The brain is a complex information-processing computer that uses a combination of chemical and electrical signals to send and receive information. Neuroscientists and physicians have long observed that you can see some of that electrical activity as waves when you put electrodes on a person’s scalp. For years scientists thought these waves were just a side effect of the brain’s activity. But new research has found that these waves are probably playing a key role in learning.
Where do brain waves come from?
Neurons use chemicals and electricity to transfer information. An individual neuron acts somewhat like a wire by transmitting signals with electrical current. When it needs to pass that signal on to another neuron, it releases a chemical signal that transmits its message. While this might seem like an inefficient way to transmit information, using two types of signals allows neurons to send a wide variety of messages depending on the chemical used to send the message. Some chemicals might activate other neurons when released, while others can prevent other neurons from firing.
The electrical signals of individual neurons are tiny and can’t easily be picked up using sensors outside of the brain. When a large number of neurons are working together and are sending electrical signal in a similar pattern, though, these signals add up to larger pulses of activity that can be picked up by electrodes on the scalp. When a wave is seen, it reflects the synchronized activity of a group of neurons together similar to the way doing the wave at a sports game only looks like a wave when everyone is standing up in coordination.
How do brain waves influence other parts of the brain?
The researchers first began to think brain waves were more than just background activity when other research found that certain wave patterns seemed to encourage neurons to form new connections. Other research on rats also showed that certain areas of the brain tended to sync up with each other during certain activities. The team wondered if there might be a code embedded in these brain waves.
What did the researchers do?
Past research on brain waves had been done in rats, but the brains of rats are very different from those of humans. These researchers used monkeys whose brains are much closer to those of humans. They looked at two areas involved in memory and learning: the hippocampus, which is involved in the formation of new memories; and the prefrontal cortex, which is responsible for the “thinking” part of learning. Past studies had found that these areas seem to synchronize with each other.
What did the researchers find?
The team looked at the brain waves of the monkeys while they learned how to perform new skills. They saw that two waves appeared: a rapidly repeating pattern called “beta waves” and a slower pattern called “theta waves.” Beta waves have been associated with shutting down neuron activity, while theta waves have been found to help neurons form new connections, which is important in learning.
The presence of these waves depended on what kind of learning was happening. If the monkey did something wrong, the hippocampus started beating in a beta pattern. If the monkey did something right, the hippocampus started beating with a theta pattern. The prefrontal cortex would then follow suit and start beating with the same pattern. According to the researchers, this wave syncing is probably helping the hippocampus communicate with the prefrontal cortex. If the hippocampus sees you did something wrong, it sends a “don’t remember that” signal to the prefrontal cortex. If it sees you did something right, it tells the prefrontal cortex to store that memory somewhere safe.
Why do I care?
The researchers think they could use this information to improve how people learn. Sometime in the near future, you might be able to use a noninvasive electrical stimulator to stimulate beta or theta waves that would clearly signal to your brain when you do something right or wrong. This would help your brain to more quickly pick up on what to repeat in the future and what to forget.