Ultrasonic vocalization in rodents: a new potential tool for detecting emotional and motivational changes produced by adverse treatments.

Several experimental models for studying emotion and motivation in laboratory animals have been developed in these last years. A new interesting approach for evaluating some emotional and motivational states in rodents is represented by the measurement of ultrasonic emission in various situations, mainly: by infants when removed from the nest and apparently under stress, cold and/or hunger; during sexual behaviour; during aggressive encounters; in response to aversive stimuli. The calls differ somewhat in their physical characteristics depending on the species and on the situation. Examples of ultrasonic emissions which could be valuable as bioassays in Behavioural Toxicology are described here together with what is known of the biological function of the calls.