Mice, and Perhaps Canines and Other Animals, Can Track Time
Do mice miss us when we're gone or know we're late in feeding them?
Posted Oct 24, 2018
Do nonhuman animals (animals) have a sense of time? I'm constantly asked this question especially when I frequent—all too frequently—dog parks. For example, people want to know if dogs miss them after a certain amount of time or if dogs understand them when they say "Okay, Harry, I’ve got a meeting soon, so go pee and poop" or if they know what they mean when they say something like, "You have two minutes to play and then we have to go home." I've also observed that if people have to call their dog more than once, they often get testy and say something like, “What took you so long? I’ve been calling you for ten minutes. We need to leave now” or "Where have you been? You sure took your time coming back to me so you only have a few minutes to see your friends." I often wonder if dogs think something like, “Huh, how long is two minutes of ten minutes?" or "How long is now?” (For more, see "Do Dogs Understand 'You Can Play 5 Minutes Then We Go Home'?," Canine Confidential: Why Dogs Do What They Do), "The effect of time left alone at home on dog welfare," and "When Leaving a Dog Home Alone, How Long Is Too Long?") The researchers who conducted the study on time left alone and dog welfare concluded, ""Although this study cannot distinguish between whether dogs were aware of the length of time they were alone (but did not signal it) or whether they were unaware until reminded of it by the return of their owner, it does confirm that dogs are affected by the duration of time at home alone."
A new study using a virtual reality environment shows mice encode time
While people often ask me about whether dogs, cats, and nonhuman primates have a sense of time, no one has asked me about rodents. Because of my long-term interests in whether or not animals have a sense of time, I was especially please to see a very important and novel study on mice published in Nature Neuroscience called "Evidence for a subcircuit in medial entorhinal cortex representing elapsed time during immobility" by Northwestern University researchers James Heys and Daniel Dombeck. Only the abstract for this essay is available online and I honestly wasn't sure what this study was all about from reading the title, but it all made sense after I saw some popular accounts, especially one titled "Yes, your pet can tell time" published in Science News, that nicely summarizes this important research project. Interestingly, this piece begins by referring to dogs, rather than to mice: "Are you taking your time when feeding your pet? Fluffy and Fido are on to you—and they can tell when you are dawdling."
I also saw two other popular essays with the catchy titles "Yes, Your Cat Can Tell if You’re Out All Night" and "How your dog tells the time: Newly-discovered neurons in pets' brains can 'turn on like a clock' and judge if it's been too long since they were fed" in which we read, "Pets can accurately judge the passage of time and know when their owners are late to feed them, a new study reveals." However, this new study doesn't really do this and the cutesy titles misrepresent the actual research..
One of of the popular accounts showed a picture of a cat and a dog and the other two showed pictures of dogs. Why not show the actual animals who were involved in the study? Well, the answer is a pretty easy one, namely, that mice aren't as appealing to as many people as are some of our other companion animals, although many people keep mice as pets. And, mice are rather smart and emotional beings who are known to display empathy.
The study conducted by Heys and Dombeck is very interesting because of how it was done. First, they focused on the medial entorhinal cortex (MEC) in the brain's temporal lobe because it is associated with memory and navigation. Because of what is known about the MEC, "Dombeck hypothesized that the area could also be responsible for encoding time." In the Science News piece, we read, "To test their hypothesis, Dombeck and Heys 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 continue down the hallway to receive its reward."
After the mice were used in several training sessions, the door was made invisible but they knew where the door was supposed to be based on the texture of the floor. Yet, mice still waited six seconds where the door had been before they went to collect their reward. "The important point here is that the mouse doesn't know when the door is open or closed because it's invisible," said Heys, the paper's first author. "The only way he can solve this task efficiently is by using his brain's internal sense of time." The researchers didn't stop with the behavioral analyses, By imaging the brain it turned out that cells in the medial entorhinal cortex (MEC) in the temporal lobe encode time and these "timing cells" only fire while the mice are resting, not when they're running.
The researchers go on to suggest that perhaps this study and others like it might help us to understand neurodegenerative diseases such as Alzheimer's because people who suffer from this forget things that happen over time. Along these lines, Dombeck notes, "So this could lead to new early-detection tests for Alzheimer's... We could start asking people to judge how much time has elapsed or ask them to navigate a virtual reality environment—essentially having a human do a 'door stop' task."
Do mice and other rodent companion animals miss us when we're gone or know we're late in feeding them?
I fully understand that mice may not be as universally appealing as cats and dogs, but right now we really don't know if and how the brains of dogs and cats track time. However, now we know that the brains of mice do encode time, and future research is needed to see if these results can be generalized to other animals. This new research shows that it's as reasonable to ask if mice and other rodent companion animals miss us when we're gone or know when we're late in feeding them as it is to ask about dogs, cats, and other animals. It also calls attention to welfare implications for the millions upon millions of mice and other animals who are used in various types of research and who languish in laboratories around the world.
Please stay tuned for more on the fascinating behavior of the animals with whom we share our homes and our magnificent planet. There really is so much to learn.
James G. Heys, Daniel A. Dombeck. Evidence for a subcircuit in medial entorhinal cortex representing elapsed time during immobility. Nature Neuroscience, 2018.