The impact of cortisol administration or exposure to stress on extinction processes will be tested in four domains. First, effects of cortisol on stimulus-based fear generalization during extinction will be explored using neuroimaging. Second, effects of a novel method of reactivation (presentation of the UCS) combined with cortisol administration on reconsolidation and fear generalization will be tested. Third, the influence of stress on context-dependent reinstatement will be investigated. Fourth, phase dependent stress effects on extinction of operant behavior will be characterized using appetitive and aversive consequences.

Guiding questions of A09:

• Does the stress hormone cortisol influence extinction generalization and what are the neural correlates?
• Does reactivation with the UCS combined with cortisol administration lead to enhanced reconsolidation and stimulus generalization?
• Does context modulate the reinstatement effect and is this further potentiated by stress?
• Are the effects of stress on the extinction of operant behavior similar to the effects observed for classical conditioning and are they comparable for appetitive and aversive learning?