Mouse facial expressions change when it tastes sweet or sour, or when it becomes anxious, as a new study by researchers at the Max Planck Institute for Neurobiology suggests.
The study, published in Science , is the first to show evidence of this kind of expression in mice . To achieve this, artificial vision has been used.
Five emotional states with the facial expressions of the mice (pleasure, disgust, nausea, pain and fear) have been identified thanks to computer vision , that is, a set of algorithms that looks for patterns in images.
According to Nadine Gogolla , who led the study, the facial expressions of mice are not just reactions to the environment. The expressions reflect the emotional value of the trigger:
Mice that licked a sugar solution when thirsty showed a much happier facial expression than satiated mice. Meanwhile, the mice that tested a slightly salty solution showed a "satisfied" expression, while a very salty solution led to a "disgusted" face.
To ensure that this was the case, the researchers also investigated how neural activity in different regions of the brain affects facial expressions. One of those areas of the brain is the insular cortex, which is associated with emotional behavior and the perception of emotions in animals and humans. So, according to Nejc Dolensek , lead author of the study:
With our automated facial recognition system, we can now measure the intensity and nature of an emotion on a millisecond time scale and compare it to neural activity in relevant brain areas.