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Palmatier MI, Kellicut MR, Brianna Sheppard A, Brown RW, Robinson DL. The incentive amplifying effects of nicotine are reduced by selective and non-selective dopamine antagonists in rats. Pharmacol Biochem Behav 2014; 126:50-62. [PMID: 25230311 PMCID: PMC4440414 DOI: 10.1016/j.pbb.2014.08.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Revised: 08/18/2014] [Accepted: 08/24/2014] [Indexed: 01/18/2023]
Abstract
Nicotine is a psychomotor stimulant with 'reinforcement enhancing' effects--the actions of nicotine in the brain increase responding for non-nicotine rewards. We hypothesized that this latter effect of nicotine depends on increased incentive properties of anticipatory cues; consistent with this hypothesis, multiple laboratories have reported that nicotine increases sign tracking, i.e. approach to a conditioned stimulus (CS), in Pavlovian conditioned-approach tasks. Incentive motivation and sign tracking are mediated by mesolimbic dopamine (DA) transmission and nicotine facilitates mesolimbic DA release. Therefore, we hypothesized that the incentive-promoting effects of nicotine would be impaired by DA antagonists. To test this hypothesis, separate groups of rats were injected with nicotine (0.4mg/kg base) or saline prior to Pavlovian conditioning sessions in which a CS (30s illumination of a light or presentation of a lever) was immediately followed by a sweet reward delivered in an adjacent location. Both saline and nicotine pretreated rats exhibited similar levels of conditioned approach to the reward location (goal tracking), but nicotine pretreatment significantly increased approach to the CS (sign tracking), regardless of type (lever or light). The DAD1 antagonist SCH-23390 and the DAD2/3 antagonist eticlopride reduced conditioned approach in all rats, but specifically reduced goal tracking in the saline pretreated rats and sign tracking in the nicotine pretreated rats. The non-selective DA antagonist flupenthixol reduced sign-tracking in nicotine rats at all doses tested; however, only the highest dose of flupenthixol reduced goal tracking in both nicotine and saline groups. The reductions in conditioned approach behavior, especially those by SCH-23390, were dissociated from simple motor suppressant effects of the antagonists. These experiments are the first to investigate the effects of dopaminergic drugs on the facilitation of sign-tracking engendered by nicotine and they implicate dopaminergic systems both in conditioned approach as well as the incentive-promoting effects of nicotine.
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Affiliation(s)
- Matthew I Palmatier
- Department of Psychology, East Tennessee State University, Johnson City, TN 37641, USA.
| | - Marissa R Kellicut
- Department of Psychology, East Tennessee State University, Johnson City, TN 37641, USA
| | - A Brianna Sheppard
- Department of Psychology, East Tennessee State University, Johnson City, TN 37641, USA
| | - Russell W Brown
- Department of Psychology, East Tennessee State University, Johnson City, TN 37641, USA
| | - Donita L Robinson
- Bowles Center for Alcohol Studies, Department of Psychiatry, University of North Carolina, Chapel Hill, NC 27599, USA
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102
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A cocaine context renews drug seeking preferentially in a subset of individuals. Neuropsychopharmacology 2014; 39:2816-23. [PMID: 24896613 PMCID: PMC4200491 DOI: 10.1038/npp.2014.131] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Revised: 05/19/2014] [Accepted: 05/30/2014] [Indexed: 11/08/2022]
Abstract
Addiction is characterized by a high propensity for relapse, in part because cues associated with drugs can acquire Pavlovian incentive motivational properties, and acting as incentive stimuli, such cues can instigate and invigorate drug-seeking behavior. There is, however, considerable individual variation in the propensity to attribute incentive salience to reward cues. Discrete and localizable reward cues act as much more effective incentive stimuli in some rats ('sign-trackers', STs), than others ('goal-trackers', GTs). We asked whether similar individual variation exists for contextual cues associated with cocaine. Cocaine context conditioned motivation was quantified in two ways: (1) the ability of a cocaine context to evoke conditioned hyperactivity and (2) the ability of a context in which cocaine was previously self-administered to renew cocaine-seeking behavior. Finally, we assessed the effects of intra-accumbens core flupenthixol, a nonselective dopamine receptor antagonist, on context renewal. In contrast to studies using discrete cues, a cocaine context spurred greater conditioned hyperactivity, and more robustly renewed extinguished cocaine seeking in GTs than STs. In addition, cocaine context renewal was blocked by antagonism of dopamine receptors in the accumbens core. Thus, contextual cues associated with cocaine preferentially acquire motivational control over behavior in different individuals than do discrete cues, and in these individuals the ability of a cocaine context to create conditioned motivation for cocaine requires dopamine in the core of the nucleus accumbens. We speculate that different individuals may be preferentially sensitive to different 'triggers' of relapse.
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103
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Tomasi D, Wang GJ, Wang R, Caparelli EC, Logan J, Volkow ND. Overlapping patterns of brain activation to food and cocaine cues in cocaine abusers: association to striatal D2/D3 receptors. Hum Brain Mapp 2014; 36:120-36. [PMID: 25142207 DOI: 10.1002/hbm.22617] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Revised: 07/16/2014] [Accepted: 08/08/2014] [Indexed: 02/05/2023] Open
Abstract
Cocaine, through its activation of dopamine (DA) signaling, usurps pathways that process natural rewards. However, the extent to which there is overlap between the networks that process natural and drug rewards and whether DA signaling associated with cocaine abuse influences these networks have not been investigated in humans. We measured brain activation responses to food and cocaine cues with fMRI, and D2/D3 receptors in the striatum with [11C]raclopride and Positron emission tomography in 20 active cocaine abusers. Compared to neutral cues, food and cocaine cues increasingly engaged cerebellum, orbitofrontal, inferior frontal, and premotor cortices and insula and disengaged cuneus and default mode network (DMN). These fMRI signals were proportional to striatal D2/D3 receptors. Surprisingly cocaine and food cues also deactivated ventral striatum and hypothalamus. Compared to food cues, cocaine cues produced lower activation in insula and postcentral gyrus, and less deactivation in hypothalamus and DMN regions. Activation in cortical regions and cerebellum increased in proportion to the valence of the cues, and activation to food cues in somatosensory and orbitofrontal cortices also increased in proportion to body mass. Longer exposure to cocaine was associated with lower activation to both cues in occipital cortex and cerebellum, which could reflect the decreases in D2/D3 receptors associated with chronicity. These findings show that cocaine cues activate similar, though not identical, pathways to those activated by food cues and that striatal D2/D3 receptors modulate these responses, suggesting that chronic cocaine exposure might influence brain sensitivity not just to drugs but also to food cues.
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Affiliation(s)
- Dardo Tomasi
- National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland
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104
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Experimental predictions drawn from a computational model of sign-trackers and goal-trackers. ACTA ACUST UNITED AC 2014; 109:78-86. [PMID: 24954026 DOI: 10.1016/j.jphysparis.2014.06.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Revised: 05/30/2014] [Accepted: 06/02/2014] [Indexed: 11/20/2022]
Abstract
Gaining a better understanding of the biological mechanisms underlying the individual variation observed in response to rewards and reward cues could help to identify and treat individuals more prone to disorders of impulsive control, such as addiction. Variation in response to reward cues is captured in rats undergoing autoshaping experiments where the appearance of a lever precedes food delivery. Although no response is required for food to be delivered, some rats (goal-trackers) learn to approach and avidly engage the magazine until food delivery, whereas other rats (sign-trackers) come to approach and engage avidly the lever. The impulsive and often maladaptive characteristics of the latter response are reminiscent of addictive behaviour in humans. In a previous article, we developed a computational model accounting for a set of experimental data regarding sign-trackers and goal-trackers. Here we show new simulations of the model to draw experimental predictions that could help further validate or refute the model. In particular, we apply the model to new experimental protocols such as injecting flupentixol locally into the core of the nucleus accumbens rather than systemically, and lesioning of the core of the nucleus accumbens before or after conditioning. In addition, we discuss the possibility of removing the food magazine during the inter-trial interval. The predictions from this revised model will help us better understand the role of different brain regions in the behaviours expressed by sign-trackers and goal-trackers.
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105
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Meyer PJ, Cogan ES, Robinson TE. The form of a conditioned stimulus can influence the degree to which it acquires incentive motivational properties. PLoS One 2014; 9:e98163. [PMID: 24905195 PMCID: PMC4048203 DOI: 10.1371/journal.pone.0098163] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 04/29/2014] [Indexed: 11/19/2022] Open
Abstract
There is considerable individual variation in the extent to which food- and drug-associated cues (conditioned stimuli, CSs) acquire incentive salience, as indicated by whether they elicit approach towards them, and/or act as conditioned reinforcers. Here we asked whether this variation is influenced by properties of the CS itself. In rats, we assessed both the attractiveness and conditioned reinforcing properties of two CSs: a manipulable lever CS versus an auditory (tone) CS. There was considerable individual variation in the extent to which a lever CS acquired incentive motivational properties, as indicated by whether it became attractive (evoked a sign-tracking or goal-tracking conditioned response) or acted as a conditioned reinforcer. However, with a tone CS all rats learned a goal-tracking response, and the tone CS was an equally effective conditioned reinforcer in sign-trackers and goal-trackers. Even when presented in compound (a lever-tone CS), the two elements of the compound differentially acquired motivational properties. In contrast, amphetamine and stress potentiated the conditioned reinforcing properties of both visual and auditory CSs similarly in rats that primarily sign-tracked or goal-tracked. We conclude that variation in the to the ability of CSs to acquire incentive salience, and thus their ability to act as incentive stimuli capable of motivating behavior, is determined in part by properties of the CS itself.
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Affiliation(s)
- Paul J. Meyer
- Department of Psychology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Elizabeth S. Cogan
- Department of Psychology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Terry E. Robinson
- Department of Psychology, University of Michigan, Ann Arbor, Michigan, United States of America
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106
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Harb MR, Almeida OFX. Pavlovian conditioning and cross-sensitization studies raise challenges to the hypothesis that overeating is an addictive behavior. Transl Psychiatry 2014; 4:e387. [PMID: 24780921 PMCID: PMC4012290 DOI: 10.1038/tp.2014.28] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 03/11/2014] [Accepted: 03/18/2014] [Indexed: 12/31/2022] Open
Abstract
Elevated glucocorticoid levels and sign tracking (ST) in Pavlovian conditioning are potential biomarkers of compulsive behaviors such as addiction. As overeating is sometimes viewed as a form of addictive behavior, we hypothesized that murine Pavlovian sign trackers would have a greater propensity to overeat and develop obesity. Using a food reward in the classical conditioning paradigm, we show that ST behavior is a robust conditioned response but not a predictor of eating and growth trajectories in mice, thus challenging the view that the development of obesity and drug addiction depend on identical mechanisms. This interpretation was supported by experiments which showed that overweight mice do not display cross-sensitization to an addictive drug (morphine), and conversely, that overweight morphine-sensitized animals do not overconsume a highly rewarding food. Although the rewarding/motivational effects of both food and drugs of abuse are mediated by similar neurochemical mechanisms, obesity and drug addiction represent a summation of other dysfunctional input and output pathways that lead to the emergence of two distinct disorders, each of which would deserve a specific pharmacotherapeutic approach.
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Affiliation(s)
- M R Harb
- NeuroAdaptations Group, Max Planck Institute of Psychiatry, Munich, Germany,Institute of Life & Health Sciences (ICVS), University of Minho, Braga, Portugal
| | - O F X Almeida
- NeuroAdaptations Group, Max Planck Institute of Psychiatry, Munich, Germany,Max Planck Institute of Psychiatry, Kraepelinstrasse 2–10, 80804 Munich, Germany. E-mail:
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107
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Barker JM, Zhang H, Villafane JJ, Wang TL, Torregrossa MM, Taylor JR. Epigenetic and pharmacological regulation of 5HT3 receptors controls compulsive ethanol seeking in mice. Eur J Neurosci 2014; 39:999-1008. [PMID: 24772465 PMCID: PMC4004969 DOI: 10.1111/ejn.12477] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 12/09/2013] [Indexed: 01/23/2023]
Abstract
Factors underlying individual vulnerability to develop alcoholism are largely unknown. In humans, the risk for alcoholism is associated with elevated cue reactivity. Recent evidence suggests that in animal models, reactivity to reward-paired cues is predictive of addictive behaviors. To model cue reactivity in mice, we used a Pavlovian approach (PA) paradigm in which mice were trained to associate a cue with delivery of a food reinforcer. We then investigated the relationship between PA status with habitual and compulsive-like ethanol seeking. After training mice to respond for 10% ethanol, habitual behavior was investigated using both an outcome devaluation paradigm, in which ethanol was devalued via association with lithium chloride-induced malaise, and a contingency degradation paradigm in which the relationship between action and outcome was disrupted. Compulsive-like behavior was investigated in a modified conditioned place preference paradigm in which footshock was paired with the reward-paired chamber. PA was found to be predictive of habitual and compulsive-like ethanol seeking. Additionally, innate risk status was related to epigenetic changes in the gene encoding the requisite subunit of the 5HT3 receptor, Htr3a, as well as 5HT3A protein expression in the amygdala. We then used pharmacological tools to demonstrate that risk status determines the ability of a 5HT3 antagonist to reduce compulsive ethanol seeking. These data indicate that risk status can be identified prior to any alcohol exposure by assessment of cue reactivity, and further that this endophenotype may be predictive of response to pharmacological treatment for components of alcoholism.
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Affiliation(s)
- Jacqueline M Barker
- Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut 06519
- Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, Connecticut 06519
| | - Huiping Zhang
- Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut 06519
- VA Connecticut Healthcare System, West Haven, Connecticut 06516
| | - J Joshua Villafane
- Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut 06519
| | - Tiffany L Wang
- Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut 06519
| | - Mary M Torregrossa
- Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut 06519
| | - Jane R Taylor
- Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut 06519
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108
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Abstract
In this paper, we contend that the psychology of addiction is similar to the psychology of ordinary, non-addictive temptation in important respects, and explore the ways in which these parallels can illuminate both addiction and ordinary action. The incentive salience account of addiction proposed by Robinson and Berridge (1-3) entails that addictive desires are not in their nature different from many of the desires had by non-addicts; what is different is rather the way that addictive desires are acquired, which in turn affects their strength. We examine these "incentive salience" desires, both in addicts and non-addicts, contrasting them with more cognitive desires. On this account, the self-control challenge faced by addicted agents is not different in kind from that faced by non-addicted agents - though the two may, of course, differ greatly in degree of difficulty. We explore a general model of self-control for both the addict and the non-addict, stressing that self-control may be employed at three different stages, and examining the ways in which it might be strengthened. This helps elucidate a general model of intentional action.
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Affiliation(s)
- Brendan Dill
- Department of Linguistics and Philosophy, Massachusetts Institute of Technology , Cambridge, MA , USA
| | - Richard Holton
- Department of Philosophy, University of Cambridge , Cambridge , UK
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109
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Cunningham KA, Anastasio NC. Serotonin at the nexus of impulsivity and cue reactivity in cocaine addiction. Neuropharmacology 2014; 76 Pt B:460-78. [PMID: 23850573 PMCID: PMC4090081 DOI: 10.1016/j.neuropharm.2013.06.030] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 06/24/2013] [Accepted: 06/28/2013] [Indexed: 01/07/2023]
Abstract
Cocaine abuse and addiction remain great challenges on the public health agendas in the U.S. and the world. Increasingly sophisticated perspectives on addiction to cocaine and other drugs of abuse have evolved with concerted research efforts over the last 30 years. Relapse remains a particularly powerful clinical problem as, even upon termination of drug use and initiation of abstinence, the recidivism rates can be very high. The cycling course of cocaine intake, abstinence and relapse is tied to a multitude of behavioral and cognitive processes including impulsivity (a predisposition toward rapid unplanned reactions to stimuli without regard to the negative consequences), and cocaine cue reactivity (responsivity to cocaine-associated stimuli) cited as two key phenotypes that contribute to relapse vulnerability even years into recovery. Preclinical studies suggest that serotonin (5-hydroxytryptamine; 5-HT) neurotransmission in key neural circuits may contribute to these interlocked phenotypes well as the altered neurobiological states evoked by cocaine that precipitate relapse events. As such, 5-HT is an important target in the quest to understand the neurobiology of relapse-predictive phenotypes, to successfully treat this complex disorder and improve diagnostic and prognostic capabilities. This review emphasizes the role of 5-HT and its receptor proteins in key addiction phenotypes and the implications of current findings to the future of therapeutics in addiction. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.
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Affiliation(s)
- Kathryn A Cunningham
- Center for Addiction Research, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, USA.
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110
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Huys QJ, Tobler PN, Hasler G, Flagel SB. The role of learning-related dopamine signals in addiction vulnerability. PROGRESS IN BRAIN RESEARCH 2014; 211:31-77. [DOI: 10.1016/b978-0-444-63425-2.00003-9] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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111
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Clinical pharmacology of eating and not eating. Curr Opin Pharmacol 2013; 14:1-5. [PMID: 24565004 DOI: 10.1016/j.coph.2013.09.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 09/12/2013] [Accepted: 09/20/2013] [Indexed: 11/20/2022]
Abstract
FDA approval of Belviq and Qsymia seems to suggest that novel pharmacological targets to modulate human abnormal eating behaviours are still to be identified. However, a renewed translational approach opens new avenues on eating disorders and female vulnerability, highlighting the role of our reward pathway in obesity and binge eating and leading to potential novel targets. Nevertheless, the 'food addiction' hypothesis is still causing much scientific debate. In this context the interest in the modulation of ghrelin pathway is still very high although, so far, only ghrelin agonism has confirmed its therapeutic potential in cachectic patients. Unfortunately, ghrelin modulation does not offer a therapeutic option for Anorexia Nervosa, where novel promising pharmacological treatments are still to be uncovered.
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112
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Day JJ, Childs D, Guzman-Karlsson MC, Kibe M, Moulden J, Song E, Tahir A, Sweatt JD. DNA methylation regulates associative reward learning. Nat Neurosci 2013; 16:1445-52. [PMID: 23974711 PMCID: PMC3785567 DOI: 10.1038/nn.3504] [Citation(s) in RCA: 152] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Accepted: 07/20/2013] [Indexed: 12/13/2022]
Abstract
Reward-related memories are essential for adaptive behavior and evolutionary fitness, but they are also a core component of maladaptive brain diseases such as addiction. Reward learning requires dopamine neurons located in the ventral tegmental area (VTA), which encode relationships between predictive cues and future rewards. Recent evidence suggests that epigenetic mechanisms, including DNA methylation, are essential regulators of neuronal plasticity and experience-driven behavioral change. However, the role of epigenetic mechanisms in reward learning is poorly understood. Here we show that the formation of reward-related associative memories in rats upregulates key plasticity genes in the VTA, which are correlated with memory strength and associated with gene-specific changes in DNA methylation. Moreover, DNA methylation in the VTA is required for the formation of stimulus-reward associations. These results provide the first evidence that that activity-dependent methylation and demethylation of DNA is an essential substrate for the behavioral and neuronal plasticity driven by reward-related experiences.
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Affiliation(s)
- Jeremy J. Day
- Department of Neurobiology and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL
| | - Daniel Childs
- Department of Neurobiology and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL
| | - Mikael C. Guzman-Karlsson
- Department of Neurobiology and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL
| | - Mercy Kibe
- Department of Neurobiology and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL
| | - Jerome Moulden
- Department of Neurobiology and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL
| | - Esther Song
- Department of Neurobiology and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL
| | - Absar Tahir
- Department of Neurobiology and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL
| | - J. David Sweatt
- Department of Neurobiology and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL
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113
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Saunders BT, Yager LM, Robinson TE. Cue-evoked cocaine "craving": role of dopamine in the accumbens core. J Neurosci 2013; 33:13989-4000. [PMID: 23986236 PMCID: PMC3756749 DOI: 10.1523/jneurosci.0450-13.2013] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 07/02/2013] [Accepted: 07/20/2013] [Indexed: 11/21/2022] Open
Abstract
Drug-associated cues can acquire powerful motivational control over the behavior of addicts, and can contribute to relapse via multiple, dissociable mechanisms. Most preclinical models of relapse focus on only one of these mechanisms: the ability of drug cues to reinforce drug-seeking actions following a period of extinction training. However, in addicts, drug cues typically do not follow seeking actions; they precede them. They often produce relapse by evoking a conditioned motivational state ("wanting" or "craving") that instigates and/or invigorates drug-seeking behavior. Here we used a conflict-based relapse model to ask whether individual variation in the propensity to attribute incentive salience to reward cues predicts variation in the ability of a cocaine cue to produce conditioned motivation (craving) for cocaine. Following self-administration training, responding was curtailed by requiring rats to cross an electrified floor to take cocaine. The subsequent response-independent presentation of a cocaine-associated cue was sufficient to reinstate drug-seeking behavior, despite the continued presence of the adverse consequence. Importantly, there were large individual differences in the motivational properties of the cocaine cue, which were predicted by variation in the propensity to attribute incentive salience to a food cue. Finally, a dopamine antagonist injected into the nucleus accumbens core attenuated, and amphetamine facilitated, cue-evoked cocaine seeking, implicating dopamine signaling in cocaine cue-evoked craving. These data provide a promising preclinical approach for studying sources of individual variation in susceptibility to relapse due to conditioned craving and implicate mesolimbic dopamine in this process.
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Affiliation(s)
- Benjamin T. Saunders
- Biopsychology Program, Department of Psychology, University of Michigan, Ann Arbor, Michigan 48109
| | - Lindsay M. Yager
- Biopsychology Program, Department of Psychology, University of Michigan, Ann Arbor, Michigan 48109
| | - Terry E. Robinson
- Biopsychology Program, Department of Psychology, University of Michigan, Ann Arbor, Michigan 48109
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114
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Robinson TE, Yager LM, Cogan ES, Saunders BT. On the motivational properties of reward cues: Individual differences. Neuropharmacology 2013; 76 Pt B:450-9. [PMID: 23748094 DOI: 10.1016/j.neuropharm.2013.05.040] [Citation(s) in RCA: 166] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Revised: 05/14/2013] [Accepted: 05/17/2013] [Indexed: 10/26/2022]
Abstract
Cues associated with rewards, such as food or drugs of abuse, can themselves acquire motivational properties. Acting as incentive stimuli, such cues can exert powerful control over motivated behavior, and in the case of cues associated with drugs, they can goad continued drug-seeking behavior and relapse. However, recent studies reviewed here suggest that there are large individual differences in the extent to which food and drug cues are attributed with incentive salience. Rats prone to approach reward cues (sign-trackers) attribute greater motivational value to discrete localizable cues and interoceptive cues than do rats less prone to approach reward cues (goal-trackers). In contrast, contextual cues appear to exert greater control over motivated behavior in goal-trackers than sign-trackers. It is possible to predict, therefore, before any experience with drugs, in which animals specific classes of drug cues will most likely reinstate drug-seeking behavior. The finding that different individuals may be sensitive to different triggers capable of motivating behavior and producing relapse suggests there may be different pathways to addiction, and has implications for thinking about individualized treatment. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.
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Affiliation(s)
- Terry E Robinson
- Department of Psychology (Biopsychology Program), University of Michigan, 530 Church Street, East Hall, Ann Arbor, MI 48109, USA.
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