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Alvarez-Sekely CS, Toscano-Zapien AL, Salles-Ize P, Zepeda-Ruiz WA, Lopez-Guzman MA, Velazquez-Martinez DN. Comparison of progressive hold and progressive response schedules of reinforcement. Behav Processes 2023; 205:104822. [PMID: 36669746 DOI: 10.1016/j.beproc.2023.104822] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 01/12/2023] [Accepted: 01/16/2023] [Indexed: 01/19/2023]
Abstract
Progressive ratio (PR) schedules have been widely used to study motivation to work for a reinforcer. After a post-reinforcer pause, subjects engage in pressing a lever until a reinforcer is obtained. However, the discrete nature of lever presses allows alternative behaviors during inter-response time and has led to several behavioral explanations of pauses and work time. A progressive hold-down (PH) is incompatible with alternative responses and may allow a precise estimation of work time. Performance of rats trained in both PR and PH that received sucrose or intracranial self-stimulation (ICSS) as reinforcer were compared. We observed that rats mastered the PR and PH schedules. Post-reinforcer pauses (PSRP), work time and inter-reinforcer time increased as a function of the response or hold requirement. However, rats' performance suggested that the PH progression may be experienced by the rats as easier that the PR progression. Elimination of consummatory behavior with ICSS reduced post-reinforcer pause in accordance with predictions of explanatory models of fixed and variable schedules of reinforcement. In the case of PH performance, pauses showed little variation across intermediate requirements but increased rapidly on later requirements; since rats controlled their pause length and work time was close to the hold requirement, time allocation between PR and PH schedules diverged. Finally, the Mathematical Principles of Reinforcement model of Bradshaw and Killeen (Psychopharmacology 2012, 222: 549) rendered a good description of the performance in both PR and PH schedules.
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Affiliation(s)
- Celeste Sofia Alvarez-Sekely
- Departamento de Ciencias Cognitivas y del Comportamiento, Facultad de Psicología.Universidad Nacional Autonoma de Mexico, Mexico 04510, Mexico
| | - Ana Laura Toscano-Zapien
- Departamento de Ciencias Cognitivas y del Comportamiento, Facultad de Psicología.Universidad Nacional Autonoma de Mexico, Mexico 04510, Mexico
| | - Paloma Salles-Ize
- Departamento de Ciencias Cognitivas y del Comportamiento, Facultad de Psicología.Universidad Nacional Autonoma de Mexico, Mexico 04510, Mexico
| | - Wendy Andrea Zepeda-Ruiz
- Departamento de Ciencias Cognitivas y del Comportamiento, Facultad de Psicología.Universidad Nacional Autonoma de Mexico, Mexico 04510, Mexico
| | - Maria Almudena Lopez-Guzman
- Departamento de Ciencias Cognitivas y del Comportamiento, Facultad de Psicología.Universidad Nacional Autonoma de Mexico, Mexico 04510, Mexico
| | - David N Velazquez-Martinez
- Departamento de Ciencias Cognitivas y del Comportamiento, Facultad de Psicología.Universidad Nacional Autonoma de Mexico, Mexico 04510, Mexico.
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Zepeda-Ruiz WA, Paez HAA, Cerbon M, Velazquez Martinez DN. Exposure to a hypercaloric diet produces long lasting changes in motivation. Behav Processes 2022; 202:104737. [PMID: 36038025 DOI: 10.1016/j.beproc.2022.104737] [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: 05/10/2022] [Revised: 08/20/2022] [Accepted: 08/24/2022] [Indexed: 11/29/2022]
Abstract
Changes in motivation have been observed following induction of diet-induced obesity. However, to date, results have been contradictory, some authors reporting an increase in motivation to obtain palatable food, but others observing a decrease. Observed differences might be associated with the length of both the evaluation period and exposure to the diet. Therefore, the aim of this study was to evaluate changes in motivation during 20 weeks of exposure to a hypercaloric diet. Performance of the subjects in a progressive ratio schedule was evaluated before and during the exposure to a high-fat, high-sugar choice diet (HFHSc). A decrease in motivation was observed after 2 weeks of diet exposure, low levels of motivation remained throughout 20 weeks. A comparable decrease in motivation took longer (3 weeks) to develop using chow diet in the control group. Overall, our results suggest that, when changes in motivation are being evaluated, long periods of diet exposure made no further contribution, once motivation decreased, it remained low up to 18 weeks. Exposure to a HFHSc diet is a useful animal model of obesity, since it replicates some pathophysiological and psychological features of human obesity such as an increase in fasting glucose levels, body weight and the weight of adipose tissue.
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Affiliation(s)
- Wendy Andrea Zepeda-Ruiz
- Departamento de Psicofisiología, Facultad de Psicología; Universidad Nacional Autónoma de México. Ciudad de México, México, 04510
| | - Héctor Alan Abonza Paez
- Departamento de Psicofisiología, Facultad de Psicología; Universidad Nacional Autónoma de México. Ciudad de México, México, 04510
| | - Marco Cerbon
- Unidad de Investigación en Reproducción Humana, Instituto Nacional de Perinatología-Facultad de Química; Universidad Nacional Autónoma de México. Ciudad de México, México, 04510
| | - David N Velazquez Martinez
- Departamento de Psicofisiología, Facultad de Psicología; Universidad Nacional Autónoma de México. Ciudad de México, México, 04510.
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Binge eating behavior and incentive motivation with a cafeteria diet. Behav Processes 2021; 190:104447. [PMID: 34174369 DOI: 10.1016/j.beproc.2021.104447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 05/21/2021] [Accepted: 06/19/2021] [Indexed: 11/21/2022]
Abstract
Binge-like eating behavior (BLE) has been characterized as an eating disorder in which subjects have an enhanced intake of food, mainly fats. However, intake of fats and carbohydrates may have differential effects on motivation. Previously it was shown that BLE produces an increase in operant responding for vegetable shortening, but others were unable to replicate the finding using sucrose as the reinforcer. Our aim was to determine if BLE behavior induced with a cafeteria-like diet (CaLD) with several options with fat content would produce an increment in performance. Male Wistar rats were trained under an exponential progressive ratio schedule of sucrose reinforcement; thereafter, the limited access model was used to induce BLE using CaLD options. Finally, subjects were tested for increments in break points (BPs) in the progressive ratio schedule. Rats with intermittent access to CaLD options showed a clear BLE with an escalation in their intake; however they showed compensatory decrements of chow intake that rendered a similar body weight gain to a continuous access group. Although we were unable to observe an increase in BPs after BLE we were able to observe a protection against the decrements of BP previously observed with sugar. Different mechanisms for processing high fat and high carbohydrate reinforcers are variables worth exploring to gain a better understanding of BLE behavior in rodent models.
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Hitchen B, Norwood K, Gault VA, Leslie JC. Behavioural evaluation of mouse models of type 2 diabetes. LEARNING AND MOTIVATION 2021. [DOI: 10.1016/j.lmot.2021.101730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Killeen PR. Moles and Molecules. J Exp Anal Behav 2021; 115:584-595. [PMID: 33428792 DOI: 10.1002/jeab.667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 11/18/2020] [Accepted: 11/19/2020] [Indexed: 11/06/2022]
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de Paz A, Vidal P, Pellón R. Exercise, diet, and the reinforcing value of food in an animal model of anorexia nervosa. Q J Exp Psychol (Hove) 2018; 72:1692-1703. [PMID: 30282528 DOI: 10.1177/1747021818807865] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Activity-based anorexia (ABA) develops when laboratory rats are subjected to a single meal per day and have access to an activity wheel for the remaining time. Here, we studied the contribution of exercise and diet to the reinforcing value of food during ABA development. Three groups of eight adult male Wistar rats were used: an ABA group with 21.5 hr (then 22 hr) of wheel access and 1 hr (then 30 min) of food access, a control group with the same time exposure to food but without exercise, and a yoked group to the ABA in terms of weight loss. Rats were daily tested on a progressive-ratio schedule to measure their motivation for food. ABA rats gradually reduced their body weight more than the food control group. Animals steadily increased their breaking points in parallel to losses in body weight, but no significant differences were found between groups. Adult rats can develop ABA, but their loss in weight neither resulted in a decrease of food intake nor in the motivation to obtain it.
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Affiliation(s)
- Ana de Paz
- 1 Laboratorios de Conducta Animal, Departamento de Psicología Básica I, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), Madrid, Spain
| | - Pedro Vidal
- 1 Laboratorios de Conducta Animal, Departamento de Psicología Básica I, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), Madrid, Spain
| | - Ricardo Pellón
- 1 Laboratorios de Conducta Animal, Departamento de Psicología Básica I, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), Madrid, Spain
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Valencia-Torres L, Olarte-Sánchez CM, Lyons DJ, Georgescu T, Greenwald-Yarnell M, Myers MG, Bradshaw CM, Heisler LK. Activation of Ventral Tegmental Area 5-HT 2C Receptors Reduces Incentive Motivation. Neuropsychopharmacology 2017; 42:1511-1521. [PMID: 27882999 PMCID: PMC5362069 DOI: 10.1038/npp.2016.264] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 11/01/2016] [Accepted: 11/16/2016] [Indexed: 11/20/2022]
Abstract
Obesity is primarily due to food intake in excess of the body's energetic requirements, intake that is not only associated with hunger but also the incentive value of food. The 5-hydroxytryptamine 2C receptor (5-HT2CR) is a target for the treatment of human obesity. Mechanistically, 5-HT2CRs are positioned to influence both homeostatic feeding circuits within the hypothalamus and reward circuits within the ventral tegmental area (VTA). Here we investigated the role of 5-HT2CRs in incentive motivation using a mathematical model of progressive ratio (PR) responding in mice. We found that the 5-HT2CR agonist lorcaserin significantly reduced both ad libitum chow intake and PR responding for chocolate pellets and increased c-fos expression in VTA 5-HT2CR expressing γ-aminobutyric acid (GABA) neurons, but not 5-HT2CR expressing dopamine (DA) neurons. We next adopted a chemogenetic approach using a 5-HT2CRCRE line to clarify the function of subset of 5-HT2C receptor expressing VTA neurons in the modulation of appetite and food-motivated behavior. Activation of VTA 5-HT2C receptor expressing neurons significantly reduced ad libitum chow intake, operant responding for chocolate pellets, and the incentive value of food. In contrast, chemogenetic inhibition of VTA 5-HT2C receptor expressing neurons had no effect on the feeding behavior. These results indicate that activation of the subpopulation of 5-HT2CR neurons within the VTA is sufficient to significantly reduce homeostatic feeding and effort-based intake of palatable food, and that this subset has an inhibitory role in motivational processes. These findings are relevant to the treatment of obesity.
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Affiliation(s)
- Lourdes Valencia-Torres
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK,Rowett Institute of Nutrition and Health, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK, Tel/Fax: +44 (0) 1224 438750, E-mail: or
| | | | - David J Lyons
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK
| | - Teodora Georgescu
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK
| | - Megan Greenwald-Yarnell
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Martin G Myers
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Christopher M Bradshaw
- Division of Psychiatry, University of Nottingham, Queen's Medical Centre, Nottingham, UK
| | - Lora K Heisler
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK,Rowett Institute of Nutrition and Health, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK, Tel/Fax: +44 (0) 1224 438750, E-mail: or
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Bezzina G, Body S, Cheung THC, Hampson CL, Bradshaw CM, Glennon JC, Szabadi E. Evidence for a role of 5-HT2C receptors in the motor aspects of performance, but not the efficacy of food reinforcers, in a progressive ratio schedule. Psychopharmacology (Berl) 2015; 232:699-711. [PMID: 25134499 DOI: 10.1007/s00213-014-3700-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2014] [Accepted: 07/28/2014] [Indexed: 12/25/2022]
Abstract
RATIONALE 5-Hydroxytryptamine2C (5-HT2C) receptor agonists reduce the breakpoint in progressive ratio schedules of reinforcement, an effect that has been attributed to a decrease of the efficacy of positive reinforcers. However, a reduction of the breakpoint may also reflect motor impairment. Mathematical models can help to differentiate between these processes. OBJECTIVE The effects of the 5-HT2C receptor agonist Ro-600175 ((αS)-6-chloro-5-fluoro-α-methyl-1H-indole-1-ethanamine) and the non-selective 5-HT receptor agonist 1-(m-chlorophenyl)piperazine (mCPP) on rats' performance on a progressive ratio schedule maintained by food pellet reinforcers were assessed using a model derived from Killeen's Behav Brain Sci 17:105-172, 1994 general theory of schedule-controlled behaviour, 'mathematical principles of reinforcement'. METHOD Rats were trained under the progressive ratio schedule, and running and overall response rates in successive ratios were analysed using the model. The effects of the agonists on estimates of the model's parameters, and the sensitivity of these effects to selective antagonists, were examined. RESULTS Ro-600175 and mCPP reduced the breakpoint. Neither agonist significantly affected a (the parameter expressing incentive value), but both agonists increased δ (the parameter expressing minimum response time). The effects of both agonists could be attenuated by the selective 5-HT2C receptor antagonist SB-242084 (6-chloro-5-methyl-N-{6-[(2-methylpyridin-3-yl)oxy]pyridin-3-yl}indoline-1-carboxamide). The effect of mCPP was not altered by isamoltane, a selective 5-HT1B receptor antagonist, or MDL-100907 ((±)2,3-dimethoxyphenyl-1-(2-(4-piperidine)methanol)), a selective 5-HT2A receptor antagonist. CONCLUSIONS The results are consistent with the hypothesis that the effect of the 5-HT2C receptor agonists on progressive ratio schedule performance is mediated by an impairment of motor capacity rather than by a reduction of the incentive value of the food reinforcer.
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Affiliation(s)
- G Bezzina
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, Medical School, Nottingham, NG7 2UH, UK
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Olarte-Sánchez CM, Valencia-Torres L, Cassaday HJ, Bradshaw CM, Szabadi E. Quantitative analysis of performance on a progressive-ratio schedule: effects of reinforcer type, food deprivation and acute treatment with Δ⁹-tetrahydrocannabinol (THC). Behav Processes 2015; 113:122-31. [PMID: 25637881 PMCID: PMC4534516 DOI: 10.1016/j.beproc.2015.01.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 01/26/2015] [Accepted: 01/26/2015] [Indexed: 12/27/2022]
Abstract
Rats' performance on a progressive-ratio schedule maintained by sucrose (0.6M, 50 μl) and corn oil (100%, 25 μl) reinforcers was assessed using a model derived from Killeen's (1994) theory of schedule-controlled behaviour, 'Mathematical Principles of Reinforcement'. When the rats were maintained at 80% of their free-feeding body weights, the parameter expressing incentive value, a, was greater for the corn oil than for the sucrose reinforcer; the response-time parameter, δ, did not differ between the reinforcer types, but a parameter derived from the linear waiting principle (T0), indicated that the minimum post-reinforcement pause was longer for corn oil than for sucrose. When the rats were maintained under free-feeding conditions, a was reduced, indicating a reduction of incentive value, but δ was unaltered. Under the food-deprived condition, the CB1 cannabinoid receptor agonist Δ(9)-tetrahydrocannabinol (THC: 0.3, 1 and 3 mg kg(-1)) increased the value of a for sucrose but not for corn oil, suggesting a selective enhancement of the incentive value of sucrose; none of the other parameters was affected by THC. The results provide new information about the sensitivity of the model's parameters to deprivation and reinforcer quality, and suggest that THC selectively enhances the incentive value of sucrose.
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Affiliation(s)
- C M Olarte-Sánchez
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, UK.
| | - L Valencia-Torres
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, UK.
| | - H J Cassaday
- School of Psychology, University of Nottingham, UK.
| | - C M Bradshaw
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, UK.
| | - E Szabadi
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, UK.
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