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Colom M, Kraev I, Stramek AK, Loza IB, Rostron CL, Heath CJ, Dommett EJ, Singer BF. Conditioning- and reward-related dendritic and presynaptic plasticity of nucleus accumbens neurons in male and female sign-tracker rats. Eur J Neurosci 2024. [PMID: 39193632 DOI: 10.1111/ejn.16513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 07/22/2024] [Accepted: 08/12/2024] [Indexed: 08/29/2024]
Abstract
For a subset of individuals known as sign-trackers, discrete Pavlovian cues associated with rewarding stimuli can acquire incentive properties and exert control over behaviour. Because responsiveness to cues is a feature of various neuropsychiatric conditions, rodent models of sign-tracking may prove useful for exploring the neurobiology of individual variation in psychiatric vulnerabilities. Converging evidence points towards the involvement of dopaminergic neurotransmission in the nucleus accumbens core (NAc) in the development of sign-tracking, yet whether this phenotype is associated with specific accumbal postsynaptic properties is unknown. Here, we examined dendritic spine structural organisation, as well as presynaptic and postsynaptic markers of activity, in the NAc core of male and female rats following a Pavlovian-conditioned approach procedure. In contrast to our prediction that cue re-exposure would increase spine density, experiencing the discrete lever-cue without reward delivery resulted in lower spine density than control rats for which the lever was unpaired with reward during training; this effect was tempered in the most robust sign-trackers. Interestingly, this same behavioural test (lever presentation without reward) resulted in increased levels of a marker of presynaptic activity (synaptophysin), and this effect was greatest in female rats. Whilst some behavioural differences were observed in females during initial Pavlovian training, final conditioning scores did not differ from males and were unaffected by the oestrous cycle. This work provides novel insights into how conditioning impacts the neuronal plasticity of the NAc core, whilst highlighting the importance of studying the behaviour and neurobiology of both male and female rats.
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Affiliation(s)
- Morgane Colom
- School of Life, Health and Chemical Sciences, The Open University, Milton Keynes, UK
- King's College, Institute of Psychiatry, Psychology and Neuroscience, London, UK
- Department of Psychology, University of Cambridge, Cambridge, UK
| | - Igor Kraev
- School of Life, Health and Chemical Sciences, The Open University, Milton Keynes, UK
| | - Agata K Stramek
- School of Life, Health and Chemical Sciences, The Open University, Milton Keynes, UK
| | - Iwona B Loza
- School of Life, Health and Chemical Sciences, The Open University, Milton Keynes, UK
| | - Claire L Rostron
- School of Life, Health and Chemical Sciences, The Open University, Milton Keynes, UK
| | - Christopher J Heath
- School of Life, Health and Chemical Sciences, The Open University, Milton Keynes, UK
| | - Eleanor J Dommett
- School of Life, Health and Chemical Sciences, The Open University, Milton Keynes, UK
- King's College, Institute of Psychiatry, Psychology and Neuroscience, London, UK
| | - Bryan F Singer
- School of Life, Health and Chemical Sciences, The Open University, Milton Keynes, UK
- School of Psychology, Sussex Neuroscience, Sussex Addiction Research and Intervention Centre, University of Sussex, Brighton, UK
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2
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Navarro V, Dwyer DM, Honey RC. Variation in the effectiveness of reinforcement and nonreinforcement in generating different conditioned behaviors. Neurobiol Learn Mem 2024; 211:107915. [PMID: 38527649 DOI: 10.1016/j.nlm.2024.107915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Revised: 03/04/2024] [Accepted: 03/19/2024] [Indexed: 03/27/2024]
Abstract
Rat autoshaping procedures generate two readily measurable conditioned responses: During lever presentations that have previously signaled food, rats approach the food well (called goal-tracking) and interact with the lever itself (called sign-tracking). We investigated how reinforced and nonreinforced trials affect the overall and temporal distributions of these two responses across 10-second lever presentations. In two experiments, reinforced trials generated more goal-tracking than sign-tracking, and nonreinforced trials resulted in a larger reduction in goal-tracking than sign-tracking. The effect of reinforced trials was evident as an increase in goal-tracking and reduction in sign-tracking across the duration of the lever presentations, and nonreinforced trials resulted in this pattern transiently reversing and then becoming less evident with further training. These dissociations are consistent with a recent elaboration of the Rescorla-Wagner model, HeiDI (Honey, R.C., Dwyer, D.M., & Iliescu, A.F. (2020a). HeiDI: A model for Pavlovian learning and performance with reciprocal associations. Psychological Review, 127, 829-852.), a model in which responses related to the nature of the unconditioned stimulus (e.g., goal-tracking) have a different origin than those related to the nature of the conditioned stimulus (e.g., sign-tracking).
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3
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María-Ríos CE, Fitzpatrick CJ, Czesak FN, Morrow JD. Effects of predictive and incentive value manipulation on sign- and goal-tracking behavior. Neurobiol Learn Mem 2023; 203:107796. [PMID: 37385521 PMCID: PMC10599606 DOI: 10.1016/j.nlm.2023.107796] [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: 01/04/2023] [Revised: 05/01/2023] [Accepted: 06/26/2023] [Indexed: 07/01/2023]
Abstract
When a neutral stimulus is repeatedly paired with an appetitive reward, two different types of conditioned approach responses may develop: a sign-tracking response directed toward the neutral cue, or a goal-tracking response directed toward the location of impending reward delivery. Sign-tracking responses have been postulated to result from attribution of incentive value to conditioned cues, while goal-tracking reflects the assignment of only predictive value to the cue. We therefore hypothesized that sign-tracking rats would be more sensitive to manipulations of incentive value, while goal-tracking rats would be more responsive to changes in the predictive value of the cue. We tested sign- and goal-tracking before and after devaluation of a food reward using lithium chloride, and tested whether either response could be learned under negative contingency conditions that precluded any serendipitous reinforcement of the behavior that might support instrumental learning. We also tested the effects of blocking the predictive value of a cue using simultaneous presentation of a pre-conditioned cue. We found that sign-tracking was sensitive to outcome devaluation, while goal-tracking was not. We also confirmed that both responses are Pavlovian because they can be learned under negative contingency conditions. Goal-tracking was almost completely blocked by a pre-conditioned cue, while sign-tracking was much less sensitive to such interference. These results indicate that sign- and goal-tracking may follow different rules of reinforcement learning and suggest a need to revise current models of associative learning to account for these differences.
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Affiliation(s)
- Cristina E María-Ríos
- Neuroscience Graduate Program, University of Michigan, 204 Washtenaw Ave., Ann Arbor, MI 48109, USA
| | | | - Francesca N Czesak
- Neuroscience Graduate Program, University of Michigan, 204 Washtenaw Ave., Ann Arbor, MI 48109, USA
| | - Jonathan D Morrow
- Neuroscience Graduate Program, University of Michigan, 204 Washtenaw Ave., Ann Arbor, MI 48109, USA; Department of Psychiatry, University of Michigan, 1500 E. Medical Center Dr., Ann Arbor, MI 48109, USA.
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4
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Gibney KD, Kypriotakis G, Versace F. Individual differences in late positive potential amplitude and theta power predict cue-induced eating. ADDICTION NEUROSCIENCE 2023; 7:100106. [PMID: 37711965 PMCID: PMC10501046 DOI: 10.1016/j.addicn.2023.100106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 09/16/2023]
Abstract
Cue-induced reward-seeking behaviors are regulated by both the affective and cognitive control systems of the brain. This study aimed at investigating how individual differences in affective and cognitive responses to cues predicting food rewards contribute to the regulation of cue-induced eating. We recorded electroencephalogram (EEG) from 59 adults while they viewed emotional and food-related images that preceded the delivery of food rewards (candies) or non-food objects (beads). We measured the amplitude of the late positive potential (LPP) in response to a variety of motivationally relevant images and power in the theta (4-8 Hz) frequency band after candies or beads were dispensed to the participants. We found that individuals with larger LPP responses to food images than to pleasant images (C>P group) ate significantly more during the experiment than those with the opposite response pattern (P>C group, p < 0.001). Furthermore, we found that individuals with higher theta power after dispensation of the candy than of the bead (θCA>θBE) ate significantly more than those with the opposite response pattern (θBE>θCA, p < 0.001). Finally, we found that the crossed P>C and θBE>θCA group ate less (p < 0.001) than did the other three groups formed by crossing the LPP and theta group assignments, who exhibited similar eating behavior on average (p = 0.662). These findings demonstrate that individual differences in both affective and cognitive responses to reward-related cues underlie vulnerability to cue-induced behaviors, underscoring the need for individualized treatments to mitigate maladaptive behaviors.
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Affiliation(s)
- Kyla D. Gibney
- Neuroscience Graduate Program MD Anderson UTHealth Graduate School of Biomedical Sciences, Houston, TX, United States
- Department of Behavioral Science, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - George Kypriotakis
- Department of Behavioral Science, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Francesco Versace
- Neuroscience Graduate Program MD Anderson UTHealth Graduate School of Biomedical Sciences, Houston, TX, United States
- Department of Behavioral Science, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
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5
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Townsend ES, Amaya KA, Smedley EB, Smith KS. Nucleus accumbens core acetylcholine receptors modulate the balance of flexible and inflexible cue-directed motivation. Sci Rep 2023; 13:13375. [PMID: 37591961 PMCID: PMC10435540 DOI: 10.1038/s41598-023-40439-4] [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: 04/13/2023] [Accepted: 08/10/2023] [Indexed: 08/19/2023] Open
Abstract
Sign-tracking is a conditioned response where animals interact with reward-predictive cues due to the cues having motivational value, or incentive salience. The nucleus accumbens core (NAc) has been implicated in mediating the sign-tracking response. Additionally, acetylcholine (ACh) transmission throughout the striatum has been attributed to both incentive motivation and behavioral flexibility. Here, we demonstrate a role for NAc ACh receptors in the flexibility of sign-tracking. Sign-tracking animals were exposed to an omission contingency, in which vigorous sign-tracking was punished by reward omission. Animals rapidly adjusted their behavior, but they maintained sign-tracking in a less vigorous manner that did not cancel reward. Within this context of sign-tracking being persistent yet flexible in structure, blockade of NAc nicotinic receptors (nAChRs) led to a persistence in the initial sign-tracking response during omission followed by a period of change in the makeup of sign-tracking, whereas blockade of muscarinic receptors (mAChRs) oppositely enhanced the omission-related development of the new sign-tracking behaviors. Later, once omission learning had occurred, nAChR blockade uniquely led to reduced sign-tracking and elevated reward-directed behaviors instead. These results indicate that NAc ACh receptors have opposing roles in maintaining learned patterns of sign-tracking, with nAChRs having a special involvement in regulating the structure of the sign-tracking response.
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Affiliation(s)
- Erica S Townsend
- Department of Psychological and Brain Sciences, Dartmouth College, 3 Maynard Street, Hanover, NH, 03755, USA.
| | - Kenneth A Amaya
- Department of Psychological and Brain Sciences, Dartmouth College, 3 Maynard Street, Hanover, NH, 03755, USA
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, USA
| | - Elizabeth B Smedley
- Department of Psychological and Brain Sciences, Dartmouth College, 3 Maynard Street, Hanover, NH, 03755, USA
- Department of Psychology, Temple University, Philadelphia, PA, USA
| | - Kyle S Smith
- Department of Psychological and Brain Sciences, Dartmouth College, 3 Maynard Street, Hanover, NH, 03755, USA
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Moin Afshar N, Cinotti F, Martin D, Khamassi M, Calu DJ, Taylor JR, Groman SM. Reward-Mediated, Model-Free Reinforcement-Learning Mechanisms in Pavlovian and Instrumental Tasks Are Related. J Neurosci 2023; 43:458-471. [PMID: 36216504 PMCID: PMC9864557 DOI: 10.1523/jneurosci.1113-22.2022] [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: 06/09/2022] [Revised: 10/03/2022] [Accepted: 10/06/2022] [Indexed: 01/25/2023] Open
Abstract
Model-free and model-based computations are argued to distinctly update action values that guide decision-making processes. It is not known, however, if these model-free and model-based reinforcement learning mechanisms recruited in operationally based instrumental tasks parallel those engaged by pavlovian-based behavioral procedures. Recently, computational work has suggested that individual differences in the attribution of incentive salience to reward predictive cues, that is, sign- and goal-tracking behaviors, are also governed by variations in model-free and model-based value representations that guide behavior. Moreover, it is not appreciated if these systems that are characterized computationally using model-free and model-based algorithms are conserved across tasks for individual animals. In the current study, we used a within-subject design to assess sign-tracking and goal-tracking behaviors using a pavlovian conditioned approach task and then characterized behavior using an instrumental multistage decision-making (MSDM) task in male rats. We hypothesized that both pavlovian and instrumental learning processes may be driven by common reinforcement-learning mechanisms. Our data confirm that sign-tracking behavior was associated with greater reward-mediated, model-free reinforcement learning and that it was also linked to model-free reinforcement learning in the MSDM task. Computational analyses revealed that pavlovian model-free updating was correlated with model-free reinforcement learning in the MSDM task. These data provide key insights into the computational mechanisms mediating associative learning that could have important implications for normal and abnormal states.SIGNIFICANCE STATEMENT Model-free and model-based computations that guide instrumental decision-making processes may also be recruited in pavlovian-based behavioral procedures. Here, we used a within-subject design to test the hypothesis that both pavlovian and instrumental learning processes were driven by common reinforcement-learning mechanisms. Sign-tracking and goal-tracking behaviors were assessed in rats using a pavlovian conditioned approach task, and then instrumental behavior was characterized using an MSDM task. We report that sign-tracking behavior was associated with greater model-free, but not model-based, learning in the MSDM task. These data suggest that pavlovian and instrumental behaviors may be driven by conserved reinforcement-learning mechanisms.
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Affiliation(s)
- Neema Moin Afshar
- Department of Psychiatry, Yale School of Medicine, New Haven, Connecticut 06511
| | - François Cinotti
- Department of Experimental Psychology, University of Oxford, Oxford OX2 6GG, United Kingdom
| | - David Martin
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Mehdi Khamassi
- Institute of Intelligent Systems and Robotics, Centre National de la Recherche Scientifique, Sorbonne University, 75005 Paris, France
| | - Donna J Calu
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland 21201
- Program in Neuroscience, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Jane R Taylor
- Department of Psychiatry, Yale School of Medicine, New Haven, Connecticut 06511
- Department of Psychology, Yale University, New Haven, Connecticut 06520
| | - Stephanie M Groman
- Department of Psychiatry, Yale School of Medicine, New Haven, Connecticut 06511
- Department of Neuroscience, University of Minnesota Medical School, Minneapolis, Minnesota 55455
- Department of Psychology, University of Minnesota, Minneapolis, Minnesota 55455
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7
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Cope LM, Gheidi A, Martz ME, Duval ER, Khalil H, Allerton T, Morrow JD. A mechanical task for measuring sign- and goal-tracking in humans: A proof-of-concept study. Behav Brain Res 2023; 436:114112. [PMID: 36115435 PMCID: PMC10153473 DOI: 10.1016/j.bbr.2022.114112] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 09/07/2022] [Accepted: 09/08/2022] [Indexed: 11/16/2022]
Abstract
Cue-based associative learning (i.e., Pavlovian conditioning) is a foundational component of behavior in almost all forms of animal life and may provide insight into individual differences in addiction liability. Cues can take on incentive-motivational properties (i.e., incentive salience) through Pavlovian learning. Extensive testing with non-human animals (primarily rats) has demonstrated significant variation among individuals in the behaviors this type of learning evokes. So-named "sign-trackers" and "goal-trackers" have been examined in many studies of non-human animals, but this work in humans is still a nascent area of research. In the present proof-of-concept study, we used a Pavlovian conditioned approach task to investigate human sign- and goal-tracking in emerging adults. Conditioned behaviors that developed over the course of the task were directed toward the reward-cue and toward the reward location. Participants' eye-gaze and behavior during the task were submitted to a latent profile analysis, which revealed three groups defined as sign-trackers (n = 10), goal-trackers (n = 4), and intermediate responders (n = 36). Impulsivity was a significant predictor of the sign-tracking group relative to the goal-tracking group. The present study provides preliminary evidence that a simple procedure can produce learned Pavlovian conditioned approach behavior in humans. Though further investigation is required, findings provide a promising step toward the long-term goal of translating important insights gleaned from basic research into treatment strategies that can be applied to clinical populations.
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Affiliation(s)
- L M Cope
- Department of Psychiatry and Addiction Center, University of Michigan, 4250 Plymouth Road, Ann Arbor, MI 48109, USA.
| | - A Gheidi
- Biomedical Science Research Building, University of Michigan, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA.
| | - M E Martz
- Department of Psychiatry and Addiction Center, University of Michigan, 4250 Plymouth Road, Ann Arbor, MI 48109, USA.
| | - E R Duval
- Department of Psychiatry, University of Michigan, 4250 Plymouth Road, Ann Arbor, MI 48109, USA.
| | - H Khalil
- Michigan Neuroscience Institute, University of Michigan, 205 Zina Pitcher Place, Ann Arbor, MI 48109, USA.
| | - T Allerton
- Biomedical Science Research Building, University of Michigan, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA.
| | - J D Morrow
- Department of Psychiatry and Addiction Center, University of Michigan, 4250 Plymouth Road, Ann Arbor, MI 48109, USA; Biomedical Science Research Building, University of Michigan, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA.
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8
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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: 5] [Impact Index Per Article: 5.0] [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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9
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Cofresí RU, Piasecki TM, Bartholow BD. Acute sensitization of the P3 event-related potential response to beverage images and the risk for alcohol use disorder. ADDICTION NEUROSCIENCE 2022; 4:100041. [PMID: 36425356 PMCID: PMC9681121 DOI: 10.1016/j.addicn.2022.100041] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Previous research suggests the amplitude of the P3 event-related potential (ERP) response reflects the incentive value of the eliciting stimulus, and that individuals with trait-like lower sensitivity (LS) to the acute effects of alcohol, a potent risk factor for alcohol use disorder (AUD), tend to show exaggerated P3 ERP responses to alcohol beverage cues (compared to their peers with higher sensitivity; HS). No prior research has examined trajectories of the cue-elicited P3 response across repeated trials of nonreinforced cue presentations. Characterizing these trajectories can be informative as to potential mechanisms linking LS with increased AUD risk. Here, we tested whether individual differences in alcohol sensitivity are associated with different trial-by-trial trajectories of the P3 elicited by alcohol and nonalcohol reward cues (infrequent oddball/target stimuli) using a large sample of emerging adults (M age = 19.53; N = 287; 55% female; 86% White; 90% right-handed) stratified for alcohol sensitivity. Multilevel models adjusted for age, sex, handedness, and alcohol use indicated that: (i) the P3 response to alcohol and nonalcohol reward cues alike sensitized (i.e., increased) across trials; (ii) across the task, the P3 response to alcohol cues was larger for the LS than the HS phenotype; and (iii) the P3 difference score (alcohol - nonalcohol) was larger for the LS than HS phenotype only across the first half of task. Findings suggest that whereas incentive value attribution may be a mechanism for alcohol cue-triggered attentional biases for both LS and HS individuals, LS individuals more consistently over-attribute incentive value to alcohol cues.
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Affiliation(s)
- Roberto U. Cofresí
- Department of Psychological Sciences, University of Missouri, Columbia, MO 65211, United States
| | - Thomas M. Piasecki
- Center for Tobacco Research and Intervention and Department of Medicine, University of Wisconsin, Madison, United States
| | - Bruce D. Bartholow
- Department of Psychological Sciences, University of Missouri, Columbia, MO 65211, United States
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10
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Appetitive 50 kHz calls in a pavlovian conditioned approach task in Cacna1c haploinsufficient rats. Physiol Behav 2022; 250:113795. [PMID: 35351494 DOI: 10.1016/j.physbeh.2022.113795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 03/23/2022] [Accepted: 03/24/2022] [Indexed: 11/21/2022]
Abstract
We have previously shown that rats emit high-frequency 50 kHz ultrasonic vocalizations (USV) during sign- and goal-tracking in a common Pavlovian conditioned approach task. Such 50 kHz calls are probably related to positive affect and are associated with meso-limbic dopamine function. In humans, the CACNA1C gene, encoding for the α1C subunit of the L-type voltage-gated calcium channel CaV1.2, is implicated in several mental disorders, including mood disorders associated with altered dopamine signaling. In the present study, we investigated sign- and goal-tracking behavior and the emission of 50 kHz USV in Cacna1c haploinsufficent rats in a task where food pellet delivery is signaled by an appearance of an otherwise inoperable lever. Over the course of this Pavlovian training, these rats not only increased their approach to the reward site, but also their rates of pressing the inoperable lever. During subsequent extinction tests, where reward delivery was omitted, extinction patterns differed between reward site (i.e. magazine entries) and lever, since magazine entries quickly declined whereas behavior towards the lever transiently increased. Based on established criteria to define sign- or goal-tracking individuals, no CACNA1C rat met a sign-tracking criterion, since around 42% of rats tested where goal-trackers and the other 58% fell into an intermediate range. Regarding USV, we found that the CACNA1C rats emitted 50 kHz calls with a clear subject-dependent pattern; also, most of them were of a flat subtype and occurred mainly during initial habituation phases without cues or rewards. Compared, to previously published wildtype controls, Cacna1c haploinsufficent rats displayed reduced numbers of appetitive 50 kHz calls. Moreover, similar to wildtype littermate controls, 50 kHz call emission in Cacna1c haploinsufficent rats was intra-individually stable over training days and was negatively associated with goal-tracking. Together, these findings provide evidence in support of 50 kHz calls as trait marker. The finding that Cacna1c haploinsufficent rats show reductions of 50 kHz calls accompanied with more goal-tracking, is consistent with the assumption of altered dopamine signaling in these rats, a finding which supports their applicability in models of mental disorders.
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11
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Quantifying the instrumental and noninstrumental underpinnings of Pavlovian responding with the Price equation. Psychon Bull Rev 2021; 29:1295-1306. [PMID: 34918283 DOI: 10.3758/s13423-021-02047-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/28/2021] [Indexed: 11/08/2022]
Abstract
The Price equation is a mathematical expression of selectionist and non-selectionist pressures on biological, cultural, and behavioral change. We use it here to specify instrumental and noninstrumental behaviors as they arise within the context of the Pavlovian autoshaping procedure, for rats trained under reward certainty and reward uncertainty. The point of departure for this endeavor is that some portion of autoshaped behavior referred to as goal-tracking appears instrumental-a function of resource attainment (the individual approaches the location where the unconditioned stimulus is to be delivered). By contrast, some other portion of autoshaped behavior referred to as sign-tracking is noninstrumental-irrelevant to making contact with the to-be-delivered unconditioned stimulus. A Price equation model is proposed that unifies our understanding of Pavlovian autoshaping behavior by isolating operant and respondent influences on goal-tracking (instrumental) and sign-tracking (noninstrumental) behavior.
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12
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Another look at the extinction of conditioned flavor preferences: Amount of training and tests for spontaneous recovery. Learn Behav 2021; 49:405-421. [PMID: 34405379 DOI: 10.3758/s13420-021-00480-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/23/2021] [Indexed: 11/08/2022]
Abstract
A conditioned flavor preference develops when hungry or thirsty rats experience a neutral flavor mixed in solution with a nutrient. In two sets of studies, we previously demonstrated that this learned preference is highly sensitive to flavor nonreinforcement (i.e., exposure to the flavor without the nutrient) either prior to (latent inhibition), during (partial reinforcement), or following (extinction) flavor-nutrient pairings. In each of these studies we employed a nutrient devaluation procedure to assess the integrity of specific flavor-nutrient associations following extinction, but more recently Gonzalez, Morillas, and Hall (Journal of Experimental Psychology: Animal Learning & Cognition, 42, 380-390, 2016) observed that sensitivity to extinction in thirsty rats in this preparation may depend upon use of a post-conditioning nutrient devaluation procedure. To assess the generality of our earlier results, but without including a post-conditioning nutrient devaluation phase, we assessed in three experiments the role of the number of flavor-nutrient pairings given prior to extinction and the possibility of spontaneous recovery following a 3-week delay. We observed that extinction consistently weakened the flavor preference in thirsty rats (in spite of the absence of a nutrient devaluation procedure) and also found no evidence for spontaneous recovery. These results establish that our prior findings that conditioned flavor preferences are weakened by extinction are quite robust in thirsty rats and that these extinction effects may be fairly permanent.
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13
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Fleming KA, Cofresí RU, Bartholow BD. Transfer of incentive salience from a first-order alcohol cue to a novel second-order alcohol cue among individuals at risk for alcohol use disorder: electrophysiological evidence. Addiction 2021; 116:1734-1746. [PMID: 33338310 PMCID: PMC8172423 DOI: 10.1111/add.15380] [Citation(s) in RCA: 10] [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: 04/20/2020] [Revised: 07/29/2020] [Accepted: 12/09/2020] [Indexed: 12/13/2022]
Abstract
BACKGROUND AND AIMS In susceptible individuals, cues associated with drug use are theorized to take on incentive-motivational properties, including the ability to reinforce higher-order, drug-related associative learning. This study aimed to test this prediction among people varying in risk for alcohol use disorder. DESIGN, SETTING AND PARTICIPANTS Repeated-measures experiment with a measured individual difference variable at a University psychology laboratory in Missouri, USA. One hundred and six young adults (96 contributed complete data) were pre-selected to represent the upper and lower quartiles of self-reported sensitivity to alcohol's acute effects. MEASUREMENTS Participants completed a second-order Pavlovian conditioning paradigm in which an initially neutral visual cue (second-order conditional stimulus; CS2 ) predicted onset of an olfactory cue (first-order conditional stimulus; CS1 ). Olfactory cues were isolated from alcoholic beverages, sweets and non-comestible substances, each presumed to have a natural history of first-order conditioning. Event-related potential responses to the CS2 across its conditioning and extinction, and to the CS1 , provided neurophysiological indices of incentive salience (IS). FINDINGS The IS of the alcohol CS1 was higher among participants low in alcohol sensitivity (LS), relative to their higher-sensitivity (HS) peers. The IS of the CS2 paired with the alcohol CS1 increased across the CS2 conditioning phase among LS but not HS participants. Also, LS (but not HS) individuals also experienced increases in alcohol craving following alcohol CS1 exposure, and this change was correlated with increases in the IS of the CS2 paired with the alcohol CS1 . CONCLUSIONS Alcoholic beverage odor, a proximal cue for alcohol consumption, appears to reinforce conditioning of neurophysiological responses to a novel cue among low alcohol sensitivity (LS) individuals but not high alcohol sensitivity individuals, providing the first evidence that the LS phenotype may be associated with differences in the conditioned reinforcing properties of alcohol-related cues. These findings support the idea that the LS phenotype may increase alcohol use disorder risk via susceptibility to incentive salience sensitization.
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Affiliation(s)
- Kimberly A. Fleming
- Psychiatric and Behavioral Health Institute, Allegheny Health Network
- Department of Psychiatry, Drexel University College of Medicine
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The synthetically produced predator odor 2,5-dihydro-2,4,5-trimethylthiazoline increases alcohol self-administration and alters basolateral amygdala response to alcohol in rats. Psychopharmacology (Berl) 2021; 238:67-82. [PMID: 32978649 PMCID: PMC7796942 DOI: 10.1007/s00213-020-05659-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 09/07/2020] [Indexed: 12/27/2022]
Abstract
Post-traumatic stress disorder (PTSD) is a psychiatric illness that can increase the risk for developing an alcohol use disorder (AUD). While clinical data has been useful in identifying similarities in the neurobiological bases of these disorders, preclinical models are essential for understanding the mechanism(s) by which stressors increase the risk for escalated alcohol consumption. The purpose of these studies was to examine if exposure of male Long-Evans rats to the synthetically derived predator odor 2,5-dihydro-2,4,5-trimethylthiazoline (TMT; a component of fox feces) would increase sweetened alcohol self-administration, potentially by facilitating transfer of salience towards cues, and alter neuronal response to alcohol as measured by the immediate early gene c-Fos. In experiment 1, rats exposed to repeated (4×) TMT showed reductions in port entries in Pavlovian conditioned approach and increases in sweetened alcohol self-administration. In experiment 2, rats exposed to repeated TMT showed blunted basolateral amygdala c-Fos response to alcohol. In experiment 3, rats exposed to single, but not repeated TMT, showed increases in sweetened alcohol self-administration, and no change in anxiety-like behavior or hyperarousal. In experiment 4, rats continued to show a significant corticosterone response to TMT after repeated exposures. In summary, exposure of male rats to TMT can cause escalations in sweetened alcohol self-administration and reduction in BLA response to alcohol. These studies outline and utilize a novel preclinical model that can be used to further neurobiological understanding of the emergence of escalated alcohol consumption following stress exposure.
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The lateral hypothalamus and orexinergic transmission in the paraventricular thalamus promote the attribution of incentive salience to reward-associated cues. Psychopharmacology (Berl) 2020; 237:3741-3758. [PMID: 32852601 PMCID: PMC7960144 DOI: 10.1007/s00213-020-05651-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 08/20/2020] [Indexed: 12/14/2022]
Abstract
RATIONALE Prior research suggests that the neural pathway from the lateral hypothalamic area (LHA) to the paraventricular nucleus of the thalamus (PVT) mediates the attribution of incentive salience to Pavlovian reward cues. However, a causal role for the LHA and the neurotransmitters involved have not been demonstrated in this regard. OBJECTIVES To examine (1) the role of LHA in the acquisition of Pavlovian conditioned approach (PavCA) behaviors, and (2) the role of PVT orexin 1 receptors (OX1r) and orexin 2 receptors (OX2r) in the expression of PavCA behaviors and conditioned reinforcement. METHODS Rats received excitotoxic lesions of the LHA prior to Pavlovian training. A separate cohort of rats characterized as sign-trackers (STs) or goal-trackers (GTs) received the OX1r antagonist SB-334867, or the OX2r antagonist TCS-OX2-29, into the PVT, to assess their effects on the expression of PavCA behavior and on the conditioned reinforcing properties of a Pavlovian reward cue. RESULTS LHA lesions attenuated the development of sign-tracking behavior. Administration of either the OX1r or OX2r antagonist into the PVT reduced sign-tracking behavior in STs. Further, OX2r antagonism reduced the conditioned reinforcing properties of a Pavlovian reward cue in STs. CONCLUSIONS The LHA is necessary for the development of sign-tracking behavior; and blockade of orexin signaling in the PVT attenuates the expression of sign-tracking behavior and the conditioned reinforcing properties of a Pavlovian reward cue. Together, these data suggest that LHA orexin inputs to the PVT are a key component of the circuitry that encodes the incentive motivational value of reward cues.
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Kochli DE, Keefer SE, Gyawali U, Calu DJ. Basolateral Amygdala to Nucleus Accumbens Communication Differentially Mediates Devaluation Sensitivity of Sign- and Goal-Tracking Rats. Front Behav Neurosci 2020; 14:593645. [PMID: 33324182 PMCID: PMC7723965 DOI: 10.3389/fnbeh.2020.593645] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 11/05/2020] [Indexed: 12/02/2022] Open
Abstract
Rats rely on communication between the basolateral amygdala (BLA) and nucleus accumbens (NAc) to express lever directed approach in a Pavlovian lever autoshaping (PLA) task that distinguishes sign- and goal-tracking rats. During PLA, sign-tracking rats preferentially approach an insertable lever cue, while goal-tracking rats approach a foodcup where rewards are delivered. While sign-tracking rats inflexibly respond to cues even after the associated reward is devalued, goal-tracking rats flexibly reduce responding to cues during outcome devaluation. Here, we sought to determine whether BLA-NAc communication, which is necessary for sign, but not goal-tracking, drives a rigid appetitive approach of sign-tracking rats that are insensitive to manipulations of outcome value. Using a contralateral chemogenetic inactivation design, we injected contralateral BLA and NAc core with inhibitory DREADD (hm4Di-mCherry) or control (mCherry) constructs. To determine sign- and goal-tracking groups, we trained rats in five PLA sessions in which brief lever insertion predicts food pellet delivery. We sated rats on training pellets (devalued condition) or chow (valued condition) before systemic clozapine injections (0.1 mg/kg) to inactivate BLA and contralateral NAc during two outcome devaluation probe tests, in which we measured lever and foodcup approach. Contralateral BLA-NAc chemogenetic inactivation promoted a flexible lever approach in sign-tracking rats but disrupted the flexible foodcup approach in goal-tracking rats. Consistent with a prior BLA-NAc disconnection lesion study, we find contralateral chemogenetic inactivation of BLA and NAc core reduces lever, but not the foodcup approach in PLA. Together these findings suggest rigid appetitive associative encoding in BLA-NAc of sign-tracking rats hinders the expression of flexible behavior when outcome value changes.
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Affiliation(s)
- Daniel E. Kochli
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Sara E. Keefer
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Utsav Gyawali
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, United States
- Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Donna J. Calu
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, United States
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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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Individual variation in the attribution of incentive salience to social cues. Sci Rep 2020; 10:2583. [PMID: 32054901 PMCID: PMC7018846 DOI: 10.1038/s41598-020-59378-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 01/02/2020] [Indexed: 11/08/2022] Open
Abstract
Research on the attribution of incentive salience to drug cues has furthered our understanding of drug self-administration in animals and addiction in humans. The influence of social cues on drug-seeking behavior has garnered attention recently, but few studies have investigated how social cues gain incentive-motivational value. In the present study, a Pavlovian conditioned approach (PCA) procedure was used to identify rats that are more (sign-trackers; STs) or less (goal-trackers; GTs) prone to attribute incentive salience to food reward cues. In Experiment 1, a novel procedure employed social ‘peers’ to compare the tendency of STs and GTs to attribute incentive salience to social reward cues as well as form a social-conditioned place preference. In Experiment 2, social behavior of STs and GTs was compared using social interaction and choice tests. Finally, in Experiment 3, levels of plasma oxytocin were measured in STs and GTs seven days after the last PCA training session, because oxytocin is known to modulate the mesolimbic reward system and social behavior. Compared to GTs, STs attributed more incentive salience to social-related cues and exhibited prosocial behaviors (e.g., social-conditioned place preference, increased social interaction, and social novelty-seeking). No group differences were observed in plasma oxytocin levels. Taken together, these experiments demonstrate individual variation in the attribution of incentive salience to both food- and social-related cues, which has important implications for the pathophysiology of addiction.
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María-Ríos CE, Morrow JD. Mechanisms of Shared Vulnerability to Post-traumatic Stress Disorder and Substance Use Disorders. Front Behav Neurosci 2020; 14:6. [PMID: 32082127 PMCID: PMC7006033 DOI: 10.3389/fnbeh.2020.00006] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 01/13/2020] [Indexed: 12/11/2022] Open
Abstract
Psychoactive substance use is a nearly universal human behavior, but a significant minority of people who use addictive substances will go on to develop an addictive disorder. Similarly, though ~90% of people experience traumatic events in their lifetime, only ~10% ever develop post-traumatic stress disorder (PTSD). Substance use disorders (SUD) and PTSD are highly comorbid, occurring in the same individual far more often than would be predicted by chance given the respective prevalence of each disorder. Some possible reasons that have been proposed for the relationship between PTSD and SUD are self-medication of anxiety with drugs or alcohol, increased exposure to traumatic events due to activities involved in acquiring illegal substances, or addictive substances altering the brain's stress response systems to make users more vulnerable to PTSD. Yet another possibility is that some people have an intrinsic vulnerability that predisposes them to both PTSD and SUD. In this review, we integrate clinical and animal data to explore these possible etiological links between SUD and PTSD, with an emphasis on interactions between dopaminergic, adrenocorticotropic, GABAergic, and glutamatergic neurobehavioral mechanisms that underlie different emotional learning styles.
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Affiliation(s)
| | - Jonathan D. Morrow
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, United States
- Department of Psychiatry, University of Michigan, Ann Arbor, MI, United States
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