Researchers have made a groundbreaking discovery by locating the brain's internal ‘mileage clock’ – a neural system that tracks how far we've travelled. The study represents the first direct evidence of how our brains measure distance.

Scientists at the University of St Andrews recorded brain activity in rats as they navigated a specially designed arena. They discovered that ‘grid cells’ in the brain's navigation centre fired in regular patterns, ticking approximately every 30 centimetres the rats travelled – just like a biological mileage counter.

The more regular this firing pattern, the better the animals estimated distances to reach their chocolate treat rewards. When researchers altered the arena's shape, disrupting the regular signal, rats consistently underestimated distances and stopped too short.

To test whether humans have the same system, researchers scaled up the experiment using a 12m x 6m arena in their university's student union. Human volunteers showed identical patterns – accurately estimating distances in regular environments but struggling when the space was altered.

This study explains why we lose our sense of distance in fog or darkness – environmental changes disrupt our internal mileage clock. The discovery has practical applications too, as these brain cells are among the first affected by Alzheimer's disease.

Researchers believe this finding could lead to smartphone-based diagnostic games that test distance estimation, potentially enabling earlier detection of cognitive decline through navigation assessment.

Reference: https://www.bbc.co.uk/news/art... (accessed 19.9.25)

ANSWER THE FOLLOWING QUESTIONS!

1. The rats received a chocolate treat when they successfully navigated the arena. Use your knowledge of operant conditioning to explain why.

2. This piece of research studied both rats and humans. Why does this improve the validity of the findings?

3. How might the human sample limit the generalisability of the findings?

4. How might the use of a controlled indoor arena limit the generalisability of the findings?

5. How could the practical applications mentioned in this research have implications for the economy?

Challenge: research the current developments in smartphone diagnostic tools for conditions such as Alzheimer’s.