By eavesdropping on the brains of living people, scientists have created the highest-resolution map yet of the neurons that encode the meanings of various words1. The results hint that, across individuals, the brain uses the same standard categories to classify words — helping us to turn sound into sense.
The study is based on words only in English. But it’s a step along the way to working out how the brain stores words in its language library, says neurosurgeon Ziv Williams at the Massachusetts Institute of Technology in Cambridge. By mapping the overlapping sets of brain cells that respond to various words, he says, “we can try to start building a thesaurus of meaning”.
The work was published today in Nature.
Mapping meaning
The brain area called the auditory cortex processes the sound of a word as it enters the ear. But it is the brain’s prefrontal cortex, a region where higher-order brain activity takes place, that works out a word’s ‘semantic meaning’ — its essence or gist.
Previous research2 has studied this process by analysing images of blood flow in the brain, which is a proxy for brain activity. This method allowed researchers to map word meaning to small regions of the brain.
But Williams and his colleagues found a unique opportunity to look at how individual neurons encode language in real time. His group recruited ten people about to undergo surgery for epilepsy, each of whom had had electrodes implanted in their brains to determine the source of their seizures. The electrodes allowed the researchers to record activity from around 300 neurons in each person’s prefrontal cortex.
As participants listened to multiple short sentences containing a total of around 450 words, the scientists recorded which neurons fired and when. Williams says that around two or three distinct neurons lit up for each word, although he points out that the team recorded only the activity of a tiny fraction of the prefrontal cortex’s billions of neurons. The researchers then looked at the similarity between the words that activated the same neuronal activity.
A neuron for everything
The words that the same set of neurons responded to fell into similar categories, such as actions, or words associated with people. The team also found that words that the brain might associate with one another, such as ‘duck’ and ‘egg’, triggered some of the same neurons. Words with similar meanings, such as ‘mouse’ and ‘rat’, triggered patterns of neuronal activity that were more similar than the patterns triggered by ‘mouse’ and ‘carrot.’ Other groups of neurons responded to words associated with more-abstract concepts: relational words such as ‘above’ and ‘behind’, for instance.
Mind-reading machines are here: is it time to worry?
The categories that the brain assigns to words were similar between participants, Williams says, suggesting human brains all group meanings in the same way.
The prefrontal cortex neurons didn’t distinguish words by their sounds, only their meanings. When a person heard the word ‘son’ in a sentence, for instance, words associated with family members lit up. But those neurons didn’t respond to ‘Sun’ in a sentence, despite these words having an identical sound.
Mind reading
To an extent, the researchers were able to determine what people were hearing by watching their neurons fire. Although they couldn’t recreate exact sentences, they could tell, for example, that a sentence contained an animal, an action and a food, in that order.
“To get this level of detail and have a peek at what’s happening at the single-neuron level is pretty cool,” says Vikash Gilja, an engineer at the University of California San Diego and chief scientific officer of the brain–computer interface company Paradromics. He was impressed that the researchers could determine not only the neurons that corresponded to words and their categories, but also the order in which they were spoken.
Recording from neurons is much faster than using imaging; understanding language at its natural speed, he says, will be important for future work developing brain–computer interface devices that restore speech to people who have lost that ability.
![](https://www.nanoappsmedical.com/wp-content/uploads/2017/05/spacer.jpg)
News
Ethics in Nanomedicine: Key Issues and Principles
Nanomedicine, a branch of nanotechnology, is revolutionizing healthcare by enabling the manipulation of materials at the nanoscale to diagnose, treat, and prevent diseases. Unlike traditional treatments, nanoparticles (NPs) are highly precise in targeting diseased [...]
A call for robust H5N1 influenza preparedness and response
As the global threat of H5N1 influenza looms with outbreaks across species and continents including the U.S., three international vaccine and public health experts say it is time to fully resource and support a [...]
Mucosal COVID-19 boosters outperform mRNA shots in preventing upper airway infections
In a recent study published in Nature Immunology, a team of researchers from the United States used non-human primate models to compare the protection conferred by an intramuscular booster dose of the bivalent messenger ribonucleic acid [...]
How Space Travel Really Changes Astronauts – From the Inside Out
International team reveals previously unknown effects on physiology that could shape the future of long-duration space missions. Researchers have discovered significant changes in the gut microbiome due to spaceflight, which affects host physiology and [...]
Breakthrough in blood stem cell development offers hope for leukemia and bone marrow failure
Melbourne researchers have made a world first breakthrough into creating blood stem cells that closely resemble those in the human body. And the discovery could soon lead to personalized treatments for children with leukemia [...]
Scientists Develop Game-Changing Needle-Free COVID-19 Intranasal Vaccine
A new mucosal COVID-19 vaccine poised to revolutionize the delivery process is especially beneficial for those with a fear of needles. A next-generation COVID-19 mucosal vaccine is set to be a game-changer not only when delivering [...]
Scientists Develop All-in-One Solution To Catch and Destroy “Forever Chemicals”
A new water treatment system developed by UBC researchers efficiently removes and destroys PFAS pollutants using a dual-action catalyst, offering a sustainable and cost-effective solution for water purification challenges. Chemical engineers at the University of [...]
New method accelerates drug discovery from years to months
Researchers from the University of Cincinnati College of Medicine and Cincinnati Children's Hospital have found a new method to increase both speed and success rates in drug discovery. The study, published Aug. 30 in [...]
A new smart mask analyzes your breath to monitor your health
Your breath can give away a lot about you. Each exhalation contains all sorts of compounds, including possible biomarkers for disease or lung conditions, that could give doctors a valuable insight into your health. [...]
Study reveals the role of blood clotting in COVID-19
In a study that reshapes what we know about COVID-19 and its most perplexing symptoms, scientists have discovered that the blood coagulation protein fibrin causes the unusual clotting and inflammation that have become hallmarks [...]
A Novel Cancer Vaccine Combining Nano-11 and ADU-S100
In a recent article published in npj Vaccines, researchers detailed the development of a novel cancer vaccine that combines a plant-derived nanoparticle adjuvant, Nano-11, with a clinically tested STING agonist, ADU-S100. The primary objective was [...]
AI spots cancer and viral infections with nanoscale precision
Researchers have developed an artificial intelligence which can differentiate cancer cells from normal cells, as well as detect the very early stages of viral infection inside cells. The findings, published today in a study [...]
Tiny shards of plastic are increasingly infiltrating our brains, study says
Human brain samples collected at autopsy in early 2024 contained more tiny shards of plastic than samples collected eight years prior, according to a preprint posted online in May. A preprint is a study which has not yet [...]
Scientists Have Discovered Strange DNA in Our Brains – and It Could Be Shortening Our Lives
According to the research, these mitochondrial DNA insertions could be linked to early death. Mitochondria in brain cells frequently insert their DNA into the nucleus, potentially impacting lifespan, as those with more insertions were found to [...]
Watch Out After a Hospital Stay: You Could Be Exposing Your Family to Superbugs
Research indicates hospitals contribute to the local spread of antibiotic-resistant infections. A recent study published in the journal Infection Control & Hospital Epidemiology by the Society for Healthcare Epidemiology of America suggests that family members of [...]
Molecular Trickery: How COVID-19 Silently Sabotages the Human Immune System
Researchers have discovered that SARS-CoV-2 manipulates the human immune system by forcing cells to produce non-functional proteins, hindering the body’s antiviral defenses. This groundbreaking study by teams from prestigious Brazilian universities highlights potential targets for new COVID-19 treatments, [...]