UC San Diego

Brain emotional systems are crucial for the etiology of addiction and are a substrate for treatment, but animal models of affective states associated with addiction remain a challenge. Rat 50 kHz ultrasonic vocalizations (USVs) are elicited by appetitive and reinforcing stimuli and are thought to be linked to motivational states, whereas 22 kHz USVs are elicited by aversive stimuli and are thought to reflect a negative emotional state. The hypothesis under test in this research was that USVs provide a novel measure of positive and negative affective states in the context of reward and stress associated with addiction. Three studies examined 50 kHz USVs emitted in anticipation for food or alcohol and stress-induced 22 kHz USVs in rats with different levels of motivation and stress. These studies demonstrate that anticipatory 50 kHz USVs represent a stable phenotype of increased motivation for food that involves dopamine and opioid systems, and that during alcohol dependence anticipatory 50 kHz USVs also may be an indicator of context-elicited negative reinforcement learning. In addition, these studies show that alcohol withdrawal-potentiated stress-induced 22 kHz USVs reflect a state of anxiety/arousal that is not mediated by corticotropin-releasing factor. The current research indicates that rat ultrasonic vocalization is a behavior that is sensitive to changes in emotional and motivational states that can be exaggerated in animal models of compulsive alcohol-seeking and withdrawal. Therefore, the study of USV behavior can help the understanding of motivational mechanisms underlying normal and pathological behaviors