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Solinas M, Lardeux V, Leblanc PM, Longueville JE, Thiriet N, Vandaele Y, Panlilio LV, Jaafari N. Delay of punishment highlights differential vulnerability to developing addiction-like behavior toward sweet food. Transl Psychiatry 2024; 14:155. [PMID: 38509086 PMCID: PMC10954751 DOI: 10.1038/s41398-024-02863-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 03/06/2024] [Accepted: 03/07/2024] [Indexed: 03/22/2024] Open
Abstract
Resistance to punishment is commonly used to measure the difficulty in refraining from rewarding activities when negative consequences ensue, which is a hallmark of addictive behavior. We recently developed a progressive shock strength (PSS) procedure in which individual rats can titrate the amount of punishment that they are willing to tolerate to obtain food rewards. Here, we investigated the effects of a range of delays (0-12 s) on resistance to punishment measured by PSS break points. As expected from delay discounting principles, we found that delayed shock was less effective as a punisher, as revealed by higher PSS breakpoints. However, this discounting effect was not equally distributed in the population of rats, and the introduction of a delay highlighted the existence of two populations: rats that were sensitive to immediate punishment were also sensitive to delayed shock, whereas rats that were resistant to immediate punishment showed strong temporal discounting of delayed punishment. Importantly, shock-sensitive rats suppressed responding even in subsequent non-punishment sessions, and they differed from shock-resistant rats in anxiety-like behavior, but not in sensitivity to pain. These results show that manipulation of temporal contingencies of punishment in the PSS procedure provides a valuable tool to identify individuals with a double vulnerability to addiction: low sensitivity to aversion and excessive discounting of negative future consequences. Conversely, the shock-sensitive population may provide a model of humans who are vulnerable to opportunity loss due to excessive anxiety.
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Affiliation(s)
- Marcello Solinas
- Université de Poitiers, INSERM, U1084, Laboratoire de Neurosciences Expérimentales et Cliniques, Poitiers, France.
- Unité de Recherche Clinique Intersectorielle en Psychiatrie, Centre Hospitalier Henri-Laborit, Poitiers, France.
| | - Virginie Lardeux
- Université de Poitiers, INSERM, U1084, Laboratoire de Neurosciences Expérimentales et Cliniques, Poitiers, France
| | - Pierre-Marie Leblanc
- Unité de Recherche Clinique Intersectorielle en Psychiatrie, Centre Hospitalier Henri-Laborit, Poitiers, France
| | - Jean-Emmanuel Longueville
- Université de Poitiers, INSERM, U1084, Laboratoire de Neurosciences Expérimentales et Cliniques, Poitiers, France
| | - Nathalie Thiriet
- Université de Poitiers, INSERM, U1084, Laboratoire de Neurosciences Expérimentales et Cliniques, Poitiers, France
| | - Youna Vandaele
- Université de Poitiers, INSERM, U1084, Laboratoire de Neurosciences Expérimentales et Cliniques, Poitiers, France
| | - Leigh V Panlilio
- Real-world Assessment, Prediction, and Treatment Unit, Translational Addiction Medicine Branch, Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD, USA
| | - Nematollah Jaafari
- Unité de Recherche Clinique Intersectorielle en Psychiatrie, Centre Hospitalier Henri-Laborit, Poitiers, France
- Université de Poitiers, CNRS, UMR 7295, Centre de Recherche sur la Cognition et l'apprentissage, Poitiers, France
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Lenoir M, Navailles S, Vandaele Y, Vouillac-Mendoza C, Guillem K, Ahmed SH. Large-scale brain correlates of sweet versus cocaine reward in rats. Eur J Neurosci 2023; 57:423-439. [PMID: 36453530 DOI: 10.1111/ejn.15879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 11/09/2022] [Accepted: 11/20/2022] [Indexed: 12/03/2022]
Abstract
Cocaine induces many supranormal changes in neuronal activity in the brain, notably in learning- and reward-related regions, in comparison with nondrug rewards-a difference that is thought to contribute to its relatively high addictive potential. However, when facing a choice between cocaine and a nondrug reward (e.g., water sweetened with saccharin), most rats do not choose cocaine, as one would expect from the extent and magnitude of its global activation of the brain, but instead choose the nondrug option. We recently showed that cocaine, though larger in magnitude, is also an inherently more delayed reward than sweet water, thereby explaining why it has less value during choice and why rats opt for the more immediate nondrug option. Here, we used a large-scale Fos brain mapping approach to measure brain responses to each option in saccharin-preferring rats, with the hope to identify brain regions whose activity may explain the preference for the nondrug option. In total, Fos expression was measured in 142 brain levels corresponding to 52 brain subregions and composing 5 brain macrosystems. Overall, our findings confirm in rats with a preference for saccharin that cocaine induces more global brain activation than the preferred nondrug option does. Only very few brain regions were uniquely activated by saccharin. They included regions involved in taste processing (i.e., anterior gustatory cortex) and also regions involved in processing reward delay and intertemporal choice (i.e., some components of the septohippocampal system and its connections with the lateral habenula).
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Affiliation(s)
- Magalie Lenoir
- Université de Bordeaux, CNRS, INCIA, UMR 5287, Bordeaux, France
| | | | - Youna Vandaele
- INSERM, U-1084, Laboratoire des Neurosciences Expérimentales et Cliniques, Université de Poitiers, Poitiers, France
| | | | - Karine Guillem
- Université de Bordeaux, CNRS, INCIA, UMR 5287, Bordeaux, France
| | - Serge H Ahmed
- Université de Bordeaux, CNRS, INCIA, UMR 5287, Bordeaux, France
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3
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Vandaele Y, Augier E, Vouillac-Mendoza C, Ahmed SH. Cocaine falls into oblivion during volitional initiation of choice trials. Addict Biol 2022; 27:e13235. [PMID: 36301214 DOI: 10.1111/adb.13235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 09/12/2022] [Indexed: 01/24/2023]
Abstract
When facing a choice, most animals quit drugs in favour of a variety of nondrug alternatives. We recently found, rather unexpectedly, that choice of the nondrug alternative is in fact inflexible and habitual. One possible contributing factor to habitual choice is the intermittency and uncontrollability of choice trials in previous studies. Here, we asked whether and to what extent volitional control over the occurrence of choice trials could change animals' preference by preventing habitual choice. To do so, rats were trained to nosepoke in a hole to trigger the presentation of two operant levers: one associated with cocaine, the other with saccharin. Rats were then free to choose among the two levers to obtain the corresponding reward, after which both levers retracted until rats self-initiated the next choice trial. Overall, we found that volitional control over choice trials did not change preference. Most rats preferred saccharin over cocaine and selected this option almost exclusively. Intriguingly, after repeated choice and consumption of saccharin, rats transiently lost interest in this option (i.e., due to sensory-specific satiety), but they did not switch to cocaine, preferring instead to pause during long periods of time before reinitiating a choice trial for saccharin. This finding suggests that during volitional initiation of a choice trial, rats fail to consider cocaine as an option. We discuss a possible associative mechanism to explain this perplexing behaviour.
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Affiliation(s)
- Youna Vandaele
- Université de Poitiers, Laboratory of Experimental and Clinical Neurosciences, INSERM U1084, Poitiers, France
| | - Eric Augier
- Center for Social and Affective Neuroscience, BKV, Linköping University, Linköping, Sweden
| | - Caroline Vouillac-Mendoza
- Université de Bordeaux, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR5287, Bordeaux, France.,CNRS, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR5287, Bordeaux, France
| | - Serge H Ahmed
- Université de Bordeaux, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR5287, Bordeaux, France.,CNRS, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR5287, Bordeaux, France
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4
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Vandaele Y, Ahmed SH. Choosing between cocaine and sucrose under the influence: testing the effect of cocaine tolerance. Psychopharmacology (Berl) 2022; 239:1053-1063. [PMID: 34596725 DOI: 10.1007/s00213-021-05987-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 09/14/2021] [Indexed: 01/05/2023]
Abstract
RATIONALE Cocaine use not only depends on the reinforcing properties of the drug, but also on its pharmacological effects on alternative nondrug activities. In animal models investigating choice between cocaine and alternative sweet rewards, the latter influence can have a dramatic impact on choice outcomes. When choosing under cocaine influence is prevented by imposing sufficiently long intervals between choice trials, animals typically prefer the sweet reward. However, when choosing under the drug influence is permitted, animals shift their preference in favor of cocaine. OBJECTIVES We previously hypothesized that this preference shift is mainly due to a direct suppression of responding for sweet reward by cocaine pharmacological effects. Here we tested this hypothesis by making rats tolerant to this drug-induced behavioral suppression. RESULTS Contrary to our expectation, tolerance did not prevent rats from shifting their preference to cocaine when choosing under the influence. CONCLUSION Thus, other mechanisms must be invoked to explain the influence of cocaine intoxication on choice outcomes.
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Affiliation(s)
| | - S H Ahmed
- Institut Des Maladies Neurodégénératives, Université de Bordeaux, Bordeaux, France.,Institut Des Maladies Neurodégénératives, CNRS, Bordeaux, France
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Vandaele Y, Ottenheimer DJ, Janak PH. Dorsomedial Striatal Activity Tracks Completion of Behavioral Sequences in Rats. eNeuro 2021; 8:ENEURO.0279-21.2021. [PMID: 34725103 PMCID: PMC8607909 DOI: 10.1523/eneuro.0279-21.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 09/24/2021] [Accepted: 10/13/2021] [Indexed: 11/21/2022] Open
Abstract
For proper execution of goal-directed behaviors, individuals require both a general representation of the goal and an ability to monitor their own progress toward that goal. Here, we examine how dorsomedial striatum (DMS), a region pivotal for forming associations among stimuli, actions, and outcomes, encodes the execution of goal-directed action sequences that require self-monitoring of behavior. We trained rats to complete a sequence of at least five consecutive lever presses (without visiting the reward port) to obtain a reward and recorded the activity of individual cells in DMS while rats performed the task. We found that the pattern of DMS activity gradually changed during the execution of the sequence, permitting accurate decoding of sequence progress from neural activity at a population level. Moreover, this sequence-related activity was blunted on trials where rats did not complete a sufficient number of presses. Overall, these data suggest a link between DMS activity and the execution of behavioral sequences that require monitoring of ongoing behavior.
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Affiliation(s)
- Youna Vandaele
- Department of Psychological and Brain Sciences, Krieger School of Arts and Sciences, Johns Hopkins University, Baltimore, MD 21218
| | - David J Ottenheimer
- Department of Psychological and Brain Sciences, Krieger School of Arts and Sciences, Johns Hopkins University, Baltimore, MD 21218
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins School of Medicine, Johns Hopkins University, Baltimore, MD 21205
| | - Patricia H Janak
- Department of Psychological and Brain Sciences, Krieger School of Arts and Sciences, Johns Hopkins University, Baltimore, MD 21218
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins School of Medicine, Johns Hopkins University, Baltimore, MD 21205
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Vandaele Y, Lenoir M, Vouillac-Mendoza C, Guillem K, Ahmed SH. Probing the decision-making mechanisms underlying choice between drug and nondrug rewards in rats. eLife 2021; 10:e64993. [PMID: 33900196 PMCID: PMC8075577 DOI: 10.7554/elife.64993] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 04/17/2021] [Indexed: 12/02/2022] Open
Abstract
Delineating the decision-making mechanisms underlying choice between drug and nondrug rewards remains a challenge. This study adopts an original approach to probe these mechanisms by comparing response latencies during sampling versus choice trials. While lengthening of latencies during choice is predicted in a deliberative choice model (DCM), the race-like response competition mechanism postulated by the Sequential choice model (SCM) predicts a shortening of latencies during choice compared to sampling. Here, we tested these predictions by conducting a retrospective analysis of cocaine-versus-saccharin choice experiments conducted in our laboratory. We found that rats engage deliberative decision-making mechanisms after limited training, but adopt a SCM-like response selection mechanism after more extended training, while their behavior is presumably habitual. Thus, the DCM and SCM may not be general models of choice, as initially formulated, but could be dynamically engaged to control choice behavior across early and extended training.
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Affiliation(s)
- Youna Vandaele
- Lausanne University Hospital, Department of PsychiatryPrillySwitzerland
| | - Magalie Lenoir
- Université de Bordeaux, Institut des Maladies NeurodégénérativesBordeauxFrance
- CNRS, Institut des Maladies NeurodégénérativesBordeauxFrance
| | - Caroline Vouillac-Mendoza
- Université de Bordeaux, Institut des Maladies NeurodégénérativesBordeauxFrance
- CNRS, Institut des Maladies NeurodégénérativesBordeauxFrance
| | - Karine Guillem
- Université de Bordeaux, Institut des Maladies NeurodégénérativesBordeauxFrance
- CNRS, Institut des Maladies NeurodégénérativesBordeauxFrance
| | - Serge H Ahmed
- Université de Bordeaux, Institut des Maladies NeurodégénérativesBordeauxFrance
- CNRS, Institut des Maladies NeurodégénérativesBordeauxFrance
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Abstract
Addiction was suggested to emerge from the progressive dominance of habits over goal-directed behaviors. However, it is generally assumed that habits do not persist in choice settings. Therefore, it is unclear how drug habits may persist in real-world scenarios where this factor predominates. Here, we discuss the poor translational validity of the habit construct, which impedes our ability to determine its role in addiction. New evidence of habitual behavior in a drug choice setting are then described and discussed. Interestingly, habitual preference did not promote drug choice but instead favored abstinence. Here, we propose several clues to reconcile these unexpected results with the habit theory of addiction, and we highlight the need in experimental research to face the complexity of drug addicts' decision-making environments by investigating drug habits in the context of choice and in the presence of cues. On a theoretical level, we need to consider more complex frameworks, taking into account continuous interactions between goal-directed and habitual systems, and alternative decision-making models more representative of real-world conditions.
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Affiliation(s)
- Y Vandaele
- Department of Psychiatry, Lausanne University Hospital, Lausanne, Switzerland.
| | - S H Ahmed
- Institut des Maladies Neurodégénératives, Université de Bordeaux, Bordeaux, France
- Institut des Maladies Neurodégénératives, CNRS, Bordeaux, France
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8
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Abstract
For adaptive and efficient decision making, it must be possible to select between habitual alternative courses of action. However, research in rodents suggests that, even in the context of simple decision-making, choice behavior remains goal-directed. In contrast, we recently found that during discrete trial choice between cocaine and water, water-restricted rats preferred water and this preference was habitual and inflexible (i.e., resistant to water devaluation by satiation). Here we sought to test the reproducibility and generality of this surprising finding by assessing habitual control of preference for saccharin over cocaine in non-restricted rats. Specifically, after the acquisition of preference for saccharin, saccharin was devalued and concurrent responding for both options was measured under extinction. As expected, rats responded more for saccharin than for cocaine during extinction, but this difference was unaffected by saccharin devaluation. Together with our previous research, this result indicates that preference for nondrug alternatives over cocaine is under habitual control, even under conditions that normally support goal-directed control of choice between nondrug options. The possible reasons for this difference are discussed.
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Affiliation(s)
- Youna Vandaele
- Department of Psychiatry, Center for Psychiatric Neuroscience, Lausanne University Hospital, Lausanne, Switzerland
| | - Karine Guillem
- Institut des Maladies Neurodégénératives, UMR 5293, Université de Bordeaux, Bordeaux, France
- CNRS, Institut des Maladies Neurodégénératives, UMR 5293, Bordeaux, France
| | - Serge H. Ahmed
- Institut des Maladies Neurodégénératives, UMR 5293, Université de Bordeaux, Bordeaux, France
- CNRS, Institut des Maladies Neurodégénératives, UMR 5293, Bordeaux, France
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Vandaele Y, Mahajan NR, Ottenheimer DJ, Richard JM, Mysore SP, Janak PH. Distinct recruitment of dorsomedial and dorsolateral striatum erodes with extended training. eLife 2019; 8:49536. [PMID: 31621583 PMCID: PMC6822989 DOI: 10.7554/elife.49536] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 10/16/2019] [Indexed: 12/20/2022] Open
Abstract
Hypotheses of striatal orchestration of behavior ascribe distinct functions to striatal subregions, with the dorsolateral striatum (DLS) especially implicated in habitual and skilled performance. Thus neural activity patterns recorded from the DLS, but not the dorsomedial striatum (DMS), should be correlated with habitual and automatized performance. Here, we recorded DMS and DLS neural activity in rats during training in a task promoting habitual lever pressing. Despite improving performance across sessions, clear changes in corresponding neural activity patterns were not evident in DMS or DLS during early training. Although DMS and DLS activity patterns were distinct during early training, their activity was similar following extended training. Finally, performance after extended training was not associated with DMS disengagement, as would be predicted from prior work. These results suggest that behavioral sequences may continue to engage both striatal regions long after initial acquisition, when skilled performance is consolidated.
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Affiliation(s)
- Youna Vandaele
- Department of Psychological and Brain Sciences, Krieger School of Arts and Sciences, Johns Hopkins University, Baltimore, United States
| | - Nagaraj R Mahajan
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, United States
| | - David J Ottenheimer
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins School of Medicine, Johns Hopkins University, Baltimore, United States
| | - Jocelyn M Richard
- Department of Neuroscience, University of Minnesota, Minneapolis, United States
| | - Shreesh P Mysore
- Department of Psychological and Brain Sciences, Krieger School of Arts and Sciences, Johns Hopkins University, Baltimore, United States.,The Solomon H. Snyder Department of Neuroscience, Johns Hopkins School of Medicine, Johns Hopkins University, Baltimore, United States
| | - Patricia H Janak
- Department of Psychological and Brain Sciences, Krieger School of Arts and Sciences, Johns Hopkins University, Baltimore, United States.,The Solomon H. Snyder Department of Neuroscience, Johns Hopkins School of Medicine, Johns Hopkins University, Baltimore, United States.,Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, United States
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10
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Vandaele Y, Noe E, Cador M, Dellu-Hagedorn F, Caille S. Attentional capacities prior to drug exposure predict motivation to self-administer nicotine. Psychopharmacology (Berl) 2018; 235:2041-2050. [PMID: 29704216 DOI: 10.1007/s00213-018-4901-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 04/09/2018] [Indexed: 12/24/2022]
Abstract
RATIONALE Nicotine can enhance attention and attribution of incentive salience to nicotine-associated stimuli. However, it is not clear whether inter-individual differences in attentional capacities prior to any exposure could play a role in vulnerability to nicotine self-administration. We further explored this vulnerability through pre-existing inter-individual differences in attention to a reward-predictive cue in drug-free animals. METHODS A cued version of the Fixed Consecutive Number schedule (FCN16cue) of reinforcement task was used to assess attention. This task consists in completing a long chain of sequential lever presses to obtain a reward, and examines the rats' ability to pay attention to a cue light that signals its availability. Rats were then trained to self-administer nicotine intravenously (30 μg/kg/0.1 mL). Drug-taking and seeking behaviors were investigated. RESULTS Our results showed important inter-individual differences in response for nicotine during the progressive ratio schedule of reinforcement. By comparing rats in the lower and upper quartiles of the mean breaking point, we showed that high-motivated rats were also more sensitive to the reinforcing properties of nicotine than low-motivated ones. We found that while both groups did not differ in premature responding in the FCN16cue task, high-motivated rats were more efficient in taking the cue light into account than low-motivated rats as shown by a higher proportion of optimal chains, indicating a higher level of attention to the reward-predictive cue. Moreover, it was positively correlated with higher motivation for nicotine, a hallmark of nicotine addiction. CONCLUSIONS These results suggest that higher attention to reward-associated cues prior to drug taking predicts vulnerability to nicotine-reinforcing properties.
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Affiliation(s)
- Youna Vandaele
- Université de Bordeaux, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, BP31, F-33076, Bordeaux, France.,Centre National de la Recherche Scientifique, UMR 5287-Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, F-33076, Bordeaux, France
| | - Emilie Noe
- Université de Bordeaux, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, BP31, F-33076, Bordeaux, France.,Centre National de la Recherche Scientifique, UMR 5287-Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, F-33076, Bordeaux, France
| | - Martine Cador
- Université de Bordeaux, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, BP31, F-33076, Bordeaux, France.,Centre National de la Recherche Scientifique, UMR 5287-Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, F-33076, Bordeaux, France
| | - Françoise Dellu-Hagedorn
- Université de Bordeaux, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, BP31, F-33076, Bordeaux, France. .,Centre National de la Recherche Scientifique, UMR 5287-Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, F-33076, Bordeaux, France.
| | - Stephanie Caille
- Université de Bordeaux, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, BP31, F-33076, Bordeaux, France. .,Centre National de la Recherche Scientifique, UMR 5287-Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, F-33076, Bordeaux, France.
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11
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Vandaele Y, Pribut HJ, Janak PH. Lever Insertion as a Salient Stimulus Promoting Insensitivity to Outcome Devaluation. Front Integr Neurosci 2017; 11:23. [PMID: 29021746 PMCID: PMC5623688 DOI: 10.3389/fnint.2017.00023] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 09/12/2017] [Indexed: 12/25/2022] Open
Abstract
Flexible and efficient decision-making in complex environments can be achieved through constant interactions between the goal-directed and habitual systems. While goal-directed behavior is considered dependent upon Response-Outcome (R-O) associations, habits instead rely on Stimulus-Response (S-R) associations. However, the stimuli that support the S-R association underlying habitual responding in typical instrumental procedures are poorly defined. To resolve this issue, we designed a discrete-trials procedure, in which rats must wait for lever insertion and complete a sequence of five lever presses to obtain a reward (20% sucrose or grain-based pellets). Lever insertion thus constituted an audio-visual stimulus signaling the opportunity for reward. Using sensory-specific satiety-induced devaluation, we found that rats trained with grain-based pellets remained sensitive to outcome devaluation over the course of training with this procedure whereas rats trained with a solution of 20% sucrose rapidly developed habit, and that insensitivity to outcome devaluation in rats trained with sucrose did not result from a bias in general satiety. Importantly, although rats trained with pellets were sensitive to satiety-induced devaluation, their performance was not affected by degradation of instrumental contingency and devaluation by conditioned taste aversion (CTA), suggesting that these rats may also have developed habitual responding. To test whether the discrete-trials procedure biases subjects towards habitual responding, we compared discrete-trials to free-running instrumental responding, and found that rats trained with sucrose in a fixed-ratio 5 (FR5) procedure with continuous presentation of the lever were goal-directed. Together, these results demonstrate that discrete presentations of a stimulus predictive of reward availability promoted the formation of S-R habit in rats trained with liquid sucrose. Further research is necessary to explain inconsistencies in sensitivity to outcome devaluation when rats are trained with grain-based pellets.
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Affiliation(s)
- Youna Vandaele
- Department of Psychological and Brain Sciences, Krieger School of Arts and Sciences, Johns Hopkins University, Baltimore, MD, United States
| | - Heather J Pribut
- Department of Psychological and Brain Sciences, Krieger School of Arts and Sciences, Johns Hopkins University, Baltimore, MD, United States
| | - Patricia H Janak
- Department of Psychological and Brain Sciences, Krieger School of Arts and Sciences, Johns Hopkins University, Baltimore, MD, United States.,The Solomon H. Snyder Department of Neuroscience, Johns Hopkins School of Medicine, Johns Hopkins University, Baltimore, MD, United States
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12
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Abstract
PURPOSE OF REVIEW To review research that tests the validity of the analogy between addictive drugs, like cocaine, and hyperpalatable foods, notably those high in added sugar (i.e., sucrose). RECENT FINDINGS Available evidence in humans shows that sugar and sweetness can induce reward and craving that are comparable in magnitude to those induced by addictive drugs. Although this evidence is limited by the inherent difficulty of comparing different types of rewards and psychological experiences in humans, it is nevertheless supported by recent experimental research on sugar and sweet reward in laboratory rats. Overall, this research has revealed that sugar and sweet reward can not only substitute to addictive drugs, like cocaine, but can even be more rewarding and attractive. At the neurobiological level, the neural substrates of sugar and sweet reward appear to be more robust than those of cocaine (i.e., more resistant to functional failures), possibly reflecting past selective evolutionary pressures for seeking and taking foods high in sugar and calories. SUMMARY The biological robustness in the neural substrates of sugar and sweet reward may be sufficient to explain why many people can have difficultly to control the consumption of foods high in sugar when continuously exposed to them.
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