An air-puff stimulus method for elicitation of ultrasonic vocalizations in rats.

Rat 22 kHz ultrasonic vocalizations (USVs) are thought to reflect an aversive behavioral state, perhaps a type of anxiety or fear, and have proven useful in the study of the neural mechanisms of these states. This paper describes a simple procedure for presentation of an aversive but non-painful air-puff stimulus for the elicitation of USVs from rats. When directed at the rat's dorsal or dorsolateral head and neck region, this stimulus reliably elicits ultrasonic vocalizations from nearly all rats tested and as such represents a valuable alternative to other stimuli such as aggressive encounters, electric shock, or acoustic startle. The USV response may attenuate with repeated testing, yet remains readily inducible and is therefore suitable for studies involving habituation. The materials for generating this stimulus and the accompanying testing procedure comprise an efficient method with which this aversively motivated rodent behavior can be examined. The potential utility of this technique in studies of aversively motivated behaviors and its relevance to studies of startle responding is discussed.