Probing the decision-making mechanisms underlying choice between drug and nondrug rewards in rats.

Youna Vandaele,Serge H Ahmed,Karine Guillem,Magalie Lenoir,Caroline Vouillac-Mendoza

doi:10.7554/elife.64993

Abstract

Delineating the decision-making mechanisms underlying choice between drug and nondrug rewards remains a challenge. This study adopts an original approach to probe these mechanisms by comparing response latencies during sampling versus choice trials. While lengthening of latencies during choice is predicted in a deliberative choice model (DCM), the race-like response competition mechanism postulated by the Sequential choice model (SCM) predicts a shortening of latencies during choice compared to sampling. Here, we tested these predictions by conducting a retrospective analysis of cocaine-versus-saccharin choice experiments conducted in our laboratory. We found that rats engage deliberative decision-making mechanisms after limited training, but adopt a SCM-like response selection mechanism after more extended training, while their behavior is presumably habitual. Thus, the DCM and SCM may not be general models of choice, as initially formulated, but could be dynamically engaged to control choice behavior across early and extended training.

Highlights

Investigating the decision-making mechanisms underlying choice between drug and nondrug rewards is essential to understand how their alterations can contribute to substance use disorders
An increase in latencies during choice is predicted from the deliberative choice model (DCM) whereas the Sequential choice model (SCM) predicts a shortening of latencies during choice compared to sampling
We tested these different predictions in a systematic retrospective analysis of all the choice experiments conducted in the laboratory over the past 12 years

Summary

Introduction

Investigating the decision-making mechanisms underlying choice between drug and nondrug rewards is essential to understand how their alterations can contribute to substance use disorders. Overall, when given a choice, most rats prefer the nondrug alternative (e.g., sweet water, food pellets or social interaction) over potent drugs of abuse, such as cocaine or heroin (Cantin et al, 2010; Lenoir et al, 2013a; Lenoir et al, 2007; Caprioli et al, 2017; Caprioli et al, 2015; Venniro et al, 2018; Vandaele et al, 2016). Investigating habitual control in a drug choice setting is challenging, mainly because there is no effective method of drug reward devaluation in animals, for drugs administered intravenously. Sufficiently versatile to probe the decision-making mechanisms underlying individual preferences in a drug choice setting, is needed

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