Electrophysiological responses to alcohol cues are not associated with Pavlovian-to-instrumental transfer in social drinkers.

Jasna Martinovic,Andrew Jones,Paul Christiansen,Lee Hogarth,Abigail K Rose,Matt Field,Ingmar Ha Franken

doi:10.1371/journal.pone.0094605

Abstract

Pavlovian to Instrumental Transfer (PIT) refers to the behavioral phenomenon of increased instrumental responding for a reinforcer when in the presence of Pavlovian conditioned stimuli that were separately paired with that reinforcer. PIT effects may play an important role in substance use disorders, but little is known about the brain mechanisms that underlie these effects in alcohol consumers. We report behavioral and electroencephalographic (EEG) data from a group of social drinkers (n = 31) who performed a PIT task in which they chose between two instrumental responses in pursuit of beer and chocolate reinforcers while their EEG reactivity to beer, chocolate and neutral pictorial cues was recorded. We examined two markers of the motivational salience of the pictures: the P300 and slow wave event-related potentials (ERPs). Results demonstrated a behavioral PIT effect: responding for beer was increased when a beer picture was presented. Analyses of ERP amplitudes demonstrated significantly larger slow potentials evoked by beer cues at various electrode clusters. Contrary to hypotheses, there were no significant correlations between behavioral PIT effects, electrophysiological reactivity to the cues, and individual differences in drinking behaviour. Our findings are the first to demonstrate a PIT effect for beer, accompanied by increased slow potentials in response to beer cues, in social drinkers. The lack of relationship between behavioral and EEG measures, and between these measures and individual differences in drinking behaviour may be attributed to methodological features of the PIT task and to characteristics of our sample.

Highlights

Instrumental and Pavlovian conditioning processes contribute to drug self-administration and the development of substance use disorders
This refers to the behavioral phenomenon of increased instrumental responding for a reinforcer when in the presence of conditioned stimuli (CS) that were previously paired with that reinforcer
Planned comparisons revealed that participants responded for beer more frequently when beer pictures were presented compared to when chocolate (t(30) = 5.80, p,.01, d = 1.66) and neutral pictures (t(30) = 4.98, p,.01, d = 0.87) were presented, i.e. a ‘beer Pavlovian to instrumental transfer (PIT)’ effect

Summary

Introduction

Instrumental and Pavlovian conditioning processes contribute to drug self-administration and the development of substance use disorders. Drug-seeking behavior is reinforced by the pharmacological actions of drugs of abuse, either because those drugs produce pleasurable consequences [1], or because they alleviate negative states such as those that occur during drug withdrawal [2] This instrumental conditioning process develops synchronously with a Pavlovian conditioning process, in which repeated experience of the rewarding effects of drugs of abuse is consistently paired with environmental drug-related cues, such as the sight and smell of beer. After multiple pairings those cues are able to evoke conditioned responses such as subjective craving, drug anticipation, physiological arousal, and behavioral approach [3,4] Pavlovian and instrumental responses develop independently, their interaction is known as Pavlovian to instrumental transfer (PIT). We predicted that individual differences in typical alcohol consumption, hazardous drinking and alcohol craving would be significantly positively correlated with the magnitude of eventrelated potentials that were evoked by alcohol-related cues

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Discussion