Wednesday, April 26, 2017

How the brain predicts speech: Key region found that could help create accurate mind-reading devices

  • Researchers found a brain region involved in identifying sounds
  • It is used to predict upcoming words during conversation
  • The region is blocked in people with disorders such as dyslexia and ADHD
  • Study authors say that companies like Google and Facebook could one day use the region to  predict user behaviour
Scientists have discovered how the brain helps us to predict what is coming next in speech. The researchers say they have found a key part of the brain involved in identifying sounds that is used to predict upcoming words during conversation 

Scientists have discovered how the brain helps us to predict what is coming next in speech.

The researchers say they have found a key part of the brain involved in identifying sounds that is used to predict upcoming words during conversation.

And companies like Google and Facebook could one day use the technology to create devices that read users' minds, one researcher suggests.

'Google and Facebook are really interested in how your brain makes predictions and learns because they want to use brain signals to control phones or to improve predictions in their software,' study lead author Professor Chris Petkov, a neuropsychologist at Newcastle University, told MailOnline.

'They want to know how they can predict what people do, and how they can then change devices to reflect this. 'Our work shows how this happens in the brain: Neurons make predictions at specific points in time and adjust those predictions when a prediction mistake happens.'

The researchers say that the area they have identified is found within the brain's 'auditory cortex', a region unchanged by evolution for millions of years.

It is inhibited in people with disorders such as dyslexia, schizophrenia and Attention Deficit Hyperactivity Disorder (ADHD). The finding could one day lead to a better understanding and treatment of these conditions, the researchers claim. 'There are groups around the world who could use these findings to see how the brain makes predictions and also how it responds when it is wrong,' Professor Petkov told MailOnline.

'Ultimately we do want to help people who struggle to make predictions, such as those with dyslexia or ADHD, to better make those predictions.

'In some cases we will be at the stage where we can help the brain to recover from these conditions.'

Using an approach developed for studying language learning in children, Professor Petkov and his team had humans and monkeys decode a made-up language.

The groups were played a sequence of sounds or short sentences of words spoken in the language, which has properties and rules that subjects could follow.

The team made their finding by having humans and monkeys decode a made-up language. This image shows the artificial grammar rules of the fake language and the phase-amplitude coupling seen by the team in the human 'auditory cortex' - a key region used to decode sound

Both species were able to learn the predictive relationships between the spoken sounds in the sequences.

Activity in the auditory cortex of the two species revealed how groups of neurons responded to the speech sounds and to the learned predictive relationships between those sounds.

'Even direct recordings from the brain do not give us access to what the neurons are doing, which is why the link to monkeys was so important to establish,' Professor Petkov told MailOnline.

'We see that certain types of neurons are constantly and actively making predictions.

'This occurs shortly before the neurons notice when a prediction mistake has occurred.

'The reason this is important relates to how it could ultimately help people with problems predicting what will happen next. 'For example, scientists can next ask whether one or both types of neuronal predictive responses rely on each other and which might be malfunctioning in people that suffer from different types of disorders.'

The brain responses in monkeys and humans were found to be remarkably similar in both species.

This suggests that the way the human auditory cortex responds to speech has been passed down through a common ancestor, rather than being uniquely specialised in humans for speech or language.

'A number of things were very similar between the monkeys and humans, suggesting a fundamental element to prediction in the brain,' Professor Petkov told MailOnline.

'Being able to predict events is vital for so much of what we do every day.'

Study coauthor Dr Yuki Kikuchi added: 'In effect we have discovered the mechanisms for speech in your brain that work like predictive text on your mobile phone, anticipating what you are going to hear next.

'This could help us better understand what is happening when the brain fails to make fundamental predictions, such as in people with dementia or after a stroke.'

Building on these results, the team are working to understand how predictive brain signals go wrong in patients with stroke or dementia.

The long-term goal is to identify strategies that yield more accurate prognoses and treatments for these patients.
video

UA researchers hope to cure diseases with a common brain parasite


A mouse brain genetically engineered to show green where Toxoplasma Gondii has infected the brain.

There might be a parasite in your brain.

It’s estimated that up to one-third of the world’s population is infected with the brain parasite Toxoplasma gondii.

The U.S. has a relatively low rate of infected people, estimated to be between 10 and 25 percent. Countries such as France have an infection rate of 60 to 80 percent.

As far as parasites go, Toxoplasma gondii isn’t’ that bad, unless you’ve had a transplant and are left immunocompromised. Folks who have a weakened immune response can suffer brain damage and even death if infected with toxoplasmosis.

University of Arizona researchers are studying whether the unique relationship between the parasite and the brain could lead to breakthroughs in understanding Alzheimer’s and other brain-related illnesses..

“There are very few microbes that can persist in the brain without causing symptoms,” said Dr. Anita Koshy, a research physician at the University of Arizona who studies Toxoplasma gondii..

How it responds in the body Toxoplasma gondii can exist within the brain for the lifespan of its host because of how it interacts with the body’s immune response. Healthy adults will show no symptoms because their immune systems keep the parasite from damaging the brain..

Infected neurons glow green, and the parasite living in the cell glows red.

“Toxo knows how to change the brain in a positive way that allows the parasite to persist, which we presume means it tunes down the immune response to toxo in the brain,” said Koshy.

“There is a lot of literature that suggest the immune response, in things from stroke to Alzheimer’s to MS to Parkinson’s disease is actually what causes the problems in those diseases and disorders," she added. "If we can learn how the parasite manipulates the brain immune response, maybe we can do it for the same reason.”

Koshy wants to understand how Toxoplasma gondii avoids being attacked by the body’s immune response. Infected brain cells are changed by the parasite so that it can survive.

They think toxo might completely block out the immune response. Another theory is that the parasite silences the cell it’s infecting, not allowing it to call out for help to nearby cells.

What’s certain is that toxo keeps itself alive by keeping the immune response in check and vice-versa. This is how it’s able to persist throughout the lifespan of its human hosts. When a person’s immune system is no longer able to keep a front with toxo, the host becomes ill and can die.

“A lot of people are infected with toxo. We think it doesn’t have any problems except in those who end up being immunocompromised,” said Koshy.

“So, if they end up getting AIDS, or get a bone marrow transplant, or if they’re infected when they’re a fetus," she continued, "then it can have huge problems in the brain. There’s no known way to cure toxo.”

Genetically engineered mice and parasite allow Koshy’s research lab to see how the parasite effects the brain.

What the studies show
Koshy and her lab use mice to study how Toxoplasma gondii interacts with the brain’s immune response. The infected mice are engineered to express a green-colored protein within their brain cells when infected with parasite proteins.

“Using mice allows us to track the cells and figure out which cells interact with the parasite. We can pull those green cells out and molecularly dissect how the parasite has modified that specific cell, compared to the cell that’s next to it,” Koshy said.

There are three studies on mice that showed being chronically infected with Toxoplasma gondii made the mice more resistant to central nervous system inflammation, the same type of inflammation that occurs in stroke and Alzheimer’s patients.

“Toxo is one of those parasites that can infect the brain and effectively hide from the immune response,” said Oscar Mendez, a graduate student in Koshy’s lab.

Toxoplasma gondii’s primary hosts are cats — the only known mammals that allow the parasite to reproduce. The parasite offspring are found with cat feces. After a gestation period, they release a spore that will infect a new host.

Mendez studies the behaviors of mice infected with toxo. His theory: The parasite might change the brain chemistry in mice, luring them to cat urine. This would make them an easier target for cats. He believes the parasite does this to infect its primary host.