown the monkeys can also learn. We then determined how the human and monkey brain evaluates the sequences of sounds from this made up language,” Petkov said.

The team first had the humans and monkeys listen to example sequences from the made up language, allowing them to hear what were correct orderings in the sequence of sounds.

They then scanned the brain activity of both species as they listened to new sequences that either had a correct order or could not have been generated by the made up language.

Functional magnetic resonance imaging (fMRI) showed that in both groups a corresponding region of the brain – the ventral frontal and opercular cortex – responded to the order that both species had learned to expect.

These results suggest that the function of this frontal region, which is one of the areas involved in processing the order of words in a sentence in human language, is shared in both humans and primates, unveiling its evolutionary origins.

This brain region seems to monitor the orderliness, or organisation, of what is heard, which is an important cognitive function that provides a foundation for the more complex language abilities of humans.

These results provide first evidence that some of the functions of this brain area, which include understanding language in humans, are shared by other animals.

“This will help us answer questions on how we learn language and on what goes wrong when we lose language, for example after a brain injury, stroke or dementia,” Petkov said.

“Identifying this similarity between the monkey and human brain is also key to understanding the brain regions that support language but are not unique to us and can be studied in animal models using state-of-the-art neuroscientific technologies,” he said.

The study was published in the journal Nature Communications.