1. Brian L. Thomas, Ph.D. Baldwin-Wallace College Berea, Ohio USA

2. Acquisition of fear in Context A  Tone -> Foot Shock Extinction of fear in Context A or B  Tone -> No shock  Tone -> No shock and No Tone -> Shock Test for relapse in Context A  Tone -> No Shock

3. Nonreinforcement of CS alone Allows for spontaneous recovery of fear after a retention interval Allows for renewal of fear outside of the extinction setting Allows for reinstatement of fear after re- exposure to the US Allows fear to relapse

4. Nonreinforcement of CS alone plus unsignaled USs Prevents spontaneous recovery of fear after a retention interval Prevents renewal of fear outside of the extinction setting Prevents reinstatement of fear after re- exposure to the US Prevents fear relapse

5. How does the intensity of the shock given during EU extinction affect extinction and relapse?  All rats received pairings of the CS with a 0.06 mA shock during Acquisition.  During Extinction:  Group EU received 4 CSs intermingled with 2 USs at 0.6 mA  Group EU/D received 4 CSs intermingled with 2 USs at 0.2 mA  Group EU/I received 4 CSs intermingled with 2 USs at 1.0 mA  Group E/B received 4 CSs  Group FC did not receive and CSs or USs

7. How does the number of shocks per extinction session affect extinction and relapse?  Every extinction session had 4 nonreinforced CSs.  The number of shocks per session varied between groups (1, 2 or 4)  Shocks were either intermingled (EU) or given after the 4th CS (CU).

9. What role do contextual stimuli play in EU extinction?  Experiment 1:  Group EU received 4 CSs and 2 USs intermingled during the same session.  Group E-U received 4 CSs and 2 USs during separate, alternating sessions in the same context.  Group E/U received 4 CSs and 2 USs during separate, alternating sessions and CSs were delivered in a different context from USs.

11. What role do contextual stimuli play in EU extinction?  Experiment 2:  Group EU/PreB received preexposure to the extinction context prior to EU extinction.  Group EU/PreC received preexposure to a non- extinction context prior to EU extinction.  Group EU/HC remained in their home cages during the Preexposure phase.

13. Does the US provided during EU extinction have to be the US that caused fear acquisition?  Group EU/SS received a shock US during Acquisition and Extinction.  Group EU/SN received a shock US during Acquisition and a loud noise US during Extinction.

15. EU extinction prevented the relapse of fear most effectively when:  The US provided during extinction was at least as intense as the US experienced during fear acquisition.  The US provided during extinction was intermingled among the CSs and at least 2 USs were given in each extinction session.  The USs provided during extinction were presented in the same context as the CSs.  The subject had not received exposure to the extinction context prior to the Extinction phase.  When the US provided during extinction was either a foot shock or a loud noise.

17. Cheryl Novak, Associate Lab Director David Revta, Technician Drina Vurbic Stephanie Damas Marlo Cutler