Scientists have for the first time located the “mileage clock” inside a brain – by recording the brain activity of running rats.Letting them loose inside a small, rat-sized arena, the researchers recorded from a part of their brains that is known to be important in navigation and memory.They found that cells there “fired” in a pattern that looked like a mileage clock – ticking with every few steps the animal travelled.A further experiment, where human volunteers walked through a scaled up version of this rat navigation test, suggested that the human brain has the same clock.This study, published in the journal Current Biology, is the first to show that the regular ticking of “grid cells”, as they are known, is directly connected to the ability to correctly gauge the distance we’ve travelled.”Imagine walking between your kitchen and living room,” said lead researcher Prof James Ainge from the University of St Andrews. “[These cells] are in the part of the brain that provides that inner map – the ability to put yourself in the environment in your mind.”This study provides insight into exactly how that internal map in our brains works – and what happens when it goes awry. If you disrupt the ticking of that mileage clock by changing the environment, both rats and humans start getting their distance estimation wrong.In real life, this happens in darkness, or when fog descends when we’re out on a hike. It suddenly becomes much more difficult to estimate how far we have travelled, because our mileage counter stops working reliably.To investigate this experimentally, r …
