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An old part of the brain, long ignored by the scientific world, seems to play a crucial role in everything from language and emotions to daily planning.
It is the cerebellum, which is found in fish, lizards and humans.
But in the human brain, this structure is connected to areas involved in higher thinking, a team led by researchers at the University of Washington in St. Louis said Thursday. Neuron.
"We believe that the cerebellum is the ultimate quality control unit of the brain," says Scott Marek, a postdoctoral researcher and first author of the study.
The discovery adds to the growing evidence that the cerebellum "is not just about sensorimotor function, it's involved in everything we do," says Dr. Jeremy Schmahmann, professor of neurology at Harvard and director of the Ataxia Treatment Unit at Massachusetts General. Hospital.
Schmahmann, who did not participate in the new study, has been arguing for decades that the cerebellum plays a key role in many aspects of human behavior, as well as in mental disorders such as schizophrenia.
But only a handful of scientists have explored the functions of the cerebellum beyond motor control.
"She has been terribly misunderstood," said Dr. Nico Dosenbach, a professor of neurology at the University of Washington, whose lab conducted the study.
Even now, many scientists believe that the cerebellum is the part of the brain that allows you to pass a roadside sobriety test. It helps you do things like walking in a straight line, standing on one leg or following a moving object, if you are not drunk.
But the University of Washington team thought there was a lot going on in that part of the brain. They used a special type of MRI to study the cerebral cabling of 10 people.
This allowed the team to quantify the different connections between the cerebellum and other areas of the brain. And they discovered that only 20% of the cerebellum was devoted to areas related to physical movement, while 80% were devoted to areas such as abstract thinking, planning, emotions, memory, and language.
"We already thought that the cerebellum was colder than most people thought," says Dosenbach. "But these results were much more exciting and clear than I could have ever dreamed of."
The cerebellum does not directly perform tasks such as thinking, just as it does not directly control movement, explains Marek. Instead, he says, this seems to monitor the areas of the brain that are doing the work and make them perform better.
In essence, this structure seems to act as a kind of publisher, constantly revising and improving a person's thoughts and decisions, says Dosenbach. If this is true, he says, it is not surprising that alcohol affects more than our physical movements.
"We have an explanation for all the bad ideas that people have when they are drunk," he says. "They lack cerebellar revision of your thoughts."
The new study suggests how the cerebellum has evolved over hundreds of millions of years, says Schmahmann.
"What has happened over time is that the cerebellum has grown enormously," he says. And this extra capacity allowed him to take on functions beyond the movement.
But the way the cerebellum works has not changed, says Schmahmann. This makes the process smoother, faster and more accurate. "What we understand now is that what the cerebellum does for motor control, it does it for cognition and emotions as well."
And the cerebellum does it all automatically, allowing our conscious mind to focus on more important things, says Schmahmann.
But when the cerebellum does not do its job, says Schmahmann, the result could be a brain disorder.
"There is more and more evidence in a variety of areas now that autism spectrum psychiatric illness, schizophrenia, depression, obsessive-compulsive disorder, all have a connection with the cerebellum," he said. he.
Schmahmann and a few other researchers have therefore begun to try to treat patients with some of these problems by improving the function of this ancient structure in the brain.
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MARY LOUISE KELLY, HOST:
The cerebellum is a part of the brain that is best known for helping us keep our balance. It turns out that this old part of the brain may have been underestimated. A new study suggests that it also helps us manage everything from emotions to social interactions to planning. Jon Hamilton of NPR has more.
JON HAMILTON, BYLINE: The cerebellum is not very respected. Scientists often see it as part of the brain that allows you to pass a roadside sobriety test. It helps you do things like walking in a straight line or standing on one leg if you are sober. Researchers at the University of Washington in St. Louis thought that the cerebellum was larger and therefore used a special type of MRI to study the cerebral cabling of 10 people. And Dr. Nico Dosenbach says that they found surprising connections.
NICO DOSENBACH: About 20% of the cerebellum is dedicated to movement, but 80% is dedicated to higher order cognitive functions.
HAMILTON: What kind of cognitive functions? Scott Marek, a postdoc at Dosenbach's laboratory, gives some examples.
SCOTT MAREK: Abstract thinking, long-term planning, even keeping something in mind, producing the words you say – it's important for all the everyday functions that you really take for granted and seem to be effortless.
HAMILTON: Marek says that the cerebellum does not perform these tasks directly, nor does it directly control the movements. Instead, he says, this seems to monitor the areas of the brain that are doing the work and make them perform better.
MAREK: So we think that the cerebellum is the ultimate quality control unit of the brain.
HAMILTON: It's still speculation, but Dosenbach says the discovery published in the journal Neuron adds to the evidence that this ancient part of the brain plays a vital role in modern life.
DOSENBACH: We already thought that the cerebellum was colder than most people, but these results were much more exciting and clear than I could have dreamed.
HAMILTON: Dosenbach says that most researchers have not paid much attention to the cerebellum, perhaps because its most obvious function involves something very banal – physical movement.
DOSENBACH: But, in reality, it is much more about modifying your thoughts and your inner life. It's just a lot harder to notice. And I think that's why scientists and neurologists have missed it for a long time.
HAMILTON: And Dosenbach says the new study provides a good reason why alcohol affects a lot more than the balance of the person when it harms the cerebellum.
DOSENBACH: We have an explanation for all the bad ideas that people have when they are drunk. They lack cerebellar revision of your thoughts.
HAMILTON: Jeremy Schmahmann, a professor at Harvard Medical School, is not surprised at the results of the new study. He has been arguing for decades that the cerebellum is involved in both human behavior and disorders such as schizophrenia. Schmahmann says that the cerebellum has changed dramatically since its appearance in fish and lizards hundreds of millions of years ago.
JEREMY SCHMAHMANN: Over time, the cerebellum has grown enormously. And the parts of the cerebellum that speak to the parts of the brain that are involved in cognition mean that the cerebellum is also involved in these processes.
HAMILTON: Schmahmann says that the cerebellum performs more or less the same function as it has always been. But instead of just making a physical movement smoother and more precise, it lessens our emotional responses or improves our ability to make good decisions and focus on a task.
SCHMAHMANN: What we understand now is that what the cerebellum does to control motor skills, it does it for cognition and emotions as well.
HAMILTON: Schmahmann says that the cerebellum does all this automatically, so we are not aware of his contribution. But when it stops working, he says, the result can be a brain disorder.
SCHMAHMANN: There is more and more evidence in a variety of areas now that psychiatric autism spectrum disorders, schizophrenia, depression, obsessive-compulsive disorder are all linked to the cerebellum.
HAMILTON: And Schmahmann says that other researchers are already trying to solve some of these problems by using treatments that improve the functioning of the cerebellum. Jon Hamilton, NPR News. Transcription provided by NPR, Copyright NPR.
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