For anyone who finds reading maps or asking for directions troublesome, GPS might seem like a godsend – that is, until it leads you to the middle of nowhere thanks to a satellite error. However, apart from occasionally leading drivers astray, researchers at University College London (UCL) suggest that simply following instructions given by your navigational app could have another negative effect: allowing parts of your brain to go dormant.

In the UCL study, 24 volunteers were taken on a two-hour walking tour of London's Soho neighborhood and shown 23 goal locations. The next day, the researchers tested navigation by showing each volunteer 10 simulations of routes through Soho. After being given a specific starting point, they had to navigate their way through the simulation to get to a goal location. Five of the movies required participants to make navigational decisions while the other half functioned like a GPS unit, merely directing the participants on which buttons to push to make turns.

An example of the navigational decisions volunteers had to make (Credit: UCL)

The researchers found that there was a spike in hippocampal and prefrontal cortex activity when volunteers navigated and entered new streets on their own. This shot up even further when the number of navigational options increased when participants were in an area with several street segments. In contrast, no additional activity was detected when they simply followed the instructions given to them, a situation not dissimilar to driving based on the directions from your GPS unit.

"Entering a junction such as Seven Dials in London, where seven streets meet, would enhance activity in the hippocampus, whereas a dead-end would drive down its activity," explains senior author Hugo Spiers, a neuroscientist at UCL Experimental Psychology. "If you are having a hard time navigating the mass of streets in a city, you are likely putting high demands on your hippocampus and prefrontal cortex."

These results corroborate that of previous studies, including one by Cornell University researchers that found GPS causes drivers to disengage from and ignore their environment.

"Our results fit with models in which the hippocampus simulates journeys on future possible paths while the prefrontal cortex helps us to plan which ones will get us to our destination," says Spiers, who was involved in an earlier UCL study focusing on London taxi drivers. That study showed that the hippocampi of would-be taxi drivers expand as they memorize 25,000 of London' streets in order to pass the Knowledge, dubbed the world's hardest geography test. According to that study, London cabbies, especially those with decades of experience, have more grey matter in that region of the brain than most other people.

"When we have technology telling us which way to go, however, these parts of the brain simply don't respond to the street network," said Spiers. "In that sense our brain has switched off its interest in the streets around us."

Better buildings

The team also analyzed the street networks of other major cities to gauge their navigability and potential impact on the brain's memory systems. They found that those with grid layouts, such as Manhattan, are less strenuous on the hippocampus than cities with a complex network, such as London, since there are only three options at most junctions: straight, left or right. These findings are important, as the information could be used to design better care centers and hospitals.

"For example, we could look at the layouts of care homes and hospitals to identify areas that might be particularly challenging for people with dementia and help to make them easier to navigate," says Spiers. "Similarly, we could design new buildings that are dementia-friendly from the outset."

The study was published in Nature Communications.

Source: UCL

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