Rats Alter Movement of Whiskers to Help Navigate in Dark

Whiskers are known to be an integral part of a rat's life, similar to what hands and fingers are for humans.

It is known that rats deliberately alter how they sense the environment around them using the facial whiskers, which again depends on whether or not the environment is new, if there exists a risk of collision or if they can see in which direction they are heading. They explore the environment around them by moving the facial whiskers forward and backwards called whisking.

 "All mammals except humans use facial whiskers as touch sensors. In humans we seem to have replaced this sense, in part, by being able to use our hand and fingers to feel our way. The rat puts its whiskers where it thinks it will get the most useful information, just as we do with our fingertips," said Professor Tony Prescott from the University of Sheffield.

The movement of whiskers offers the animals the tactile sense to move around with ease in the dark. But scientists were not sure to what extent the rats could control the movement of the whiskers.

In the latest study, researchers at the University of Sheffield, used high speed-videography to observe the animals that had been trained for several days to run circuits for food.  The rats were placed in different scenarios that included unexpected obstacles in the path and eliminating visual cues.

The researchers discovered strong evidence that the rats moved their whiskers in a deliberate manner in order to navigate safely. As the rats got accustomed to the environment, they moved faster and also changed the movement of the facial whiskers- by changing from broad exploratory whisker sweeps directed at nearby surfaces, such as the floor, to pushing their whisker forwards  to detect obstacles and avoid collisions.

In those scenarios where collision was more likely to happen, they navigated slowly and pushed their whiskers forward further, indicating the rats were aware of the increased risk of collision and were being extremely cautious.

 "This new research show that rats do much the same thing but using their facial whiskers. That is, they purposefully use their whisker to detect nearby objects and surfaces when moving slowly in unfamiliar environments, and push them out in front of themselves, to avoid collisions, when the environment is familiar and they want to move more quickly," Professor Prescott, said.

The finding was documented in Current Biology.