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Look Up: Research into Innate Visual Behavior in Mice
At DRD Knaagdierwinkel, we are always fascinated by the behavior of our little friends, and recent research has given us another glimpse into the world of mice. Did you know that for a mouse in the wild, spotting aerial predators like hawks and owls is crucial for survival? But how do mice process these visual signals into behaviors that help them avoid attacks?
The Research
Researchers at the California Institute of Technology (Caltech) have developed a simple visual stimulus using an innovative video technique to study the defense mechanisms of mice. This stimulus, an expanding black disk, mimics the appearance of an approaching predator and triggers instinctive reactions in mice: freezing in place or fleeing to a safe spot.
A total of 40 mice were studied. They were placed one by one in a small space called a behavioral arena. After each mouse was given a chance to explore the new environment, videos of different visual stimuli were played on a computer monitor mounted on the ceiling. The researchers then observed the behavior of the mice via a camera located on one of the walls of the arena.
Remarkable Responses
To everyone’s surprise, all the mice responded to the expanding black disk. About 25% of the mice completely froze, not moving a muscle until the disk disappeared. “When I first saw this behavior, my first thought was that the video recording had stopped,” says Melis Yilmaz, the lead researcher.
However, the majority of the mice, around 75%, fled to a tent-like nest in one corner of the arena. This behavior was fascinating, as it all happened during the mice's first encounter with both the arena and the stimulus. “It’s impressive that this reflexive response occurs so quickly, within a quarter of a second,” adds Professor Markus Meister.
How This Behavior Works
Although the study wasn’t designed to evaluate the purposes of the two responses, the researchers suspect that different environmental conditions in the wild could lead to different visual behaviors. "If you were out in nature, freezing might be a good reaction to a predatory bird that is far away because it would help you blend into the surroundings," explains Meister. This would confuse the bird’s visual system, which uses movement to track targets.
Furthermore, when a threat is closer and there is a safe spot nearby, fleeing might be a better strategy.
Enlightening Insights
When Yilmaz and Meister began linking these specific behavioral observations with other information about the mouse visual system, they were able to make predictions about which neurons and circuits were involved in this rapid response. "We tested four different speeds of the expanding disk video, and we found that only one of those speeds caused this behavior robustly," explains Meister.
The findings of this research are not only important for understanding mouse behavior but also help validate the mouse model for studying visual processing. It is remarkable that laboratory mice, bred for dozens of generations in captivity and who have never seen an aerial predator, still exhibit this instinctual behavior. “They never had to learn that a dark object from above was bad news,” says Meister.
What Does This Mean for Us?
While humans don’t have to escape the threat of predatory birds, the results from this research could eventually provide insights into human visual behavior. “The retinas of mice and humans are really very similar, so many of the circuits that are important for the mouse have analogous circuits in the human retina,” says Meister. “Humans also react instinctively to approaching objects, but obviously, we don’t freeze. So how did nature change a circuit that helps one animal escape from predators so that it serves a different function in another animal?”
At DRD Knaagdierwinkel, we like to stay informed about such research. They not only help enhance our understanding of the behavior of our pets but also provide valuable insights into the world around us. Stay tuned for more interesting stories and tips on caring for your little friends!
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