Targeting avoidance via compound extinction

ABSTRACT

Avoidance towards innocuous cues is a key diagnostic criterion across anxiety-related disorders. Importantly, the most effective intervention for anxiety-related disorders, exposure therapy with response prevention, sometimes does not prevent the relapse of anxiety's symptomatology. We tested whether extinction effects, the experimental proxy of exposure, are enhanced by increasing the discrepancy between the prediction of an unpleasant event happening (shock presentation), and the actual event (shock omission). Forty-eight individuals first saw pictures of three stimuli. Two pictures (CSA, CSB) were followed by a shock (US) and one (CS-) was not. Next, participants learned to avoid the US by pressing a computer key. An extinction and response prevention procedure followed. In the first part of it, participants saw unreinforced presentations of all CSs. In the second part, the single group saw unreinforced presentations of the CSA and CS-. The compound group encountered compound unreinforced presentations of the CSA and CSB, and separate presentations of the CS-. Return of avoidance and fear was tested after unsignalled presentations of the US. Compound extinction resulted in comparable reduction of fear and avoidance compared to standard extinction. We discuss how future research could enhance extinction effects by adding costs to the avoidance behaviour.     

Interhemispheric transfer of extinction of the active avoidance reaction in rats.

Cortical spreading depression (CSD) was employed in rats to study the lateralization of extinction of a jumping avoidance reaction. Under unilateral CSD, 181 nonreinforced trials were needed to extinguish the avoidance reaction acquired in three 100-trial sessions of intact-brain training. During a second extinction session, either with the same or with the contralateral hemisphere depressed, the mean number of trials to the extinction criterion (9/10) was 39 (n = 12) or 186 (n = 15), respectively. Five extinction trials performed with the brain intact 1 hr before extinction with contralateral CSD decreased the number of trials to extinction of 98 (n = 11). Thus, extinction of active avoidance can be lateralized and interhemispherically transferred in the same way as acquisition of this habit.     

Using drugs to modify the effect of response prevention on avoidance extinction

Amobarbital and chlordiazepoxide were administered during avoidance response prevention and the effect evaluated in the nondrugged state in a subsequent test for avoidance extinction. It was found that Ss administered 15 mg/kg and 30 mg/kg amobarbital, and 30 mg/kg chlordiazepoxide during response prevention differed significantly from the control Ss in extinction performance. Rather than showing either reduced avoidance performance or no difference with the nondrugged Ss, the Ss drugged during response prevention showed increased avoidance performance in the subsequent test of avoidance extinction. That is, preventing avoidance responding under a drugged (versus nondrugged) state produced increased resistance to extinction of the avoidance response.     

The effects of single-component extinction of a three-component serial CS on resistance to extinction of the conditioned avoidance response

Central to a fear interpretation of how avoidance responses are maintained in the absence of further CS-UCS pairings is the underlying assumption of an existing gradient of fear across the CS-UCS interval. Extrapolations based on this gradient lead to a number of differential predictions concerning the topography of avoidance responding during extinction. The present research was concerned with the differential effects of extinguishing separate components of the CS complex upon responding to the complete CS complex during extinction. In Phase 1 of the study, rats were classically conditioned to a three-component serial CS (S₁/S₂/S₃) followed by shock. Each subject was then given avoidance training in a one-way apparatus to a criterion of one successful avoidance. In Phase 2, subjects were divided into four groups, with three of the groups receiving nonreinforced exposure for 25 trials to one of the components of the serial CS (S₁, S₂, or S₃). The fourth group (S₀) was exposed for the same period of time to the apparatus cues. In Phase 3, the total stimulus complex was reintroduced in its original order, and animals were tested until extinction of the instrumental response was reached. The results are consistent with the hypothesis that a fear gradient exists in extinction and decreases in magnitude as the distance from the point of UCS onset increases.     

The development and the extinction of hyperthermia induced by conditioned avoidance behavior in rats

Hyperthermia was observed at the end of each conditioning session in rats trained to avoid electric shocks by jumping on a platform. The temperature rise was also observed after the conditioned behavioral response was well established and was elicited even in the absence of shocks. There was no tendency for the hyperthermia to diminish over the course of nine extinction sessions.     

Effects of temporal placement of response prevention on extinction of avoidance in rats

Two experiments investigated the effects of prior extinction trials upon the effectiveness of response prevention procedures (flooding) in facilitating extinction of avoidance in rats. The results showed that both prior CS only extinction trials and response prevention independently hastened extinction and that response prevention is enhanced if prior extinction has already taken place. The results were interpreted as being consistent with a relaxation interpretation of extinction of avoidance behavior providing a ‘distraction’ or ‘attention shift’ factor is incorporated into theory.