Images of the brain refute a theory of the 1960s on the domain of language

December 20, 2017, Spanish Foundation for Science and Technology (FECYT)
Credit: Wikimedia Commons

In 1968, when there were no techniques to observe how the brain worked in vivo, the neurologist Norman Geschwind discovered that a region of the temporal lobe in deceased persons, the planum temporale, was larger in the left than in the right hemisphere. As in most of the population, language processing is located in that hemisphere, so the neurologist proposed that asymmetry was an indicator of the lateralization of that function.

Almost 50 years later, a team of researchers from the European MULTI-LATERAL project has used to study brain areas in vivo and has refuted that theory. The anatomical of the planum temporale that hosts auditory functions is not a marker of the lateralization in the left hemisphere of .

In the research, published in Brain Structure & Function, 287 adults, right-handed and left-handed, participated. "It is the first study with such a large sample of individuals and includes the entire range of language variability implemented in the brain," explains Nathalie Tzourio-Mazoyer, head of the Neurofunctional Imaging Group at the Institute of Neurodegenerative Diseases of the University of Bordeaux (France) and principal author of the work.

In most of the participants, the left hemisphere was specialized in , but the opposite was true in a minority, in whom the right side was in charge of these functions. They all performed several tasks while the researchers analyzed their brain activity—describing an image with a sentence and listening to phrases and lists of words. No evidence showed that this region of the was a marker of tasks related to language, but there was a local correlation between the anatomical asymmetry and the functional asymmetry during the auditory processing of speech.

"This study shows that the largest leftward asymmetry of the is not a marker of the leftward lateralization of language functions in humans," says the researcher.

In the few participants who processed language with the , the results were the same, not inverted as might be expected, which reinforces the hypothesis of the researchers. "The results of the study show that the planum temporale does not explain the rare but strong individual variability of the language domain that exists in humans and, therefore, cannot be considered as a marker of language asymmetry at individual level," they write.

The European MULTI-LATERAL project in which the study is framed tries to give answers to these and other questions related to the lateralization of , a process that develops up to eleven years.

"MULTI-LATERAL has been in operation for about 18 months and for most of the time, different teams in Spain, France and the Netherlands have been collecting and processing data sets," explains Clyde Francks head of the Human Neurogenetic Group of the Max Planck Institute of Psycholinguistics and project coordinator to Sinc.

Explore further: Chimp study reveals how brain's structure shaped our evolution

More information: Nathalie Tzourio-Mazoyer et al. Is the planum temporale surface area a marker of hemispheric or regional language lateralization?, Brain Structure and Function (2017). DOI: 10.1007/s00429-017-1551-7

Related Stories

Chimp study reveals how brain's structure shaped our evolution

November 15, 2017
The pattern of asymmetry in human brains could be a unique feature of our species and may hold the key to explaining how we first developed language ability, experts say.

A dominant hemisphere for handedness and language?

July 4, 2014
Through an innovative approach using a large psychometric and brain imaging database, researchers in the Groupe d'Imagerie Neurofonctionnelle (CNRS/CEA/Université de Bordeaux) have demonstrated that the location of language ...

Decoding biological asymmetry

July 12, 2016
Our bodies, our behaviour, but also our brains are anything other than symmetrical. And that seems to be an important factor in the seamless functioning of our thought, speech and motor faculties. Researchers at the Max Planck ...

Right brain also important for learning a new language

October 17, 2017
Novel language learning activates different neural processes than was previously thought. A Leiden research team has discovered parallel but separate contributions from the hippocampus and Broca's area, the learning centre ...

'Broca's area' processes both language and music at the same time

November 10, 2015
When you read a book and listen to music, the brain doesn't keep these two tasks nicely separated. A new study shows there is an area in the brain which is busy with both at the same time: Broca's area. This area has been ...

Whistled Turkish challenges notions about language and the brain

August 17, 2015
Generally speaking, language processing is a job for the brain's left hemisphere. That's true whether that language is spoken, written, or signed. But researchers reporting in the Cell Press journal Current Biology on August ...

Recommended for you

New insights into the way the brain combines memories to solve problems

September 19, 2018
Humans have the ability to creatively combine their memories to solve problems and draw new insights, a process that depends on memories for specific events known as episodic memory. But although episodic memory has been ...

What your cell phone camera tells you about your brain

September 19, 2018
Driving down a dark country road at night, you see a shape ahead on the roadside. Is it a deer or a mailbox? Your brain is structured to make the best possible decision given its limited resources, according to new research ...

Neuroscience of envy: Activated brain region when others are rewarded revealed

September 19, 2018
How we feel about our own material wellbeing and status in society is largely determined by our evaluation of others. However, the neurological underpinnings of how we monitor the complex social environments under conditions ...

Plasticity is enhanced but dysregulated in the aging brain

September 19, 2018
They say you can't teach old dogs new tricks, but new research shows you can teach an old rat new sounds, even if the lesson doesn't stick very long.

The 'real you' is a myth – we constantly create false memories to achieve the identity we want

September 19, 2018
We all want other people to "get us" and appreciate us for who we really are. In striving to achieve such relationships, we typically assume that there is a "real me". But how do we actually know who we are? It may seem simple ...

The brain predicts words before they are pronounced

September 18, 2018
The brain is not only able to finish the sentences of others: A study by the Basque research centre BCBL has shown for the first time that it can also anticipate an auditory stimulus and determine the phonemes and specific ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.