Virtual Reality Environments (IMAGE) Northwestern University Caption Mice in the experiment are trained on a virtual reality environment that has a visible door. Then, they run the course where the door is made invisible. The only way they can solve the task is by using their internal sense of time. Credit Daniel Dombeck/Northwestern University Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.