The stories a rat's whiskers can tell
Add airflow to the information about location and surroundings provided to rodents by their facial hair. Amy Middleton reports.
Rats use their whiskers to help them detect movements in the air, says a new study published in Science Advances.
It’s long been assumed that whiskers relate to an animal’s awareness of airflow, but this is the first scientific evidence to back this theory.
This awareness of wind and air is called anemotaxis, and it allows land-dwelling animals to track odours and follow scents, navigate from place to place and understand and process information about their location and surroundings.
Previous studies have shown the significance of hair and fur in anemotaxis, and now a research team at Northwestern University has shown that whiskers, too, have evolved to assist in airflow-awareness.
The team led by Mitra Hartmann trained five female rats to locate the source of airflow. They were placed in front of a series of fans, one of which was on at random during any given session. The rats were taught to expect a reward when they correctly identified which fan was blowing.
The study was repeated until the rats learned to follow a direct path from their entry point to the source of the airflow – the spinning fan – using their awareness of wind movement.
After 10 days of successful tests, the rats’ whiskers were trimmed to less than two millimetres, and the test repeated.
The rats performed the same task with around 20% less success after their whisker-trim, and walked a less direct path to the source of the airflow.
But the rats still were able to identify the spinning fan, suggesting their awareness of wind and airflow relies on a combination of traits, not just information processed from their whiskers.
Alongside this experiment, a control group of rats were challenged to find a source of light before and after their whiskers were trimmed. The control group was established to make sure the rats weren’t generally disorientated by changes in their whiskers and, sure enough, rats located light sources just as effectively without their whiskers.
“Our results indicate that rats can perform anemotaxis and that whiskers greatly facilitate this ability,” say the researchers.
The team also point to a possible connection between the information gained from a rat’s whiskers and its sense of smell, given that both sets of information are believed to be processed in similar parts of the brain.
In this instance, the researchers suggested that “during an animal’s natural exploration, the most behaviourally relevant information to be obtained from air currents is the location of distant odour sources”.
The team is keen to discover more about the use of smell in rat navigation and awareness in future research.