Understanding Time

Active timing cells at work

Ever wonder how your cat knows you’re late coming home from work? A recent study found evidence that mice can judge time. By examining mouse brains’ medial entorhinal cortex, researchers discovered neurons that turn on like a clock when they wait.

The researchers hypothesized that the medial entorhinal cortex, an area in the brain associated with memory and navigation, could be responsible for encoding time.

They set up an experiment called the virtual “door stop” task. In the experiment, a mouse runs on a physical treadmill in a virtual reality environment. The mouse learns to run down a hallway to a door that is located about halfway down the track. After six seconds, the door opens, allowing the mouse to go receive its reward.

After running several training sessions, researchers made the door invisible. In that scenario, the mouse knew where the now-invisible “door” was located and still waited six seconds at the door before racing to its reward. The study found that the “timing cells” didn’t fire during active running, only during rest. While more study is warranted, the findings may relate to the ability of animals, including cats, to track time.

Heys, JG et al. Evidence for a subcircuit in medial entorhinal cortex representing elapsed time during immobility.Nature Neuroscience, 2018