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Lamb RJ, Schindler CW, Ginsburg BC. Effects of an ethanol-paired conditioned stimulus on responding for ethanol suppressed by a conditioned-taste-aversion. Alcohol 2024; 116:1-8. [PMID: 37774959 DOI: 10.1016/j.alcohol.2023.09.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 09/25/2023] [Accepted: 09/26/2023] [Indexed: 10/01/2023]
Abstract
Ethanol-Paired Conditioned Stimuli (CS) can increase ethanol-responding either in extinction or occurring at low rates late in a session. To examine the generality of CS-induced increases in ethanol-responding, we examined whether a CS could increase responding suppressed by Conditioned-Taste-Aversion (CTA), which presumably suppresses responding by changing ethanol's valence from positive to negative. Rats were trained to respond for ethanol under a Random Interval (RI) schedule. We then removed the lever and paired Random-Time ethanol deliveries with illumination of a stimulus light (i.e., CS) for 10 sessions. Results were compared with a Truly Random Control group, in which the light and ethanol deliveries occurred independently. In a subsequent experiment, rats were treated similarly, except the light served as a discriminative stimulus, as the lever was extended and ethanol deliveries were available under a RI during light presentations. After this training, the lever was returned and rats again responded for ethanol. Subsequently, sessions were followed by LiCl administration. When responding reached low levels, LiCl administration stopped and the light was occasionally illuminated during the session. Responding during the light presentation was compared to responding during the period preceding light presentation. Responding partially recovered across 10 sessions and was greater during light presentations than in the period before it in all three groups. Increases were not reliably different between the groups, indicating that explanations for these increases such as CS-induced increases in motivation or approach toward the light are unlikely to be correct. The most likely explanation for these light-induced increases is that during sessions in which the light had been presented previously, LiCl had never been presented and thus, the light had come to signal that ethanol was safe to drink.
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Affiliation(s)
- R J Lamb
- Department of Psychiatry and Behavioral Sciences, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States.
| | - C W Schindler
- Designer Drug Unit, Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD, United States
| | - Brett C Ginsburg
- Department of Psychiatry and Behavioral Sciences, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
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2
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Hilz EN, Lee HJ. Estradiol and progesterone in female reward-learning, addiction, and therapeutic interventions. Front Neuroendocrinol 2023; 68:101043. [PMID: 36356909 DOI: 10.1016/j.yfrne.2022.101043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 09/24/2022] [Accepted: 10/28/2022] [Indexed: 11/09/2022]
Abstract
Sex steroid hormones like estradiol (E2) and progesterone (P4) guide the sexual organization and activation of the developing brain and control female reproductive behavior throughout the lifecycle; importantly, these hormones modulate functional activity of not just the endocrine system, but most of the nervous system including the brain reward system. The effects of E2 and P4 can be seen in the processing of and memory for rewarding stimuli and in the development of compulsive reward-seeking behaviors like those seen in substance use disorders. Women are at increased risk of developing substance use disorders; however, the origins of this sex difference are not well understood and therapeutic interventions targeting ovarian hormones have produced conflicting results. This article reviews the contribution of the E2 and P4 in females to functional modulation of the brain reward system, their possible roles in origins of addiction vulnerability, and the development and treatment of compulsive reward-seeking behaviors.
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Affiliation(s)
- Emily N Hilz
- The University of Texas at Austin, Department of Pharmacology, USA.
| | - Hongjoo J Lee
- The University of Texas at Austin, Department of Psychology, USA; The University of Texas at Austin, Institute for Neuroscience, USA
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3
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Martin DA, Keefer SE, Calu DJ. Investigating discriminative stimulus modulation of opioid seeking after conflict-induced abstinence in sign- and goal-tracking rats. Psychopharmacology (Berl) 2022; 239:3223-3236. [PMID: 35971032 PMCID: PMC10500549 DOI: 10.1007/s00213-022-06204-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 07/26/2022] [Indexed: 12/23/2022]
Abstract
RATIONALE Discriminative stimuli (DS) are cues that predict reward availability. DS are resistant to extinction and motivate drug seeking even after long periods of abstinence. Previous studies have demonstrated that sign-tracking (ST) and goal-tracking (GT) differences in Pavlovian approach predict distinct cue-modulated vulnerabilities to cocaine reinstatement. GT rats show heightened reinstatement to contextual and DS, while ST rats show heightened reinstatement to discrete stimuli. Here we examine whether DS modulate reinstatement after electric barrier-induced abstinence and whether tracking-related relapse vulnerabilities generalize to opioid relapse. OBJECTIVES We examine whether DS-modulated reinstatement to fentanyl seeking persists in the presence of reduced adverse consequences after electric barrier-induced abstinence. We also examine whether tracking differences predict the magnitude of DS-modulated reinstatement of fentanyl seeking after electric barrier-induced abstinence. METHODS We used Pavlovian lever autoshaping (PLA) training to determine sign-, goal-, and intermediate tracking groups in male and female Sprague Dawley rats. We then trained rats in a DS model of intermittent fentanyl self-administration, and extinguished drug seeking by imposing an electric barrier of increasing intensity. We then measured the level of DS-modulated reinstatement in the presence of a reduced electric barrier intensity. RESULTS We report that DS strongly modulate fentanyl seeking after electric barrier-induced abstinence. DS-modulation of fentanyl acquisition, electric barrier-induced abstinence, and reinstatement was similar for sign- and goal-tracking groups. CONCLUSIONS Discriminative stimuli powerfully motivate opioid seeking, despite continued aversive consequences. Pavlovian approach differences do not predict the level of DS-modulated reinstatement to fentanyl seeking after conflict-induced abstinence.
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Affiliation(s)
- David A Martin
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, 20 Penn Street, Baltimore, MD, 21201, USA
| | - Sara E Keefer
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, 20 Penn Street, Baltimore, MD, 21201, USA
| | - Donna J Calu
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, 20 Penn Street, Baltimore, MD, 21201, USA.
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4
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Lay BPP, Khoo SYS. Associative processes in addiction relapse models: A review of their Pavlovian and instrumental mechanisms, history, and terminology. NEUROANATOMY AND BEHAVIOUR 2021. [DOI: 10.35430/nab.2021.e18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Animal models of relapse to drug-seeking have borrowed heavily from associative learning approaches. In studies of relapse-like behaviour, animals learn to self-administer drugs then receive a period of extinction during which they learn to inhibit the operant response. Several triggers can produce a recovery of responding which form the basis of a variety of models. These include the passage of time (spontaneous recovery), drug availability (rapid reacquisition), extinction of an alternative response (resurgence), context change (renewal), drug priming, stress, and cues (reinstatement). In most cases, the behavioural processes driving extinction and recovery in operant drug self-administration studies are similar to those in the Pavlovian and behavioural literature, such as context effects. However, reinstatement in addiction studies have several differences with Pavlovian reinstatement, which have emerged over several decades, in experimental procedures, associative mechanisms, and terminology. Interestingly, in cue-induced reinstatement, drug-paired cues that are present during acquisition are omitted during lever extinction. The unextinguished drug-paired cue may limit the model’s translational relevance to cue exposure therapy and renders its underlying associative mechanisms ambiguous. We review major behavioural theories that explain recovery phenomena, with a particular focus on cue-induced reinstatement because it is a widely used model in addiction. We argue that cue-induced reinstatement may be explained by a combination of behavioural processes, including reacquisition of conditioned reinforcement and Pavlovian to Instrumental Transfer. While there are important differences between addiction studies and the behavioural literature in terminology and procedures, it is clear that understanding associative learning processes is essential for studying relapse.
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Affiliation(s)
- Belinda Po Pyn Lay
- Center for Studies in Behavioral Neurobiology/Groupe de Recherche en Neurobiologie Comportementale, Department of Psychology, Concordia University, Montreal, Canada
| | - Shaun Yon-Seng Khoo
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada
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5
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Drame ML, Balaet M, Lee JLC. Memory reconsolidation impairments in sign-tracking to an audiovisual compound stimulus. Behav Brain Res 2020; 393:112774. [PMID: 32553756 DOI: 10.1016/j.bbr.2020.112774] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 05/11/2020] [Accepted: 05/26/2020] [Indexed: 10/24/2022]
Abstract
Studies of memory reconsolidation of pavlovian memories have typically employed unimodal conditioned stimuli, despite the use of multimodal compound stimuli in other settings. Here we studied sign-tracking behaviour to a compound audiovisual stimulus. First, we observed not unexpectedly that sign-tracking was poorer to the audiovisual compound than to unimodal visual stimuli. Then, we showed that, depending on the parameters of compound stimulus re-exposure at memory reactivation, systemic MK-801 treatment either impaired extinction to improve sign-tracking at test, or disrupted reconsolidation to impair test behaviour. When memory reactivation consisted of re-exposure to only the auditory component of the compound stimulus, we observed sign-tracking impairments following MK-801 treatment, but only under certain test conditions. This was in contrast to the consistent impairment following reactivation with the full audiovisual compound. Moreover, the parameters of auditory stimulus presentation to enable MK-801-induced impairment at test varied depending on whether the stimulus was presented within or outside the training context. These findings suggest that behaviour under the control of appetitive pavlovian compound stimuli can be modulated by targeting both extinction and reconsolidation, and that it is not necessary to re-expose to the full compound stimulus in order to achieve a degree of modulation of behaviour.
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Affiliation(s)
| | - Maria Balaet
- University of Birmingham, Birmingham, B15 2TT, UK
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6
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Lamb RJ, Schindler CW, Ginsburg BC. Ethanol-paired stimuli can increase reinforced ethanol responding. Alcohol 2020; 85:27-34. [PMID: 31689483 DOI: 10.1016/j.alcohol.2019.10.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 10/24/2019] [Accepted: 10/25/2019] [Indexed: 11/29/2022]
Abstract
While ethanol-paired stimuli are frequently postulated to increase drinking motivation and thus increase ethanol responding and precipitate relapse, no study has demonstrated increases in ethanol-reinforced responding following presentation of an ethanol-paired stimulus that had not previously been part of a contingent relationship. Previous studies have shown that food-paired stimuli can increase food responding that is at low rates and increase food consumption in food-sated rats. In Experiment 1, we show that an ethanol-paired stimulus can increase ethanol responding that is at low levels late in the experimental session, presumably due to satiation. However, these increases may have resulted from either associative or non-associative mechanisms. In Experiment 2, we compared the effects of an ethanol-paired stimulus to those of the same stimulus in a Truly-Random-Control group. In a Truly-Random-Control, the stimulus and ethanol each are presented on independent random schedules, and thus any differences between the effects of the stimulus in the experimental and control groups is likely attributable to the association between the stimulus and ethanol. The stimulus increased ethanol-reinforced responding in both the experimental and control groups, but these increases were greater in the experimental than the control group. Thus, both stimulus-change and the pairing of the stimulus with ethanol may result in increases in ethanol-reinforced responding.
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Affiliation(s)
- R J Lamb
- Department of Psychiatry, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States.
| | - Charles W Schindler
- Designer Drug Unit, Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD, United States
| | - Brett C Ginsburg
- Department of Psychiatry, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
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7
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Vazquez M, Frazier JH, Reichel CM, Peters J. Acute ovarian hormone treatment in freely cycling female rats regulates distinct aspects of heroin seeking. Learn Mem 2020; 27:6-11. [PMID: 31843977 PMCID: PMC6919190 DOI: 10.1101/lm.050187.119] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 10/20/2019] [Indexed: 12/15/2022]
Abstract
Females are at higher risk for certain opioid addictive behaviors, but the influence of ovarian hormones is unknown. In our rat model of heroin self-administration, females exhibited higher relapse rates that correlated with rates of heroin seeking on the first extinction session. We administered estradiol alone, or in combination with progesterone, 30 min prior to the first extinction session in freely cycling, heroin-seeking female rats. Although neither treatment produced long-term effects on relapse, each treatment regulated distinct aspects of heroin seeking. Estradiol treatment enhanced extinction memory retention, whereas the combination treatment acutely reduced expression of heroin seeking.
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Affiliation(s)
- Maribel Vazquez
- Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina 29425, USA
| | - Jessica H Frazier
- Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina 29425, USA
| | - Carmela M Reichel
- Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina 29425, USA
| | - Jamie Peters
- Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina 29425, USA
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Lamb R, Ginsburg BC, Greig A, Schindler CW. Effects of rat strain and method of inducing ethanol drinking on Pavlovian-Instrumental-Transfer with ethanol-paired conditioned stimuli. Alcohol 2019; 79:47-57. [PMID: 30641121 DOI: 10.1016/j.alcohol.2019.01.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 01/04/2019] [Accepted: 01/07/2019] [Indexed: 12/21/2022]
Abstract
Ethanol-paired conditioned stimuli (CSs) are widely thought to invigorate ethanol responding, and thus, precipitate relapse to drinking. However, preclinical studies investigating this issue using Pavlovian-Instrumental-Transfer (PIT) procedures have had mixed results, with some studies finding PIT while others did not. The studies failing to show PIT used Lewis rats and induced ethanol drinking using a post-prandial drinking procedure. The present experiments examined whether either of these two variables influenced the magnitude of PIT observed. In the first experiment, ethanol drinking in Lewis rats was induced using either sucrose fading or post-prandial drinking. In the second experiment, ethanol drinking was induced using post-prandial drinking in either Long-Evans Hooded or Lewis rats. In both experiments, rats were trained to respond for ethanol under a random interval schedule. Subsequently with the lever removed, 2-min light presentations were paired with ethanol deliveries. Finally, with the lever returned, the effect of light presentations on responding was tested while responding was in extinction. Light presentations similarly affected responding in Lewis rats regardless of the method of drinking induction. Likewise, light presentations similarly affected responding in both Lewis and Long-Evans Hooded rats. Neither ethanol induction method nor rat strain affected the magnitude of PIT observed, and thus, neither likely explains previous failures to observe PIT with ethanol-maintained behavior.
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9
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Stringfield SJ, Boettiger CA, Robinson DL. Nicotine-enhanced Pavlovian conditioned approach is resistant to omission of expected outcome. Behav Brain Res 2018; 343:16-20. [PMID: 29407412 DOI: 10.1016/j.bbr.2018.01.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Revised: 01/18/2018] [Accepted: 01/19/2018] [Indexed: 11/30/2022]
Abstract
Conditioned stimuli contribute to the resilience of nicotine addiction in that nicotine-associated cues can influence smokers and promote relapse. These stimuli are thought to acquire incentive motivational properties through a Pavlovian mechanism, and this phenomenon can be measured in animals by observing conditioned approach to the conditioned stimulus (sign-tracking) or to the location of unconditioned stimulus delivery (goal-tracking). Goal-tracking is thought to be more flexible than sign-tracking in response to changes in expected outcome. Nicotine exposure can increase the expression of conditioned responses, and we hypothesized that animals exposed to nicotine would also exhibit less flexible conditioned responses after a change in the expected unconditioned stimulus. Adult male rats were exposed to nicotine (0.4mg/kg, s.c.) or saline before Pavlovian conditioned approach training sessions. After training, animals underwent test sessions that reduced (water substitution) or withheld (omission) the unconditioned stimulus (US, 20% sucrose). As expected, nicotine enhanced sign- and goal-tracking. Water substitution moderately and nonspecifically reduced both sign- and goal-tracking in all rats. In contrast, US omission only reduced goal-tracking, with robust effects in saline-exposed rats and smaller effects in nicotine-exposed rats. These data support the hypothesis that both sign-tracking and nicotine exposure confer behavioral inflexibility under US omission.
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Affiliation(s)
- Sierra J Stringfield
- Bowles Center for Alcohol Studies, University of North Carolina, Chapel Hill, NC, USA; Neuroscience Curriculum, University of North Carolina, Chapel Hill, NC, USA
| | - Charlotte A Boettiger
- Bowles Center for Alcohol Studies, University of North Carolina, Chapel Hill, NC, USA; Neuroscience Curriculum, University of North Carolina, Chapel Hill, NC, USA; Department of Psychology and Neuroscience, University of North Carolina, Chapel Hill, NC, USA
| | - Donita L Robinson
- Bowles Center for Alcohol Studies, University of North Carolina, Chapel Hill, NC, USA; Neuroscience Curriculum, University of North Carolina, Chapel Hill, NC, USA; Department of Psychiatry, University of North Carolina, Chapel Hill, NC, USA.
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10
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Madayag AC, Stringfield SJ, Reissner KJ, Boettiger CA, Robinson DL. Sex and Adolescent Ethanol Exposure Influence Pavlovian Conditioned Approach. Alcohol Clin Exp Res 2017; 41:846-856. [PMID: 28196273 DOI: 10.1111/acer.13354] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 02/08/2017] [Indexed: 01/03/2023]
Abstract
BACKGROUND Alcohol use among adolescents is widespread and a growing concern due to long-term behavioral deficits, including altered Pavlovian behavior, that potentially contribute to addiction vulnerability. We tested the hypothesis that adolescent intermittent ethanol (AIE) exposure alters Pavlovian behavior in males and females as measured by a shift from goal-tracking to sign-tracking. Additionally, we investigated GLT-1, an astrocytic glutamate transporter, as a potential contributor to a sign-tracking phenotype. METHODS Male and female Sprague-Dawley rats were exposed to AIE (5 g/kg, intragastric) or water intermittently 2 days on and 2 days off from postnatal day (P) 25 to 54. Around P70, animals began 20 daily sessions of Pavlovian conditioned approach (PCA), where they learned that a cue predicted noncontingent reward delivery. Lever pressing indicated interaction with the cue, or sign-tracking, and receptacle entries indicated approach to the reward delivery location, or goal-tracking. To test for effects of AIE on nucleus accumbens (NAcc) excitatory signaling, we isolated membrane subfractions and measured protein levels of the glutamate transporter GLT-1 after animals completed behavior as a measure of glutamate homeostasis. RESULTS Females exhibited elevated sign-tracking compared to males with significantly more lever presses, faster latency to first lever press, and greater probability to lever press in a trial. AIE significantly increased lever pressing while blunting goal-tracking, as indicated by fewer cue-evoked receptacle entries, slower latency to receptacle entry, and lower probability to enter the receptacle in a trial. No significant sex-by-exposure interactions were observed in sign- or goal-tracking metrics. Moreover, we found no significant effects of sex or exposure on membrane GLT-1 expression in the NAcc. CONCLUSIONS Females exhibited enhanced sign-tracking compared to males, while AIE decreased goal-tracking compared to control exposure. Our findings support the hypothesis that adolescent binge ethanol can shift conditioned behavior from goal- to cue-directed in PCA, especially in females.
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Affiliation(s)
- Aric C Madayag
- Bowles Center for Alcohol Studies, University of North Carolina, Chapel Hill, North Carolina.,Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina
| | - Sierra J Stringfield
- Bowles Center for Alcohol Studies, University of North Carolina, Chapel Hill, North Carolina.,Neurobiology Curriculum, University of North Carolina, Chapel Hill, North Carolina
| | - Kathryn J Reissner
- Neurobiology Curriculum, University of North Carolina, Chapel Hill, North Carolina.,Department of Psychology and Neuroscience, University of North Carolina, Chapel Hill, North Carolina
| | - Charlotte A Boettiger
- Bowles Center for Alcohol Studies, University of North Carolina, Chapel Hill, North Carolina.,Neurobiology Curriculum, University of North Carolina, Chapel Hill, North Carolina.,Department of Psychology and Neuroscience, University of North Carolina, Chapel Hill, North Carolina
| | - Donita L Robinson
- Bowles Center for Alcohol Studies, University of North Carolina, Chapel Hill, North Carolina.,Neurobiology Curriculum, University of North Carolina, Chapel Hill, North Carolina.,Department of Psychiatry, University of North Carolina, Chapel Hill, North Carolina
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11
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Lamb R, Ginsburg BC, Schindler CW. Effects of an ethanol-paired CS on responding for ethanol and food: Comparisons with a stimulus in a Truly-Random-Control group and to a food-paired CS on responding for food. Alcohol 2016; 57:15-27. [PMID: 27916139 DOI: 10.1016/j.alcohol.2016.10.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Revised: 09/13/2016] [Accepted: 10/18/2016] [Indexed: 12/17/2022]
Abstract
Motivational increases due to exposure to alcohol-paired Conditioned Stimuli (CS) are central to some accounts of alcoholism. However, few studies isolate a stimulus's function as a CS from its other potential functions. Pavlovian-Instrumental-Transfer (PIT) procedures isolate a stimulus's function as a CS from its other functions. Though there are several relevant studies using PIT, knowledge gaps exist. Particularly, it is not clear that an alcohol-paired CS will increase alcohol seeking compared to the same stimulus in a Truly-Random-Control group, nor whether such increases are specific to alcohol seeking. To address these knowledge gaps in Experiment 1, rats responded for ethanol (0.1 ml 8% w/v) under an RI 30-sec schedule, then the lever was removed and half the rats had ethanol delivered during occasional 120-sec light presentations, while the remainder had ethanol and the light presented under independent RT schedules. Later the lever was returned and the light was presented during responding in extinction (PIT test). Following this test, levers were again removed and the light was presented without ethanol (light extinction), following again by a PIT test. Responding in the two groups during light presentations did not differ in either PIT test. Experiment 2 repeated Experiment 1 using food instead of ethanol. In Experiment 2, responding during light presentations increased in the paired group. In Experiment 3, rats were trained on a concurrent FR schedule of food and ethanol delivery. Ethanol was delivered following 5 responses and the response requirement for food adjusted so that similar numbers of food and ethanol deliveries were obtained. Subsequently, rats underwent conditioning, control and testing procedures identical to those in Experiment 1. In Experiment 3, the ethanol-paired CS increased ethanol-responding, but not food-responding. These results are most easily interpreted as changes in responding resulting from CS-elicited behavior rather than motivational changes. This interpretation is more compatible with some descriptions of the role of an alcohol-paired CS in alcoholism than others.
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12
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Lamb RJ, Schindler CW, Pinkston JW. Conditioned stimuli's role in relapse: preclinical research on Pavlovian-Instrumental-Transfer. Psychopharmacology (Berl) 2016; 233:1933-44. [PMID: 26800688 PMCID: PMC4863941 DOI: 10.1007/s00213-016-4216-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 01/12/2016] [Indexed: 01/24/2023]
Abstract
RATIONALE AND OBJECTIVE Pavlovian learning is central to many theories of addiction. In these theories, stimuli paired with drug ingestion become conditioned stimuli (CS) and subsequently elicit drug-seeking and drug-taking. However, in most relevant studies, Pavlovian and instrumental learning are confounded. This confound may be avoided in Pavlovian-Instrumental-Transfer (PIT) procedures. In PIT, Pavlovian and instrumental learning are established separately and then combined. In order to better understand the role of CSs in addiction, we review the relevant studies using PIT. FINDINGS We identified seven articles examining PIT effects of ethanol- or cocaine-paired CSs. Under at least one condition, six of these articles reported CS-elicited increases in responding previously maintained by drug. However, the only study using the optimal control condition failed to find a CS-elicited increase. Two studies examining CS specificity found the CS also increased responding maintained by a different reinforcer. Two studies examined if CSs elicit increases in actual drug-taking. Both failed to find CS-elicited increases, i.e., no study shows CS-elicited increases in actual drug-taking. Further, CS-elicited increases in extinguished responding are short-lived. CONCLUSIONS These findings are not entirely consistent with Pavlovian learning playing a central role in addiction. However, design issues can explain most of these inconsistencies. Studies without these design issues are needed. Additionally, existing theories hypothesize drug-paired CSs increase drug-taking by increasing motivation, by eliciting conditioned responses that make drug-seeking more probable, or by a combination of these. Work distinguishing between these mechanisms would also be useful.
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Affiliation(s)
- R J Lamb
- Departments of Psychiatry & Pharmacology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, 78229-3900, USA.
| | - Charles W Schindler
- Preclinical Pharmacology Section, Behavioral Neuroscience Research Branch, Intramural Research Program, National Institute on Drug Abuse, 251 Bayview Blvd, Baltimore, MD, 21224, USA
| | - Jonathan W Pinkston
- Department of Behavioral Analysis, University of North Texas, 360 G Chilton Hall, Avenue C, Denton, TX, 76208, USA
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13
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Yager LM, Robinson TE. Individual variation in the motivational properties of a nicotine cue: sign-trackers vs. goal-trackers. Psychopharmacology (Berl) 2015; 232:3149-60. [PMID: 25980485 PMCID: PMC4536151 DOI: 10.1007/s00213-015-3962-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Accepted: 05/08/2015] [Indexed: 12/26/2022]
Abstract
RATIONALE Individuals vary in the extent to which they attribute incentive salience to reward cues. Discrete food and drug (cocaine and opioid) cues become more attractive, eliciting approach toward them, and more "wanted," in that they serve as more effective conditioned reinforcers, in some rats (sign-trackers, STs), than in others (goal-trackers, GTs). OBJECTIVES We asked whether there is similar variation in the extent to which a cue associated with a drug from another class, nicotine, acquires incentive motivational properties. METHODS First, a Pavlovian conditioned approach procedure was used to identify rats that attribute incentive salience to a food cue (i.e., STs and GTs). We then measured the extent to which a cue (a light) paired with intravenous nicotine injections acquired two properties of an incentive stimulus: (1) the ability to elicit approach toward it, and (2) the ability to act as a conditioned reinforcer. RESULTS In contrast to previous findings with food, cocaine, and opioid cues, we found that the nicotine cue was equally attractive in STs and GTs, eliciting dose-dependent approach behavior in both. However, the nicotine cue was a more effective conditioned reinforcer in STs than in GTs. CONCLUSIONS We suggest the dissociation between these two measures of incentive salience attribution may be related to the fact that when present (as in the test of Pavlovian approach), nicotine can act as a potent "incentive amplifier," and by this action, nicotine may render cues especially salient for all animals.
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Affiliation(s)
| | - Terry E. Robinson
- To whom correspondence should be addressed: Terry E. Robinson, Ph.D., Department of Psychology, University of Michigan, 530 Church St, East Hall, Ann Arbor, MI 48109, Tel.: +1 734 763 4361,
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14
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Madsen HB, Ahmed SH. Drug versus sweet reward: greater attraction to and preference for sweet versus drug cues. Addict Biol 2015; 20:433-44. [PMID: 24602027 DOI: 10.1111/adb.12134] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Despite the unique ability of addictive drugs to directly activate brain reward circuits, recent evidence suggests that drugs induce reinforcing and incentive effects that are comparable to, or even lower than some nondrug rewards. In particular, when rats have a choice between pressing a lever associated with intravenous cocaine or heroin delivery and another lever associated with sweet water delivery, most respond on the latter. This outcome suggests that sweet water is more reinforcing and attractive than either drug. However, this outcome may also be due to the differential ability of sweet versus drug levers to elicit Pavlovian feeding-like conditioned responses that can cause involuntary lever pressing, such as pawing and biting the lever. To test this hypothesis, rats first underwent Pavlovian conditioning to associate one lever with sweet water (0.2% saccharin) and a different lever with intravenous cocaine (0.25 mg) or heroin (0.01 mg). Choice between these two levers was then assessed under two operant choice procedures: one that permitted the expression of Pavlovian-conditioned lever press responses during choice, the other not. During conditioning, Pavlovian-conditioned lever press responses were considerably higher on the sweet lever than on either drug lever, and slightly greater on the heroin lever than on the cocaine lever. Importantly, though these differences in Pavlovian-conditioned behavior predicted subsequent preference for sweet water during choice, they were not required for its expression. Overall, this study confirms that rats prefer the sweet lever because sweet water is more reinforcing and attractive than cocaine or heroin.
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Affiliation(s)
- Heather B. Madsen
- Institut des Maladies Neurodégénératives; Université de Bordeaux; France
- Institut des Maladies Neurodégénératives; CNRS; France
- Florey Institute of Neuroscience and Mental Health; University of Melbourne; Australia
| | - Serge H. Ahmed
- Institut des Maladies Neurodégénératives; Université de Bordeaux; France
- Institut des Maladies Neurodégénératives; CNRS; France
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Individual variation in the motivational and neurobiological effects of an opioid cue. Neuropsychopharmacology 2015; 40:1269-77. [PMID: 25425322 PMCID: PMC4367472 DOI: 10.1038/npp.2014.314] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 11/13/2014] [Accepted: 11/23/2014] [Indexed: 11/08/2022]
Abstract
A discrete cue associated with intravenous injections of cocaine acquires greater control over motivated behavior in some rats ('sign-trackers', STs) than others ('goal-trackers', GTs). It is not known, however, if such variation generalizes to cues associated with other drugs. We asked, therefore, whether a discrete cue (a light) associated with the intravenous administration of an opioid drug (the short-acting mu receptor agonist, remifentanil) acquires incentive motivational properties differently in STs and GTs, as indicated by tests of Pavlovian conditioned approach and conditioned reinforcement. Consistent with studies using cocaine, STs approached a classically conditioned opioid cue more readily than GTs, and in a test of conditioned reinforcement worked more avidly to get it. Interestingly, STs and GTs did not differ in the acquisition of a conditioned orienting response. In addition, the performance of conditioned approach behavior, but not conditioned orientation, was attenuated by pretreatment with the dopamine receptor antagonist, flupenthixol, into the core of the nucleus accumbens. Lastly, food and opioid cues engaged similar amygdalo-striatal-thalamic circuitry to a much greater extent in STs than GTs, as indicated by Fos expression. Taken together, these data demonstrate that, similar to food and cocaine cues: (1) a discrete opioid cue attains greater incentive motivational value in STs than GTs; (2) the attribution of incentive motivational properties to an opioid cue is dopamine dependent; and (3) an opioid cue engages the so-called 'motive circuit' only if it is imbued with incentive salience.
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16
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Srey CS, Maddux JMN, Chaudhri N. The attribution of incentive salience to Pavlovian alcohol cues: a shift from goal-tracking to sign-tracking. Front Behav Neurosci 2015; 9:54. [PMID: 25784867 PMCID: PMC4347508 DOI: 10.3389/fnbeh.2015.00054] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 02/13/2015] [Indexed: 11/22/2022] Open
Abstract
Environmental stimuli that are reliably paired with alcohol may acquire incentive salience, a property that can operate in the use and abuse of alcohol. Here we investigated the incentive salience of Pavlovian alcohol cues using a preclinical animal model. Male, Long-Evans rats (Harlan) with unrestricted access to food and water were acclimated to drinking 15% ethanol (v/v) in their home-cages. Rats then received Pavlovian autoshaping training in which the 10 s presentation of a retractable lever served as the conditioned stimulus (CS) and 15% ethanol served as the unconditioned stimulus (US) (0.2 ml/CS; 12 CS presentations/session; 27 sessions). Next, in an operant test of conditioned reinforcement, nose pokes into an active aperture delivered presentations of the lever-CS, whereas nose pokes into an inactive aperture had no consequences. Across initial autoshaping sessions, goal-tracking behavior, as measured by entries into the fluid port where ethanol was delivered, developed rapidly. However, with extended training goal-tracking diminished, and sign-tracking responses, as measured by lever-CS activations, emerged. Control rats that received explicitly unpaired CS and US presentations did not show goal-tracking or sign-tracking responses. In the test for conditioned reinforcement, rats with CS-US pairings during autoshaping training made more active relative to inactive nose pokes, whereas rats in the unpaired control group did not. Moreover, active nose pokes were positively correlated with sign-tracking behavior during autoshaping. Extended training may produce a shift in the learned properties of Pavlovian alcohol cues, such that after initially predicting alcohol availability they acquire robust incentive salience.
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Affiliation(s)
- Chandra S Srey
- Department of Psychology, Center for Studies in Behavioral Neurobiology/FRQS Groupe de Recherche en Neurobiologie Comportementale, Concordia University Montreal, QC, Canada
| | - Jean-Marie N Maddux
- Department of Psychology, Center for Studies in Behavioral Neurobiology/FRQS Groupe de Recherche en Neurobiologie Comportementale, Concordia University Montreal, QC, Canada
| | - Nadia Chaudhri
- Department of Psychology, Center for Studies in Behavioral Neurobiology/FRQS Groupe de Recherche en Neurobiologie Comportementale, Concordia University Montreal, QC, Canada
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Beckmann JS, Chow JJ. Isolating the incentive salience of reward-associated stimuli: value, choice, and persistence. ACTA ACUST UNITED AC 2015; 22:116-27. [PMID: 25593298 PMCID: PMC4341364 DOI: 10.1101/lm.037382.114] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Sign- and goal-tracking are differentially associated with drug abuse-related behavior. Recently, it has been hypothesized that sign- and goal-tracking behavior are mediated by different neurobehavioral valuation systems, including differential incentive salience attribution. Herein, we used different conditioned stimuli to preferentially elicit different response types to study the different incentive valuation characteristics of stimuli associated with sign- and goal-tracking within individuals. The results demonstrate that all stimuli used were equally effective conditioned stimuli; however, only a lever stimulus associated with sign-tracking behavior served as a robust conditioned reinforcer and was preferred over a tone associated with goal-tracking. Moreover, the incentive value attributed to the lever stimulus was capable of promoting suboptimal choice, leading to a significant reduction in reinforcers (food) earned. Furthermore, sign-tracking to a lever was more persistent than goal-tracking to a tone under omission and extinction contingencies. Finally, a conditional discrimination procedure demonstrated that sign-tracking to a lever and goal-tracking to a tone were dependent on learned stimulus–reinforcer relations. Collectively, these results suggest that the different neurobehavioral valuation processes proposed to govern sign- and goal-tracking behavior are independent but parallel processes within individuals. Examining these systems within individuals will provide a better understanding of how one system comes to dominate stimulus–reward learning, thus leading to the differential role these systems play in abuse-related behavior.
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Affiliation(s)
- Joshua S Beckmann
- Behavioral Neuroscience and Psychopharmacology, Department of Psychology, University of Kentucky, Lexington, Kentucky 40536-0509, USA
| | - Jonathan J Chow
- Behavioral Neuroscience and Psychopharmacology, Department of Psychology, University of Kentucky, Lexington, Kentucky 40536-0509, USA
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