Animals Can Tell the Time, Study Says

A new study has found that animals can tell how much time has elapsed. Northwestern University researchers examined a mouse’s medial entorhinal /en-tə-ˈrī-nəl/ cortex (MEC), the part of the brain linked with memory and navigation. The study revealed an undiscovered set of brain cells in the mouse’s MEC that are activated to calculate the number of minutes during an animal’s waiting period. To obtain the results, the researchers placed a mouse on a treadmill while immersed in a virtual environment. While on the treadmill, the mouse had to run through a virtual hallway that led to a closed virtual door. When the door opened after six seconds, the mouse got a reward. After the mouse ran repeatedly, the virtual door became invisible. Although the mouse was unable to see whether the invisible door was open or not, it still stopped and waited for six seconds before getting the reward. The researchers thus concluded that the mouse used an internal clock to measure how much time had passed. To support their observation, the researchers further analyzed the mouse’s brain activity during the experiment. They found out that when the mouse stopped, the brain cells that recorded how much time goes by became active. These cells were previously inactive when the mouse was running. The researchers believe that the results may also be useful for humans because the MEC is one of the parts of the brain that will be first affected by Alzheimer’s disease, a condition that involves memory loss. The researchers hope that early detection procedures for Alzheimer’s can be devised by having potential study participants undergo the same virtual experiment.