When we navigate without a GPS or smartphone, we’re using two different regions in our brains to do so, according to new research published in Current Biology. And our brain is capable of computing distance in two ways: tracking the straight-line distance to the destination and identifying the distance on the path along the way.

The research — funded by the Wellcome Trust — provides a fresh outlook on how humans navigate, especially since it was previously uncertain whether the brain calculates only a straight-line route from point A to point B. “Our team developed a new strategy for testing navigation and found that the way our brain directs our navigation is more complex than we imagined, calculating two types of distance in separate areas of the brain,” Dr. Hugo Spiers of University College London (UCL), one of the authors of the study, said in a press release. “Our results indicate that it is the daily demand on processing paths in their posterior hippocampus that leads to the impressive expansion in their grey matter.”

The study required participants to wander the streets of Soho in London, while the authors monitored brain activity. They kept track of the different phases the wanderers went through while finding their way to the destination: planning how to get there, keeping track of the destination, and making decisions at cross streets. During the planning part of the travelling, the entorhinal cortex — a region of the brain known for navigation and memory — was more active in defining straight-line distance to the destination. The rest of the journey activated the posterior hippocampus, which is also known for its connection to navigation and memory. When participants used satellite navigation, or GPS, the brain was overall far less active.

A previous study out of the University of California, San Diego, published in 2011, found that it was in the entorhinal cortex that certain neuronal “grid cells” defined navigation through physical environments by managing an internal representation.

“These findings provide insight into the underlying biology of mental health conditions which affect our memory,” Dr. John Williams, head of clinical activities, neuroscience and mental health at the Wellcome Trust, said in the press release. “The hippocampus and entorhinal cortex are among the first regions to be damaged in the dementia associated with Alzheimer’s disease and these results provide some explanation as to why such patients struggle to find their way and become lost. Combining these findings with clinical work could enable medical benefits in the future.”

Spiers echoed his sentiments, noting that "The research is also a substantial step towards understanding how we use our brain in real world environments, of which we currently know very little.”

Source: Howard LR, Javadi AH, Spiers HJ, et al. Hippocampus and entorhinal cortex encode the path and Euclidean distance to goals during navigation. Current Biology. 2014.