Brain’s GPS cells map time and distance, not just location

When rats run on a treadmill, grid cells act like clocks and odometers

KEEPING TIME  A grid cell fires off signals at particular times as a rat runs on a treadmill. The cell behaved similarly as the rat ran at slow (blue), moderate (brown) and fast (green) speeds. 

B. Kraus et al/Neuron 2015

Specialized cells that make up the brain’s GPS system have an expanding job description.