Oxytocin and Memory of Emotional Stimuli: Some Dance to Remember, Some Dance to Forget.

An ever-growing body of evidence suggests that the hypothalamic neuropeptide oxytocin plays a central role in the regulation of mammalian social behavior and relationships. Yet, mammalian social interactions are extremely complex, involving both approach and avoidance behaviors toward specific individuals. While in the past oxytocin was conceived merely as a prosocial molecule that nonselectively facilitated affiliative emotions and behavior, it is now recognized that oxytocin plays a role in a wide range of social relationships, some of which involve negative emotions such as fear, aggression, and envy and lead to avoidance behavior. However, the way by which a single molecule such as oxytocin contributes to contrasting emotions and opposite behaviors is yet to be discovered. Here, we discuss the role of oxytocin in the modulation of emotional memories in rodents, focusing on two paradigms: social recognition and fear conditioning, representing approach and avoidance behaviors, respectively. We review recent pioneering studies that address the complex effects of oxytocin in a mechanistic approach, using genetic animal models and brain region-specific manipulations of oxytocin activity. These studies suggest that the multiple roles of oxytocin in social and fear behavior are due to its local effects in various brain areas, most notably distinct regions of the amygdala. Finally, we propose a model explaining some of the contradictory effects of oxytocin as products of the balance between two networks in the amygdala that are controlled by the medial prefrontal cortex.