The key learning regions in the brain, the hippocampus and the prefrontal cortex, use different wave frequencies during memory-based decision making, a new research says.
The study was carried out by Massachusetts Institute of Technology neuroscientists and published in the Nature Neuroscience’s online edition on February 23.
As neurons fire in the brain they generate brain waves at different frequencies. Formerly, it was thought the frequencies were just a byproduct of neurons activity.
The new research shows that as the brain correctly links the objects during the learning process, the waves oscillate at a higher frequency, named beta, and when the link is incorrect, the waves oscillate at a lower theta frequency.
“It’s like you’re playing a computer game and you get a ding when you get it right, and a buzz when you get it wrong. These two areas of the brain are playing two different ‘notes’ for correct guesses and wrong guesses,” said senior author of the paper professor Earl Miller.
The research also shows that the oscillations may act as reinforcement for correct guesses and repression for incorrect guesses.
During the research, the brains of animals were examined for activity while they form explicit memories relating to events and facts such as names, faces, locations and events.
The subjects were shown pairs of pictures and through trial and error they gradually learned which pairs were associated.
The researchers found brain waves occurred at various frequencies depending on the correctness or incorrectness of the answers.
In relation to correct associations, the waves occurred at the beta frequency, about 9 to 16 hertz, and when they were incorrect the oscillation happened at the theta frequency, around 2 to 6 hertz.
“When the animal guesses correctly, the brain hums at the correct answer note, and that frequency reinforces the strengthening of connections,” Earl Miller said. “When the animal guesses incorrectly, the ‘wrong’ buzzer buzzes, and that frequency is what weakens connections, so it’s basically telling the brain to forget about what it just did”.
The study stresses the importance of brain waves during cognitive function.
“Brain waves had been ignored for decades in neuroscience. It’s been thought of as the humming of a car engine,” said Miller. “What we’re discovering through this experiment and others is that these brain waves may be the infrastructure that supports neural communication.”
The research team is currently carrying out investigations into whether learning can be speeded up by noninvasive electrical stimulation to simulate the Beta and Theta waves.
“The idea is that you make the correct guesses feel more correct to the brain, and the incorrect guesses feel more incorrect,” Miller said.
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