Brian L. Thomas, Ph.D.Baldwin-Wallace College

Berea, Ohio USA

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

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

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

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

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).

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.

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.

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.

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.

Cheryl Novak, Associate Lab Director

David Revta, Technician

Drina Vurbic

Stephanie Damas

Marlo Cutler