Deep learning deciphers what rats are saying

For many years, researchers knew that rodents' squeaks tell a lot about how the animals are feeling. Much like a wagging tail on a dog, certain vocalizations indicate the rodents are happy. Conversely, other vocalizations indicate the rodents are stressed, or even depressed. But why were they interested in the rodents' moods? These researchers wanted to understand the rodents' responses to various stimuli.