Pain is an important physiological response in living organisms. While physical pain is an outcome of tissue damage, pain can manifest as diverse unpleasant sensory and emotional experiences.

Many studies report that emotional or psychological stress enhances pain responses. Furthermore, mice housed with other mice experiencing inflammatory pain exhibit a ‘bystander effect’ with heightened pain sensitivity, or “hyperalgesia.” However, the effects that underpin social pain transmission remain elusive.

Rodents emit ultrasonic vocalizations in the form of high-pitched squeaks in response to various stimuli, including pain, in both audible and ultrasound frequencies that are inaudible to humans. Recently, a team of researchers led by Assistant Professor Satoka Kasai from the Department of Pharmacy, Tokyo University of Science (TUS), Japan, conducted a series of experiments to understand how ultrasonic vocalizations emitted by mice in response to pain stimuli affect the other mice. The study, published in the journal PLOS One, was co-authored by Professor Satoru Miyazaki, Professor Akiyoshi Saitoh, (the late) Professor Satoshi Iriyama, and Professor Kazumi Yoshizawa, all from TUS.