Impacts of inter-trial interval duration on a computational model of sign-tracking vs. goal-tracking behaviour

François Cinotti,Benoît Girard,Mehdi Khamassi,Matthew R. Roesch,Alain R. Marchand

doi:10.1007/s00213-019-05323-y

Abstract

In the context of Pavlovian conditioning, two types of behaviour may emerge within the population (Flagel et al. Nature, 469(7328): 53–57, 2011). Animals may choose to engage either with the conditioned stimulus (CS), a behaviour known as sign-tracking (ST) which is sensitive to dopamine inhibition for its acquisition, or with the food cup in which the reward or unconditioned stimulus (US) will eventually be delivered, a behaviour known as goal-tracking (GT) which is dependent on dopamine for its expression only. Previous work by Lesaint et al. (PLoS Comput Biol, 10(2), 2014) offered a computational explanation for these phenomena and led to the prediction that varying the duration of the inter-trial interval (ITI) would change the relative ST-GT proportion in the population as well as phasic dopamine responses. A recent study verified this prediction, but also found a rich variance of ST and GT behaviours within the trial which goes beyond the original computational model. In this paper, we provide a computational perspective on these novel results.

Highlights

Individual differences in response to conditioned stimuli (CSs) have elicited much interest in the recent years as a model of differential susceptibility to drug addiction (Saunders and Robinson 2013)
Sign-tracking is thought to be a stable trait of individuals that are more prone to display an automatic behaviour towards reward-predicting cues, in the sense that the same animals may be less sensitive to extinction of conditioning (Ahrens et al 2016) or to devaluation of the reward (Morrison et al 2015; Nasser et al 2015; Patitucci et al 2016) than individuals exhibiting goaltracking this has recently been contested by Derman et al (2018)
This latter study was itself designed to test some specific predictions of the STGT model, namely that manipulating the duration of the inter-trial interval (ITI) so that animals have either more or less time to visit the unrewarded magazine during that period would change the relative proportions of sign- versus goal-tracking behaviour in the population, as well as the dopamine response pattern

Summary

Introduction

Individual differences in response to conditioned stimuli (CSs) have elicited much interest in the recent years as a model of differential susceptibility to drug addiction (Saunders and Robinson 2013). As predicted, when food cup value revision is low, as should be the case during short ITIs, the FMF-only model shows a definite increase in goal-tracking.

Results

Conclusion