Pavlovian-to-instrumental transfer after human threat conditioning.

Yanfang Xia,Angelina Gurkina,Dominik R Bach

doi:10.1101/lm.049338.119

Abstract

Threat conditioning is a common associative learning model with translational relevance. How threat-conditioned cues impact on formally unrelated instrumental behavior in humans is not well known. Such an effect is known as Pavlovian-to-instrumental transfer (PIT). While PIT with aversive primary Pavlovian reinforcers is established in nonhuman animals, this is less clear in humans, where secondary reinforcers or instructed instrumental responses are most often investigated. We modified an existing human PIT procedure to include primary reinforcers. Participants first learned to obtain (or avoid losing) appetitive instrumental reinforcement (chocolate) by appropriate approach or avoidance actions. They either had to act (Go) or to withhold an action (NoGo), and in the Go condition either to approach a reward target to collect it or to withdraw from the reward target to avoid losing it. Then they learned to associate screen color (CS) with aversive Pavlovian reinforcement (electric shock US). In the transfer phase, we conducted the instrumental task during the presence of Pavlovian CS. In a first experiment, we show that the aversive Pavlovian CS+, compared to CS−, increased response rate in Go-Withdraw trials, i.e., induce conditioned facilitation of avoidance responses. This finding was confirmed in a second and independent experiment with an increased number of Go-Withdraw trials. Notably, we observed no appreciable conditioned suppression of approach responses. Effect size to distinguish CS+/CS− in Go-Withdraw trials was d = 0.42 in the confirmation sample. This would require n = 37 participants to demonstrate threat learning with 80% power. Thus, the effect size is on a practically useful scale although smaller than for model-based analysis of autonomic measures. In summary, our results indicate conditioned facilitation of formally unrelated instrumental avoidance behavior in humans and provide a novel behavioral threat learning measure that requires only key presses.

Highlights

Learning to predict threat from neutral cues, often termed Pavlovian threat conditioning or fear conditioning, is a crossspecies paradigm in which a neutral conditioned stimulus (CS+) is contingently paired with an aversive unconditioned stimulus (US), while another neutral stimulus is not (CS−)
Certain outcomes within the game are obstructive to the goal, and these can be predicted from Pavlovian CS, or avoided by instrumental responses
Both skin conductance responses (SCR) and pupil size responses differed between CS+ and CS− trials (SCR mean ± SEM: 0.27 ± 0.05 μS vs. 0.21 ± 0.05 μS, t(20) = 3.00; P = 0.007, and pupil size response 2.90 ± 0.11 mm vs. 2.77 ± 0.09 mm, t(20) = 3.09; P = 0.006)

Summary

Introduction

Learning to predict threat from neutral cues, often termed Pavlovian threat conditioning or fear conditioning, is a crossspecies paradigm in which a neutral conditioned stimulus (CS+) is contingently paired with an aversive unconditioned stimulus (US), while another neutral stimulus is not (CS−). Interest in the mechanisms governing reward learning and addiction led researchers to implement appetitive PIT paradigms in which both Pavlovian and instrumental contingencies were experimentally established with primary reinforcers like tobacco and junk food, and secondary reinforcers such as financial reward (Hogarth et al 2007; Bray et al 2008; Talmi et al 2008; Lovibond and Colagiuri 2013; Quail et al 2017a,b) Among these latter paradigms, the instrumental task developed by Huys et al (2011) is of particular interest as it allows simultaneously assessing conditioned facilitation (increase of punishment avoidance) and conditioned suppression (decrease of reinforcer approach). The reason for these discrepant results has not been followed up until now

Methods

Results

Conclusion