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Lonstein JS, Vitale EM, Olekanma D, McLocklin A, Pence N, Bredewold R, Veenema AH, Johnson AW, Burt SA. Anxiety, aggression, reward sensitivity, and forebrain dopamine receptor expression in a laboratory rat model of early-life disadvantage. Dev Psychobiol 2023; 65:e22421. [PMID: 37860907 DOI: 10.1002/dev.22421] [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: 04/07/2023] [Revised: 07/24/2023] [Accepted: 08/17/2023] [Indexed: 10/21/2023]
Abstract
Despite early-life disadvantage (ELD) in humans being a highly heterogenous construct, it consistently predicts negative neurobehavioral outcomes. The numerous environmental contributors and neural mechanisms underlying ELD remain unclear, though. We used a laboratory rat model to evaluate the effects of limited resources and/or heavy metal exposure on mothers and their adult male and female offspring. Dams and litters were chronically exposed to restricted (1-cm deep) or ample (4-cm deep) home cage bedding postpartum, with or without lead acetate (0.1%) in their drinking water from insemination through 1-week postweaning. Restricted-bedding mothers showed more pup-directed behaviors and behavioral fragmentation, while lead-exposed mothers showed more nestbuilding. Restricted bedding-raised male offspring showed higher anxiety and aggression. Either restricted bedding or lead exposure impaired goal-directed performance in a reinforcer devaluation task in females, whereas restricted bedding alone disrupted it in males. Lead exposure, but not limited bedding, also reduced sucrose reward sensitivity in a progressive ratio task in females. D1 and D2 receptor mRNA in the medial prefrontal cortex and nucleus accumbens (NAc) were each affected by the early-life treatments and differently between the sexes. Most notably, adult males (but not females) exposed to both early-life treatments had greatly increased D1 receptor mRNA in the NAc core. These results illuminate neural mechanisms through which ELD threatens neurobehavioral development and highlight forebrain dopamine as a factor.
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Affiliation(s)
- Joseph S Lonstein
- Department of Psychology, Michigan State University, East Lansing, Michigan, USA
| | - Erika M Vitale
- Department of Psychology, Michigan State University, East Lansing, Michigan, USA
| | - Doris Olekanma
- Department of Psychology, Michigan State University, East Lansing, Michigan, USA
| | - Andrew McLocklin
- Department of Psychology, Michigan State University, East Lansing, Michigan, USA
| | - Nathan Pence
- Department of Psychology, Michigan State University, East Lansing, Michigan, USA
| | - Remco Bredewold
- Department of Psychology, Michigan State University, East Lansing, Michigan, USA
| | - Alexa H Veenema
- Department of Psychology, Michigan State University, East Lansing, Michigan, USA
| | - Alexander W Johnson
- Department of Psychology, Michigan State University, East Lansing, Michigan, USA
| | - S Alexandra Burt
- Department of Psychology, Michigan State University, East Lansing, Michigan, USA
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2
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Varma MM, Zhen S, Yu R. Not all discounts are created equal: Regional activity and brain networks in temporal and effort discounting. Neuroimage 2023; 280:120363. [PMID: 37673412 DOI: 10.1016/j.neuroimage.2023.120363] [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: 04/14/2023] [Revised: 08/31/2023] [Accepted: 09/03/2023] [Indexed: 09/08/2023] Open
Abstract
Reward outcomes associated with costs like time delay and effort investment are generally discounted in decision-making. Standard economic models predict rewards associated with different types of costs are devalued in a similar manner. However, our review of rodent lesion studies indicated partial dissociations between brain regions supporting temporal- and effort-based decision-making. Another debate is whether options involving low and high costs are processed in different brain substrates (dual-system) or in the same regions (single-system). This research addressed these issues using coordinate-based, connectivity-based, and activation network-based meta-analyses to identify overlapping and separable neural systems supporting temporal (39 studies) and effort (20 studies) discounting. Coordinate-based activation likelihood estimation and resting-state connectivity analyses showed immediate-small reward and delayed-large reward choices engaged distinct regions with unique connectivity profiles, but their activation network mapping was found to engage the default mode network. For effort discounting, salience and sensorimotor networks supported low-effort choices, while the frontoparietal network supported high-effort choices. There was little overlap between the temporal and effort networks. Our findings underscore the importance of differentiating different types of costs in decision-making and understanding discounting at both regional and network levels.
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Affiliation(s)
- Mohith M Varma
- Department of Management, Marketing, and Information Systems, Hong Kong Baptist University, Hong Kong, China
| | - Shanshan Zhen
- Department of Social and Behavioural Sciences, City University of Hong Kong, Hong Kong, China.
| | - Rongjun Yu
- Department of Management, Marketing, and Information Systems, Hong Kong Baptist University, Hong Kong, China.
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3
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Batra A, Cuesta S, Alves MB, Restrepo JM, Giroux M, Laureano DP, Mucellini Lovato AB, Miguel PM, Machado TD, Molle RD, Flores C, Silveira PP. Relationship between insulin and Netrin-1/DCC guidance cue pathway regulation in the prefrontal cortex of rodents exposed to prenatal dietary restriction. J Dev Orig Health Dis 2023; 14:501-507. [PMID: 37431265 PMCID: PMC10988268 DOI: 10.1017/s204017442300017x] [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] [Indexed: 07/12/2023]
Abstract
Fetal restriction (FR) alters insulin sensitivity, but it is unknown how the metabolic profile associated with restriction affects development of the dopamine (DA) system and DA-related behaviors. The Netrin-1/DCC guidance cue system participates in maturation of the mesocorticolimbic DA circuitry. Therefore, our objective was to identify if FR modifies Netrin-1/DCC receptor protein expression in the prefrontal cortex (PFC) at birth and mRNA in adulthood in rodent males. We used cultured HEK293 cells to assess if levels of miR-218, microRNA regulator of DCC, are sensitive to insulin. To assess this, pregnant dams were subjected to a 50% FR diet from gestational day 10 until birth. Medial PFC (mPFC) DCC/Netrin-1 protein expression was measured at P0 at baseline and Dcc/Netrin-1 mRNA levels were quantified in adults 15 min after a saline/insulin injection. miR-218 levels in HEK-293 cells were measured in response to insulin exposure. At P0, Netrin-1 levels are downregulated in FR animals in comparison to controls. In adult rodents, insulin administration results in an increase in Dcc mRNA levels in control but not FR rats. In HEK293 cells, there is a positive correlation between insulin concentration and miR-218 levels. Since miR-218 is a Dcc gene expression regulator and our in vitro results show that insulin regulates miR-218 levels, we suggest that FR-induced changes in insulin sensitivity could be affecting Dcc expression via miR-218, impacting DA system maturation and organization. As fetal adversity is linked to nonadaptive behaviors later in life, this may contribute to early identification of vulnerability to chronic diseases associated with fetal adversity.
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Affiliation(s)
- Aashita Batra
- Integrated Program in Neuroscience, McGill University, Montreal, QC, Canada
- Ludmer Centre for Neuroinformatics and Mental Health, McGill University, Montreal, QC, Canada
- Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada
| | - Santiago Cuesta
- Department of Cell Biology and Neuroscience, Rutgers University, New Brunswick, NJ, USA
- Department of Psychiatry, McGill University, Montreal, QC, Canada
| | - Marcio Bonesso Alves
- Ludmer Centre for Neuroinformatics and Mental Health, McGill University, Montreal, QC, Canada
- Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada
- Department of Psychiatry, McGill University, Montreal, QC, Canada
| | - Jose Maria Restrepo
- Integrated Program in Neuroscience, McGill University, Montreal, QC, Canada
- Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada
| | - Michel Giroux
- Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada
| | - Daniela Pereira Laureano
- Programa de Pós-Graduação em Saúde da Criança e do Adolescente, Faculdade de Medicina, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
- Programa de Pós-Graduação em Neurociências, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Amanda Brondani Mucellini Lovato
- Programa de Pós-Graduação em Psiquiatria e Ciências do Comportamento, Faculdade de Medicina, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Patrícia Maidana Miguel
- Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada
- Department of Psychiatry, McGill University, Montreal, QC, Canada
| | - Tania Diniz Machado
- Programa de Pós-Graduação em Saúde da Criança e do Adolescente, Faculdade de Medicina, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Roberta Dalle Molle
- Ludmer Centre for Neuroinformatics and Mental Health, McGill University, Montreal, QC, Canada
- Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada
| | - Cecilia Flores
- Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada
- Department of Psychiatry, McGill University, Montreal, QC, Canada
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
| | - Patricia Pelufo Silveira
- Ludmer Centre for Neuroinformatics and Mental Health, McGill University, Montreal, QC, Canada
- Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada
- Department of Psychiatry, McGill University, Montreal, QC, Canada
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White SM, Morningstar MD, De Falco E, Linsenbardt DN, Ma B, Parks MA, Czachowski CL, Lapish CC. Flexible coding schemes in dorsomedial prefrontal cortex underlie decision-making during delay discounting. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.15.545101. [PMID: 37398190 PMCID: PMC10312702 DOI: 10.1101/2023.06.15.545101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Determining how an agent decides between a small, immediate versus a larger, delayed reward has provided insight into the psychological and neural basis of decision-making. The tendency to excessively discount the value of delayed rewards is thought to reflect deficits in brain regions critical for impulse control such as the prefrontal cortex (PFC). This study tested the hypothesis that dorsomedial PFC (dmPFC) is critically involved in flexibly managing neural representations of strategies that limit impulsive choices. Optogenetic silencing of neurons in the rat dmPFC increased impulsive choices at an 8 sec, but not 4 sec, delay. Neural recordings from dmPFC ensembles revealed that, at the 8-sec delay, the encoding landscape transitions to reflect a deliberative-like process rather than the schema-like processes observed at the 4-sec delay. These findings show that changes in the encoding landscape reflect changes in task demands and that dmPFC is uniquely involved in decisions requiring deliberation.
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Bellés L, Arrondeau C, Urueña-Méndez G, Ginovart N. Concurrent measures of impulsive action and choice are partially related and differentially modulated by dopamine D 1- and D 2-like receptors in a rat model of impulsivity. Pharmacol Biochem Behav 2023; 222:173508. [PMID: 36473517 DOI: 10.1016/j.pbb.2022.173508] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 11/29/2022] [Accepted: 11/30/2022] [Indexed: 12/12/2022]
Abstract
Impulsivity is a multidimensional construct, but the relationships between its constructs and their respective underlying dopaminergic underpinnings in the general population remain unclear. A cohort of Roman high- (RHA) and low- (RLA) avoidance rats were tested for impulsive action and risky decision-making in the rat gambling task, and then for delay discounting in the delay-discounting task to concurrently measure the relationships among the three constructs of impulsivity using a within-subject design. Then, we evaluated the effects of dopaminergic drugs on the three constructs of impulsivity, considering innate differences in impulsive behaviors at baseline. Risky decision-making and delay-discounting were positively correlated, indicating that both constructs of impulsive choice are related. Impulsive action positively correlated with risky decision-making but not with delay discounting, suggesting partial overlap between impulsive action and impulsive choice. RHAs showed a more impulsive phenotype in the three constructs of impulsivity compared to RLAs, demonstrating the comorbid nature of impulsivity in a population of rats. Amphetamine increased impulsive action and had no effect on risky decision-making regardless of baseline levels of impulsivity, but it decreased delay discounting only in high impulsive RHAs. In contrast, while D1R and D3R agonism as well as D2/3R partial agonism decreased impulsive action regardless of baseline levels of impulsivity, D2/3R agonism decreased impulsive action exclusively in high impulsive RHAs. Irrespective of baseline levels of impulsivity, risky decision-making was increased by D1R and D2/3R agonism but not by D3R agonism or D2/3R partial agonism. Finally, while D1R and D3R agonism, D2/3R partial agonism and D2R blockade increased delay discounting irrespective of baseline levels of impulsivity, D2/3R agonism decreased it in low impulsive RLAs only. These findings indicate that the acute effects of dopamine drugs were partially overlapping across dimensions of impulsivity, and that only D2/3R agonism showed baseline-dependent effects on impulsive action and impulsive choice.
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Affiliation(s)
- Lidia Bellés
- Department of Psychiatry, Faculty of Medicine, University of Geneva, Rue Michel Servet 1, CH-1211 Geneva, Switzerland; Department of Basic Neurosciences, Faculty of Medicine, University of Geneva, Rue Michel Servet 1, CH-1211 Geneva, Switzerland.
| | - Chloé Arrondeau
- Department of Psychiatry, Faculty of Medicine, University of Geneva, Rue Michel Servet 1, CH-1211 Geneva, Switzerland; Department of Basic Neurosciences, Faculty of Medicine, University of Geneva, Rue Michel Servet 1, CH-1211 Geneva, Switzerland.
| | - Ginna Urueña-Méndez
- Department of Psychiatry, Faculty of Medicine, University of Geneva, Rue Michel Servet 1, CH-1211 Geneva, Switzerland; Department of Basic Neurosciences, Faculty of Medicine, University of Geneva, Rue Michel Servet 1, CH-1211 Geneva, Switzerland.
| | - Nathalie Ginovart
- Department of Psychiatry, Faculty of Medicine, University of Geneva, Rue Michel Servet 1, CH-1211 Geneva, Switzerland; Department of Basic Neurosciences, Faculty of Medicine, University of Geneva, Rue Michel Servet 1, CH-1211 Geneva, Switzerland.
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6
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Obray JD, Landin JD, Vaughan DT, Scofield MD, Chandler LJ. Adolescent alcohol exposure reduces dopamine 1 receptor modulation of prelimbic neurons projecting to the nucleus accumbens and basolateral amygdala. ADDICTION NEUROSCIENCE 2022; 4:100044. [PMID: 36643604 PMCID: PMC9836047 DOI: 10.1016/j.addicn.2022.100044] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Binge drinking during adolescence is highly prevalent despite increasing evidence of its long-term impact on behaviors associated with modulation of behavioral flexibility by the medial prefrontal cortex (mPFC). In the present study, male and female rats underwent adolescent intermittent ethanol (AIE) exposure by vapor inhalation. After aging to adulthood, retrograde bead labelling and viral tagging were used to identify populations of neurons in the prelimbic region (PrL) of the mPFC that project to specific subcortical targets. Electrophysiological recording from bead-labelled neurons in PrL slices revealed that AIE did not alter the intrinsic excitability of PrL neurons that projected to either the NAc or the BLA. Similarly, recordings of spontaneous inhibitory and excitatory post-synaptic currents revealed no AIE-induced changes in synaptic drive onto either population of projection neurons. In contrast, AIE exposure was associated with a loss of dopamine receptor 1 (D1), but no change in dopamine receptor 2 (D2), modulation of evoked firing of both populations of projection neurons. Lastly, confocal imaging of proximal and apical dendritic tufts of viral-labelled PrL neurons that projected to the nucleus accumbens (NAc) revealed AIE did not alter the density of dendritic spines. Together, these observations provide evidence that AIE exposure results in disruption of D1 receptor modulation of PrL inputs to at least two major subcortical target regions that have been implicated in AIE-induced long-term changes in behavioral control.
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Affiliation(s)
- J. Daniel Obray
- Department of Neuroscience, Medical University of South Carolina, 30 Courtenay Drive, Charleston SC 29425, USA
| | - Justine D. Landin
- Department of Neuroscience, Medical University of South Carolina, 30 Courtenay Drive, Charleston SC 29425, USA
| | - Dylan T. Vaughan
- Department of Neuroscience, Medical University of South Carolina, 30 Courtenay Drive, Charleston SC 29425, USA
| | - Michael D. Scofield
- Department of Neuroscience, Medical University of South Carolina, 30 Courtenay Drive, Charleston SC 29425, USA,Department of Anesthesiology, Medical University of South Carolina, Charleston SC, USA
| | - L. Judson Chandler
- Department of Neuroscience, Medical University of South Carolina, 30 Courtenay Drive, Charleston SC 29425, USA,Corresponding author. (L.J. Chandler)
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7
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Abstract
Deciding whether to forgo a good choice in favour of exploring a potentially more rewarding alternative is one of the most challenging arbitrations both in human reasoning and in artificial intelligence. Humans show substantial variability in their exploration, and theoretical (but only limited empirical) work has suggested that excessive exploration is a critical mechanism underlying the psychiatric dimension of impulsivity. In this registered report, we put these theories to test using large online samples, dimensional analyses, and computational modelling. Capitalising on recent advances in disentangling distinct human exploration strategies, we not only demonstrate that impulsivity is associated with a specific form of exploration—value-free random exploration—but also explore links between exploration and other psychiatric dimensions. The Stage 1 protocol for this Registered Report was accepted in principle on 19/03/2021. The protocol, as accepted by the journal, can be found at 10.6084/m9.figshare.14346506.v1. Deciding between known rewarding options and exploring novel avenues is central to decision making. Humans show variability in their exploration. Here, the authors show that impulsivity is associated to an increased usage of a cognitively cheap (and sometimes sub-optimal) exploration strategy.
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8
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Antunes DF, Soares MC, Taborsky M. Dopamine modulates social behaviour in cooperatively breeding fish. Mol Cell Endocrinol 2022; 550:111649. [PMID: 35436519 DOI: 10.1016/j.mce.2022.111649] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Revised: 03/24/2022] [Accepted: 04/11/2022] [Indexed: 10/18/2022]
Abstract
Dopamine is part of the reward system triggering the social decision-making network in the brain. It has hence great potential importance in the regulation of social behaviour, but its significance in the control of behaviour in highly social animals is currently limited. We studied the role of the dopaminergic system in social decision-making in the cooperatively breeding cichlid fish, Neolamprologus pulcher, by blocking or stimulating the dopaminergic D1-like and D2-like receptors. We first tested the effects of different dosages and timing of administration on subordinate group members' social behaviour within the group in an unchallenging environment. In a second experiment we pharmacologically manipulated D1-like and D2-like receptors while experimentally challenging N. pulcher groups by presenting an egg predator, and by increasing the need for territory maintenance through digging out sand from the shelter. Our results show that the D1-like and D2-like receptor pathways are differently involved in the modulation of aggressive, submissive and affiliative behaviours. Interestingly, the environmental context seems particularly crucial regarding the role of the D2-like receptors in behavioural regulation of social encounters among group members, indicating a potential pathway in agonistic and cooperative interactions in a pay-to-stay scenario. We discuss the importance of environmental information in mediating the role of dopamine for the modulation of social behaviour.
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Affiliation(s)
- Diogo F Antunes
- Behavioural Ecology, Institute of Ecology and Evolution, University of Bern, CH-3032, Hinterkappelen, Switzerland; Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016, Lisboa, Portugal.
| | - Marta C Soares
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Campus de Vairão, Universidade do Porto, 4485-661, Vairão, Portugal; BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Campus de Vairão, 4485-661, Vairão, Portugal
| | - Michael Taborsky
- Behavioural Ecology, Institute of Ecology and Evolution, University of Bern, CH-3032, Hinterkappelen, Switzerland
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9
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Sanchez EO, Bangasser DA. The effects of early life stress on impulsivity. Neurosci Biobehav Rev 2022; 137:104638. [PMID: 35341796 DOI: 10.1016/j.neubiorev.2022.104638] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 01/19/2022] [Accepted: 03/21/2022] [Indexed: 01/08/2023]
Abstract
Elevated impulsivity is a symptom shared by various psychiatric disorders such as substance use disorder, bipolar disorder, and attention-deficit/hyperactivity disorder. However, impulsivity is not a unitary construct and impulsive behaviors fall into two subcategories: impulsive action and impulsive choice. Impulsive choice refers to the tendency to prefer immediate, small rewards over delayed, large rewards, whereas impulsive action involves difficulty inhibiting rash, premature, or mistimed behaviors. These behaviors are mediated by the mesocorticolimbic dopamine (DA) system, which consists of projections from the ventral tegmental area to the nucleus accumbens and prefrontal cortex. Early life stress (ELS) alters both impulsive choice and impulsive action in rodents. ELS also changes DA receptor expression, transmission, and activity within the mesocorticolimbic system. This review integrates the dopamine, impulsivity, and ELS literature to provide evidence that ELS alters impulsivity via inducing changes in the mesocorticolimbic DA system. Understanding how ELS affects brain circuits associated with impulsivity can help advance treatments aimed towards reducing impulsivity symptoms in a variety of psychiatric disorders.
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Affiliation(s)
- Evelyn Ordoñes Sanchez
- Department of Psychology and Neuroscience Program, Temple University, Philadelphia, PA 19122, USA.
| | - Debra A Bangasser
- Department of Psychology and Neuroscience Program, Temple University, Philadelphia, PA 19122, USA.
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10
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Jones JA, Zuhlsdorff K, Dalley JW. Neurochemical substrates linked to impulsive and compulsive phenotypes in addiction: A preclinical perspective. J Neurochem 2021; 157:1525-1546. [PMID: 33931861 DOI: 10.1111/jnc.15380] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 04/24/2021] [Accepted: 04/25/2021] [Indexed: 01/18/2023]
Abstract
Drug compulsion manifests in some but not all individuals and implicates multifaceted processes including failures in top-down cognitive control as drivers for the hazardous pursuit of drug use in some individuals. As a closely related construct, impulsivity encompasses rash or risky behaviour without foresight and underlies most forms of drug taking behaviour, including drug use during adverse emotional states (i.e., negative urgency). While impulsive behavioural dimensions emerge from drug-induced brain plasticity, burgeoning evidence suggests that impulsivity also predates the emergence of compulsive drug use. Although the neural substrates underlying the apparently causal relationship between trait impulsivity and drug compulsion are poorly understood, significant advances have come from the interrogation of defined limbic cortico-striatal circuits involved in motivated behaviour and response inhibition, together with chemical neuromodulatory influences from the ascending neurotransmitter systems. We review what is presently known about the neurochemical mediation of impulsivity, in its various forms, and ask whether commonalities exist in the neurochemistry of compulsive drug-motivated behaviours that might explain individual risk for addiction.
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Affiliation(s)
- Jolyon A Jones
- Department of Psychology, University of Cambridge, Cambridge, UK
| | | | - Jeffrey W Dalley
- Department of Psychology, University of Cambridge, Cambridge, UK.,Department of Psychiatry, Hershel Smith Building for Brain and Mind Sciences, Cambridge, UK
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11
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Huggett SB, Stallings MC. Genetic Architecture and Molecular Neuropathology of Human Cocaine Addiction. J Neurosci 2020; 40:5300-5313. [PMID: 32457073 PMCID: PMC7329314 DOI: 10.1523/jneurosci.2879-19.2020] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 05/04/2020] [Accepted: 05/10/2020] [Indexed: 01/12/2023] Open
Abstract
We integrated genomic and bioinformatic analyses, using data from the largest genome-wide association study of cocaine dependence (CD; n = 6546; 82.37% with CD; 57.39% male) and the largest postmortem gene-expression sample of individuals with cocaine use disorder (CUD; n = 36; 51.35% with CUD; 100% male). Our genome-wide analyses identified one novel gene (NDUFB9) associated with the genetic predisposition to CD in African-Americans. The genetic architecture of CD was similar across ancestries. Individual genes associated with CD demonstrated modest overlap across European-Americans and African-Americans, but the genetic liability for CD converged on many similar tissue types (brain, heart, blood, liver) across ancestries. In a separate sample, we investigated the neuronal gene expression associated with CUD by using RNA sequencing of dorsal-lateral prefrontal cortex neurons. We identified 133 genes differentially expressed between CUD case patients and cocaine-free control subjects, including previously implicated candidates for cocaine use/addiction (FOSB, ARC, KCNJ9/GIRK3, NR4A2, JUNB, and MECP2). Differential expression analyses significantly correlated across European-Americans and African-Americans. While genes significantly associated with CD via genome-wide methods were not differentially expressed, two of these genes (NDUFB9 and C1qL2) were part of a robust gene coexpression network associated with CUD involved in neurotransmission (GABA, acetylcholine, serotonin, and dopamine) and drug addiction. We then used a "guilt-by-association" approach to unravel the biological relevance of NDUFB9 and C1qL2 in the context of CD. In sum, our study furthers the understanding of the genetic architecture and molecular neuropathology of human cocaine addiction and provides a framework for translating biological meaning into otherwise obscure genome-wide associations.SIGNIFICANCE STATEMENT Our study further clarifies the genetic and neurobiological contributions to cocaine addiction, provides a rapid approach for generating testable hypotheses for specific candidates identified by genome-wide research, and investigates the cross-ancestral biological contributions to cocaine use disorder/dependence for individuals of European-American and African-American ancestries.
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Affiliation(s)
- Spencer B Huggett
- Department of Psychology and Neuroscience, University of Colorado, Boulder, Colorado 80309-0345
- Institute for Behavioral Genetics, University of Colorado, Boulder, Colorado 80309-0447
| | - Michael C Stallings
- Department of Psychology and Neuroscience, University of Colorado, Boulder, Colorado 80309-0345
- Institute for Behavioral Genetics, University of Colorado, Boulder, Colorado 80309-0447
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12
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Dopaminergic D 1 Receptor Stimulation Affects Effort and Risk Preferences. Biol Psychiatry 2020; 87:678-685. [PMID: 31668477 DOI: 10.1016/j.biopsych.2019.09.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 09/02/2019] [Accepted: 09/03/2019] [Indexed: 12/17/2022]
Abstract
BACKGROUND Activation of D1 receptors has been related to successful goal-directed behavior, but it remains unclear whether D1 receptor activation causally tips the balance of weighing costs and benefits in humans. Here, we tested the impact of pharmacologically stimulated D1 receptors on sensitivity to risk, delay, and effort costs in economic choice and investigated whether D1 receptor stimulation would bias preferences toward options with increased costs in a cost-specific manner. METHODS In a randomized, double-blind, placebo-controlled, parallel-group phase 1 study, 120 healthy young volunteers received either placebo or 1 of 3 doses (6 mg, 15 mg, or 30 mg) of a novel, selective D1 agonist (PF-06412562). After drug administration, participants performed decision tasks measuring their preferences for risky, delayed, and effortful outcomes. RESULTS Higher doses of the D1 agonist increased the willingness to exert physical effort for reward as well as reduced the preference for risky outcomes. We observed no effects on preferences for delayed rewards. CONCLUSIONS The current results provide evidence that D1 receptor stimulation causally affects core aspects of cost-benefit decision making in humans.
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13
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Groman SM. The Neurobiology of Impulsive Decision-Making and Reinforcement Learning in Nonhuman Animals. Curr Top Behav Neurosci 2020; 47:23-52. [PMID: 32157666 DOI: 10.1007/7854_2020_127] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Impulsive decisions are those that favor immediate over delayed rewards, involve the acceptance of undue risk or uncertainty, or fail to adapt to environmental changes. Pathological levels of impulsive decision-making have been observed in individuals with mental illness, but there may be substantial heterogeneity in the processes that drive impulsive choices. Understanding this behavioral heterogeneity may be critical for understanding associated diverseness in the neural mechanisms that give rise to impulsivity. The application of reinforcement learning algorithms in the deconstruction of impulsive decision-making phenotypes can help bridge the gap between biology and behavior and provide insights into the biobehavioral heterogeneity of impulsive choice. This chapter will review the literature on the neurobiological mechanisms of impulsive decision-making in nonhuman animals; specifically, the role of the amine neuromodulatory systems (dopamine, serotonin, norepinephrine, and acetylcholine) in impulsive decision-making and reinforcement learning processes is discussed. Ultimately, the integration of reinforcement learning algorithms with sophisticated behavioral and neuroscience techniques may be critical for advancing the understanding of the neurochemical basis of impulsive decision-making.
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Abstract
Neuropharmacological interventions in preclinical translational models of impulsivity have tremendously contributed to a better understanding of the neurochemistry and neural basis of impulsive behaviour. In this regard, much progress has been made over the last years, also due to the introduction of novel techniques in behavioural neuroscience such as optogenetics and chemogenetics. In this chapter, we will provide an update of how the behavioural pharmacology field has progressed and built upon existing data since an earlier review we wrote in 2008. To this aim, we will first give a brief background on preclinical translational models of impulsivity. Next, recent interesting evidence of monoaminergic modulation of impulsivity will be highlighted with a focus on the neurotransmitters dopamine and noradrenaline. Finally, we will close the chapter by discussing some novel directions and drug leads in the neuropharmacological modulation of impulsivity.
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Affiliation(s)
- Tommy Pattij
- Department of Anatomy and Neurosciences, Amsterdam Neuroscience, Amsterdam University Medical Centers, VU University Medical Center, Amsterdam, The Netherlands.
| | - Louk J M J Vanderschuren
- Division of Behavioural Neuroscience, Department of Animals in Science and Society, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
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15
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Meda S, Freund N, Norman KJ, Thompson BS, Sonntag KC, Andersen SL. The use of laser capture microdissection to identify specific pathways and mechanisms involved in impulsive choice in rats. Heliyon 2019; 5:e02254. [PMID: 31485508 PMCID: PMC6716106 DOI: 10.1016/j.heliyon.2019.e02254] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 03/29/2019] [Accepted: 08/05/2019] [Indexed: 01/08/2023] Open
Abstract
Background Microinjections, lesions, viral-mediated gene transfer, or designer receptors exclusively activated by designer drugs (DREADDs) can identify brain signaling pathways and their pharmacology in research animals. Genetically modified animals are used for more precise assessment of neural circuits. However, only a few of the gene-based pathway modifications are available for use in outbred rat strains. New method Behaviorally characterized Sprague-Dawley rats undergo tract tracing through microinjection of fluorospheres, followed by laser capture microdissection (LCM) and qPCR for detecting mRNA of pathway-associated gene products. Correlations between mRNA expression and behavior identify specific involvement of pharmacologically relevant molecules within cells of interest. Here, we examined this methodology in an impulsive choice paradigm and targeted projections from the orbital and medial prefrontal cortex. Results In this proof of concept study, we demonstrate relationships between measures of impulsive choice with distinct neurotransmitter receptor expression in cell populations from four different signaling pathways. Comparisons with existing methods Combining behavior, tract tracing, LCM, and gene expression profiling provides more cellular selectivity than localized lesions and DREADDs, and greater pharmacological specificity than microinjections and viral-mediated gene transfer due to targeting identified neurons. Furthermore, the assessment of inter-individual pathways provides insight into the complex nature of underlying mechanisms involved in typical and atypical behavior. Conclusions The novel combination of behavior, tract tracing, LCM, and single gene or potential whole genome transcriptome analysis allows for a more targeted understanding of the interconnection of neural circuitry with behavior, and holds promise to identify more specific drug targets that are relevant to behavioral phenotypes.
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Affiliation(s)
- Shirisha Meda
- Laboratory of Developmental Neuropharmacology, McLean Hospital, Harvard Medical School, USA
| | - Nadja Freund
- Laboratory of Developmental Neuropharmacology, McLean Hospital, Harvard Medical School, USA.,Experimental and Molecular Psychiatry, Ruhr-University, Germany
| | - Kevin J Norman
- Laboratory of Developmental Neuropharmacology, McLean Hospital, Harvard Medical School, USA
| | - Britta S Thompson
- Laboratory of Developmental Neuropharmacology, McLean Hospital, Harvard Medical School, USA
| | - Kai-C Sonntag
- Laboratory for Translational Research on Neurodegeneration, Program for Neuropsychiatric Research, McLean Hospital, Harvard Medical School, USA.,Basic Neuroscience Division, McLean Hospital, Harvard Medical School, USA.,Department of Psychiatry, McLean Hospital, Harvard Medical School, USA
| | - Susan L Andersen
- Laboratory of Developmental Neuropharmacology, McLean Hospital, Harvard Medical School, USA.,Basic Neuroscience Division, McLean Hospital, Harvard Medical School, USA.,Department of Psychiatry, McLean Hospital, Harvard Medical School, USA
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Alves MB, Laureano DP, Dalle Molle R, Machado TD, Salvador APDA, Miguel PM, Lupinsky D, Dalmaz C, Silveira PP. Intrauterine growth restriction increases impulsive behavior and is associated with altered dopamine transmission in both medial prefrontal and orbitofrontal cortex in female rats. Physiol Behav 2019; 204:336-346. [PMID: 30880239 DOI: 10.1016/j.physbeh.2019.03.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 02/20/2019] [Accepted: 03/11/2019] [Indexed: 12/25/2022]
Abstract
Recent studies have implicated a role for impulsivity in the altered eating behaviors and the increased risk for obesity consistently associated with intrauterine growth restriction (IUGR). Changes in dopamine transmission within prefrontal areas are believed to contribute to these adverse outcomes. Here we investigated the impulsive behavior toward a delayed reward and evaluated dopamine levels and its receptors in the medial prefrontal (mPFC) and orbitofrontal (OFC) cortex of female adult rats exposed to IUGR. From day 10 of pregnancy and until birth, Sprague-Dawley dams received either an ad libitum (Adlib) or a 50% food-restricted (FR) diet. At birth, all pups were adopted by Adlib mothers, generating the groups Adlib/Adlib (control) and FR/Adlib (intrauterine growth-restricted). Adult impulsive behavior was evaluated using a Tolerance to Delay of Reward Task. In vivo dopamine responses to sweet food intake were measured by voltammetry, and D1, D2 and DAT levels were accessed by Western Blot. Animals from FR group showed a pronounced aversion to delayed rewards. DA response to sweet food was found to be blunted in the mPFC of FR animals, whereas in the OFC, the DA levels appear to be unaffected by reward consumption. Moreover, FR animals presented reduced D1 receptors in the OFC and a later increase in the mPFC D2 levels. These findings suggest that IUGR female rats are more impulsive and that the associated mechanism involves changes in the dopamine signaling in both the mPFC and OFC.
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Affiliation(s)
- Márcio Bonesso Alves
- Programa de Pós Graduação em Bioquímica, Departamento de Bioquímica, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
| | - Daniela Pereira Laureano
- Programa de Pós Graduação em Neurociências, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Roberta Dalle Molle
- Programa de Pós Graduação em Saúde da Criança e do Adolescente, Faculdade de Medicina, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Tania Diniz Machado
- Programa de Pós Graduação em Saúde da Criança e do Adolescente, Faculdade de Medicina, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | | | - Patrícia Maidana Miguel
- Programa de Pós Graduação em Neurociências, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Derek Lupinsky
- Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada; Department of Psychiatry, Faculty of Medicine, McGill University, Montreal, QC, Canada
| | - Carla Dalmaz
- Programa de Pós Graduação em Bioquímica, Departamento de Bioquímica, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; Programa de Pós Graduação em Neurociências, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Patrícia Pelufo Silveira
- Programa de Pós Graduação em Neurociências, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada; Department of Psychiatry, Faculty of Medicine, McGill University, Montreal, QC, Canada; Sackler Program for Epigenetics & Psychobiology, McGill University, Canada
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D'Souza MS. Brain and Cognition for Addiction Medicine: From Prevention to Recovery Neural Substrates for Treatment of Psychostimulant-Induced Cognitive Deficits. Front Psychiatry 2019; 10:509. [PMID: 31396113 PMCID: PMC6667748 DOI: 10.3389/fpsyt.2019.00509] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 06/28/2019] [Indexed: 01/10/2023] Open
Abstract
Addiction to psychostimulants like cocaine, methamphetamine, and nicotine poses a continuing medical and social challenge both in the United States and all over the world. Despite a desire to quit drug use, return to drug use after a period of abstinence is a common problem among individuals dependent on psychostimulants. Recovery for psychostimulant drug-dependent individuals is particularly challenging because psychostimulant drugs induce significant changes in brain regions associated with cognitive functions leading to cognitive deficits. These cognitive deficits include impairments in learning/memory, poor decision making, and impaired control of behavioral output. Importantly, these drug-induced cognitive deficits often impact adherence to addiction treatment programs and predispose abstinent addicts to drug use relapse. Additionally, these cognitive deficits impact effective social and professional rehabilitation of abstinent addicts. The goal of this paper is to review neural substrates based on animal studies that could be pharmacologically targeted to reverse psychostimulant-induced cognitive deficits such as impulsivity and impairment in learning and memory. Further, the review will discuss neural substrates that could be used to facilitate extinction learning and thus reduce emotional and behavioral responses to drug-associated cues. Moreover, the review will discuss some non-pharmacological approaches that could be used either alone or in combination with pharmacological compounds to treat the above-mentioned cognitive deficits. Psychostimulant addiction treatment, which includes treatment for cognitive deficits, will help promote abstinence and allow for better rehabilitation and integration of abstinent individuals into society.
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Affiliation(s)
- Manoranjan S D'Souza
- Department of Pharmaceutical and Biomedical Sciences, The Raabe College of Pharmacy, Ohio Northern University, Ada, OH, United States
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18
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Contributions of medial prefrontal cortex to decision making involving risk of punishment. Neuropharmacology 2018; 139:205-216. [PMID: 30009836 DOI: 10.1016/j.neuropharm.2018.07.018] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 07/10/2018] [Accepted: 07/12/2018] [Indexed: 12/13/2022]
Abstract
The prefrontal cortex (PFC) plays an important role in several forms of cost-benefit decision making. Its contributions to decision making under risk of explicit punishment, however, are not well understood. A rat model was used to investigate the role of the medial PFC (mPFC) and its monoaminergic innervation in a Risky Decision-making Task (RDT), in which rats chose between a small, "safe" food reward and a large, "risky" food reward accompanied by varying probabilities of mild footshock punishment. Inactivation of mPFC increased choice of the large, risky reward when the punishment probability increased across the session ("ascending RDT"), but decreased choice of the large, risky reward when the punishment probability decreased across the session ("descending RDT"). In contrast, enhancement of monoamine availability via intra-mPFC amphetamine reduced choice of the large, risky reward only in the descending RDT. Systemic administration of amphetamine reduced choice of the large, risky reward in both the ascending and descending RDT; however, this reduction was not attenuated by concurrent mPFC inactivation, indicating that mPFC is not a critical locus of amphetamine's effects on risk taking. These findings suggest that mPFC plays an important role in adapting choice behavior in response to shifting risk contingencies, but not necessarily in risk-taking behavior per se.
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19
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Jhang CL, Huang TN, Hsueh YP, Liao W. Mice lacking cyclin-dependent kinase-like 5 manifest autistic and ADHD-like behaviors. Hum Mol Genet 2018; 26:3922-3934. [PMID: 29016850 DOI: 10.1093/hmg/ddx279] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2017] [Accepted: 07/10/2017] [Indexed: 01/02/2023] Open
Abstract
Neurodevelopmental disorders frequently share common clinical features and appear high rate of comorbidity, such as those present in patients with attention-deficit hyperactivity disorder (ADHD) and autism spectrum disorders (ASD). While characterizing behavioral phenotypes in the mouse model of cyclin-dependent kinase-like 5 (CDKL5) disorder, a neurodevelopmental disorder caused by mutations in the X-linked gene encoding CDKL5, we found that these mice manifested behavioral phenotypes mimicking multiple key features of ASD, such as impaired social interaction and communication, as well as increased stereotypic digging behaviors. These mice also displayed hyper-locomotion, increased aggressiveness and impulsivity, plus deficits in motor and associative learning, resembling primary symptoms of ADHD. Through brain region-specific biochemical analysis, we uncovered that loss of CDKL5 disrupts dopamine synthesis and the expression of social communication-related key genes, such as forkhead-box P2 and mu-opioid receptor, in the corticostriatal circuit. Together, our findings support that CDKL5 plays a role in the comorbid features of autism and ADHD, and mice lacking CDKL5 may serve as an animal model to study the molecular and circuit mechanisms underlying autism-ADHD comorbidity.
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Affiliation(s)
- Cian-Ling Jhang
- Institute of Neuroscience, National Cheng-Chi University, Taipei 116, Taiwan
| | - Tzyy-Nan Huang
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Yi-Ping Hsueh
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Wenlin Liao
- Institute of Neuroscience, National Cheng-Chi University, Taipei 116, Taiwan.,Research Center for Mind, Brain and Learning, National Cheng-Chi University, Taipei 116, Taiwan
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Yates JR. Dissecting drug effects in preclinical models of impulsive choice: emphasis on glutamatergic compounds. Psychopharmacology (Berl) 2018; 235:607-626. [PMID: 29305628 PMCID: PMC5823766 DOI: 10.1007/s00213-017-4825-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 12/27/2017] [Indexed: 01/10/2023]
Abstract
RATIONALE Impulsive choice is often measured with delay discounting paradigms. Because there are multiple discounting procedures, as well as different statistical analyses that can be applied to data generated from these paradigms, there are some inconsistencies in the literature regarding drug effects on impulsive choice. OBJECTIVES The goal of the current paper is to review the methodological and analytic approaches used to measure discounting and to discuss how these differences can account for differential drug effects observed across studies. RESULTS Because some procedures/analyses use a single data point as the dependent variable, changes in this value following pharmacological treatment may be interpreted as alterations in sensitivity to delayed reinforcement, but when other procedures/analyses are used, no changes in behavior are observed. Even when multiple data points are included, some studies show that the statistical analysis (e.g., ANOVA on raw proportion of responses vs. using hyperbolic/exponential functions) can lead to different interpretations. Finally, procedural differences (e.g., delay presentation order, signaling the delay to reinforcement, etc.) in the same discounting paradigm can alter how drugs affect sensitivity to delayed reinforcement. CONCLUSIONS Future studies should utilize paradigms that allow one to observe alterations in responding at each delay (e.g., concurrent-chains schedules). Concerning statistical analyses, using parameter estimates derived from nonlinear functions or incorporating the generalized matching law can allow one to determine if drugs affect sensitivity to delayed reinforcement or impair discrimination of the large and small magnitude reinforcers. Using these approaches can help further our understanding of the neurochemical underpinnings of delay discounting.
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Affiliation(s)
- Justin R Yates
- Department of Psychological Science, Northern Kentucky University, 1 Nunn Drive, Highland Heights, KY, 41099, USA.
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21
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Tobiansky DJ, Wallin-Miller KG, Floresco SB, Wood RI, Soma KK. Androgen Regulation of the Mesocorticolimbic System and Executive Function. Front Endocrinol (Lausanne) 2018; 9:279. [PMID: 29922228 PMCID: PMC5996102 DOI: 10.3389/fendo.2018.00279] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 05/11/2018] [Indexed: 12/21/2022] Open
Abstract
Multiple lines of evidence indicate that androgens, such as testosterone, modulate the mesocorticolimbic system and executive function. This review integrates neuroanatomical, molecular biological, neurochemical, and behavioral studies to highlight how endogenous and exogenous androgens alter behaviors, such as behavioral flexibility, decision making, and risk taking. First, we briefly review the neuroanatomy of the mesocorticolimbic system, which mediates executive function, with a focus on the ventral tegmental area (VTA), nucleus accumbens (NAc), medial prefrontal cortex (mPFC), and orbitofrontal cortex (OFC). Second, we present evidence that androgen receptors (AR) and other steroid receptors are expressed in the mesocorticolimbic system. Using sensitive immunohistochemistry and quantitative polymerase chain reaction (qPCR) techniques, ARs are detected in the VTA, NAc, mPFC, and OFC. Third, we describe recent evidence for local androgens ("neuroandrogens") in the mesocorticolimbic system. Steroidogenic enzymes are expressed in mesocorticolimbic regions. Furthermore, following long-term gonadectomy, testosterone is nondetectable in the blood but detectable in the mesocorticolimbic system, using liquid chromatography tandem mass spectrometry. However, the physiological relevance of neuroandrogens remains unknown. Fourth, we review how anabolic-androgenic steroids (AAS) influence the mesocorticolimbic system. Fifth, we describe how androgens modulate the neurochemistry and structure of the mesocorticolimbic system, particularly with regard to dopaminergic signaling. Finally, we discuss evidence that androgens influence executive functions, including the effects of androgen deprivation therapy and AAS. Taken together, the evidence indicates that androgens are critical modulators of executive function. Similar to dopamine signaling, there might be optimal levels of androgen signaling within the mesocorticolimbic system for executive functioning. Future studies should examine the regulation and functions of neurosteroids in the mesocorticolimbic system, as well as the potential deleterious and enduring effects of AAS use.
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Affiliation(s)
- Daniel J. Tobiansky
- Department of Psychology, University of British Columbia, Vancouver, BC, Canada
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada
- *Correspondence: Daniel J. Tobiansky,
| | - Kathryn G. Wallin-Miller
- Neuroscience Graduate Program, University of Southern California, Los Angeles, CA, United States
| | - Stan B. Floresco
- Department of Psychology, University of British Columbia, Vancouver, BC, Canada
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada
| | - Ruth I. Wood
- Department of Integrative Anatomical Sciences, Keck School of Medicine of the University of Southern California, Los Angeles, CA, United States
| | - Kiran K. Soma
- Department of Psychology, University of British Columbia, Vancouver, BC, Canada
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
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Beyer DKE, Freund N. Animal models for bipolar disorder: from bedside to the cage. Int J Bipolar Disord 2017; 5:35. [PMID: 29027157 PMCID: PMC5638767 DOI: 10.1186/s40345-017-0104-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 09/11/2017] [Indexed: 12/28/2022] Open
Abstract
Bipolar disorder is characterized by recurrent manic and depressive episodes. Patients suffering from this disorder experience dramatic mood swings with a wide variety of typical behavioral facets, affecting overall activity, energy, sexual behavior, sense of self, self-esteem, circadian rhythm, cognition, and increased risk for suicide. Effective treatment options are limited and diagnosis can be complicated. To overcome these obstacles, a better understanding of the neurobiology underlying bipolar disorder is needed. Animal models can be useful tools in understanding brain mechanisms associated with certain behavior. The following review discusses several pathological aspects of humans suffering from bipolar disorder and compares these findings with insights obtained from several animal models mimicking diverse facets of its symptomatology. Various sections of the review concentrate on specific topics that are relevant in human patients, namely circadian rhythms, neurotransmitters, focusing on the dopaminergic system, stressful environment, and the immune system. We then explain how these areas have been manipulated to create animal models for the disorder. Even though several approaches have been conducted, there is still a lack of adequate animal models for bipolar disorder. Specifically, most animal models mimic only mania or depression and only a few include the cyclical nature of the human condition. Future studies could therefore focus on modeling both episodes in the same animal model to also have the possibility to investigate the switch from mania-like behavior to depressive-like behavior and vice versa. The use of viral tools and a focus on circadian rhythms and the immune system might make the creation of such animal models possible.
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Affiliation(s)
- Dominik K. E. Beyer
- Experimental and Molecular Psychiatry, LWL University Hospital, Ruhr University Bochum, Universitätsstr. 150, 44801 Bochum, Germany
| | - Nadja Freund
- Experimental and Molecular Psychiatry, LWL University Hospital, Ruhr University Bochum, Universitätsstr. 150, 44801 Bochum, Germany
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Yates JR, Bardo MT. Effects of intra-accumbal administration of dopamine and ionotropic glutamate receptor drugs on delay discounting performance in rats. Behav Neurosci 2017; 131:392-405. [PMID: 28956947 PMCID: PMC5679283 DOI: 10.1037/bne0000214] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Nucleus accumbens core (NAcc) has been implicated in impulsive choice, as measured in delay discounting. The role of dopamine (DA) in impulsive choice has received considerable attention, whereas glutamate (Glu) has recently been shown to be an important mediator of discounting. However, research has not examined how DA or Glu receptors in NAcc mediate different aspects of delay discounting performance, that is, (a) sensitivity to reinforcer magnitude and (b) sensitivity to delayed reinforcement. Adult male Sprague-Dawley rats were first trained in a delay discounting task, in which the delay to a large magnitude food reinforcer increased across blocks of trials. Following behavioral training, rats received bilateral implantation of guide cannulas into NAcc. Half of the rats (n = 12) received infusions of the DA-selective ligands SKF 38393 (D1-like agonist: 0.03 or 0.1 μg), SCH 23390 (D1-like antagonist: 0.3 or 1.0 μg), quinpirole (D2-like agonist: 0.3 or 1.0 μg), and eticlopride (D2-like antagonist: 0.3 or 1.0 μg). The other half received infusions of the ionotropic Glu ligands MK-801 (NMDA uncompetitive antagonist: 0.3 or 1.0 μg), AP-5 (NMDA competitive antagonist: 0.3 or 1.0 μg), ifenprodil (noncompetitive antagonist at NR2B-containing NMDA receptors: 0.3 or 1.0 μg), and CNQX (AMPA competitive antagonist: 0.2 or 0.5 μg). Results showed that SCH 23390 (0.3 μg) decreased sensitivity to reinforcer magnitude without altering impulsive choice, whereas ifenprodil (1.0 μg) decreased sensitivity to delayed reinforcement (i.e., impulsive choice). The current results show that DA and NMDA receptors in NAcc mediate distinct aspects of discounting performance. (PsycINFO Database Record
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MESH Headings
- 2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine
- Animals
- Benzazepines
- Choice Behavior/drug effects
- Delay Discounting/drug effects
- Dopamine/administration & dosage
- Dopamine/pharmacology
- Glutamic Acid/metabolism
- Glutamic Acid/pharmacology
- Impulsive Behavior/drug effects
- Male
- Nucleus Accumbens/drug effects
- Nucleus Accumbens/physiology
- Quinpirole
- Rats
- Rats, Sprague-Dawley
- Receptors, Dopamine D1/antagonists & inhibitors
- Receptors, Dopamine D1/metabolism
- Receptors, Dopamine D2/metabolism
- Receptors, Ionotropic Glutamate/drug effects
- Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors
- Receptors, N-Methyl-D-Aspartate/metabolism
- Reinforcement, Psychology
- Salicylamides
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Wang Z, Liang S, Yu S, Xie T, Wang B, Wang J, Li Y, Shan B, Cui C. Distinct Roles of Dopamine Receptors in the Lateral Thalamus in a Rat Model of Decisional Impulsivity. Neurosci Bull 2017; 33:413-422. [PMID: 28585114 DOI: 10.1007/s12264-017-0146-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 04/12/2017] [Indexed: 01/02/2023] Open
Abstract
The thalamus and central dopamine signaling have been shown to play important roles in high-level cognitive processes including impulsivity. However, little is known about the role of dopamine receptors in the thalamus in decisional impulsivity. In the present study, rats were tested using a delay discounting task and divided into three groups: high impulsivity (HI), medium impulsivity (MI), and low impulsivity (LI). Subsequent in vivo voxel-based magnetic resonance imaging revealed that the HI rats displayed a markedly reduced density of gray matter in the lateral thalamus compared with the LI rats. In the MI rats, the dopamine D1 receptor antagonist SCH23390 or the D2 receptor antagonist eticlopride was microinjected into the lateral thalamus. SCH23390 significantly decreased their choice of a large, delayed reward and increased their omission of lever presses. In contrast, eticlopride increased the choice of a large, delayed reward but had no effect on the omissions. Together, our results indicate that the lateral thalamus is involved in decisional impulsivity, and dopamine D1 and D2 receptors in the lateral thalamus have distinct effects on decisional impulsive behaviors in rats. These results provide a new insight into the dopamine signaling in the lateral thalamus in decisional impulsivity.
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Affiliation(s)
- Zhiyan Wang
- Neuroscience Research Institute, Peking University, Beijing, 100191, China.,Department of Neurobiology, School of Basic Medical Sciences, Peking University, Beijing, 100191, China.,Key Laboratory of Neuroscience, The Ministry of Education and Ministry of Public Health, Beijing, 100191, China
| | - Shengxiang Liang
- Division of Nuclear Technology and Applications, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Shuangshuang Yu
- Neuroscience Research Institute, Peking University, Beijing, 100191, China.,Department of Neurobiology, School of Basic Medical Sciences, Peking University, Beijing, 100191, China.,Key Laboratory of Neuroscience, The Ministry of Education and Ministry of Public Health, Beijing, 100191, China
| | - Tong Xie
- Neuroscience Research Institute, Peking University, Beijing, 100191, China.,Department of Neurobiology, School of Basic Medical Sciences, Peking University, Beijing, 100191, China.,Key Laboratory of Neuroscience, The Ministry of Education and Ministry of Public Health, Beijing, 100191, China
| | - Baicheng Wang
- Neuroscience Research Institute, Peking University, Beijing, 100191, China.,Department of Neurobiology, School of Basic Medical Sciences, Peking University, Beijing, 100191, China.,Key Laboratory of Neuroscience, The Ministry of Education and Ministry of Public Health, Beijing, 100191, China
| | - Junkai Wang
- Neuroscience Research Institute, Peking University, Beijing, 100191, China.,Department of Neurobiology, School of Basic Medical Sciences, Peking University, Beijing, 100191, China.,Key Laboratory of Neuroscience, The Ministry of Education and Ministry of Public Health, Beijing, 100191, China
| | - Yijing Li
- Neuroscience Research Institute, Peking University, Beijing, 100191, China.,Department of Neurobiology, School of Basic Medical Sciences, Peking University, Beijing, 100191, China.,Key Laboratory of Neuroscience, The Ministry of Education and Ministry of Public Health, Beijing, 100191, China
| | - Baoci Shan
- Division of Nuclear Technology and Applications, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Cailian Cui
- Neuroscience Research Institute, Peking University, Beijing, 100191, China. .,Department of Neurobiology, School of Basic Medical Sciences, Peking University, Beijing, 100191, China. .,Key Laboratory of Neuroscience, The Ministry of Education and Ministry of Public Health, Beijing, 100191, China.
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[Effect of baicalin on ATPase and LDH and its regulatory effect on the AC/cAMP/PKA signaling pathway in rats with attention deficit hyperactivity disorder]. ZHONGGUO DANG DAI ER KE ZA ZHI = CHINESE JOURNAL OF CONTEMPORARY PEDIATRICS 2017. [PMID: 28506353 PMCID: PMC7389122 DOI: 10.7499/j.issn.1008-8830.2017.05.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
OBJECTIVE To study the effect of baicalin on synaptosomal adenosine triphosphatase (ATPase) and lactate dehydrogenase (LDH) and its regulatory effect on the adenylate cyclase (AC)/cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) signaling pathway in rats with attention deficit hyperactivity disorder (ADHD). METHODS A total of 40 SHR rats were randomly divided into five groups: ADHD model, methylphenidate hydrochloride treatment (0.07 mg/mL), and low-dose (3.33 mg/mL), medium-dose (6.67 mg/mL), and high-dose (10 mg/mL) baicalin treatment (n=8 each). Eight WKY rats were selected as normal control group. Percoll density gradient centrifugation was used to prepare brain synaptosomes and an electron microscope was used to observe their structure. Colorimetry was used to measure the activities of ATPase and LDH in synaptosomes. ELISA was used to measure the content of AC, cAMP, and PKA. RESULTS Compared with the normal control group, the ADHD model group had a significant reduction in the ATPase activity, a significant increase in the LDH activity, and significant reductions in the content of AC, cAMP, and PKA (P<0.05). Compared with the ADHD model group, the methylphenidate hydrochloride group and the medium- and high-dose baicalin groups had a significant increase in the ATPase activity (P<0.05), a significant reduction in the LDH activity (P<0.05), and significant increases in the content of AC, cAMP, and PKA (P<0.05). Compared with the methylphenidate hydrochloride group, the high-dose baicalin group had significantly greater changes in these indices (P<0.05). Compared with the low-dose baicalin group, the high-dose baicalin group had a significant increase in the ATPase activity (P<0.05); the medium- and high-dose baicalin groups had a significant reduction in the LDH activity (P<0.05) and significant increases in the content of AC, cAMP, and PKA (P<0.05). Compared with the medium-dose baicalin group, the high-dose baicalin group had a significant increase in the ATPase activity (P<0.05). CONCLUSIONS Both methylphenidate hydrochloride and baicalin can improve synaptosomal ATPase and LDH activities in rats with ADHD. The effect of baicalin is dose-dependent, and high-dose baicalin has a significantly greater effect than methylphenidate hydrochloride. Baicalin exerts its therapeutic effect possibly by upregulating the AC/cAMP/PKA signaling pathway.
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Vonder Haar C, Martens KM, Riparip LK, Rosi S, Wellington CL, Winstanley CA. Frontal Traumatic Brain Injury Increases Impulsive Decision Making in Rats: A Potential Role for the Inflammatory Cytokine Interleukin-12. J Neurotrauma 2017; 34:2790-2800. [PMID: 28376700 DOI: 10.1089/neu.2016.4813] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Traumatic brain injury (TBI) is associated with the development of numerous psychiatric diseases. Of particular concern for TBI patients is the impact of chronic impulsivity on daily functioning. Despite the scope of the human problem, little has been done to address impulsivity in animal models of brain injury. In the current study, we examined the effects of either a severe or a milder bilateral frontal controlled cortical impact injury on impulsivity using the Delay Discounting Task (DDT), in which preference for smaller-sooner over larger-later rewards is indicative of greater impulsive choice. Both milder and severe TBI caused a significant, chronic increase in impulsive decision making. Despite these pronounced changes in performance of the DDT, memory function, as assessed by the Morris Water Maze, was not impaired in more mildly injured rats and only transiently impacted in the severe TBI group. Whereas a significant lesion was only evident in severely injured rats, analysis of cytokine levels within the frontal cortex revealed a selective increase in interleukin (IL)-12 that was associated with the magnitude of the change in impulsive choice caused by both milder and severe TBI. These findings suggest that tissue loss alone cannot explain the increased impulsivity observed, and that inflammatory pathways mediated by IL-12 may be a contributing factor. The findings from this study highlight the sensitivity of sophisticated behavioral measures designed to assess neuropsychiatric dysfunction in the detection of TBI-induced cognitive impairments and their utility in identifying potential mechanistic pathways and therapeutic targets.
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Affiliation(s)
- Cole Vonder Haar
- 1 Djavad Mowafaghian Centre for Brain Health, University of British Columbia , Vancouver, British Columbia, Canada
| | - Kris M Martens
- 1 Djavad Mowafaghian Centre for Brain Health, University of British Columbia , Vancouver, British Columbia, Canada
| | - Lara-Kirstie Riparip
- 2 Brain and Spinal Injury Center, Departments of Physical Therapy Rehabilitation Science and Neurological Surgery, University of California San Francisco , San Francisco, California
| | - Susanna Rosi
- 2 Brain and Spinal Injury Center, Departments of Physical Therapy Rehabilitation Science and Neurological Surgery, University of California San Francisco , San Francisco, California
| | - Cheryl L Wellington
- 1 Djavad Mowafaghian Centre for Brain Health, University of British Columbia , Vancouver, British Columbia, Canada
| | - Catharine A Winstanley
- 1 Djavad Mowafaghian Centre for Brain Health, University of British Columbia , Vancouver, British Columbia, Canada
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Schippers MC, Bruinsma B, Gaastra M, Mesman TI, Denys D, De Vries TJ, Pattij T. Deep Brain Stimulation of the Nucleus Accumbens Core Affects Trait Impulsivity in a Baseline-Dependent Manner. Front Behav Neurosci 2017; 11:52. [PMID: 28386221 PMCID: PMC5362621 DOI: 10.3389/fnbeh.2017.00052] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 03/07/2017] [Indexed: 12/29/2022] Open
Abstract
Deep brain stimulation (DBS) of the nucleus accumbens (NA) is explored as a treatment for refractory psychiatric disorders, such as obsessive-compulsive disorder (OCD), depressive disorder (MDD), and substance use disorder (SUD). A common feature of some of these disorders is pathological impulsivity. Here, the effects of NAcore DBS on impulsive choice and impulsive action, two distinct forms of impulsive behavior, were investigated in translational animal tasks, the delayed reward task (DRT) and five-choice serial reaction time task (5-CSRTT), respectively. In both tasks, the effects of NAcore DBS were negatively correlated with baseline impulsive behavior, with more pronounced effects in the 5-CSRTT. To further examine the effects of DBS on trait impulsive action, rats were screened for high (HI) and low (LI) impulsive responding in the 5-CSRTT. NAcore DBS decreased impulsive, premature responding in HI rats under conventional conditions. However, upon challenged conditions to increase impulsive responding, NAcore DBS did not alter impulsivity. These results strongly suggest a baseline-dependent effect of DBS on impulsivity, which is in line with clinical observations.
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Affiliation(s)
- Maria C Schippers
- Amsterdam Neuroscience, Department of Anatomy and Neurosciences, VU University Medical Center Amsterdam, Netherlands
| | - Bastiaan Bruinsma
- Amsterdam Neuroscience, Department of Anatomy and Neurosciences, VU University Medical Center Amsterdam, Netherlands
| | - Mathijs Gaastra
- Amsterdam Neuroscience, Department of Anatomy and Neurosciences, VU University Medical Center Amsterdam, Netherlands
| | - Tanja I Mesman
- Amsterdam Neuroscience, Department of Anatomy and Neurosciences, VU University Medical Center Amsterdam, Netherlands
| | - Damiaan Denys
- Amsterdam Neuroscience, Department of Psychiatry, Academic Medical Center, University of Amsterdam Amsterdam, Netherlands
| | - Taco J De Vries
- Amsterdam Neuroscience, Department of Anatomy and Neurosciences, VU University Medical Center Amsterdam, Netherlands
| | - Tommy Pattij
- Amsterdam Neuroscience, Department of Anatomy and Neurosciences, VU University Medical Center Amsterdam, Netherlands
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Moschak TM, Carelli RM. Impulsive Rats Exhibit Blunted Dopamine Release Dynamics during a Delay Discounting Task Independent of Cocaine History. eNeuro 2017; 4:ENEURO.0119-17.2017. [PMID: 28451642 PMCID: PMC5402299 DOI: 10.1523/eneuro.0119-17.2017] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 04/10/2017] [Indexed: 11/21/2022] Open
Abstract
The inability to wait for a large, delayed reward when faced with a small, immediate one, known as delay discounting, has been implicated in a number of disorders including substance abuse. Individual differences in impulsivity on the delay discounting task are reflected in differences in neural function, including in the nucleus accumbens (NAc) core. We examined the role of a history of cocaine self-administration, as well as individual differences in impulsivity, on rapid dopamine (DA) release dynamics in the NAc core. Rats with a history of cocaine or water/saline self-administration were tested on delay discounting while being simultaneously assayed for rapid DA release using electrochemical methods. In controls, we found that cue DA release was modulated by reward delay and magnitude, consistent with prior reports. A history of cocaine had no effect on either delay discounting or DA release dynamics. Nonetheless, independent of drug history, individual differences in impulsivity were related to DA release in the NAc core. First, high impulsive animals exhibited dampened cue DA release during the delay discounting task. Second, reward delay and magnitude in high impulsive animals failed to robustly modulate changes in cue DA release. Importantly, these two DAergic mechanisms were uncorrelated with each other and, together, accounted for a high degree of variance in impulsive behavior. Collectively, these findings demonstrate two distinct mechanisms by which rapid DA signaling may influence impulsivity, and illustrate the importance of NAc core DA release dynamics in impulsive behavior.
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Affiliation(s)
- Travis M Moschak
- Department of Psychology and Neuroscience, University of North Carolina, Chapel Hill, NC 27599
| | - Regina M Carelli
- Department of Psychology and Neuroscience, University of North Carolina, Chapel Hill, NC 27599
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Wang Y, Yin F, Guo H, Zhang J, Yan P, Lai J. The Role of Dopamine D1 and D3 Receptors in N-Methyl-D-Aspartate (NMDA)/GlycineB Site-Regulated Complex Cognitive Behaviors following Repeated Morphine Administration. Int J Neuropsychopharmacol 2017; 20:562-574. [PMID: 28199666 PMCID: PMC5492807 DOI: 10.1093/ijnp/pyx010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 02/08/2017] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Opiate addiction is associated with complex cognitive impairment, which contributes to the development of compulsive drug use and relapses. Dopamine and N-methyl-D-aspartate receptors play critical roles in opiate-induced cognitive deficits. However, the roles of D1 and D3 receptors in the N-methyl-D-aspartate/glycineB receptor-regulated cognitive behaviors induced by morphine remain unknown. METHODS The 5-choice serial reaction time task was used to investigate the cognitive profiles associated with repeated morphine administration in D1 (D1-/-)- and D3 (D3-/-)-receptor knockout mice. The expression of phosphorylated NR1, Ca2+/calmodulin-dependent protein kinase II (CaMKII), and cAMP response element-binding protein (CREB) in the brain was examined by western blotting. D1-/- and D3-/- mice were treated with the N-methyl-D-aspartate/glycineB site agonist l-aminocyclopropanecarboxylic acid and the antagonist L-701,324 to chronically disrupt N-methyl-D-aspartate receptor function and investigate their effects on morphine-induced cognitive changes. RESULTS Repeated morphine administration impaired attentional function and caused impulsive and compulsive behaviors. D1-/- mice exhibited hardly any premature nosepokes. D3-/- mice showed robustly increased morphine-induced impulsive behavior. The numbers of premature responses were decreased by L-701,324 administration and increased by ACPC administration; these effects were completely abolished in D1-/- mice due to their inability to perform reward-based tasks. In contrast, the inhibitory effects of L-701,324 on impulsive behavior were significantly augmented in D3-/- mice. CONCLUSIONS N-methyl-D-aspartate/glycineB site functions may contribute to morphine-induced cognitive deficits, especially those related to impulsive behavior. D1 and D3 receptors may have contrasting effects with respect to modulating impulsive behavior. D3 receptors have inhibitory effects on impulsive behaviors, and these effects are clearly mediated by N-methyl-D-aspartate/glycineB receptor and μ-opioid receptor interactions.
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Affiliation(s)
- Yunpeng Wang
- College of Forensic Science, Xi’an Jiaotong University, Xi’an, Shaanxi 710061, China
| | - Fangyuan Yin
- College of Forensic Science, Xi’an Jiaotong University, Xi’an, Shaanxi 710061, China
| | - Hao Guo
- College of Forensic Science, Xi’an Jiaotong University, Xi’an, Shaanxi 710061, China
| | - Jing Zhang
- College of Forensic Science, Xi’an Jiaotong University, Xi’an, Shaanxi 710061, China
| | - Peng Yan
- College of Forensic Science, Xi’an Jiaotong University, Xi’an, Shaanxi 710061, China
| | - Jianghua Lai
- College of Forensic Science, Xi’an Jiaotong University, Xi’an, Shaanxi 710061, China
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Fobbs WC, Mizumori SJY. A framework for understanding and advancing intertemporal choice research using rodent models. Neurobiol Learn Mem 2017; 139:89-97. [PMID: 28065715 DOI: 10.1016/j.nlm.2017.01.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 01/02/2017] [Accepted: 01/04/2017] [Indexed: 02/04/2023]
Abstract
Intertemporal choices are common and consequential to private and public life. Thus, there is considerable interest in understanding the neural basis of intertemporal decision making. In this minireview, we briefly describe conceptual and psychological perspectives on intertemporal choice and then provide a comprehensive evaluation of the neural structures and signals that comprise the underlying cortico-limbic-striatal circuit. Even though great advances have been made, our understanding of the neurobiology of intertemporal choice is still in its infancy because of the complex and dynamic nature of this form of decision making. We close by briefly discussing recommendations for the future study of intertemporal choice research.
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Affiliation(s)
- Wambura C Fobbs
- Neuroscience Program, University of Washington, Seattle, WA 98195, United States
| | - Sheri J Y Mizumori
- Neuroscience Program, University of Washington, Seattle, WA 98195, United States; Psychology Department, University of Washington, Seattle, WA 98195, United States.
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Zhu Y, Wang Y, Lai J, Wei S, Zhang H, Yan P, Li Y, Qiao X, Yin F. Dopamine D1 and D3 Receptors Modulate Heroin-Induced Cognitive Impairment through Opponent Actions in Mice. Int J Neuropsychopharmacol 2016; 20:257-268. [PMID: 27815417 PMCID: PMC5408975 DOI: 10.1093/ijnp/pyw099] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 11/02/2016] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND Chronic abuse of heroin leads to long-lasting and complicated cognitive impairment. Dopamine receptors are critically involved in the impulsive drug-driven behavior and the altered attention, processing speed, and mental flexibility that are associated with higher relapse rates. However, the effects of the different dopamine receptors and their possible involvement in heroin-induced cognitive impairment remain unclear. METHODS The 5-choice serial reaction time task was used to investigate the profiles of heroin-induced cognitive impairment in mice. The expression levels of dopamine D1- and D2-like receptors in the prefrontal cortex, nucleus accumbens, and caudate-putamen were determined. The effects of dopamine receptors on heroin-induced impulsivity in the 5-choice serial reaction time task were examined by agonist/antagonist treatment on D1 or D3 receptor mutant mice. RESULTS Systemic heroin administration influences several variables in the 5-choice serial reaction time task, most notably premature responses, a measure of motor impulsivity. These behavioral impairments are associated with increased D1 receptor and decreased D3 receptor mRNA and protein levels in 3 observed brain areas. The heroin-evoked increase in premature responses is mimicked by a D1 agonist and prevented by a D1 antagonist or genetic ablation of the D1 receptor gene. In contrast, a D3 agonist decreases both basal and heroin-evoked premature responses, while genetic ablation of the D3 receptor gene results in increased basal and heroin-evoked premature responses. CONCLUSIONS Heroin-induced impulsive behavior in the 5-choice serial reaction time task is oppositely modulated by D1 and D3 receptor activation. The D1 receptors in the cortical-mesolimbic region play an indispensable role in modulating such behaviors.
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Affiliation(s)
- Yongsheng Zhu
- College of Forensic Science, Xi’an Jiaotong University, Xi’an, Shaanxi, China (Drs Zhu, Wang, Lai, Wei, Zhang, Yan, Li, and Qiao and Ms Yin); Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi’an, Shaanxi, China (Drs Lai and Wei)
| | - Yunpeng Wang
- College of Forensic Science, Xi’an Jiaotong University, Xi’an, Shaanxi, China (Drs Zhu, Wang, Lai, Wei, Zhang, Yan, Li, and Qiao and Ms Yin); Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi’an, Shaanxi, China (Drs Lai and Wei)
| | - Jianghua Lai
- College of Forensic Science, Xi’an Jiaotong University, Xi’an, Shaanxi, China (Drs Zhu, Wang, Lai, Wei, Zhang, Yan, Li, and Qiao and Ms Yin); Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi’an, Shaanxi, China (Drs Lai and Wei)
| | - Shuguang Wei
- College of Forensic Science, Xi’an Jiaotong University, Xi’an, Shaanxi, China (Drs Zhu, Wang, Lai, Wei, Zhang, Yan, Li, and Qiao and Ms Yin); Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi’an, Shaanxi, China (Drs Lai and Wei)
| | - Hongbo Zhang
- College of Forensic Science, Xi’an Jiaotong University, Xi’an, Shaanxi, China (Drs Zhu, Wang, Lai, Wei, Zhang, Yan, Li, and Qiao and Ms Yin); Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi’an, Shaanxi, China (Drs Lai and Wei)
| | - Peng Yan
- College of Forensic Science, Xi’an Jiaotong University, Xi’an, Shaanxi, China (Drs Zhu, Wang, Lai, Wei, Zhang, Yan, Li, and Qiao and Ms Yin); Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi’an, Shaanxi, China (Drs Lai and Wei)
| | - Yunxiao Li
- College of Forensic Science, Xi’an Jiaotong University, Xi’an, Shaanxi, China (Drs Zhu, Wang, Lai, Wei, Zhang, Yan, Li, and Qiao and Ms Yin); Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi’an, Shaanxi, China (Drs Lai and Wei)
| | - Xiaomeng Qiao
- College of Forensic Science, Xi’an Jiaotong University, Xi’an, Shaanxi, China (Drs Zhu, Wang, Lai, Wei, Zhang, Yan, Li, and Qiao and Ms Yin); Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi’an, Shaanxi, China (Drs Lai and Wei)
| | - Fangyuan Yin
- College of Forensic Science, Xi’an Jiaotong University, Xi’an, Shaanxi, China (Drs Zhu, Wang, Lai, Wei, Zhang, Yan, Li, and Qiao and Ms Yin); Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi’an, Shaanxi, China (Drs Lai and Wei)
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Bailey MR, Simpson EH, Balsam PD. Neural substrates underlying effort, time, and risk-based decision making in motivated behavior. Neurobiol Learn Mem 2016; 133:233-256. [PMID: 27427327 PMCID: PMC5007005 DOI: 10.1016/j.nlm.2016.07.015] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 07/11/2016] [Accepted: 07/12/2016] [Indexed: 11/16/2022]
Abstract
All mobile organisms rely on adaptive motivated behavior to overcome the challenges of living in an environment in which essential resources may be limited. A variety of influences ranging from an organism's environment, experiential history, and physiological state all influence a cost-benefit analysis which allows motivation to energize behavior and direct it toward specific goals. Here we review the substantial amount of research aimed at discovering the interconnected neural circuits which allow organisms to carry-out the cost-benefit computations which allow them to behave in adaptive ways. We specifically focus on how the brain deals with different types of costs, including effort requirements, delays to reward and payoff riskiness. An examination of this broad literature highlights the importance of the extended neural circuits which enable organisms to make decisions about these different types of costs. This involves Cortical Structures, including the Anterior Cingulate Cortex (ACC), the Orbital Frontal Cortex (OFC), the Infralimbic Cortex (IL), and prelimbic Cortex (PL), as well as the Baso-Lateral Amygdala (BLA), the Nucleus Accumbens (NAcc), the Ventral Pallidal (VP), the Sub Thalamic Nucleus (STN) among others. Some regions are involved in multiple aspects of cost-benefit computations while the involvement of other regions is restricted to information relating to specific types of costs.
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Affiliation(s)
- Matthew R Bailey
- Department of Psychology, Columbia University, New York, NY, USA.
| | - Eleanor H Simpson
- Department of Psychiatry, Columbia University, New York, NY, USA; New York State Psychiatric Institute, New York, NY, USA
| | - Peter D Balsam
- Department of Psychiatry, Columbia University, New York, NY, USA; New York State Psychiatric Institute, New York, NY, USA; Barnard College, Columbia University, New York, NY, USA
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Lukkes JL, Freund N, Thompson BS, Meda S, Andersen SL. Preventative treatment in an animal model of ADHD: Behavioral and biochemical effects of methylphenidate and its interactions with ovarian hormones in female rats. Eur Neuropsychopharmacol 2016; 26:1496-1506. [PMID: 27397110 PMCID: PMC5204118 DOI: 10.1016/j.euroneuro.2016.06.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 06/06/2016] [Accepted: 06/10/2016] [Indexed: 12/26/2022]
Abstract
Clinical and preclinical studies on attention deficit hyperactivity disorder (ADHD) show that juvenile males that are exposed to methylphenidate (MPH) show reduced risk for substance use later in life. In contrast, little is known about whether females have the same enduring treatment response to stimulants and how gonadal hormones influence their behavior later in life. Females received either a sham or 6-hydroxydopamine (6-OHDA) microinjection in the prefrontal cortex (PFC) at postnatal day (P)10. Subjects were then treated with Vehicle or MPH (2mg/kg, p.o.) between P20-35 and tested during late adolescence/young adulthood (P60); half of these subjects underwent ovariectomy at P55 to determine hormonal influences. Females with 6-OHDA were depleted of PFC dopamine by 61% and demonstrated increased impulsive choice (delayed discounting) and preferences for cocaine-associated environments relative to control females. Both MPH and ovariectomy reduced impulsive choice and cocaine preferences in 6-OHDA females, but had no enduring effect in Sham females. Ovariectomy itself did not significantly affect impulsivity. Juvenile MPH interacted strongly with 6-OHDA to increase D4, D5, Alpha-1A, Alpha-2A, and 5-HT-1A mRNA receptor expression in the PFC. MPH alone effected D1 mRNA, while 6-OHDA increased BDNF; all markers were decreased by ovariectomy. Together, these data suggest that 6-OHDA changes in dopamine are not only relevant for ADHD-like behaviors, but their long-term modulation by treatment and the influence of cyclical differences in menstrual cycle.
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Affiliation(s)
- Jodi L Lukkes
- Laboratory for Developmental Neuropharmacology, McLean Hospital, USA; Harvard Medical School, USA
| | - Nadja Freund
- Laboratory for Developmental Neuropharmacology, McLean Hospital, USA; Department of Psychiatry and Psychotherapy, University of Tübingen, Tübingen, Germany
| | - Britta S Thompson
- Laboratory for Developmental Neuropharmacology, McLean Hospital, USA
| | - Shirisha Meda
- Laboratory for Developmental Neuropharmacology, McLean Hospital, USA
| | - Susan L Andersen
- Laboratory for Developmental Neuropharmacology, McLean Hospital, USA; Harvard Medical School, USA.
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Simon NW, Moghaddam B. Methylphenidate has nonlinear dose effects on cued response inhibition in adults but not adolescents. Brain Res 2016; 1654:171-176. [PMID: 27431940 DOI: 10.1016/j.brainres.2016.07.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 06/16/2016] [Accepted: 07/15/2016] [Indexed: 01/03/2023]
Abstract
Ongoing development of the dopamine system during adolescence may provide a partial mechanism for behavioral and psychiatric vulnerabilities. Despite early evidence for a hyperactive adolescent dopaminergic system, recent data suggest that adolescent dopamine may be functionally hypoactive compared to in adults. While this distinction has been established in response to dopaminergic drugs and natural rewards, little is known about age-related differences in cognitive efficacy of dopaminergic drugs. Using a recently established Cued Response Inhibition Task, we tested the effects of acute systemic methylphenidate, commonly known as Ritalin, on response inhibition and response initiation in adolescent and adults rats. First, we replicated previous data that adolescents are able to inhibit a response to a cue on par with adults, but are slower to produce a rewarded response after a stop cue. Next, we observed that methylphenidate modulated response inhibition in adult rats, with low dose (0.3mg/kg) improving inhibition, and high dose (3mg/kg) impairing performance. This dose-response pattern is commonly observed with psychostimulant cognitive modulation. In adolescents, however, methylphenidate had no effect on response inhibition at any dose. Latency of response initiation after the stop cue was not affected by methylphenidate in either adult or adolescent rats. These data establish that dose-response of a commonly prescribed psychostimulant medication is different in adolescents and adults. They further demonstrate that healthy adolescent response inhibition is not as sensitive to psychostimulants as in adults, supporting the idea that the dopamine system is hypoactive in adolescence. This article is part of a Special Issue entitled SI: Adolescent plasticity.
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Affiliation(s)
- Nicholas W Simon
- University of Pittsburgh, Department of Neuroscience, A210 Langley Hall, Pittsburgh, PA 15260, United States
| | - Bita Moghaddam
- University of Pittsburgh, Department of Neuroscience, A210 Langley Hall, Pittsburgh, PA 15260, United States.
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Vijayraghavan S, Major AJ, Everling S. Dopamine D1 and D2 Receptors Make Dissociable Contributions to Dorsolateral Prefrontal Cortical Regulation of Rule-Guided Oculomotor Behavior. Cell Rep 2016; 16:805-16. [PMID: 27373147 DOI: 10.1016/j.celrep.2016.06.031] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2016] [Revised: 03/28/2016] [Accepted: 06/02/2016] [Indexed: 11/25/2022] Open
Abstract
Studies of neuromodulation of spatial short-term memory have shown that dopamine D1 receptor (D1R) stimulation in dorsolateral prefrontal cortex (DLPFC) dose-dependently modulates memory activity, whereas D2 receptors (D2Rs) selectively modulate activity related to eye movements hypothesized to encode movement feedback. We examined localized stimulation of D1Rs and D2Rs on DLPFC neurons engaged in a task involving rule representation in memory to guide appropriate eye movements toward or away from a visual stimulus. We found dissociable effects of D1R and D2R on DLPFC physiology. D1R stimulation degrades memory activity for the task rule and increases stimulus-related selectivity. In contrast, D2R stimulation affects motor activity tuning only when eye movements are made to the stimulus. Only D1R stimulation degrades task performance and increases impulsive responding. Our results suggest that D1Rs regulate rule representation and impulse control, whereas D2Rs selectively modulate eye-movement-related dynamics and not rule representation in the DLPFC.
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Affiliation(s)
- Susheel Vijayraghavan
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario, Medical Sciences Building, Room 216, London, ON N6A 5C1, Canada
| | - Alex James Major
- Graduate Program in Neuroscience, The University of Western Ontario, Robarts Research Institute, RRI 3203, 1151 Richmond Street North, London, ON N6A 5B7, Canada
| | - Stefan Everling
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario, Medical Sciences Building, Room 216, London, ON N6A 5C1, Canada; Graduate Program in Neuroscience, The University of Western Ontario, Robarts Research Institute, RRI 3203, 1151 Richmond Street North, London, ON N6A 5B7, Canada; Robarts Research Institute, The University of Western Ontario, Room EB-120, 1151 Richmond Street North, London, ON N6A 5B7, Canada.
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Freund N, Thompson BS, Sonntag K, Meda S, Andersen SL. When the party is over: depressive-like states in rats following termination of cortical D1 receptor overexpression. Psychopharmacology (Berl) 2016; 233:1191-201. [PMID: 26762379 PMCID: PMC4915915 DOI: 10.1007/s00213-015-4200-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 12/29/2015] [Indexed: 11/29/2022]
Abstract
RATIONALE Increased activity of prefrontal D1 dopamine receptors (D1R) is involved in reward-related behavior found in bipolar disorder and drug addiction. While the effects of elevated D1R are known, depressive-like behaviors also occur in these disorders after reward-seeking ends. OBJECTIVES The goal is to characterize how termination of D1R overexpression influences depressive-like behaviors. METHODS An inducible (Tet.On), lentiviral vector was used to manipulate the expression of the DRD1 gene in glutamate neurons within the prefrontal cortex in male, adult rats. Sexual activity and sucrose preference were studied in both D1R elevated ON and relatively reduced OFF states. Following termination of the D1R ON state, depressive-like behavior was determined in the OFF state. Expression of the transcriptional regulator, cyclic AMP-responsive element-binding protein (CREB), was used as an indication of downstream effects in the nucleus accumbens (NA). RESULTS ON D1R expression increased sexual activity that returned to baseline in the OFF state. Sucrose preferences increased ~6 % in ON state but fell 11 % below control levels when OFF. Consistent with a depressive-like phenotype, D1R OFF decreased activity by 40 %, impaired the ability to control (43 %) and motivation to escape shock (27 % more impaired) relative to dsRed OFF. CREB increased 29 % in the NA in the D1R OFF state relative to the ON state. CONCLUSIONS This novel approach demonstrates that elevated D1R expression increased hedonic behavior, whereas the termination of D1R overexpression often resulted in depressive-like behavior. These observations support a role for D1R expression cycling in bipolar-associated behaviors and addiction.
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Affiliation(s)
- Nadja Freund
- Laboratory for Developmental Neuropharmacology, McLean Hospital and Harvard Medical School, Belmont, MA, 02478, USA.
- Klinik für Psychiatrie und Psychotherapie, Calwerstr. 14, 72076, Tübingen, Germany.
| | - Britta S Thompson
- Laboratory for Developmental Neuropharmacology, McLean Hospital and Harvard Medical School, Belmont, MA, 02478, USA
| | - Kai Sonntag
- Laboratory for Developmental Neuropharmacology, McLean Hospital and Harvard Medical School, Belmont, MA, 02478, USA
| | - Shirisha Meda
- Laboratory for Developmental Neuropharmacology, McLean Hospital and Harvard Medical School, Belmont, MA, 02478, USA
| | - Susan L Andersen
- Laboratory for Developmental Neuropharmacology, McLean Hospital and Harvard Medical School, Belmont, MA, 02478, USA
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Wang FL, Pandika D, Chassin L, Lee M, King K. Testing the Relations Among Family Disorganization, Delay Discounting, and Adolescent Alcohol Use: A Genetically Informed Study. Alcohol Clin Exp Res 2016; 40:846-56. [PMID: 26926310 DOI: 10.1111/acer.12999] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2015] [Accepted: 12/31/2015] [Indexed: 01/19/2023]
Abstract
BACKGROUND Delay discounting is a potential etiological factor in adolescents' alcohol use, making it important to understand its antecedents. Family disorganization might contribute to delay discounting, but few studies have tested this relation. Moreover, because delay discounting is heritable, the effects of family disorganization on delay discounting might be moderated by adolescents' genetic risk for delay discounting. Thus, the current study examined the role of family disorganization, in interaction with genetic risk, in predicting adolescents' delay discounting and subsequent alcohol use. METHODS Adolescents participated in 4 waves of data collection. Adolescents self-reported their family disorganization at T1, completed a delay discounting questionnaire at T3, and self-reported their alcohol use both at T2 (covariate) and T4 (outcome). Using results from an independent sample, we created a polygenic risk score consisting of dopaminergic genes to index genetic risk for delay discounting. RESULTS Greater family disorganization predicted adolescents' greater delay discounting, but only for adolescents with low levels of genetic risk for delay discounting. Adolescents with high and mean levels of genetic risk for delay discounting showed elevated delay discounting regardless of their family's disorganization. Greater delay discounting prospectively predicted adolescents' greater alcohol use. Finally, the effects of family disorganization on adolescents' alcohol use were mediated through delay discounting, but only for adolescents with low levels of genetic risk. CONCLUSIONS Results suggest multiple pathways to delay discounting. Although there are genetically influenced pathways to delay discounting, family disorganization might represent an environmental pathway to delay discounting (and subsequent alcohol use) for a subset of adolescents at low genetic risk. These findings reinforce the utility of family interventions for reducing adolescents' delay discounting and alcohol use, at least for a subgroup of adolescents. Because higher family organization did not buffer against delay discounting among adolescents with high genetic risk, future research should explore other early environmental influences that could protect these high-risk adolescents from developing these risky behaviors.
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Affiliation(s)
- Frances L Wang
- Department of Psychology, Arizona State University, Tempe, Arizona
| | - Danielle Pandika
- Department of Psychology, Arizona State University, Tempe, Arizona
| | - Laurie Chassin
- Department of Psychology, Arizona State University, Tempe, Arizona
| | - Matthew Lee
- Department of Psychological Sciences, University of Missouri, Columbia, Missouri
| | - Kevin King
- Department of Psychology, University of Washington, Seattle, Washington
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Tian L, Qin X, Sun J, Li X, Wei L. Differential effects of co-administration of oxotremorine with SCH 23390 on impulsive choice in high-impulsive rats and low-impulsive rats. Pharmacol Biochem Behav 2016; 142:56-63. [PMID: 26772787 DOI: 10.1016/j.pbb.2016.01.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 12/23/2015] [Accepted: 01/04/2016] [Indexed: 10/22/2022]
Abstract
The effect of acetylcholine on impulsive choice is thought to be due to interactions between cholinergic and dopaminergic systems, but this hypothesis has not been proven. This study investigated whether D1-like receptors were involved in the effects of the muscarinic cholinergic agonist oxotremorine on impulsive choice in high-impulsive rats (HI rats, n=8) and low-impulsive rats (LI rats, n=8) characterized by basal levels of impulsive choice in a delay-discounting task. The results revealed that oxotremorine (0.05mg/kg) significantly increased the choice of the large reinforcer in HI rats, whereas decreased the choice of the large reinforcer in LI rats. The D1-like antagonist SCH 23390 produced significant reductions in the large-reinforcer choice in HI rats (0.01mg/kg) and LI rats (0.005, 0.0075, and 0.01mg/kg). SCH 23390 significantly inhibited the increase in the choice of the large reinforcer induced by oxotremorine (0.05mg/kg) in HI rats at doses of 0.005 and 0.0075mg/kg, but enhanced the effect of oxotremorine in LI rats only at the dose of 0.0075mg/kg. These findings suggested that D1-like receptors might be involved in the differential effects of oxotremorine on impulsive choice between HI rats and LI rats.
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Affiliation(s)
- Lin Tian
- Beijing Key Laboratory of Learning and Cognition, Department of Psychology, Capital Normal University, Beijing 100048, China
| | - Xingna Qin
- Beijing Key Laboratory of Learning and Cognition, Department of Psychology, Capital Normal University, Beijing 100048, China
| | - Jinling Sun
- Beijing Key Laboratory of Learning and Cognition, Department of Psychology, Capital Normal University, Beijing 100048, China
| | - Xinwang Li
- Beijing Key Laboratory of Learning and Cognition, Department of Psychology, Capital Normal University, Beijing 100048, China.
| | - Li Wei
- Department of Endocrinology and Metabolism, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai 200233, China.
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Manfré G, Doyère V, Bossi S, Riess O, Nguyen HP, El Massioui N. Impulsivity trait in the early symptomatic BACHD transgenic rat model of Huntington disease. Behav Brain Res 2015; 299:6-10. [PMID: 26592164 DOI: 10.1016/j.bbr.2015.11.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 11/05/2015] [Accepted: 11/07/2015] [Indexed: 10/22/2022]
Abstract
Impulsivity trait was characterized in 3-5 months old BACHD rats, a transgenic model of Huntington disease, using (1) the delay discounting task to assess cognitive/choice impulsivity, and (2) the Differential Reinforcement of Low Rate of Responding task to evaluate motor/action impulsivity. Transgenic animals showed a high level of choice impulsivity and, to a lesser extent, action impulsivity. Our results provide the first evidence that the transgenic BACHD rat (TG5 line) displays impulsivity disorder as early as 3 months old, as described in early symptomatic HD patients, thus adding to the face validity of the rat model.
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Affiliation(s)
- Giuseppe Manfré
- Institute of Medical Genetics and Applied Genomics, University of Tuebingen, Tuebingen, Germany; IMPRS for Cognitive and Systems Neuroscience, University of Tuebingen, Tuebingen, Germany
| | - Valérie Doyère
- Paris-Saclay Institute of Neuroscience (Neuro-PSI), UMR 9197, Université Paris-Sud, Orsay F-91405, France; CNRS, Orsay F-91405, France
| | - Simon Bossi
- Paris-Saclay Institute of Neuroscience (Neuro-PSI), UMR 9197, Université Paris-Sud, Orsay F-91405, France; CNRS, Orsay F-91405, France
| | - Olaf Riess
- Institute of Medical Genetics and Applied Genomics, University of Tuebingen, Tuebingen, Germany
| | - Huu Phuc Nguyen
- Institute of Medical Genetics and Applied Genomics, University of Tuebingen, Tuebingen, Germany
| | - Nicole El Massioui
- Paris-Saclay Institute of Neuroscience (Neuro-PSI), UMR 9197, Université Paris-Sud, Orsay F-91405, France; CNRS, Orsay F-91405, France.
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Yildirim BO, Derksen JJL. Mesocorticolimbic dopamine functioning in primary psychopathy: A source of within-group heterogeneity. Psychiatry Res 2015; 229:633-77. [PMID: 26277034 DOI: 10.1016/j.psychres.2015.07.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 04/08/2015] [Accepted: 07/05/2015] [Indexed: 01/17/2023]
Abstract
Despite similar emotional deficiencies, primary psychopathic individuals can be situated on a continuum that spans from controlled to disinhibited. The constructs on which primary psychopaths are found to diverge, such as self-control, cognitive flexibility, and executive functioning, are crucially regulated by dopamine (DA). As such, the goal of this review is to examine which specific alterations in the meso-cortico-limbic DA system and corresponding genes (e.g., TH, DAT, COMT, DRD2, DRD4) might bias development towards a more controlled or disinhibited expression of primary psychopathy. Based on empirical data, it is argued that primary psychopathy is generally related to a higher tonic and population activity of striatal DA neurons and lower levels of D2-type DA receptors in meso-cortico-limbic projections, which may boost motivational drive towards incentive-laden goals, dampen punishment sensitivity, and increase future reward-expectancy. However, increasingly higher levels of DA activity in the striatum (moderate versus pathological elevations), lower levels of DA functionality in the prefrontal cortex, and higher D1-to-D2-type receptor ratios in meso-cortico-limbic projections may lead to increasingly disinhibited and impetuous phenotypes of primary psychopathy. Finally, in order to provide a more coherent view on etiological mechanisms, we discuss interactions between DA and serotonin that are relevant for primary psychopathy.
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Affiliation(s)
- Bariş O Yildirim
- Department of Clinical Psychology, Radboud University Nijmegen, De Kluyskamp 1002, 6545 JD Nijmegen, The Netherlands.
| | - Jan J L Derksen
- Department of Clinical Psychology, Room: A.07.04B, Radboud University Nijmegen, Montessorilaan 3, 6525 HR Nijmegen, The Netherlands.
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Rangel-Barajas C, Coronel I, Florán B. Dopamine Receptors and Neurodegeneration. Aging Dis 2015; 6:349-68. [PMID: 26425390 DOI: 10.14336/ad.2015.0330] [Citation(s) in RCA: 144] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2014] [Accepted: 03/30/2015] [Indexed: 01/19/2023] Open
Abstract
Dopamine (DA) is one of the major neurotransmitters and participates in a number of functions such as motor coordination, emotions, memory, reward mechanism, neuroendocrine regulation etc. DA exerts its effects through five DA receptors that are subdivided in 2 families: D1-like DA receptors (D1 and D5) and the D2-like (D2, D3 and D4). All DA receptors are widely expressed in the central nervous system (CNS) and play an important role in not only in physiological conditions but also pathological scenarios. Abnormalities in the DAergic system and its receptors in the basal ganglia structures are the basis Parkinson's disease (PD), however DA also participates in other neurodegenerative disorders such as Huntington disease (HD) and multiple sclerosis (MS). Under pathological conditions reorganization of DAergic system has been observed and most of the times, those changes occur as a mechanism of compensation, but in some cases contributes to worsening the alterations. Here we review the changes that occur on DA transmission and DA receptors (DARs) at both levels expression and signals transduction pathways as a result of neurotoxicity, inflammation and in neurodegenerative processes. The better understanding of the role of DA receptors in neuropathological conditions is crucial for development of novel therapeutic approaches to treat alterations related to neurodegenerative diseases.
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Affiliation(s)
- Claudia Rangel-Barajas
- 1Department of Psychological and Brain Sciences Program in Neurosciences, Indiana University Bloomington, Bloomington, IN 47405, USA ; 2Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Israel Coronel
- 3Health Sciences Faculty, Anahuac University, Mexico Norte, State of Mexico, Mexico
| | - Benjamín Florán
- 4Department of Physiology, Biophysics and Neurosciences CINVESTAV-IPN, Mexico
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42
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Role of basolateral amygdala dopamine D2 receptors in impulsive choice in acute cocaine-treated rats. Behav Brain Res 2015; 287:187-95. [DOI: 10.1016/j.bbr.2015.03.039] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 03/13/2015] [Accepted: 03/22/2015] [Indexed: 02/08/2023]
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Smith AP, Marshall AT, Kirkpatrick K. Mechanisms of impulsive choice: II. Time-based interventions to improve self-control. Behav Processes 2015; 112:29-42. [PMID: 25444771 PMCID: PMC4314470 DOI: 10.1016/j.beproc.2014.10.010] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 09/29/2014] [Accepted: 10/22/2014] [Indexed: 02/03/2023]
Abstract
Impulsive choice behavior has been proposed as a primary risk factor for other maladaptive behaviors (e.g., gambling, substance abuse). Recent research has suggested that timing processes may play a key role in impulsive choice behavior, and could provide an avenue for altering impulsive choice. Accordingly, the current experiments assessed a set of time-based behavioral interventions to increase self-control while simultaneously assessing effects on timing processes within the impulsive choice task. Three experiments assessed temporal interventions using a differential reinforcement of low rates task (Experiment 1) and exposure to either a variable or fixed interval schedule (Experiments 2-3). The efficacy of the interventions was assessed in Sprague-Dawley (Experiments 1-2) and Lewis (Experiment 3) rat strains. Impulsive choice behavior was assessed by measuring preferences of a smaller-sooner (SS) versus a larger-later (LL) reward, while timing of the SS and LL durations was measured during peak trials within the impulsive choice procedure. The rats showed an increased preference for the LL following all three time-based interventions and also displayed increased temporal precision. These results add to the increasing evidence that supports a possible role for temporal processing in impulsive choice behavior and supply novel behavioral interventions to decrease impulsive behavior.
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Affiliation(s)
- Aaron P Smith
- Department of Psychological Sciences, Kansas State University, 492 Bluemont Hall, 1100 Mid-Campus, Manhattan, KS 66506-5302, United States
| | - Andrew T Marshall
- Department of Psychological Sciences, Kansas State University, 492 Bluemont Hall, 1100 Mid-Campus, Manhattan, KS 66506-5302, United States
| | - Kimberly Kirkpatrick
- Department of Psychological Sciences, Kansas State University, 492 Bluemont Hall, 1100 Mid-Campus, Manhattan, KS 66506-5302, United States.
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44
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Do the adjusting-delay and increasing-delay tasks measure the same construct: delay discounting? Behav Pharmacol 2015; 25:306-15. [PMID: 24978484 DOI: 10.1097/fbp.0000000000000055] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Delay discounting describes the subjective devaluation of a reward when it is delayed. In animals, the adjusting-delay (AD) and increasing-delay (ID) tasks often are used to assess individual differences in, and drug effects on, delay discounting. No study to date, however, has compared systematically the measures of discounting produced in these tasks. The current study examined the correlation between measures of delay discounting derived from AD and ID procedures. Twenty rats completed 30 sessions under each task (order counterbalanced across rats). Quantitative measures of delay discounting produced by the two tasks were positively correlated, suggesting that the AD and ID tasks measure the same underlying facet of impulsive choice (i.e. individual or conjoint sensitivities to reward delay and magnitude). The measures derived from either task, however, depended on the sequences in which the tasks were experienced. That is, pre-exposure to one task decreased discounting of delayed rewards in the second task. Consistent with other published findings, exposure to delayed consequences during the initial discounting assessment might explain this effect. Despite the observed correlation between ID and AD indifference delays, we suggest that the ID procedure might be a more appropriate procedure for pharmacological studies.
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45
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Jupp B, Dalley JW. Convergent pharmacological mechanisms in impulsivity and addiction: insights from rodent models. Br J Pharmacol 2014; 171:4729-66. [PMID: 24866553 PMCID: PMC4209940 DOI: 10.1111/bph.12787] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 05/02/2014] [Accepted: 05/12/2014] [Indexed: 01/15/2023] Open
Abstract
Research over the last two decades has widely demonstrated that impulsivity, in its various forms, is antecedent to the development of drug addiction and an important behavioural trait underlying the inability of addicts to refrain from continued drug use. Impulsivity describes a variety of rapidly and prematurely expressed behaviours that span several domains from impaired response inhibition to an intolerance of delayed rewards, and is a core symptom of attention deficit hyperactivity disorder (ADHD) and other brain disorders. Various theories have been advanced to explain how impulsivity interacts with addiction both causally and as a consequence of chronic drug abuse; these acknowledge the strong overlaps in neural circuitry and mechanisms between impulsivity and addiction and the seemingly paradoxical treatment of ADHD with stimulant drugs with high abuse potential. Recent years have witnessed unprecedented progress in the elucidation of pharmacological mechanisms underpinning impulsivity. Collectively, this work has significantly improved the prospect for new therapies in ADHD as well as our understanding of the neural mechanisms underlying the shift from recreational drug use to addiction. In this review, we consider the extent to which pharmacological interventions that target impulsive behaviour are also effective in animal models of addiction. We highlight several promising examples of convergence based on empirical findings in rodent-based studies.
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Affiliation(s)
- B Jupp
- Behavioural and Clinical Neuroscience Institute and Department of Psychology, University of CambridgeCambridge, UK
- Florey Institute of Neuroscience and Mental Health, University of MelbourneParkville, Australia
| | - J W Dalley
- Behavioural and Clinical Neuroscience Institute and Department of Psychology, University of CambridgeCambridge, UK
- Department of Psychiatry, University of CambridgeCambridge, UK
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Abstract
Impulsivity is associated with various psychopathologies, and elevated impulsivity is typically disadvantageous. This manuscript reviews recent investigations into the neurobiology of impulsivity using human imaging techniques and animal models. Both human imaging and preclinical pharmacological manipulations have yielded important insights into the neurobiological underpinnings of impulsivity. A more thorough understanding of the complex neurobiology underlying aspects of impulsivity may provide insight into new treatment options that target elevated impulsivity and psychopathologies such as addictions.
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Affiliation(s)
- Marci R Mitchell
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT
| | - Marc N Potenza
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT ; Department of Neurobiology, Yale University School of Medicine, New Haven, CT ; Child Study Center, Yale University School of Medicine, New Haven, CT
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47
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Mitchell MR, Weiss VG, Ouimet DJ, Fuchs RA, Morgan D, Setlow B. Intake-dependent effects of cocaine self-administration on impulsive choice in a delay discounting task. Behav Neurosci 2014; 128:419-29. [PMID: 24841739 PMCID: PMC4107092 DOI: 10.1037/a0036742] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cocaine use is associated with high levels of impulsive choice (greater discounting of delayed rewards) in humans, but the cause/effect relationships between cocaine use and impulsive choice are not fully understood. In previous work, we found that both experimenter- and self-administration of fixed quantities of cocaine caused lasting increases in impulsive choice in rats. The present study extended these findings by taking into account baseline impulsive choice prior to self-administration and by allowing rats free access to cocaine. Male Long-Evans rats were trained in a delay discounting task in which they made discrete-trial choices between small immediate and large delayed food rewards. Half of the rats were then implanted with intravenous catheters and, following recovery, allowed to self-administer cocaine HCl (1.0 mg/kg/infusion) in 6-hr sessions over 14 days. Control rats orally self-administered a sucrose solution under similar conditions. Upon completion of self-administration, rats remained abstinent for 3 weeks before retesting in the delay discounting task. Cocaine and control groups did not differ prior to self-administration, but afterward, the cocaine group showed greater impulsive choice (fewer choices of large, delayed rewards) than controls. Additional analyses revealed that the effects of cocaine on impulsive choice were intake-dependent; rats classified as "low intake" did not differ from controls, whereas rats classified as "high intake" were significantly more impulsive than both controls and their precocaine baseline. These findings are consistent with the idea that cocaine-induced, pharmacologically based neural adaptations promote the development of impulsive decision making.
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Affiliation(s)
- Marci R. Mitchell
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT
| | | | - Dominique J. Ouimet
- Department of Psychiatry, University of Florida College of Medicine, Gainesville, FL
| | - Rita A. Fuchs
- Integrative Physiology and Neuroscience, Washington State University College of Veterinary Medicine, Pullman, WA
| | - Drake Morgan
- Department of Psychiatry, University of Florida College of Medicine, Gainesville, FL
| | - Barry Setlow
- Department of Psychiatry, University of Florida College of Medicine, Gainesville, FL
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL
- Department of Psychology, University of Florida, Gainesville, FL
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Moschak TM, Mitchell SH. Partial inactivation of nucleus accumbens core decreases delay discounting in rats without affecting sensitivity to delay or magnitude. Behav Brain Res 2014; 268:159-68. [PMID: 24704637 PMCID: PMC4084517 DOI: 10.1016/j.bbr.2014.03.044] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Revised: 03/21/2014] [Accepted: 03/25/2014] [Indexed: 10/25/2022]
Abstract
Increased preference for smaller, sooner rewards (delay discounting) is associated with several behavioral disorders, including ADHD and substance use disorders. However, delay discounting is a complex cognitive process and the relationship is unclear between the pathophysiology of the disorders and the component processes underlying delay discounting, including sensitivity to reinforcer delay and sensitivity to reinforcer magnitude. To investigate these processes, male Long Evans rats were trained in one of three tasks measuring sensitivity to delay, sensitivity to magnitude, or both (typical delay discounting task). After learning the task, animals were implanted with bilateral cannulae into either the nucleus accumbens core (AcbC) or the lateral orbitofrontal cortex (lOFC), both of which have been implicated in delay discounting. Upon recovering from the surgery, a baclofen/muscimol cocktail was infused to temporarily inactivate each of these two regions and task performance was assessed. Unlike previous studies showing that lesions of the AcbC increased delay discounting, partial inactivation of the AcbC decreased delay discounting, although it had no effects on the tasks independently assessing either sensitivity to delay or magnitude. The effects of AcbC inactivation were larger in animals that had low levels of delay discounting at baseline. Inactivation of the lOFC had no effects on behavior in any task. These findings suggest that the AcbC may act to promote impulsive choice in individuals with low impulsivity. Furthermore, the data suggest that the AcbC is able to modulate delay and magnitude sensitivity together, but not either of the two in isolation.
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Yates JR, Perry JL, Meyer AC, Gipson CD, Charnigo R, Bardo MT. Role of medial prefrontal and orbitofrontal monoamine transporters and receptors in performance in an adjusting delay discounting procedure. Brain Res 2014; 1574:26-36. [PMID: 24928616 DOI: 10.1016/j.brainres.2014.06.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Revised: 06/02/2014] [Accepted: 06/03/2014] [Indexed: 11/29/2022]
Abstract
Performance in an adjusting delay discounting procedure is predictive of drug abuse vulnerability; however, the shared underlying specific prefrontal neural systems linking delay discounting and increased addiction-like behaviors are unclear. Rats received direct infusions of methylphenidate (MPH; 6.25, 25.0, or 100μg), amphetamine (AMPH; 0.25, 1.0, or 4.0μg), or atomoxetine (ATO; 1.0, 4.0, or 16.0μg) into either medial prefrontal cortex (mPFC) or orbitofrontal cortex (OFC) immediately prior to performance in an adjusting delay task. These drugs were examined because they are efficacious in treating impulse control disorders. Because dopamine (DA) and serotonin (5-HT) receptors are implicated in impulsive behavior, separate groups of rats received microinfusions of the DA receptor-selective drugs SKF 81297 (0.1 or 0.4µg), SCH 23390 (0.25 or 1.0µg), quinpirole (1.25 or 5.0µg), and eticlopride (0.25 or 1.0µg), or received microinfusions of the 5-HT receptor-selective drugs 8-OH-DPAT (0.025 or 0.1μg), WAY 100635 (0.01 or 0.04μg), DOI (2.5 or 10.0μg), and ketanserin (0.1 or 0.4μg). Impulsive choice was not altered significantly by MPH, AMPH, or ATO into either mPFC or OFC, indicating that neither of these prefrontal regions alone may mediate the systemic effect of ADHD medications on impulsive choice. However, quinpriole (1.25μg) and eticlopride infused into mPFC increased impulsive choice, whereas 8-OH-DPAT infused into OFC decreased impulsive choice. These latter results demonstrate that blockade of DA D2 receptors in mPFC or activation of 5-HT1A receptors in OFC increases impulsive choice in the adjusting delay procedure.
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Affiliation(s)
- Justin R Yates
- Department of Psychology, University of Kentucky, Lexington, KY 40536, USA; Center for Drug Abuse Research Translation, University of Kentucky, Lexington, KY 40536, USA
| | - Jennifer L Perry
- Department of Psychology, Kalamazoo College, Kalamazoo, MI 49006, USA
| | - Andrew C Meyer
- Department of Psychiatry, University of Vermont, Burlington VT 05401, USA
| | - Cassandra D Gipson
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Richard Charnigo
- Department of Biostatistics, University of Kentucky, Lexington, KY 40506, USA; Center for Drug Abuse Research Translation, University of Kentucky, Lexington, KY 40536, USA
| | - Michael T Bardo
- Department of Psychology, University of Kentucky, Lexington, KY 40536, USA; Center for Drug Abuse Research Translation, University of Kentucky, Lexington, KY 40536, USA.
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Kirkpatrick K, Marshall AT, Clarke J, Cain ME. Environmental rearing effects on impulsivity and reward sensitivity. Behav Neurosci 2014; 127:712-24. [PMID: 24128360 DOI: 10.1037/a0034124] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Previous research has indicated that rearing in an enriched environment may promote self-control in an impulsive choice task. To further assess the effects of rearing environment on impulsivity, 2 experiments examined locomotor activity, impulsive action, impulsive choice, and different aspects of reward sensitivity and discrimination. In Experiment 1, rats reared in isolated or enriched conditions were tested on an impulsive choice procedure with a smaller-sooner versus a larger-later reward, revealing that the isolated rats valued the smaller-sooner reward more than the enriched rats. A subsequent reward challenge was presented in which the delay to the 2 rewards was the same but the magnitude difference remained. The enriched rats did not choose the larger reward as often as the isolated rats, reflecting poorer reward discrimination. Impulsive action was assessed using a differential-reinforcement-of-low-rate task, which revealed deficits in the enriched rats. In Experiment 2, rats reared in isolated, standard, or enriched conditions were tested on reward contrast and reward magnitude sensitivity procedures. The rats were presented with 2 levers that delivered different magnitudes of food on variable interval 30-s schedules. Across all tests, the enriched and social rats displayed more generalized responding to the small-reward lever, but a similar response to the large-reward lever, compared with the isolated rats. This confirmed the results of Experiment 1, indicating poorer reward discrimination in the enriched condition compared with the isolated condition. The results suggest that enrichment may moderate reward generalization/discrimination processes through alterations in incentive motivational processes.
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