Given recent advances in teleportation, it's reassuring to know that the human brain's navigation system appears to work just fine when we're beamed from place to place.
People who experienced virtual teleportation in a video game were able to mentally navigate to known destinations without relying on visual information or perceived motion, according to a study published Thursday by the journal Neuron. And during "teleportation," their brains produced a distinctive electrical signal that's associated with navigation.
So if teleporters do start showing up, don't worry. "Our brain will be OK with that," says Arne Ekstrom, an associate professor of psychology at the University of California, Davis and the study's senior author.
The study was part of an effort to understand the role of a distinctive low-frequency electrical oscillation in the hippocampus, a part of the brain that plays an important role in navigation.
"There's been all these studies over decades trying to figure out what this signal does," says Lindsay Vass, a postdoctoral scholar at UC Davis and the study's lead author.
The oscillation occurs when a person or animal is traveling from one place to another. When the person or animal stops, so does the oscillation. But it's never been clear whether the signal is truly helping with navigation or just a related function, like movement or processing visual information.
"When you're walking around the world you have all this incoming information," Vass says. "You have your feet moving and stepping on the ground. You've got landmarks and buildings that you recognize and street signs."
So the UC Davis team designed an experiment that allowed them to eliminate all that information by having people travel in a virtual environment via teleporter. "With teleportation, you don't see anything," Vass says. "And nobody feels anything. You're not walking anywhere."
Yet you are still traveling. So your brain still needs to somehow navigate itself to a particular place.
The team figured that if the slow oscillations in the hippocampus were associated with movement or sensory information, they would stop during teleportation. But if they were involved in navigation, they would continue.
To find out, the team recruited three volunteers who were awaiting surgery for severe epilepsy. As part of the treatment, surgeons had temporarily placed wires in the patient's brains that monitored electrical activity. This let the UC Davis team measure low frequency oscillations coming from the hippocampus as they happened.
The volunteers were asked to navigate from place to place in a virtual town. One option was to walk. But in several spots, players could enter a teleportation port that would act as a short cut to a specific spot in town.
"They would pop out of the teleporter, and we would give them a new place to find," Vass says. "So we would say OK, now go find the pet store. And they have to know, 'OK, based on the direction I'm facing now, do I need to turn to the right or the left or is it behind me?' "
As expected, the brain oscillations in the hippocampus were present while players were moving about in the virtual environment and absent when they stopped.
"So the critical question for us was what happens as soon as you enter the teleporter," Vass says. "What happens to the oscillation? And what we found was it was still present."
What's more, the oscillation changed a bit depending on whether the person had been teleported a long distance or a short one.
And, when the volunteers arrived, they knew where they were. During teleportation, their brains had successfully navigated to the new destination.
"This is what we call mental navigation," says Gyorgy Buzsaki, a brain scientist at New York University who wasn't involved in the teleportation study. "Somehow the brain can disengage from the environment and we are still navigating mentally."
And the study's results suggest those low frequency oscillations are coordinating the activity of neurons involved in mental navigation, Buzsaki says.
ROBERT SIEGEL, HOST:
Only in science fiction do people beam themselves from place to place.
(SOUNDBITE OF TV SHOW, "STAR TREK")
UNIDENTIFIED ACTOR #1: (As character) Ready to transport.
UNIDENTIFIED ACTOR #2: (As character) Energize.
SIEGEL: We don't have the technology to teleport ourselves in real life, but if we ever do, a new study finds our brains will be ready. NPR's Jon Hamilton reports.
JON HAMILTON, BYLINE: When we travel, a place deep in the brain produces a distinctive electrical signal. This signal from the hippocampus starts up when we begin a trip and stops when we stop. Lindsay Vass at the University of California, Davis, says no one knows why.
LINDSAY VASS: There's been all of these studies over decades trying to understand what this signal does.
HAMILTON: Vaas says one possibly is that the signal is triggered by the things we experience along the way.
VAAS: When you're walking around the world, you have all of this incoming information, right? You have your feet moving and stepping on the ground. You've got all the visual stuff that you can see, right? There's landmarks, and there's buildings that you recognize - street signs.
HAMILTON: But it's also possible that the signal is generated by the brain itself to help it navigate. When you're trying to get somewhere, you're using memory, planning, imagination and your senses. Maybe the signal helps all these elements work together. Vaas was part of a team that came up with a plan to figure out just what this signal did using teleportation.
VAAS: With teleportation, what happens is, you don't see anything, and nobody feels anything, right? You're not walking anywhere.
HAMILTON: Actual teleportation wasn't an option, so they settled for a video game set in a virtual town.
VAAS: There's an ice cream store and a bank and a flower shop.
HAMILTON: The idea is to navigate from place to place. You can walk, but in several spots, players can also enter a teleportation port. Each one acts as a shortcut to a specific place in town. Vaas says teleportation offered a different way to test players' navigation skills.
VAAS: They would pop out of the teleporter, and we would give them a new place to find. So we would say, OK, now go find the pet store, and they have to know, OK, based on the direction I'm facing now, do I need to turn to left or to the right, or is it behind me?
HAMILTON: The research team studied the brains of three volunteers as they played the game. As expected, Vaas says, the signal from hippocampus was present while players were walking about and absent when they stopped.
VAAS: The critical question for us was, what happens as soon as you enter the teleporter - right? - as soon as that screen goes black reads goes black and you can't see anything or feel anything?
HAMILTON: The team figured that if the signal was just a response to sensory information, it would stop, but it didn't. During teleportation, the volunteers' brains were still navigating, and when they arrived, they knew whether the pet store was in front of them or behind them. Their brains had successfully guided them the new destination using memory and imagination instead of relying on sights and sounds. Gyuri Buzsaki, a brain scientist at New York University, says the findings show just how flexible the brain's navigation system is.
GYURI BUZSAKI: Somehow, the brain can disengage from the environment, and this is what we call mental navigation, which is - we are field navigating mentally when we are recalling the past or planning for the future.
HAMILTON: As for the mysterious signal from the hippocampus, Buzsaki thinks it is generated by the brain itself, and he says the signal's purpose is probably to help the brain's many parts work together during navigation. Arne Ekstrom is an associate professor of psychology at UC Davis and the senior author of the new study, which appears in the journal Neuron. He says the results are good news for Trekkies.
ARNE EKSTROM: There's a potential for teleportation at some point in our future, and I think the really interesting sort of implication here is that our brain will be OK with that. Our brain has mechanisms that allow this to happen even if teleportation is something that we would never physically experience in the natural world.
HAMILTON: At least not for a while. Jon Hamilton, NPR News. Transcript provided by NPR, Copyright NPR.