
When thinking of a word it may seem like its meaning is plucked from the ether, but new research has revealed the brain uses a highly organised system for storing words based on their meaning and context.

Scientists in the US have produced a 'semantic atlas' that pinpoints where in the brain definitions of individual words are stored, in stunning detail, and it could lead to a map of the brain that helps experts decode people's inner thoughts.

The mesmerising atlas shows the words in vivid colours and multiple dimensions and it has been dubbed 'brain's dictionary.'

New research has revealed that the brain uses a highly organised archiving system for language, where words are grouped by related meaning and context (pictured). Scientists at the University of California, Berkeley produced an atlas pinpointing where in the brain definitions of individual words are stored, illustrating the brain's semantic system in stunning detail

The model shows that rather than every word having its own chunk of brain real estate, networks of words are grouped together.

Different parts of the brain are given over to different tasks, such as the vision, hearing or emotional processing.

For understanding language, this is called the semantic system and was believed to be largely based near the back of the brain.

In order to focus in on the semantic system, and to explore how the brain accesses definitions, scientists at the University of California, Berkeley recorded brain activity of volunteers as they listened to narrative stories.

Different areas of the cortex were roughly arranged according to categories of words, such as green for visual words, red for social and brown for places. One region of the brain (pictured) showed increased activity for words such as 'wife' and 'mother'. By splitting up the surface into tiny cubes, the team was able to produce the detailed atlas of activity for groups of words

The study found that although the atlas for each person may be slightly different, the way in which information is archived and accessed is broadly similar, with similar regions of the brain accessed for similar word groups (pictured are the atlases for three individuals)

Functional MRI scans showed increased blood flow to different regions of the brain which coincided with words being spoken, indicating that this was where the brain was going to for the definitions and context

But the team was surprised to find activity across the brain.

As volunteers listened to two hours of audio stories, their brain activity was captured through functional MRI scans.

The scans showed increased blood flow to different regions of the brain which coincided with when words were spoken, indicating that this was where the brain was going to for the definitions and context.

By splitting up the surface into tiny cubes, the team was able to produce the detailed atlas of activity for groups of words.

Another region of the brain (pictured) located next to the previous 'wife/mother' area was found to be activated by related words, including those those relating to location, such as 'household' and 'apartment'

The word 'top' was seen to trigger activity in the middle frontal gyrus in a specific context, but it is also found to trigger activity at multiple locations around the brain and is clustered in areas with associated words depending on the context. So one region is active when 'top' refers to clothing or appearance, while another region is active when top is used in the context of numbers and measurements

For example, the word 'top' was seen to trigger activity in the middle frontal gyrus in a specific context.

But it is found to trigger activity at multiple locations around the brain and is clustered in areas with associated words depending on the context.

So one region is active when 'top' refers to clothing or appearance, while another region is active when top is used in the context of numbers and measurements, or buildings and places.

What's more, the models show that brain regions related to meaning of visual characteristics are located closely to related functional regions.

IMAGING THE BRAIN'S DICTIONARY The latest study focused on the brain's system for decoding language, called the semantic system. Scientists at the University of California, Berkeley played seven volunteers two hours of narrative stories and recorded their brain activity using functional MRI scanners. These scans recorded changes in the flow of oxygenated blood to different regions of the brain - measured as tiny cubes called voxels - which coincided with words being spoken. In the first round of experiments, volunteers were played the audio while being scanned, and the audio was then transcribed to synchronise the words and fMRI responses. But as a second test, to see if they could predict the fMRI activity, the team made the volunteers listen to a new story. Analysis from the first test showed increased activity in the voxels correlated with the meanings and context - so the fMRI observations served as an indirect measurement of brain activity for more than 10,470 words in total. The team used this information to build computer models to predict brain activity for the new story, and found that their models could predict the brain responses relatively well, building up the detailed views of the semantic system. The UCB team explained: 'These semantic maps give us, for the first time, a detailed map of how meaning is represented across the human cortex. Rather than being limited to a few brain areas, we find that language engages very broad regions of the brain.' The models show brain regions related to meaning of visual characteristics were found close to related functional regions. So the area for words such as stripes or spots is located close to the visual cortex, where the brain processes vision Advertisement

So the area for words such as stripes or spots is located close to the visual cortex, where the brain processes vision.

The researchers found that although the maps for each person may be different, the way in which information is archived and accessed is broadly similar, with similar regions of the brain accessed for similar word groups.

The team, led by Professor Jack Gallant, has published its findings today in the journal Nature.

'We expect that the semantic atlas presented here will be useful for many researchers investigating the neurobiological basis of language,' they wrote.

In terms of applications, the team explains the models could be used to make a 'language decoder' which could potentially even be used to help people with communication disorders such as motor neuron disease and locked-in syndrome.

As volunteers listened to hours of narrative stories in the lab their brain activity was monitored using fMRI. These scans recorded increased blood flow to different regions of the brain, broken down into tiny cubes called voxels

After the audio was transcribed and words and fMRI activity synchronised, the increased activity in a voxel correlated with the meanings and context for more than 10,470 words in total. So the fMRI observations served as an indirect measurement of brain activity