Learning to Like: A Role for Human Orbitofrontal Cortex in Conditioned Reward

Abstract

A great deal of human behavior and motivation is based on the intrinsic emotional significance of rewarding or aversive events, as well as on the associations formed between such emotional events and concurrent environmental stimuli. Recent functional neuroimaging studies have implicated the ventral striatum, orbitofrontal cortex (OFC), and amygdala in the representation of reward values and/or in the anticipation of rewarding events. Here, we use functional magnetic resonance imaging to compare brain activation during the presentation of reward with that during presentation of (conditioned) stimuli that have been paired previously with reward. Specifically, we aimed to investigate conditioned reward in the absence of explicit reward anticipation. Twenty-two healthy volunteers were scanned while monochrome visual patterns were incidentally associated with reward or negative feedback in the context of a simple card game. In the subsequent session, visual patterns, including the conditioned stimuli, were presented without reward or negative feedback, and the affective valence of these stimuli was assessed behaviorally. The presentation of reward compared with negative feedback activated the ventral striatum and OFC. Activation in the same OFC region was observed when, in the subsequent session, subjects passively viewed the stimuli that had been paired with reward, without the administration of reward and with subjects being essentially unaware of the conditioning manipulation. These findings suggest that the OFC in humans plays an important role in the representation of both rewarding stimuli and conditioned stimuli that have acquired reward value.

Individual Differences in Nicotine Dependence, Withdrawal Symptoms, and Sex Predict Transient fMRI-BOLD Responses to Smoking Cues

“…Of particular note were correlations in vACG and OFCFboth of which are regions previously implicated in drug dependence, cue reactivity, and conditioned reward (Brody et al, 2002;Cox et al, 2005;London et al, 2000;Rose et al, 2007). These findings suggest that higher levels of nicotine dependence may result in enhanced sensitivity to drug cues in these regions.…”

Food and Drug Reward: Overlapping Circuits in Human Obesity and Addiction

“…The enhanced OFC activation by the food stimulation is likely to reflect downstream dopaminergic effects and participate in DA's involvement in the drive for food consumption. The OFC plays a role in learning stimulus-reinforcement associations and conditioning (Cox et al 2005;Gallagher et al 1999), supports conditioned-cue elicited feeding (Weingarten 1983), and probably contributes to overeating irrespective of hunger signals (Ogden and Wardle 1990). Indeed, dysfunction of the OFC has been linked to overeating (Machado and Bachevalier 2007).…”

Appetitive conditioning: Neural bases and implications for psychopathology

“…Many of them involved evaluative conditioning rather than classical conditioning. These studies used conditioning to different valences (pleasant and unpleasant) with first-order US, such as odor (Gottfried et al, 2002) and taste (O'Doherty et al, 2003), or second-order US such as money (Kirsch et al, 2003, Cox et al, 2005. Other works employed classical conditioning.…”

“…Another study reported a sub-threshold correlation between neural activation in the amygdala and post-conditioning pleasantness ratings associated with cues (CS) that predicted the delivery of different juices (US) (O'Doherty et al, 2006). In contrast, studies using money as US did not find activation in the amygdala in the processing of appetitive conditioning (Kirsch et al, 2003, Cox et al, 2005. Therefore, the role of the amygdala in appetitive conditioning in humans remains to be clarified…”