The Human GPS: How a Brain Navigates in Unfamiliar Environments
How do we navigate an unfamiliar environment? It turns out that our brains contain a type of GPS cell which allows us to keep track of our relative location. Now, scientists have identified that cell and have learned a little bit more about how we keep track of where we are.
The new type of cell is called the "grid cell," so called since during navigation it activates in a triangle grid pattern. It's distinct among brain cells since its activation represents multiple spatial locations. This behavior is how grid cells allow the brain to keep track of navigational cues such as how far you are from a starting point; this type of navigation is called path integration.
In order to learn a bit more about how people navigate, the researchers studied the brain recordings of epilepsy patients with electrodes implanted deep inside their brains as part of their treatment. During brain recording, the 14 participants played a video game that challenged them to navigate from one point to another to retrieve objects and then recall how to get back to the places where the original objects were located. The scientists then examined the relation between how the participants navigated in the video game and the activity of individual neurons.
"Each grid cell responds at multiple spatial locations that are arranged in the shape of a grid," said Joshua Jacobs, one of the researchers, in a news release. "This triangular grid pattern thus appears to be a brain pattern that plays a fundamental role in navigation. Without grid cells, it is likely that humans would frequently get lost or have to navigate based only on landmarks. Grid cells are thus critical for maintaining a sense of location in an environment."
Finding grid cells in humans provides compelling evidence for a common mapping and navigational system across most species. In fact, past research found that these grid cells were also present in rats. The findings, though, also suggest that the grid patterns may be more prevalent in humans than rats. In addition, the new study could help shed some light on Alzheimer's.
"Grid cells are found in a critical location in the human memory system called the entorhinal cortex," said Itzhak Fried, one of the researchers, in a news release. "This discovery sheds new light on a region of the brain that is the first to be affected in Alzheimer 's disease with devastating effects on memory."
The findings are published in the journal Nature Neuroscience.