It turns out that human brains form brain waves that are eerily similar in spatial perception when moving, and scientists have discovered this thanks to inventing a way to examine our brains during free movements, rather than lying down.
“Our results indicate that our brains create a universal signature for putting ourselves in someone else’s shoes,” said neurosurgeon Nantia Suthana, of the University of California, Los Angeles.
Previous studies in mice revealed that low-frequency brain waves help rodents track their locations when exploring a new location – by delineating place boundaries. Similar waves have also been identified to mark boundaries in humans, but only as they navigate a virtual environment while they are conducting brain scans.
“We wanted to investigate this idea in people – and test whether they could also monitor others in their vicinity – but current technology is holding them back,” said neuroscientist Matthias Stangl at the University of California, Los Angeles.
So Stangl and his colleagues devised a portable brain scanner, consisting of a backpack equipped with a computer that wirelessly connects to electrodes implanted in the brain (a system called intracranial EEG), to help them study how our brains form and retrieve spatial memories.
Their subject was five patients with epilepsy, and had already had electrodes implanted in their brains to help control their seizures. These implants reside in the medial temporal lobe – parts of our brain are thought to encode long-term intentional memories and spatial perception.
The participants participated in a 15-minute navigation mission, during which they were asked to find and find the locations of hidden targets within the room. This was followed by a 15-minute observation task where participants had to track another person moving around the room, and press a button when the other person crossed unspecified target locations.
The researchers found that as participants approached a physical boundary – such as a room wall – the flow of low-frequency oscillations in their brains increased strongly. The same thing happened when they saw another person approach the walls.
“We found that oscillatory changes related to boundaries were strikingly similar between tasks requiring autonomous mobility versus observing another person,” they write in their paper.
Recent studies in mice and bats also found the same set of neurons in the hippocampus for both the animal’s location and the location of others of its species.
The strength of these brainwave representations also increased when the focus was on finding the target site. And the oscillating signals were not continuous, did not change the amount of their occurrence, only their strength.
“Our results support the idea that, in certain mental states, this pattern of brain waves might help us recognize boundaries. And in this case, it was when people focus on a target and search for something,” said Stangl.
The oscillating electrical activity is measured within a frequency range referred to as theta waves. We generally produce these slow, clear waves on the go, so it’s not surprising that they’re crisp in a mission like this.
Interestingly, gamma waves that are somewhat more loud also appeared in similar patterns, with a slightly greater difference between different conditions. And these are the waves that we produce when we use more of our brains to think, and map experiences into our working memory.
The team believes that the brainwaves they observed are generated by multiple groups of neurons that may include cells that specifically encode boundaries and objects. A better understanding of this neural language may help us detect brain disorders.
And in an interesting twist, they made their backpack design available to other researchers. Soon, we can expect to learn more about our brain wave patterns in complex social situations.
The study was published in a journal Nature.