WASHINGTON, Oct. 25 (Xinhua) -- American researchers found that only 20 percent of the cerebellum was devoted to movement control, what people initially thought it is used for, and the remaining 80 percent occupied by networks involved in higher-order cognition.
The study published on Thursday in the journal Neuron showed that the cerebellum participate in every aspect of higher brain functions, not just movement, but attention, thinking, planning and decision-making.
"Everyone thought the cerebellum was about movement. If your cerebellum is damaged, you can't move smoothly. Your hand jerks around when you try to reach for something," said the paper's senior author Nico Dosenbach, assistant professor of neurology at Washington University School of Medicine.
"Our research strongly suggests that just as the cerebellum serves as a quality check on movement, it also checks your thoughts as well: smoothing them out, correcting them, perfecting things," said Dosenbach.
The researchers found that the cerebellum was consistently the last step in neurologic circuits. Signals were received through sensory systems and processed in intermediate networks in the cerebral cortex before being sent to the cerebellum.
The researchers proposed that the signals underwent final quality checks in cerebellum before the output was sent back to the cerebral cortex for implementation.
"If you think of an assembly line, the cerebellum is the person at the end who inspects the car and says, 'This one is good; we'll sell it,' or 'This one has a dent; we have to go back and repair it,'" said Dosenbach. "It's where all your thoughts and actions get refined and quality controlled."
It is known that drunken people tend to stumble around, but the new study help explain why someone who is inebriated also shows poor judgment.
Just as a person staggers drunkenly because cerebellum is unable to perform the quality checks on motor function, bad decisions due to excessive drinking might also reflect a breakdown of quality control over executive functions, according to the researchers.
"The executive function networks are way overrepresented in the cerebellum," said the paper's first author Scott Marek, a postdoctoral researcher at Washington University.
"Our whole understanding of the cerebellum needs to shift away from it being involved in motor control to it being more involved in general control of higher-level cognition."