April 24, 2024

Scientists Find Mysterious Brain Wave Source That Could Boost Memory and Creativity

The human brain is a bit like a rudimentary radio with five channels. Electrical signals from neurons coordinate across the brain, generating oscillations called brain waves. Each wave corresponds to a state of the brain. Some of them come fast and furious, and usually have a high frequency when we are awake and thinking. Others are more relaxed, with slower undulations that occur during deep, restful sleep.

In a way, the brain changes its ways as we go about our day to match our inner mood with external needs – but at any time, the ways can bleed.

But there is a mysterious outcast: a frequency called heat waves. They happen while we are awake or asleep. For decades, these waves have puzzled neuroscientists trying to figure out their functions. Theta waves appear to help navigate meandering mice, but they also support memory in humans.

It is not just an academic curiosity. Our ability to cope with new complex environments and retain those memories diminishes with age. It is especially difficult for people with Alzheimer’s disease. By finding the driving source of the heat waves, we could improve them – using neurostimulation or other methods – to slow cognitive decline.

Study in Neurons took the first step. Thanks to Xbox and some virtual mall shopping, a team led by Dr. Arne Ekstrom from the University of Arizona digs deep into what drives heat waves. The study recruited people with epilepsy who already had electrodes implanted in their brains to look for the source of the seizures.

When imagining a previous route, participants’ brains were stimulated with heated activity, a much stronger response than guiding the route with an Xbox joystick.

The brain has a way of generating heat waves internally using memory, the team said.

An Ocean of Brain Waves

Our brains operate on multiple electrical frequencies. By using electroencephalography (EEG), we can record the speed and sequence of brain activity and capture its relative speed. Like calm or stormy waters, these brain oscillations rise and fall at different frequencies, each reflecting a different state of mind.

Beta waves spark, for example, when the brain is fully engaged – for example, when you are stimulated by a conversation. Alpha waves are slower, and are usually present when you are sitting down and ready to relax.

Then there are heat waves. The amplitude of these waves is greater and they cycle even more slowly at 3 to 12Hz per second. Earlier studies found that they pop up when you’re zoned out: during highway driving, on a long drive, or in the shower. These waves are temporarily linked to creativity – ideas or solutions come to you suddenly – or when you are dreaming or meditating.

Despite decades of research, we don’t really understand what they encode. While we are awake, heat waves are found mostly in the hippocampus, a brain region that is critical to both memory and navigation. So it’s no surprise that the waves are seen in mice and rats trying to find their way through complex mazes, suggesting that they help integrate emotion and movement as the rodents explore a new environment.

It is surprising that the waves are also visible in people who are still completely challenged remembering lists of words or pictures. One study the oscillations were found to be crucial in combining different concepts. In another, artificially enhancing brainwaves with an off-the-shelf training device—which uses a combination of sound and lights to stimulate certain brainwave bands—increased memory performance for recalling words in 50 volunteers.

There is a direct link between heated activity and memory performance, the UC Davis team concluded at the time.

So what makes heat waves? Do they help guide us as we navigate the world? Or do they help us lay down precious memories?

Both theories were contending in the new study.

A Digital Shopping Spree

The team started with a valuable group of volunteers: 12 men and women with epilepsy who unfortunately did not respond to medication. Each of them already had up to 17 electrodes implanted in their brains to search for the source of the seizures.

The task itself is one of my worst nightmares: navigating a mall. Here they did it almost using an Xbox joystick, with the digital center displayed on a laptop.

The first step is to get used to six different storefronts and their locations – for example, an ice cream shop, a camera shop, and a comic shop – like wandering around a new mall in person for the first time.

After two rounds, the volunteers were challenged with a navigation task. They were “teleported” to a random store in first-person view, and were prompted with an on-screen message to find another store using the Xbox joystick. The trial ended after they had gone to each store.

Then came the memory task, and it was all hands. The participant still started at a random storefront. Instead of using a joystick, they were instructed to mentally simulate walking over to another destination – pressing “A” on the controller to indicate when they started and when they arrived. All the while, the graphics were gone, leaving only a tiny white cross on the screen for the volunteers to focus on. They performed a total of 44 trials, and their brain activity was monitored the entire time.

It’s hard to read what’s going on in someone’s head: are they really mentally simulating the route, or just relaxing? The study added several guardrails. First, the volunteers had to successfully complete another mental navigation task, but in a familiar environment: they were instructed to imagine standing in their bedrooms at home and walking to their kitchens.

Next, the researchers cleverly introduced “capture tests.” Here, participants used the controller to simulate their imagined routes during memory tasks, which helped ensure that they were actually remembering the route.

Finally, with a dose of statistics, the team found that the time it took each participant to find a target store was correlated between the two tasks, suggesting that they were imagining the same way rather than dreaming.

The brain wave analyzes came back with a clear answer. Both navigation and mental simulation induced heat waves, growing stronger as the trials progressed. However, remembering the way – without any movement – generated much bigger waves that lasted longer. They found the same results regardless of analyzing each individual electrode or each volunteer.

Memory appears to be a much stronger driver of heat waves compared to simple navigation, the team said. Theta waves appear to occur naturally in the brain even without external stimulation, supporting the idea that they are internally generated in the brain and integral to memory.

That’s great news. As memory is closely intertwined with heat waves, the unique frequencies can be harnessed and improved memory during aging or in patients with dementia or other mental disorders. There are already researchers exploring different brain stimulation methods – from electrical to magnetic – with promising results at first.

But perhaps more broadly, the recent study suggests trend which explores brain waves as a new way to treat difficult neurological disorders, including Alzheimer’s and stroke. Dozens are in now clinical trials. They can turn the tide to tackle intractable neurological disorders. The storyteller likes the weather.

Image Credit: Lucas Kapla on Unsplash

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