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Tchalova K, Lydon JE, Atkinson L, Fleming AS, Kennedy J, Lecompte V, Meaney MJ, Moss E, O'Donnell KA, O'Donnell KJ, Silveira PP, Sokolowski MB, Steiner M, Bartz JA. Variation in the mu-opioid receptor gene (OPRM1) moderates the influence of maternal sensitivity on child attachment. Transl Psychiatry 2024; 14:181. [PMID: 38580654 PMCID: PMC10997775 DOI: 10.1038/s41398-024-02888-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 03/15/2024] [Accepted: 03/20/2024] [Indexed: 04/07/2024] Open
Abstract
The endogenous opioid system is thought to play an important role in mother-infant attachment. In infant rhesus macaques, variation in the μ-opioid receptor gene (OPRM1) is related to differences in attachment behavior that emerges following repeated separation from the mother; specifically, infants carrying at least one copy of the minor G allele of the OPRM1 C77G polymorphism show heightened and more persistent separation distress, as well as a pattern of increased contact-seeking behavior directed towards the mother during reunions (at the expense of affiliation with other group members). Research in adult humans has also linked the minor G allele of the analogous OPRM1 A118G polymorphism with greater interpersonal sensitivity. Adopting an interactionist approach, we examined whether OPRM1 A118G genotype and maternal (in)sensitivity are associated with child attachment style, predicting that children carrying the G allele may be more likely to develop an ambivalent attachment pattern in response to less sensitive maternal care. The sample consisted of 191 mothers participating with their children (n = 223) in the Maternal Adversity, Vulnerability and Neurodevelopment (MAVAN) project, a community-based, birth cohort study of Canadian mothers and their children assessed longitudinally across the child's development. Maternal sensitivity was coded from at-home mother-child interactions videotaped when the child was 18 months of age. Child attachment was assessed at 36 months using the Strange Situation paradigm. As predicted, G allele carriers, but not AA homozygotes, showed increasing odds of being classified as ambivalently attached with decreasing levels of maternal sensitivity. Paralleling earlier non-human animal research, this work provides support for the theory that endogenous opioids contribute to the expression of attachment behaviors in humans.
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Affiliation(s)
- K Tchalova
- Department of Psychology, McGill University, Montréal, QC, Canada
| | - J E Lydon
- Department of Psychology, McGill University, Montréal, QC, Canada
| | - L Atkinson
- Department of Psychology, Toronto Metropolitan University, Toronto, ON, Canada
| | - A S Fleming
- Department of Psychology, University of Toronto Mississauga, Toronto, ON, Canada
| | - J Kennedy
- Department of Psychiatry, University of Toronto, Toronto, ON, Canada
| | - V Lecompte
- L'Université du Québec à Montréal, Montréal, QC, Canada
| | - M J Meaney
- Department of Psychology, McGill University, Montréal, QC, Canada
- Douglas Research Centre, Montréal, QC, Canada
- Singapore Institute for Clinical Sciences, A*STAR, Singapore, Singapore
| | - E Moss
- L'Université du Québec à Montréal, Montréal, QC, Canada
| | - K A O'Donnell
- Yale School of Medicine, Yale University, New Haven, CT, USA
| | - K J O'Donnell
- Department of Psychology, Simon Fraser University, Burnaby, BC, Canada
| | - P P Silveira
- Department of Psychiatry, McGill University, Montréal, QC, Canada
| | - M B Sokolowski
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada
| | - M Steiner
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON, Canada
| | - J A Bartz
- Department of Psychology, McGill University, Montréal, QC, Canada.
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2
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Rusu AS. Endogenous Opioids and Volunteering: On the Evolutionary Significance of Helping Others. ADVANCES IN NEUROBIOLOGY 2024; 35:251-265. [PMID: 38874727 DOI: 10.1007/978-3-031-45493-6_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2024]
Abstract
The human tendency to help others in need has been subject to trans-, inter-, and multidisciplinary studies (e.g., anthropology, neurobiology, evolutionary psychology, economy), within the frame of studying the mechanisms and adaptive significance of human prosocial behavior. Volunteering directed to unrelated and unfamiliar individuals is one common form of such helping behavior. Helping others may be adaptive for a species at a macro-level, which in turn is mediated by neurobiological mechanisms. A key target for analysis of the neurobiological underpinnings of volunteering is the endogenous opioid system (EOS). This chapter discusses EOS activity as a potential mediator of volunteering behavior. Evidence of the congruence between EOS involvement in social group behavior and social bonding and the role of these phenomena in volunteerism is reviewed. Models and empirical evidence of the mechanisms and adaptive value of helping unrelated others are discussed and integrated, including the mammalian caregiving system, the neurobiological model of prosocial behavior, synchrony promoting social bonding, and stress-driven motivation of prosocial action in immediate needs.
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Affiliation(s)
- Alina Simona Rusu
- Department of Fundamental Sciences, Faculty of Animal Science and Biotechnologies, University of Agricultural Sciences and Veterinary Medicine, Cluj-Napoca, Romania.
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3
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Bartlett A, Grinsted L, Freeman MS. Behaviour, Furnishing and Vertical Space Use of Captive Callimico ( Callimico goeldii): Implications for Welfare. Animals (Basel) 2023; 13:2147. [PMID: 37443945 DOI: 10.3390/ani13132147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 06/22/2023] [Accepted: 06/24/2023] [Indexed: 07/15/2023] Open
Abstract
Provision of optimal captive care should be supported by species-specific evidence. Callimico (Callimico goeldii) is a small South American callitrichid primate. This study sought to address gaps in species-specific knowledge and captive management research by examining differences in callimico behaviour across multiple collections, investigating vertical enclosure use and a possible association between specific behaviours and vertical zones. Observational research was conducted at five European Association of Zoos and Aquaria (EAZA) organisations, in exhibits that were visually divided into four vertical zones. Instantaneous scan sampling was used to record behaviour and location of callimico over a six-day period at each collection, exceeding 160 observational hours. Significant differences were observed in foraging between collections and were much lower than the recommendations in Best Practice Guidelines, although near-wild levels were recorded in one enclosure. At an average height of 2 m, callimico utilized a similar vertical space across very different enclosures, regardless of overall available height, reflective of their natural ecology. The association between whole food items and increased foraging time, horizontal branches and locomotion and deep substrate and diversity of behaviours, offers further species-specific evidence of how the callimico use their captive environment. Our findings complement current EAZA guidelines to support species appropriate care for callimico and makes specific recommendations for further research.
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Affiliation(s)
- Amanda Bartlett
- School of Biological Sciences, University of Portsmouth, Portsmouth PO1 2UP, UK
| | - Lena Grinsted
- School of Biological Sciences, University of Portsmouth, Portsmouth PO1 2UP, UK
| | - Marianne Sarah Freeman
- Animal Health and Welfare Research, University Centre Sparsholt, Winchester SO21 2NF, UK
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4
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Naturalistic learning and reproduction in ring neck doves (Streptopelia risoria). Learn Behav 2022; 50:298-305. [DOI: 10.3758/s13420-022-00534-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/27/2022] [Indexed: 11/08/2022]
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5
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Putnam PT, Chang SWC. Interplay between the oxytocin and opioid systems in regulating social behaviour. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210050. [PMID: 35858101 PMCID: PMC9272147 DOI: 10.1098/rstb.2021.0050] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 04/25/2022] [Indexed: 07/30/2023] Open
Abstract
The influence of neuromodulators on brain activity and behaviour is undeniably profound, yet our knowledge of the underlying mechanisms, or ability to reliably reproduce effects across varying conditions, is still lacking. Oxytocin, a hormone that acts as a neuromodulator in the brain, is an example of this quandary; it powerfully shapes behaviours across nearly all mammalian species, yet when manipulated exogenously can produce unreliable or sometimes unexpected behavioural results across varying contexts. While current research is rapidly expanding our understanding of oxytocin, interactions between oxytocin and other neuromodulatory systems remain underappreciated in the current literature. This review highlights interactions between oxytocin and the opioid system that serve to influence social behaviour and proposes a parallel-mechanism hypothesis to explain the supralinear effects of combinatorial neuropharmacological approaches. This article is part of the theme issue 'Interplays between oxytocin and other neuromodulators in shaping complex social behaviours'.
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Affiliation(s)
- Philip T. Putnam
- Department of Psychology, Yale University, New Haven, CT 06520, USA
| | - Steve W. C. Chang
- Department of Psychology, Yale University, New Haven, CT 06520, USA
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA
- Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA
- Wu Tsai Institute, Yale University, New Haven, CT 06510, USA
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6
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The effects of allogrooming and social network position on behavioural indicators of stress in female lion-tailed macaques (Macaca silenus). Behav Processes 2022; 202:104740. [PMID: 36038022 DOI: 10.1016/j.beproc.2022.104740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 08/18/2022] [Accepted: 08/24/2022] [Indexed: 11/24/2022]
Abstract
Allogrooming serves an important social function in primates and confers short term benefits such as parasite removal and stress-relief. There is currently mixed evidence as to the immediate impact of allogrooming on an individual's stress levels, which may be influenced by their role in the grooming dyad, position in their social network, or their relationship with their grooming partner. In this study of seven captive adult female lion-tailed macaques (Macaca silenus) in a mixed sex group at Chester Zoo, UK, we found evidence to support a tension-reduction function of allogrooming. Focal animal sampling showed that the duration of self-directed behaviour (SDB), which indicates moderate to high levels of stress, was significantly lower in the five-minute period following allogrooming than the five-minute minute period preceding it for both recipients and groomers. However, when compared to match-control periods, both SDB rates and durations were significantly lower across all individuals in the five-minute period both before and after allogrooming, indicating that although allogrooming reduces stress, it is also more likely to occur when individuals are already in a relatively relaxed state. The rate and duration of SDB post-grooming did not correlate with the strength of a dyad's bond (based on proximity). This suggests that it is the act of allogrooming itself, rather than the identity of the partner, that reduces stress for both parties. Analysis of the proximity network highlighted a clear cost to social integration; node strength, a measure of the number and strength of an individual's direct relationships, positively correlated with the duration of self-directed behaviour, suggesting that more gregarious individuals may experience higher levels of stress. These findings add to the growing body of literature that examines the effect of the individual social environment on primate stress levels, and also highlight the need to further investigate the link between social integration and the stress experienced by group-living animals.
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7
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Cultural transmission of traditional songs in the Ryukyu Archipelago. PLoS One 2022; 17:e0270354. [PMID: 35749479 PMCID: PMC9231793 DOI: 10.1371/journal.pone.0270354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 06/08/2022] [Indexed: 11/19/2022] Open
Abstract
Geographic patterns of cultural variations are affected by how cultural traits are transmitted within and between populations. It has been argued that cultural traits are transmitted in different manners depending on their characteristics; for example, words for basic concepts are less liable to horizontal transmission between populations (i.e., borrowing) than other words. Here we examine the geographic variation of traditional songs in the Ryukyu Archipelago, southwestern islands of Japan, to explore cultural evolution of music with a focus on different social contexts in which songs are sung. Published scores of 1,342 traditional songs are coded using the CantoCore song classification scheme and distances between the songs are calculated from the codings. Neighbor-Net graphs of regions/islands are generated on the basis of the musical distances, and delta scores are obtained to examine the treelikeness of the networks. We also perform analysis of molecular variance (AMOVA) to evaluate the extent of musical diversification among regions/islands. Our results suggest that horizontal transmission between populations has played a greater role in the formation of musical diversity than that of linguistic diversity in the Ryukyu Archipelago and that the social context in which songs are sung has an effect on how they are transmitted within and between populations. In addition, we compare the observed patterns of song diversity among regions/islands with those of lexical and mitochondrial-DNA (mtDNA) diversity, showing that the variation of songs sung in the "work" context are associated with the linguistic variation, whereas no association is found between the musical and genetic variation.
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8
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Beckes L, Medina-DeVilliers SE, Gunderson EW, Coan JA. Mechanisms supporting the social regulation of neural threat responding with marital partners: A test of the opioid hypothesis. Psychophysiology 2022; 59:e14076. [PMID: 35438799 DOI: 10.1111/psyp.14076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 12/26/2021] [Accepted: 03/26/2022] [Indexed: 11/28/2022]
Abstract
Positive social contact predicts better health, but the mechanisms for this association remain debated. One way to explore this link is through the social regulation of emotion, particularly anticipatory anxiety. Previous research finds less neural threat response during partner handholding than when people are alone or stranger handholding. Various mechanistic accounts have been forwarded, including the hypothesis that this effect is mediated by endogenous opioid activity. This experiment critically tested the opioid hypothesis in 60 married participants and their partners. The study used a naltrexone opioid blockade in a double-blind placebo control with functional magnetic resonance imaging to determine whether endogenous opioids were necessary for handholding effects. Regulatory effects of supportive handholding manifested in threat network regions during opioid blockade, but not with placebo. Despite a surprising lack of effect in the placebo group, the overall study findings provide initial evidence that endogenous opioids may not be necessary for the social regulation of neural threat responding.
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Affiliation(s)
- Lane Beckes
- Department of Psychology, Bradley University, Peoria, Illinois, USA
| | | | - Erik W Gunderson
- Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, Virginia, USA
| | - James A Coan
- Department of Psychology, University of Virginia, Charlottesville, Virginia, USA
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9
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Vitale EM, Smith AS. Neurobiology of Loneliness, Isolation, and Loss: Integrating Human and Animal Perspectives. Front Behav Neurosci 2022; 16:846315. [PMID: 35464141 PMCID: PMC9029604 DOI: 10.3389/fnbeh.2022.846315] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Accepted: 02/21/2022] [Indexed: 12/30/2022] Open
Abstract
In social species such as humans, non-human primates, and even many rodent species, social interaction and the maintenance of social bonds are necessary for mental and physical health and wellbeing. In humans, perceived isolation, or loneliness, is not only characterized by physical isolation from peers or loved ones, but also involves negative perceptions about social interactions and connectedness that reinforce the feelings of isolation and anxiety. As a complex behavioral state, it is no surprise that loneliness and isolation are associated with dysfunction within the ventral striatum and the limbic system - brain regions that regulate motivation and stress responsiveness, respectively. Accompanying these neural changes are physiological symptoms such as increased plasma and urinary cortisol levels and an increase in stress responsivity. Although studies using animal models are not perfectly analogous to the uniquely human state of loneliness, studies on the effects of social isolation in animals have observed similar physiological symptoms such as increased corticosterone, the rodent analog to human cortisol, and also display altered motivation, increased stress responsiveness, and dysregulation of the mesocortical dopamine and limbic systems. This review will discuss behavioral and neuropsychological components of loneliness in humans, social isolation in rodent models, and the neurochemical regulators of these behavioral phenotypes with a neuroanatomical focus on the corticostriatal and limbic systems. We will also discuss social loss as a unique form of social isolation, and the consequences of bond disruption on stress-related behavior and neurophysiology.
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Affiliation(s)
- Erika M. Vitale
- Department of Pharmacology and Toxicology, School of Pharmacy, University of Kansas, Lawrence, KS, United States
| | - Adam S. Smith
- Department of Pharmacology and Toxicology, School of Pharmacy, University of Kansas, Lawrence, KS, United States
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10
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Gothard KM, Fuglevand AJ. The role of the amygdala in processing social and affective touch. Curr Opin Behav Sci 2022; 43:46-53. [PMID: 35602667 PMCID: PMC9119433 DOI: 10.1016/j.cobeha.2021.08.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The amygdala plays a central role in emotion and social behavior, yet its role in processing social and affective touch is not well established. Longitudinal studies reveal that touch-deprived infants show later in life exaggerated emotional reactivity related to structural and functional changes in the amygdala and other brain structures. The internal organization and connectivity of the amygdala is well-suited to process the sensory features of tactile stimuli and also the socio-cognitive dimensions of the received touch. The convergent processing of bottom-up and top-down pathways that carry information about touch results in the elaboration of context appropriate autonomic responses. Indeed, the positive value of affective touch in humans and social grooming in non-human primates is correlated with vagal tone and the release of oxytocin and endogenous opioids. Grooming, the non-human primate equivalent of affective touch in humans, reduces vigilance, that depends on the amygdala. During touch-induced vagal tone and low vigilance, neural activity in the amygdala is substantially different from activity corresponding to the attentive processing of tactile stimuli. Under these circumstances neurons no longer respond phasically to each touch stimulus, rather they signal a sustained functional state in which the amygdala appears decoupled from monitoring the external environment.
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Affiliation(s)
- Katalin M Gothard
- Departments of Physiology and Neuroscience, College of Medicine, University of Arizona, Tucson, AZ, USA
| | - Andrew J Fuglevand
- Departments of Physiology and Neuroscience, College of Medicine, University of Arizona, Tucson, AZ, USA
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11
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Dunbar RIM, Frangou A, Grainger F, Pearce E. Laughter influences social bonding but not prosocial generosity to friends and strangers. PLoS One 2021; 16:e0256229. [PMID: 34388212 PMCID: PMC8362988 DOI: 10.1371/journal.pone.0256229] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 08/03/2021] [Indexed: 12/30/2022] Open
Abstract
Humans deploy a number of specific behaviours for forming social bonds, one of which is laughter. However, two questions have not yet been investigated with respect to laughter: (1) Does laughter increase the sense of bonding to those with whom we laugh? and (2) Does laughter facilitate prosocial generosity? Using changes in pain threshold as a proxy for endorphin upregulation in the brain and a standard economic game (the Dictator Game) as an assay of prosociality, we show that laughter does trigger the endorphin system and, through that, seems to enhance social bonding, but it does not reliably influence donations to others. This suggests that social bonding and prosociality may operate via different mechanisms, or on different time scales, and relate to different functional objectives.
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Affiliation(s)
- R. I. M. Dunbar
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
| | - Anna Frangou
- Big Data Institute, University of Oxford, Oxford, United Kingdom
| | - Felix Grainger
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
| | - Eiluned Pearce
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
- Department of Psychiatry, University College London, London, United Kingdom
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12
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Dunbar RIM, Pearce E, Tarr B, Makdani A, Bamford J, Smith S, McGlone F. Cochlear SGN neurons elevate pain thresholds in response to music. Sci Rep 2021; 11:14547. [PMID: 34267302 PMCID: PMC8282857 DOI: 10.1038/s41598-021-93969-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 06/28/2021] [Indexed: 11/22/2022] Open
Abstract
The C-tactile (CLTM) peripheral nervous system is involved in social bonding in primates and humans through its capacity to trigger the brain’s endorphin system. Since the mammalian cochlea has an unusually high density of similar neurons (type-II spiral ganglion neurons, SGNs), we hypothesise that their function may have been exploited for social bonding by co-opting head movements in response to music and other rhythmic movements of the head in social contexts. Music provides one of many cultural behavioural mechanisms for ‘virtual grooming’ in that it is used to trigger the endorphin system with many people simultaneously so as to bond both dyadic relationships and large groups. Changes in pain threshold across an activity are a convenient proxy assay for endorphin uptake in the brain, and we use this, in two experiments, to show that pain thresholds are higher when nodding the head than when sitting still.
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Affiliation(s)
- R I M Dunbar
- Department of Experimental Psychology, University of Oxford, Anna Watts Building, Radcliffe Observatory Quarter, Oxford, OX1 6GG, UK.
| | - Eiluned Pearce
- Department of Experimental Psychology, University of Oxford, Anna Watts Building, Radcliffe Observatory Quarter, Oxford, OX1 6GG, UK.,Division of Psychiatry, University College London, London, WC1A 4AA, UK
| | - Bronwyn Tarr
- Institute of Cognitive and Evolutionary Anthropology, University of Oxford, Banbury Road, Oxford, OX2 6PE, UK
| | - Adarsh Makdani
- Research Centre Brain and Behaviour, Liverpool John Moores University, Liverpool, L3 3AF, UK
| | - Joshua Bamford
- Institute of Cognitive and Evolutionary Anthropology, University of Oxford, Banbury Road, Oxford, OX2 6PE, UK
| | - Sharon Smith
- Research Centre Brain and Behaviour, Liverpool John Moores University, Liverpool, L3 3AF, UK
| | - Francis McGlone
- Research Centre Brain and Behaviour, Liverpool John Moores University, Liverpool, L3 3AF, UK.,Institute of Psychology, Health and Society, University of Liverpool, Liverpool, UK
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13
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Brown JG. Ticks, Hair Loss, and Non-Clinging Babies: A Novel Tick-Based Hypothesis for the Evolutionary Divergence of Humans and Chimpanzees. Life (Basel) 2021; 11:435. [PMID: 34066043 PMCID: PMC8150933 DOI: 10.3390/life11050435] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 04/12/2021] [Accepted: 04/30/2021] [Indexed: 02/06/2023] Open
Abstract
Human straight-legged bipedalism represents one of the earliest events in the evolutionary split between humans (Homo spp.) and chimpanzees (Pan spp.), although its selective basis is a mystery. A carrying-related hypothesis has recently been proposed in which hair loss within the hominin lineage resulted in the inability of babies to cling to their mothers, requiring mothers to walk upright to carry their babies. However, a question remains for this model: what drove the hair loss that resulted in upright walking? Observers since Darwin have suggested that hair loss in humans may represent an evolutionary strategy for defence against ticks. The aim of this review is to propose and evaluate a novel tick-based evolutionary hypothesis wherein forest fragmentation in hominin paleoenvironments created conditions that were favourable for tick proliferation, selecting for hair loss in hominins and grooming behaviour in chimpanzees as divergent anti-tick strategies. It is argued that these divergent anti-tick strategies resulted in different methods for carrying babies, driving the locomotor divergence of humans and chimpanzees.
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14
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Inagaki TK, Hazlett LI, Andreescu C. Opioids and social bonding: Effect of naltrexone on feelings of social connection and ventral striatum activity to close others. J Exp Psychol Gen 2020; 149:732-745. [PMID: 31414860 PMCID: PMC7021584 DOI: 10.1037/xge0000674] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Close social bonds are critical to immediate and long-term well-being. However, the neurochemical mechanisms by which we remain connected to our closest loved ones are not well understood. Opioids have long been theorized to contribute to social bonding via their actions on the brain. But feelings of social connection toward one's own close others and direct comparisons of ventral striatum (VS) activity in response to close others and strangers, a neural correlate of social bonding, have not been explored. Therefore, the current clinical trial examined whether opioids causally affect neural and experiential signatures of social bonding. Eighty participants were administered naltrexone (n = 40), an opioid antagonist that blocks natural opioid processing, or placebo (n = 40) before completing a functional MRI scan where they viewed images of their close others and individuals they had not seen before (i.e., strangers). Feelings of social connection to the close others and physical symptoms commonly experienced when taking naltrexone were also collected. In support of hypotheses, naltrexone (vs. placebo) reduced feelings of social connection toward the close others (e.g., family, friends, romantic partners). Furthermore, naltrexone (vs. placebo) reduced left VS activity in response to images of the same close others, but did not alter left VS activity to strangers. Finally, the positive correlation between feelings of connection and VS activity to close others present in the placebo condition was erased by naltrexone. Effects remained after adjusting for physical symptoms. Together, results lend support to theories suggesting that opioids contribute to social bonding, especially with our closest loved ones. (PsycINFO Database Record (c) 2020 APA, all rights reserved).
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Affiliation(s)
| | | | - Carmen Andreescu
- University of Pittsburgh School of Medicine, Department of Psychiatry, Pittsburgh, PA
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15
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Taneja P, Olausson H, Trulsson M, Vase L, Svensson P, Baad-Hansen L. Modulation of experimental facial pain via somatosensory stimuli targeting sensations of different valence. J Oral Rehabil 2020; 47:720-730. [PMID: 32187404 DOI: 10.1111/joor.12963] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 02/07/2020] [Accepted: 03/12/2020] [Indexed: 11/25/2022]
Abstract
BACKGROUND Knowledge of pain modulation from oro-facial somatosensory stimuli with different valence (pleasant-unpleasant) is limited. OBJECTIVES To investigate (a) the modulatory effects of painful, pleasant and unpleasant somatosensory stimuli on two models of experimental facial pain, (b) whether modulation could be changed by blocking peripheral nerves via application of a local anaesthetic, EMLA, or blocking endogenous opioid receptors via naltrexone and (c) whether pain ratings were significantly correlated with participant psychological profiles. METHODS Thirty-eight healthy women received experimental facial skin burning pain or jaw myalgia for four randomised sessions on different days. The painful region was stimulated with mechanical or thermal painful, pleasant, unpleasant and control stimuli, with ratings recorded before and during stimulation. Sessions differed in pre-treatment: EMLA/naltrexone/placebo tablet/cream. RESULTS Significant effects of thermal or mechanical stimuli (P < .017), but not session (P > .102), were found on pain ratings for both models. In myalgia, painful cold resulted in a greater reduction in pain ratings than unpleasant cold, pleasant cold, control and pleasant warmth (P < .004). Decreases in pain ratings from painful, unpleasant and pleasant mechanical stimuli were greater than control (P < .002). In burning pain, painful cold resulted in a greater reduction in pain ratings than all but one of the other thermal stimuli (P < .033). The pleasant mechanical stimulus reduced pain ratings more than all other mechanical stimuli (P ≤ .003). There were no significant correlations between pain and psychometrics. CONCLUSION Valence-targeted thermal and mechanical stimuli modulated experimental myalgia and skin burning pain (P < .017). Partially blocking peripheral afferents or opioid receptors did not affect modulation.
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Affiliation(s)
- Pankaj Taneja
- Section of Orofacial Pain and Jaw Function, Department of Dentistry and Oral Health, Aarhus University, Aarhus, Denmark.,Scandinavian Centre for Orofacial Neurosciences (SCON), Aarhus, Denmark
| | - Håkan Olausson
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
| | - Mats Trulsson
- Scandinavian Centre for Orofacial Neurosciences (SCON), Aarhus, Denmark.,Department of Dental Medicine, Karolinska Institute, Huddinge, Sweden
| | - Lene Vase
- Department of Psychology and Behavioural Sciences, Aarhus University, Aarhus, Denmark
| | - Peter Svensson
- Section of Orofacial Pain and Jaw Function, Department of Dentistry and Oral Health, Aarhus University, Aarhus, Denmark.,Scandinavian Centre for Orofacial Neurosciences (SCON), Aarhus, Denmark.,Department of Orofacial Pain and Jaw Function, Faculty of Odontology, Malmö University, Malmö, Sweden
| | - Lene Baad-Hansen
- Section of Orofacial Pain and Jaw Function, Department of Dentistry and Oral Health, Aarhus University, Aarhus, Denmark.,Scandinavian Centre for Orofacial Neurosciences (SCON), Aarhus, Denmark
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16
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Løseth GE, Eikemo M, Leknes S. Effects of opioid receptor stimulation and blockade on touch pleasantness: a double-blind randomised trial. Soc Cogn Affect Neurosci 2020; 14:411-422. [PMID: 30951167 PMCID: PMC6523440 DOI: 10.1093/scan/nsz022] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 02/21/2019] [Accepted: 03/23/2019] [Indexed: 11/23/2022] Open
Abstract
The μ-opioid receptor (MOR) system has long been thought to underpin the rewarding properties of pleasant touch. Numerous non-human animal studies implicate MORs in social behaviours involving touch, but little is currently known about MOR involvement in human touch reward. Here, we employed a bi-directional pharmacological double-blind crossover design to assess the role of the human MOR system for touch pleasantness and motivation. Forty-nine male volunteers received 10 mg per-oral morphine, 50 mg per-oral naltrexone and placebo before being brushed on their forearm at three different velocities (0.3, 3 and 30 cm/s). In a touch liking task, pleasantness ratings were recorded after each 15 s brushing trial. In a touch wanting task, participants actively manipulated trial duration through key presses. As expected, 3 cm/s was the preferred velocity, producing significantly higher pleasantness ratings and wanting scores than the other stimuli. Contrary to our hypothesis, MOR drug manipulations did not significantly affect either touch pleasantness or wanting. The null effects were supported by post hoc Bayesian analyses indicating that the models with no drug effect were more than 25 times more likely than the alternative models given the data. We conclude that μ-opioid signalling is unlikely to underpin non-affiliative touch reward in humans.
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Affiliation(s)
- Guro E Løseth
- Department of Psychology, University of Oslo, Blindern, N Oslo, Norway
| | - Marie Eikemo
- Department of Psychology, University of Oslo, Blindern, N Oslo, Norway.,Department of Diagnostic Physics, Oslo University Hospital, Nydalen, N Oslo, Norway
| | - Siri Leknes
- Department of Psychology, University of Oslo, Blindern, N Oslo, Norway
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17
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Charles SJ, Farias M, Dunbar RI. The aetiology of social deficits within mental health disorders: The role of the immune system and endogenous opioids. Brain Behav Immun Health 2020; 1:100003. [PMID: 38377411 PMCID: PMC8474498 DOI: 10.1016/j.bbih.2019.100003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 09/30/2019] [Indexed: 10/25/2022] Open
Abstract
The American National Institute for Mental Health (NIMH) has put out a set of research goals that include a long-term plan to identify more reliable endogenous explanations for a wide variety of mental health disorders (Insel, 2013). In response to this, we have identified a major symptom that underlies multiple mental health disorders - social bonding dysfunction. We suggest that endogenous opioid abnormalities can lead to altered social bonding, which is a symptom of various mental health disorders, including depression, schizophrenia and ASD. This article first outlines how endogenous opioids play a role in social bonding. Then we show their association with the body's inflammation immune function, and review recent literature linking inflammation to mental health 'immunophenotypes'. We finish by explaining how these immunophenotypes may be caused by alterations in the endogenous opioid system. This is the first overview of the role of inflammation across multiple disorders where we provide a biochemical explanation for why immunophenotypes might exist across diagnoses. We propose a novel mechanism of how the immune system may be causing 'sickness-type' behaviours (fatigue, appetite change, social withdrawal and inhibited motivation) in those who have these immunophenotypes. We hope that this novel aetiology can be used as a basis for future research in mental health.
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Affiliation(s)
- Sarah J. Charles
- Brain, Belief and Behaviour Research Lab, Centre for Trust Peace and Social Relations, Coventry University, United Kingdom
| | - Miguel Farias
- Brain, Belief and Behaviour Research Lab, Centre for Trust Peace and Social Relations, Coventry University, United Kingdom
| | - Robin I.M. Dunbar
- Department of Experimental Psychology, University of Oxford, United Kingdom
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18
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Marshall AG, Sharma ML, Marley K, Olausson H, McGlone FP. Spinal signalling of C-fiber mediated pleasant touch in humans. eLife 2019; 8:e51642. [PMID: 31872799 PMCID: PMC6964968 DOI: 10.7554/elife.51642] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 12/23/2019] [Indexed: 01/06/2023] Open
Abstract
C-tactile afferents form a distinct channel that encodes pleasant tactile stimulation. Prevailing views indicate they project, as with other unmyelinated afferents, in lamina I-spinothalamic pathways. However, we found that spinothalamic ablation in humans, whilst profoundly impairing pain, temperature and itch, had no effect on pleasant touch perception. Only discriminative touch deficits were seen. These findings preclude privileged C-tactile-lamina I-spinothalamic projections and imply integrated hedonic and discriminative spinal processing from the body.
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Affiliation(s)
- Andrew G Marshall
- Institute of Aging and Chronic DiseaseUniversity of LiverpoolLiverpoolUnited Kingdom
- School of Natural Sciences and PsychologyLiverpool John Moores UniversityLiverpoolUnited Kingdom
- Department of Pain MedicineWalton Centre NHS Foundation TrustLiverpoolUnited Kingdom
| | - Manohar L Sharma
- Department of Pain MedicineWalton Centre NHS Foundation TrustLiverpoolUnited Kingdom
| | - Kate Marley
- Specialist Palliative Care TeamUniversity Hospital AintreeLiverpoolUnited Kingdom
| | - Hakan Olausson
- Specialist Palliative Care TeamUniversity Hospital AintreeLiverpoolUnited Kingdom
- Center for Social and Affective NeuroscienceLinköping UniversityLinköpingSweden
- Department of Clinical NeurophysiologyLinköping University HospitalLinköpingSweden
| | - Francis P McGlone
- School of Natural Sciences and PsychologyLiverpool John Moores UniversityLiverpoolUnited Kingdom
- Institute of Psychology, Health and SocietyUniversity of LiverpoolLiverpoolUnited Kingdom
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19
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20
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Dunbar RIM. The Anatomy of Friendship. Trends Cogn Sci 2018; 22:32-51. [PMID: 29273112 DOI: 10.1016/j.tics.2017.10.004] [Citation(s) in RCA: 118] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 10/16/2017] [Accepted: 10/18/2017] [Indexed: 12/22/2022]
Abstract
Friendship is the single most important factor influencing our health, well-being, and happiness. Creating and maintaining friendships is, however, extremely costly, in terms of both the time that has to be invested and the cognitive mechanisms that underpin them. Nonetheless, personal social networks exhibit many constancies, notably in their size and their hierarchical structuring. Understanding the processes that give rise to these patterns and their evolutionary origins requires a multidisciplinary approach that combines social and neuropsychology as well as evolutionary biology.
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Affiliation(s)
- R I M Dunbar
- Department of Experimental Psychology, University of Oxford, New Richards Building, Old Road Campus, Headington, Oxford OX3 7LG, UK.
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21
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The Influence of Endogenous Opioids on the Relationship between Testosterone and Romantic Bonding. HUMAN NATURE-AN INTERDISCIPLINARY BIOSOCIAL PERSPECTIVE 2018; 30:98-116. [PMID: 30519832 DOI: 10.1007/s12110-018-9332-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The endogenous opioid system has received attention and extensive research for its effects on reward, pleasure, and pain. However, relative to other neurochemicals, such as oxytocin, vasopressin and dopamine, the function of opioids in regulating human attachment, sociosexuality, and other aspects of human sociality has not received much consideration. For example, nonapeptides (oxytocin and vasopressin) have been extensively studied in animals and humans for their possible roles in mother-offspring attachment, romantic attachment, fatherhood, and social cognition. Likewise, others have proposed models wherein oxytocin and vasopressin are moderators of the relationship between steroid hormones and human social behaviors. Recently, opioids have generated renewed interest in relation to social pain, and importantly, the brain opioid hypothesis of social attachment (BOTSA), which suggests that endogenous opioids are a key implementer in primate and human bonding, has received some support. Here we focus on romantic bonds by proposing that endogenous opioids are an important mechanism mediating reproductive trade-offs through their inhibitory effects on testosterone production.
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22
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Social style and resilience of macaques' networks, a theoretical investigation. Primates 2018; 60:233-246. [PMID: 30242533 DOI: 10.1007/s10329-018-0684-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 08/31/2018] [Indexed: 10/28/2022]
Abstract
Group-living animals rely on efficient transmission of information for optimal exploitation of their habitat. How efficient and resilient a network is depend on its structure, which is a consequence of the social interactions of the individuals that comprise the network. In macaques, network structure differs according to dominance style. Networks of intolerant species are more modular, more centralized, and less connected than those of tolerant ones. Given these structural differences, networks of intolerant species are potentially more vulnerable to fragmentation and decreased information transmission when central individuals disappear. Here we studied network resilience and efficiency in artificial societies of macaques. The networks were produced with an individual-based model that has been shown to reproduce the structural features of networks of tolerant and intolerant macaques. To study network resilience, we deleted either central individuals or individuals at random and studied the effects of these deletions on network cohesiveness and efficiency. The deletion of central individuals had more negative effects than random deletions from the networks of both tolerant and intolerant artificial societies. Central individuals thus appeared to aid in the maintenance of network cohesiveness and efficiency. Further, the networks of both intolerant and tolerant societies appeared to be robust to the loss of individuals, as network fragmentation was never observed. Our results suggest that despite differences in network structure, networks of tolerant and intolerant macaques may be equally resilient.
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23
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Puga-Gonzalez I, Ostner J, Schülke O, Sosa S, Thierry B, Sueur C. Mechanisms of reciprocity and diversity in social networks: a modeling and comparative approach. Behav Ecol 2018. [DOI: 10.1093/beheco/ary034] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Ivan Puga-Gonzalez
- Institute for Religion, Philosophy and History, University of Agder, Kristiansand, Gimlemoen, Kristiansand S, Norway
| | - Julia Ostner
- Department for Behavioural Ecology, University of Göttingen, Kellnerweg, Göttingen, Germany
- Primate Social Evolution Group, German Primate Center Göttingen, Kellnerweg, Göttingen, Germany
- Leibniz Science Campus Primate Cognition, Kellnerweg, Göttingen, Germany
| | - Oliver Schülke
- Department for Behavioural Ecology, University of Göttingen, Kellnerweg, Göttingen, Germany
- Primate Social Evolution Group, German Primate Center Göttingen, Kellnerweg, Göttingen, Germany
- Leibniz Science Campus Primate Cognition, Kellnerweg, Göttingen, Germany
| | - Sebastian Sosa
- School of Sociology and Anthropology, Sun Yat-sen University, Guangzhou, PR China
| | - Bernard Thierry
- Ethologie Cognitive et Sociale, Centre National de la Recherche Scientifique, rue du loess, Strasbourg, France
| | - Cedric Sueur
- Université de Strasbourg, CNRS, IPHC UMR, rue Becquerel Strasbourg Cedex, France
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24
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Puga-Gonzalez I, Sueur C. Emergence of complex social networks from spatial structure and rules of thumb: a modelling approach. ECOLOGICAL COMPLEXITY 2017. [DOI: 10.1016/j.ecocom.2017.07.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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25
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Henning M, Fox GR, Kaplan J, Damasio H, Damasio A. A Potential Role for mu-Opioids in Mediating the Positive Effects of Gratitude. Front Psychol 2017; 8:868. [PMID: 28680408 PMCID: PMC5478726 DOI: 10.3389/fpsyg.2017.00868] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 05/11/2017] [Indexed: 12/19/2022] Open
Abstract
Gratitude is a complex emotional feeling associated with universally desirable positive effects in personal, social, and physiological domains. Why or how gratitude achieves these functional outcomes is not clear. Toward the goal of identifying its' underlying physiological processes, we recently investigated the neural correlates of gratitude. In our study, participants were exposed to gratitude-inducing stimuli, and rated each according to how much gratitude it provoked. As expected, self-reported gratitude intensity correlated with brain activity in distinct regions of the medial pre-frontal cortex associated with social reward and moral cognition. Here we draw from our data and existing literature to offer a theoretical foundation for the physiological correlates of gratitude. We propose that mu-opioid signaling (1) accompanies the mental experience of gratitude, and (2) may account for the positive effects of gratitude on social relationships, subjective wellbeing, and physiological health.
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Affiliation(s)
- Max Henning
- Psychology, Brain and Creativity Institute, University of Southern CaliforniaLos Angeles, CA, United States.,Performance Science Institute, University of Southern CaliforniaLos Angeles, CA, United States
| | - Glenn R Fox
- Psychology, Brain and Creativity Institute, University of Southern CaliforniaLos Angeles, CA, United States.,Performance Science Institute, University of Southern CaliforniaLos Angeles, CA, United States
| | - Jonas Kaplan
- Psychology, Brain and Creativity Institute, University of Southern CaliforniaLos Angeles, CA, United States
| | - Hanna Damasio
- Psychology, Brain and Creativity Institute, University of Southern CaliforniaLos Angeles, CA, United States
| | - Antonio Damasio
- Psychology, Brain and Creativity Institute, University of Southern CaliforniaLos Angeles, CA, United States
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26
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Goldstein P, Weissman-Fogel I, Shamay-Tsoory SG. The role of touch in regulating inter-partner physiological coupling during empathy for pain. Sci Rep 2017; 7:3252. [PMID: 28607375 PMCID: PMC5468314 DOI: 10.1038/s41598-017-03627-7] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 05/02/2017] [Indexed: 12/12/2022] Open
Abstract
The human ability to synchronize with other individuals is critical for the development of social behavior. Recent research has shown that physiological inter-personal synchronization may underlie behavioral synchrony. Nevertheless, the factors that modulate physiological coupling are still largely unknown. Here we suggest that social touch and empathy for pain may enhance interpersonal physiological coupling. Twenty-two romantic couples were assigned the roles of target (pain receiver) and observer (pain observer) under pain/no-pain and touch/no-touch conditions, and their ECG and respiration rates were recorded. The results indicate that the partner touch increased interpersonal respiration coupling under both pain and no-pain conditions and increased heart rate coupling under pain conditions. In addition, physiological coupling was diminished by pain in the absence of the partner’s touch. Critically, we found that high partner’s empathy and high levels of analgesia enhanced coupling during the partner’s touch. Collectively, the evidence indicates that social touch increases interpersonal physiological coupling during pain. Furthermore, the effects of touch on cardio-respiratory inter-partner coupling may contribute to the analgesic effects of touch via the autonomic nervous system.
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Affiliation(s)
- Pavel Goldstein
- Department of Psychology, University of Haifa, Haifa, Israel. .,Department of Statistics, University of Haifa, Haifa, Israel. .,The Emili Sagol Creative Arts Therapies Research Center, University of Haifa, Haifa, Israel.
| | - Irit Weissman-Fogel
- Physical Therapy Department, Faculty of Social Welfare and Health Sciences, University of Haifa, Haifa, Israel
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27
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‘Naltrexone Blocks Endorphins Released when Dancing in Synchrony’. ADAPTIVE HUMAN BEHAVIOR AND PHYSIOLOGY 2017. [DOI: 10.1007/s40750-017-0067-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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28
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Oxytocin under opioid antagonism leads to supralinear enhancement of social attention. Proc Natl Acad Sci U S A 2017; 114:5247-5252. [PMID: 28461466 DOI: 10.1073/pnas.1702725114] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
To provide new preclinical evidence toward improving the efficacy of oxytocin (OT) in treating social dysfunction, we tested the benefit of administering OT under simultaneously induced opioid antagonism during dyadic gaze interactions in monkeys. OT coadministered with a μ-opioid receptor antagonist, naloxone, invoked a supralinear enhancement of prolonged and selective social attention, producing a stronger effect than the summed effects of each administered separately. These effects were consistently observed when averaging over entire sessions, as well as specifically following events of particular social importance, including mutual eye contact and mutual reward receipt. Furthermore, attention to various facial regions was differentially modulated depending on social context. Using the Allen Institute's transcriptional atlas, we further established the colocalization of μ-opioid and κ-opioid receptor genes and OT genes at the OT-releasing sites in the human brain. These data across monkeys and humans support a regulatory relationship between the OT and opioid systems and suggest that administering OT under opioid antagonism may boost the therapeutic efficacy of OT for enhancing social cognition.
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29
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Hill EM, Hunt L, Duryea DG. Evolved Vulnerability to Addiction: The Problem of Opiates. EVOLUTIONARY PSYCHOLOGY 2017. [DOI: 10.1007/978-3-319-60576-0_6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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30
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Launay J, Tarr B, Dunbar RIM. Synchrony as an Adaptive Mechanism for Large-Scale Human Social Bonding. Ethology 2016. [DOI: 10.1111/eth.12528] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Jacques Launay
- Department of Experimental Psychology; University of Oxford; Oxford UK
- Division of Psychology; Brunel University London; Uxbridge UK
| | - Bronwyn Tarr
- Department of Experimental Psychology; University of Oxford; Oxford UK
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31
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Touch Perception Altered by Chronic Pain and by Opioid Blockade. eNeuro 2016; 3:eN-NWR-0138-15. [PMID: 27022625 PMCID: PMC4785385 DOI: 10.1523/eneuro.0138-15.2016] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 02/09/2016] [Accepted: 02/22/2016] [Indexed: 12/01/2022] Open
Abstract
Touch plays a significant role in human social behavior and social communication, and its rewarding nature has been suggested to involve opioids. Opioid blockade in monkeys leads to increased solicitation and receipt of grooming, suggesting heightened enjoyment of touch. We sought to study the role of endogenous opioids in perception of affective touch in healthy adults and in patients with fibromyalgia, a chronic pain condition shown to involve reduced opioid receptor availability. The pleasantness of touch has been linked to the activation of C-tactile fibers, which respond maximally to slow gentle touch and correlate with ratings of pleasantness. We administered naloxone to patients and healthy controls to directly observe the consequences of µ-opioid blockade on the perceived pleasantness and intensity of touch. We found that at baseline chronic pain patients showed a blunted distinction between slow and fast brushing for both intensity and pleasantness, suggesting reduced C-tactile touch processing. In addition, we found a differential effect of opioid blockade on touch perception in healthy subjects and pain patients. In healthy individuals, opioid blockade showed a trend toward increased ratings of touch pleasantness, while in chronic pain patients it significantly decreased ratings of touch intensity. Further, in healthy individuals, naloxone-induced increase in touch pleasantness was associated with naloxone-induced decreased preference for slow touch, suggesting a possible effect of opioid levels on processing of C-tactile fiber input. These findings suggest a role for endogenous opioids in touch processing, and provide further evidence for altered opioid functioning in chronic pain patients.
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32
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Weinstein D, Launay J, Pearce E, Dunbar RIM, Stewart L. Group music performance causes elevated pain thresholds and social bonding in small and large groups of singers. EVOL HUM BEHAV 2016; 37:152-158. [PMID: 27158219 DOI: 10.1016/j.evolhumbehav.2015.10.002] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Over our evolutionary history, humans have faced the problem of how to create and maintain social bonds in progressively larger groups compared to those of our primate ancestors. Evidence from historical and anthropological records suggests that group music-making might act as a mechanism by which this large-scale social bonding could occur. While previous research has shown effects of music making on social bonds in small group contexts, the question of whether this effect 'scales up' to larger groups is particularly important when considering the potential role of music for large-scale social bonding. The current study recruited individuals from a community choir that met in both small (n = 20 - 80) and large (a 'megachoir' combining individuals from the smaller subchoirs n = 232) group contexts. Participants gave self-report measures (via a survey) of social bonding and had pain threshold measurements taken (as a proxy for endorphin release) before and after 90 minutes of singing. Results showed that feelings of inclusion, connectivity, positive affect, and measures of endorphin release all increased across singing rehearsals and that the influence of group singing was comparable for pain thresholds in the large versus small group context. Levels of social closeness were found to be greater at pre- and post-levels for the small choir condition. However, the large choir condition experienced a greater change in social closeness as compared to the small condition. The finding that singing together fosters social closeness - even in large contexts where individuals are not known to each other - is consistent with evolutionary accounts that emphasize the role of music in social bonding, particularly in the context of creating larger cohesive groups than other primates are able to manage.
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Affiliation(s)
- Daniel Weinstein
- Goldsmiths, University of London, Lewisham Way, New Cross, London SE14 6NW, United Kingdom, +44 20 7919 7171
| | - Jacques Launay
- University of Oxford, Department of Experimental Psychology, Tinbergen Building, Oxford, OX1 3UD, United Kingdom, +44 1865 271367
| | - Eiluned Pearce
- University of Oxford, Department of Experimental Psychology, Tinbergen Building, Oxford, OX1 3UD, United Kingdom, +44 1865 271367
| | - Robin I M Dunbar
- University of Oxford, Department of Experimental Psychology, Tinbergen Building, Oxford, OX1 3UD, United Kingdom, +44 1865 271367
| | - Lauren Stewart
- Goldsmiths, University of London, Lewisham Way, New Cross, London SE14 6NW, United Kingdom, +44 20 7919 7171
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33
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Weinstein D, Launay J, Pearce E, Dunbar RI, Stewart L. Singing and social bonding: changes in connectivity and pain threshold as a function of group size. EVOL HUM BEHAV 2016. [DOI: 10.10.1016/j.evolhumbehav.2015.10.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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34
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Ballesta S, Reymond G, Pozzobon M, Duhamel JR. Effects of MDMA Injections on the Behavior of Socially-Housed Long-Tailed Macaques (Macaca fascicularis). PLoS One 2016; 11:e0147136. [PMID: 26840064 PMCID: PMC4739726 DOI: 10.1371/journal.pone.0147136] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 12/29/2015] [Indexed: 01/26/2023] Open
Abstract
3,4-methylenedioxy-N-methyl amphetamine (MDMA) is one of the few known molecules to increase human and rodent prosocial behaviors. However, this effect has never been assessed on the social behavior of non-human primates. In our study, we subcutaneously injected three different doses of MDMA (1.0, 1.5 or 2.0mg/kg) to a group of three, socially housed, young male long-tailed macaques. More than 200 hours of behavioral data were recorded, during 68 behavioral sessions, by an automatic color-based video device that tracked the 3D positions of each animal and of a toy. This data was then categorized into 5 exclusive behaviors (resting, locomotion, foraging, social contact and object play). In addition, received and given social grooming was manually scored. Results show several significant dose-dependent behavioral effects. At 1.5mg/kg only, MDMA induces a significant increase in social grooming behavior, thus confirming the prosocial effect of MDMA in macaques. Additionally, at 1.5 and 2.0 mg/kg MDMA injection substantially decreases foraging behavior, which is consistent with the known anorexigenic effect of this compound. Furthermore, at 2.0 mg/kg MDMA injection induces an increase in locomotor behavior, which is also in accordance with its known stimulant property. Interestingly, MDMA injected at 1.0mg/kg increases the rate of object play, which might be interpreted as a decrease of the inhibition to manipulate a unique object in presence of others, or, as an increase of the intrinsic motivation to manipulate this object. Together, our results support the effectiveness of MDMA to study the complex neurobiology of primates' social behaviors.
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Affiliation(s)
- Sébastien Ballesta
- Centre de Neuroscience Cognitive, Centre National de la Recherche Scientifique, 69675 Bron, France
- Département de Biologie Humaine, Université Lyon 1, 69622 Villeurbanne, France
| | - Gilles Reymond
- Centre de Neuroscience Cognitive, Centre National de la Recherche Scientifique, 69675 Bron, France
- Département de Biologie Humaine, Université Lyon 1, 69622 Villeurbanne, France
| | - Matthieu Pozzobon
- Centre de Neuroscience Cognitive, Centre National de la Recherche Scientifique, 69675 Bron, France
- Département de Biologie Humaine, Université Lyon 1, 69622 Villeurbanne, France
| | - Jean-René Duhamel
- Centre de Neuroscience Cognitive, Centre National de la Recherche Scientifique, 69675 Bron, France
- Département de Biologie Humaine, Université Lyon 1, 69622 Villeurbanne, France
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35
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Wardle MC, Bershad AK, de Wit H. Naltrexone alters the processing of social and emotional stimuli in healthy adults. Soc Neurosci 2016; 11:579-91. [PMID: 26710657 DOI: 10.1080/17470919.2015.1136355] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Endogenous opioids have complex social effects that may depend on specific receptor actions and vary depending on the "stage" of social behavior (e.g., seeking vs. responding to social stimuli). We tested the effects of a nonspecific opioid antagonist, naltrexone (NTX), on social processing in humans. NTX is used to treat alcohol and opiate dependence, and may affect both mu and kappa-opioid systems. We assessed attention ("seeking"), and subjective and psychophysiological responses ("responding") to positive and negative social stimuli. Based on literature suggesting mu-opioid blockade impairs positive social responses, we hypothesized that NTX would decrease responses to positive social stimuli. We also tested responses to negative stimuli, which might be either increased by NTX's mu-opioid effects or decreased by its kappa-opioid effects. Thirty-four healthy volunteers received placebo, 25 mg, or 50 mg NTX across three sessions under double-blind conditions. At each session, participants completed measures of attention, identification, and emotional responses for emotional faces and scenes. NTX increased attention to emotional expressions, slowed identification of sadness and fear, and decreased ratings of arousal for social and nonsocial emotional scenes. These findings are more consistent with anxiolytic kappa-antagonist than mu-blocking effects, suggesting effects on kappa receptors may contribute to the clinical effects of NTX.
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Affiliation(s)
- Margaret C Wardle
- a Department of Psychiatry and Behavioral Sciences , University of Texas Health Science Center at Houston , Houston , TX, USA
| | - Anya K Bershad
- b Department of Psychiatry and Behavioral Neuroscience , University of Chicago , Chicago , IL , USA
| | - Harriet de Wit
- b Department of Psychiatry and Behavioral Neuroscience , University of Chicago , Chicago , IL , USA
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Bershad AK, Seiden JA, de Wit H. Effects of buprenorphine on responses to social stimuli in healthy adults. Psychoneuroendocrinology 2016; 63:43-9. [PMID: 26409030 PMCID: PMC4695221 DOI: 10.1016/j.psyneuen.2015.09.011] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 08/25/2015] [Accepted: 09/09/2015] [Indexed: 12/27/2022]
Abstract
In addition to its classical role in mediating responses to pain, the opioid system is strongly implicated in the regulation of social behavior. In young laboratory animals, low doses of opioid analgesic drugs reduce responses to isolation distress and increase play behavior. However, little is known about how opioid drugs affect responses to social stimuli in humans. Here we examined the effects of buprenorphine, a mu-opioid partial agonist and kappa-antagonist, on three dimensions of social processing: (i) responses to simulated social rejection, (ii) attention to emotional facial expressions, and (iii) emotional responses to images with and without social content. Healthy adults (N=36) attended two sessions during which they received either placebo or 0.2mg sublingual buprenorphine in randomized order, under double-blind conditions. Ninety minutes after drug administration, they completed three behavioral tasks: (i) a virtual ball-toss game in which they were first included and then excluded by the other players; (ii) an attention task in which they were shown pairs of faces (one emotional and one neutral), while the direction of their gazes was recorded using electrooculography, and (iii) a picture-viewing task, in which they rated standardized images with and without social content. During the ball-toss game, buprenorphine decreased perceived social rejection. During the attention task, the drug reduced initial attention to fearful facial expressions, without influencing attention to angry, happy, or sad faces. Finally, during the picture-viewing task, buprenorphine increased ratings of positivity of images with social content without affecting ratings of nonsocial images. These results suggest that even at low doses, opioid analgesic drugs reduce responses to some types of negative social stimuli while enhancing positive responses to social stimuli. This provides further support for the role of the opioid system in mediating responses to social rejection and social reward.
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Affiliation(s)
- Anya K. Bershad
- Department of Psychiatry and Behavioral Neuroscience, University of Chicago, Chicago, IL USA,Interdisciplinary Scientist Training Program, University of Chicago, Chicago, IL USA
| | - Jacob A. Seiden
- Department of Psychiatry and Behavioral Neuroscience, University of Chicago, Chicago, IL USA
| | - Harriet de Wit
- Department of Psychiatry and Behavioral Neuroscience, University of Chicago, Chicago, IL, USA.
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Converse AK, Aubert Y, Allers KA, Sommer B, Abbott DH. Flibanserin-Stimulated Partner Grooming Reflects Brain Metabolism Changes in Female Marmosets. J Sex Med 2015; 12:2256-66. [PMID: 26635207 PMCID: PMC5681869 DOI: 10.1111/jsm.13068] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
INTRODUCTION Female sexual interest and arousal disorder is personally distressing for women. To better understand the mechanism of the candidate therapeutic, flibanserin, we determined its effects on an index of brain glucose metabolism. AIM We hypothesized that chronic treatment with flibanserin would alter metabolism in brain regions associated with serotonergic function and female sexual behavior. METHODS In a crossover design, eight adult female common marmosets (Calithrix jacchus) received daily flibanserin or vehicle. After 7-12 weeks of treatment, the glucose metabolism radiotracer [(18) F]fluorodeoxyglucose (FDG) was administered to each female immediately prior to 30 minutes of interaction with her male pairmate, after which females were anesthetized and imaged by positron emission tomography. Whole-brain normalized images were analyzed with anatomically defined regions of interest. Whole-brain voxelwise mapping was used to explore treatment effects. Correlations were examined between alterations in metabolism and pairmate social grooming. MAIN OUTCOME MEASURES Changes in metabolism associated with flibanserin were determined for dorsal raphe, medial prefrontal cortex (mPFC), medial preoptic area of hypothalamus (mPOA), ventromedial nucleus of hypothalamus, and field cornu ammonis 1 (CA1) of the hippocampus. RESULTS In response to chronic flibanserin, metabolism in mPOA declined, and this reduction correlated with increases in pairmate grooming. A cluster of voxels in frontal cortico-limbic regions exhibited reduced metabolism in response to flibanserin and overlapped with a voxel cluster in which reductions in metabolism correlated with increases in pairmate grooming. Finally, reductions in mPOA metabolism correlated with increases in metabolism in a cluster of voxels in somatosensory cortex. CONCLUSIONS Taken together, these results suggest that flibanserin-induced reductions in female mPOA neural activity increase intimate affiliative behavior with male pairmates.
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Affiliation(s)
| | - Yves Aubert
- Wisconsin National Primate Research Center, University of Wisconsin-Madison, US
- Department of Biological and Medical Psychology, University of Bergen, NO
| | - Kelly A. Allers
- Department of CNS Diseases, Boehringer Ingelheim, Biberach, DE
| | - Bernd Sommer
- Department of CNS Diseases, Boehringer Ingelheim, Biberach, DE
| | - David H. Abbott
- Wisconsin National Primate Research Center, University of Wisconsin-Madison, US
- Department of Obstetrics and Gynecology, University of Wisconsin-Madison, US
- Endocrinology-Reproductive Physiology Training Program, University of Wisconsin-Madison, US
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38
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Gentsch A, Panagiotopoulou E, Fotopoulou A. Active Interpersonal Touch Gives Rise to the Social Softness Illusion. Curr Biol 2015; 25:2392-7. [PMID: 26365257 PMCID: PMC4580302 DOI: 10.1016/j.cub.2015.07.049] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 06/15/2015] [Accepted: 07/20/2015] [Indexed: 12/03/2022]
Abstract
Social touch plays a powerful role in human life, with important physical and mental health benefits in development and adulthood. Touch is central in building the foundations of social interaction, attachment, and cognition [1–5], and early, social touch has unique, beneficial neurophysiological and epigenetic effects [6–9]. The recent discovery of a separate neurophysiological system for affectively laden touch in humans has further kindled scientific interest in the area [10, 11]. Remarkably, however, little is known about what motivates and sustains the human tendency to touch others in a pro-social manner. Given the importance of social touch, we hypothesized that active stroking elicits more sensory pleasure when touching others’ skin than when touching one’s own skin. In a set of six experiments (total N = 133) we found that healthy participants, mostly tested in pairs to account for any objective differences in skin softness, consistently judged another’s skin as feeling softer and smoother than their own skin. We further found that this softness illusion appeared selectively when the touch activated a neurophysiological system for affective touch in the receiver. We conclude that this sensory illusion underlies a novel, bodily mechanism of socio-affective bonding and enhances our motivation to touch others. The social softness illusion reflects the sensory hedonics of active social touch Stroking others’ skin feels softer and smoother than stroking our own skin The illusion appears when the touch activates the receiver’s affective touch system The illusion reflects a tactile mechanism of emotional sharing between individuals
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Affiliation(s)
- Antje Gentsch
- Research Department of Clinical, Educational and Health Psychology, University College London, London WC1E 6BT, UK
| | - Elena Panagiotopoulou
- Research Department of Clinical, Educational and Health Psychology, University College London, London WC1E 6BT, UK
| | - Aikaterini Fotopoulou
- Research Department of Clinical, Educational and Health Psychology, University College London, London WC1E 6BT, UK.
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39
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Ragen BJ, Freeman SM, Laredo SA, Mendoza SP, Bales KL. μ and κ opioid receptor distribution in the monogamous titi monkey (Callicebus cupreus): implications for social behavior and endocrine functioning. Neuroscience 2015; 290:421-34. [PMID: 25637809 DOI: 10.1016/j.neuroscience.2015.01.023] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2014] [Revised: 01/09/2015] [Accepted: 01/15/2015] [Indexed: 11/17/2022]
Abstract
The opioid system is involved in infant-mother bonds and adult-adult bonds in many species. We have previously shown that μ opioid receptors (MORs) and κ opioid receptors (KORs) are involved in regulating the adult attachment of the monogamous titi monkey. The present study sought to determine the distribution of MOR and KOR in the titi monkey brain using receptor autoradiography. We used [(3)H][D-Ala(2),N-Me-Phe(4),Gly(5)-ol]-enkephalin (DAMGO) to label MORs and [(3)H]U69,593 to label KORs. MOR binding was heterogeneous throughout the titi monkey brain. Specifically, MOR binding was observed in the cingulate gyrus (CG), striatum, septal regions, diagonal band, amygdala, hypothalamus, hippocampus, and thalamus. Binding was particularly dense in the septum, medial amygdala, paraventricular nucleus of the hypothalamus, mediodorsal thalamus with moderate binding in the nucleus accumbens. Consistent with other primate species, MOR were also observed in "neurochemically unique domains of the accumbens and putamen" (NUDAPs). In general KOR binding was more homogenous. KORs were primarily found in the CG, striatum, amygdala and hippocampus. Dense KOR binding was observed in the claustrum. Relative MOR and KOR binding in the titi monkey striatum was similar to other humans and primates, but was much lower compared to rodents. Relative MOR binding in the titi monkey hypothalamus was much greater than that found in rodents. This study was the first to examine MOR and KOR binding in a monogamous primate. The location of these receptors gives insight into where ligands may be acting to regulate social behavior and endocrine function.
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Affiliation(s)
- B J Ragen
- California National Primate Research Center, Davis, CA 95616, United States; Department of Psychology, University of California-Davis, Davis, CA 95616, United States.
| | - S M Freeman
- California National Primate Research Center, Davis, CA 95616, United States
| | - S A Laredo
- Animal Behavior Graduate Group, University of California-Davis, Davis, CA 95616, United States
| | - S P Mendoza
- California National Primate Research Center, Davis, CA 95616, United States
| | - K L Bales
- California National Primate Research Center, Davis, CA 95616, United States; Department of Psychology, University of California-Davis, Davis, CA 95616, United States
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Chen HH, Chiang YC, Yuan ZF, Kuo CC, Lai MD, Hung TW, Ho IK, Chen ST. Buprenorphine, methadone, and morphine treatment during pregnancy: behavioral effects on the offspring in rats. Neuropsychiatr Dis Treat 2015; 11:609-18. [PMID: 25834439 PMCID: PMC4358634 DOI: 10.2147/ndt.s70585] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Methadone and buprenorphine are widely used for treating people with opioid dependence, including pregnant women. Prenatal exposure to opioids has devastating effects on the development of human fetuses and may induce long-term physical and neurobehavioral changes during postnatal maturation. This study aimed at comparing the behavioral outcomes of young rats prenatally exposed to buprenorphine, methadone, and morphine. Pregnant Sprague-Dawley rats were administered saline, morphine, methadone, and buprenorphine during embryonic days 3-20. The cognitive function, social interaction, anxiety-like behaviors, and locomotor activity of offsprings were examined by novel object recognition test, social interaction test, light-dark transition test, elevated plus-maze, and open-field test between 6 weeks and 10 weeks of age. Prenatal exposure to methadone and buprenorphine did not affect locomotor activity, but significantly impaired novel object recognition and social interaction in both male and female offsprings in the same manner as morphine. Although prenatal exposure to methadone or buprenorphine increased anxiety-like behaviors in the light-dark transition in both male and female offsprings, the effects were less pronounced as compared to that of morphine. Methadone affected elevated plus-maze in both sex, but buprenorphine only affected the female offsprings. These findings suggest that buprenorphine and methadone maintenance therapy for pregnant women, like morphine, produced detrimental effects on cognitive function and social behaviors, whereas the offsprings of such women might have a lower risk of developing anxiety disorders.
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Affiliation(s)
- Hwei-Hsien Chen
- Center for Neuropsychiatric Research, National Health Research Institutes, Miaoli County, Taiwan ; Master and PhD Program in Pharmacology and Toxicology, Tzu Chi University, Hualien, Taiwan
| | - Yao-Chang Chiang
- Center for Drug Abuse and Addiction, China Medical University Hospital, Taichung, Taiwan ; Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan
| | - Zung Fan Yuan
- Master Program in Physiological and Anatomical Medicine, School of Medicine, Tzu Chi University, Hualien, Taiwan ; Department of Physiology, School of Medicine, Tzu Chi University, Hualien, Taiwan
| | - Chung-Chih Kuo
- Master Program in Physiological and Anatomical Medicine, School of Medicine, Tzu Chi University, Hualien, Taiwan ; Department of Physiology, School of Medicine, Tzu Chi University, Hualien, Taiwan
| | - Mei-Dan Lai
- Master and PhD Program in Pharmacology and Toxicology, Tzu Chi University, Hualien, Taiwan
| | - Tsai-Wei Hung
- Center for Neuropsychiatric Research, National Health Research Institutes, Miaoli County, Taiwan
| | - Ing-Kang Ho
- Center for Neuropsychiatric Research, National Health Research Institutes, Miaoli County, Taiwan ; Center for Drug Abuse and Addiction, China Medical University Hospital, Taichung, Taiwan ; Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan
| | - Shao-Tsu Chen
- Master and PhD Program in Pharmacology and Toxicology, Tzu Chi University, Hualien, Taiwan ; Department of Psychiatry, Buddhist Tzu Chi General Hospital, Hualien, Taiwan
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Loseth GE, Ellingsen DM, Leknes S. State-dependent μ-opioid modulation of social motivation. Front Behav Neurosci 2014; 8:430. [PMID: 25565999 PMCID: PMC4264475 DOI: 10.3389/fnbeh.2014.00430] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 11/25/2014] [Indexed: 12/02/2022] Open
Abstract
Social mammals engage in affiliative interactions both when seeking relief from negative affect and when searching for pleasure and joy. These two motivational states are both modulated by μ-opioid transmission. The μ-opioid receptor (MOR) system in the brain mediates pain relief and reward behaviors, and is implicated in social reward processing and affiliative bonding across mammalian species. However, pharmacological manipulation of the μ-opioid system has yielded opposite effects on rodents and primates: in rodents, social motivation is generally increased by MOR agonists and reduced by antagonists, whereas the opposite pattern has been shown in primates. Here, we address this paradox by taking into account differences in motivational state. We first review evidence for μ-opioid mediation of reward processing, emotion regulation, and affiliation in humans, non-human primates, rodents and other species. Based on the consistent cross-species similarities in opioid functioning, we propose a unified, state-dependent model for μ-opioid modulation of affiliation across the mammalian species. Finally, we show that this state-dependent model is supported by evidence from both rodent and primate studies, when species and age differences in social separation response are taken into account.
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Affiliation(s)
- Guro E. Loseth
- Department of Psychology, University of OsloOslo, Norway
| | | | - Siri Leknes
- Department of Psychology, University of OsloOslo, Norway
- The Intervention Centre, Oslo University HospitalOslo, Norway
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42
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Ragen BJ, Maninger N, Mendoza SP, Bales KL. The effects of morphine, naloxone, and κ opioid manipulation on endocrine functioning and social behavior in monogamous titi monkeys (Callicebus cupreus). Neuroscience 2014; 287:32-42. [PMID: 25485481 DOI: 10.1016/j.neuroscience.2014.11.053] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Revised: 11/18/2014] [Accepted: 11/25/2014] [Indexed: 01/01/2023]
Abstract
The μ opioid receptor (MOR) and κ opioid receptor (KOR) have been implicated in pair-bond formation and maintenance in socially monogamous species. Utilizing monogamous titi monkeys (Callicebus cupreus), the present study examined the potential role opioids play in modulating the response to separation, a potent challenge to the pair-bond. In Experiment 1, paired male titi monkeys were separated from their pair-mate for 30-min and then received saline, naloxone (1.0mg/kg), morphine (0.25mg/kg), or the KOR agonist, U50,488 (0.01, 0.03, or 0.1mg/kg) in a counter-balanced fashion, immediately prior to a 30-min reunion with their mate. Blood samples were collected immediately prior to and after the reunion. Males receiving morphine approached females less, initiated contact less, and females broke contact with the males less. The increase in cortisol in response to naloxone was greater compared to vehicle, and the increase in cortisol in response to the high dose of U50,488 compared to vehicle approached significance. In Experiment 2, paired males were treated with the KOR antagonist, GNTI (0.1, 0.3, or 1.0mg/kg), or saline 24h prior to a 60-min separation from their mate. Blood samples were collected at the time of injection and immediately before and after separation. Administration of the low dose of GNTI decreased the locomotor component of the separation response compared to vehicle. The present study found that the opioid system is involved in both the affiliative and separation distress components of a pair-bond, and these components are regulated by different opioid receptors.
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Affiliation(s)
- B J Ragen
- Psychology Department, University of California-Davis, One Shields Avenue, Davis, CA 95616, USA; California National Primate Research Center, One Shields Avenue, Davis, CA 95616, USA.
| | - N Maninger
- California National Primate Research Center, One Shields Avenue, Davis, CA 95616, USA
| | - S P Mendoza
- California National Primate Research Center, One Shields Avenue, Davis, CA 95616, USA
| | - K L Bales
- Psychology Department, University of California-Davis, One Shields Avenue, Davis, CA 95616, USA; California National Primate Research Center, One Shields Avenue, Davis, CA 95616, USA
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Tarr B, Launay J, Dunbar RIM. Music and social bonding: "self-other" merging and neurohormonal mechanisms. Front Psychol 2014; 5:1096. [PMID: 25324805 PMCID: PMC4179700 DOI: 10.3389/fpsyg.2014.01096] [Citation(s) in RCA: 178] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2014] [Accepted: 09/10/2014] [Indexed: 01/13/2023] Open
Abstract
It has been suggested that a key function of music during its development and spread amongst human populations was its capacity to create and strengthen social bonds amongst interacting group members. However, the mechanisms by which this occurs have not been fully discussed. In this paper we review evidence supporting two thus far independently investigated mechanisms for this social bonding effect: self-other merging as a consequence of inter-personal synchrony, and the release of endorphins during exertive rhythmic activities including musical interaction. In general, self-other merging has been experimentally investigated using dyads, which provide limited insight into large-scale musical activities. Given that music can provide an external rhythmic framework that facilitates synchrony, explanations of social bonding during group musical activities should include reference to endorphins, which are released during synchronized exertive movements. Endorphins (and the endogenous opioid system (EOS) in general) are involved in social bonding across primate species, and are associated with a number of human social behaviors (e.g., laughter, synchronized sports), as well as musical activities (e.g., singing and dancing). Furthermore, passively listening to music engages the EOS, so here we suggest that both self-other merging and the EOS are important in the social bonding effects of music. In order to investigate possible interactions between these two mechanisms, future experiments should recreate ecologically valid examples of musical activities.
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Affiliation(s)
- Bronwyn Tarr
- Social and Evolutionary Neuroscience Research Group, Department of Experimental Psychology, University of OxfordOxford, UK
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Ragen BJ, Maninger N, Mendoza SP, Jarcho MR, Bales KL. Presence of a pair-mate regulates the behavioral and physiological effects of opioid manipulation in the monogamous titi monkey (Callicebus cupreus). Psychoneuroendocrinology 2013; 38:2448-61. [PMID: 23768970 PMCID: PMC3812423 DOI: 10.1016/j.psyneuen.2013.05.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Revised: 03/07/2013] [Accepted: 05/13/2013] [Indexed: 10/26/2022]
Abstract
The role of opioid receptors in infant-mother attachment has been well established. Morphine, a preferential μ opioid receptor (MOR) agonist, attenuates separation distress vocalizations and decreases physical contact between infant and mother. However, there is little research on how opioid receptors are involved in adult attachment. The present study used the monogamous titi monkey (Callicebus cupreus) to explore the role of opioid receptors in the behavioral and physiological components of pair-bonding. In Experiment 1, paired male titi monkeys (N=8) received morphine (0.1, 0.5, or 1.0mg/kg), the opioid antagonist naloxone (1.0mg/kg), vehicle, or a disturbance control and were filmed with their pair-mate for 1h. In Experiment 2, the same eight males received morphine (0.25mg/kg), naloxone (1.0mg/kg), vehicle, or a disturbance control and were filmed for an hour without their pair-mates. All video sessions were scored for social and non-social behaviors. Blood was sampled immediately prior to drug administration and at the end of the hour session. Plasma was assayed for cortisol, oxytocin, and vasopressin. In Experiment 1, opioid manipulation had no effect on affiliative behaviors; however, morphine dose-dependently decreased locomotor behavior and increased scratching. In Experiment 2 in which males were separated from their pair-mates, naloxone increased locomotion. Morphine dose-dependently attenuated the rise in cortisol, while naloxone potentiated the increase of cortisol. The cortisol increase following naloxone administration was greater when a male was alone compared to when the male was with his pair-mate. Naloxone increased vasopressin but only when the male was tested without his pair-mate. The present study found that the absence of a pair-mate magnified naloxone's effects on stress-related hormones and behaviors, suggesting that the presence of a pair-mate can act as a social buffer against the stress-inducing effects of naloxone.
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Affiliation(s)
- Benjamin J. Ragen
- Psychology Department, University of California-Davis, CA 95616, USA
,California National Primate Research Center, Davis, CA 95616, USA
,Psychology Department University of California, Davis One Shields Avenue Davis, CA 95616 Phone: 530-752-0875 Fax: 530-754-1866
| | - Nicole Maninger
- California National Primate Research Center, Davis, CA 95616, USA
| | - Sally P. Mendoza
- California National Primate Research Center, Davis, CA 95616, USA
| | - Michael R. Jarcho
- Psychology Department, University of California-Davis, CA 95616, USA
,California National Primate Research Center, Davis, CA 95616, USA
,Department of Neuroscience, Loras College, Dubuque, IA 52001, USA
| | - Karen L. Bales
- Psychology Department, University of California-Davis, CA 95616, USA
,California National Primate Research Center, Davis, CA 95616, USA
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Molesti S, Majolo B. Grooming increases self-directed behaviour in wild Barbary macaques, Macaca sylvanus. Anim Behav 2013. [DOI: 10.1016/j.anbehav.2013.05.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Pomerantz O, Meiri S, Terkel J. Socio-ecological factors correlate with levels of stereotypic behavior in zoo-housed primates. Behav Processes 2013; 98:85-91. [PMID: 23694743 DOI: 10.1016/j.beproc.2013.05.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2012] [Revised: 03/20/2013] [Accepted: 05/10/2013] [Indexed: 12/30/2022]
Abstract
Stereotypic behavior often indicates poor welfare. It may develop when the animal's ability to carry out appropriate behavioral responses is limited, despite a high motivation to express them. Behavioral motivations vary across species. Consequently, under similar captive conditions, the sustained inability of animals to express certain behaviors is likely to affect some species more than others. We used a phylogenetic comparative approach to evaluate the socio-ecological factors affecting the manifestation of stereotypic behavior in 24 species of zoo-housed primates. We examined the relationship between two stereotypic behaviors: hair-pulling and pacing, and the species' natural socio-ecological factors and captivity conditions. The degree of stereotypic behaviors was unaffected by phylogenetic relatedness between species. Stereotypic hair-pulling behavior levels were positively correlated with natural group size. Stereotypic pacing levels were positively correlated with the animals' natural day journey length. These findings suggest large-group and wide-ranging primate species are more prone to suffer in captivity. Our findings facilitate the detection of species that are more susceptible to behaving stereotypically in captivity. We suggest that providing appropriate social stimuli, and increasing the complexity of the captive environment rather than enlarging it, are both attainable and expected to improve the animals' welfare.
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Affiliation(s)
- Ori Pomerantz
- Department of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Israel.
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Neuroanatomical distribution of μ-opioid receptor mRNA and binding in monogamous prairie voles (Microtus ochrogaster) and non-monogamous meadow voles (Microtus pennsylvanicus). Neuroscience 2013; 244:122-33. [PMID: 23537838 DOI: 10.1016/j.neuroscience.2013.03.035] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 03/08/2013] [Accepted: 03/16/2013] [Indexed: 01/06/2023]
Abstract
The opiate system has long been implicated in the rewarding properties of social interactions. In particular, the μ-opioid receptor (MOR) mediates multiple forms of social attachment, including the attachment of offspring to the mother and social bonding between mates. We have previously shown that MOR in the caudate-putamen is involved in partner preference formation in monogamous prairie voles. Here, using in situ hybridization and receptor autoradiography, we mapped in detail the distribution of MOR mRNA and ligand binding in monogamous prairie vole brains and compared MOR binding density with that of promiscuous meadow vole brains. Comparison of MOR binding in these closely related species with distinctly different social behavior revealed that while the distribution of MOR is similar, prairie voles have significantly higher densities of MOR than meadow voles in a majority of regions in the forebrain, including the caudate-putamen, nucleus accumbens shell, lateral septum and several thalamic nuclei, including the anteroventral and anteromedial thalamic nuclei. These differences in MOR expression between prairie and meadow voles could potentially contribute to species differences in behavior, including social attachment.
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Burkett JP, Young LJ. The behavioral, anatomical and pharmacological parallels between social attachment, love and addiction. Psychopharmacology (Berl) 2012; 224:1-26. [PMID: 22885871 PMCID: PMC3469771 DOI: 10.1007/s00213-012-2794-x] [Citation(s) in RCA: 138] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Accepted: 06/26/2012] [Indexed: 01/31/2023]
Abstract
RATIONALE Love has long been referred to as an addiction in literature and poetry. Scientists have often made comparisons between social attachment processes and drug addiction, and it has been suggested that the two may share a common neurobiological mechanism. Brain systems that evolved to govern attachments between parents and children and between monogamous partners may be the targets of drugs of abuse and serve as the basis for addiction processes. OBJECTIVES Here, we review research on drug addiction in parallel with research on social attachments, including parent-offspring attachments and social bonds between mating partners. This review focuses on the brain regions and neurochemicals with the greatest overlap between addiction and attachment and, in particular, the mesolimbic dopamine (DA) pathway. RESULTS Significant overlap exists between these two behavioral processes. In addition to conceptual overlap in symptomatology, there is a strong commonality between the two domains regarding the roles and sites of action of DA, opioids, and corticotropin-releasing factor. The neuropeptides oxytocin and vasopressin are hypothesized to integrate social information into attachment processes that is not present in drug addiction. CONCLUSIONS Social attachment may be understood as a behavioral addiction, whereby the subject becomes addicted to another individual and the cues that predict social reward. Understandings from both fields may enlighten future research on addiction and attachment processes.
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Affiliation(s)
- James P Burkett
- Center for Translational Social Neuroscience, Division of Behavioral Neuroscience and Psychiatric Disorders, Department of Psychiatry and Behavioral Sciences, Yerkes National Primate Research Center, Emory University, 954 Gatewood Road, Atlanta, GA 30329, USA.
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Hemelrijk CK, Puga-Gonzalez I. An individual-oriented model on the emergence of support in fights, its reciprocation and exchange. PLoS One 2012; 7:e37271. [PMID: 22666348 PMCID: PMC3364247 DOI: 10.1371/journal.pone.0037271] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 04/17/2012] [Indexed: 11/19/2022] Open
Abstract
Complex social behaviour of primates has usually been attributed to the operation of complex cognition. Recently, models have shown that constraints imposed by the socio-spatial structuring of individuals in a group may result in an unexpectedly high number of patterns of complex social behaviour, resembling the dominance styles of egalitarian and despotic species of macaques and the differences between them. This includes affiliative patterns, such as reciprocation of grooming, grooming up the hierarchy, and reconciliation. In the present study, we show that the distribution of support in fights, which is the social behaviour that is potentially most sophisticated in terms of cognitive processes, may emerge in the same way. The model represents the spatial grouping of individuals and their social behaviour, such as their avoidance of risks during attacks, the self-reinforcing effects of winning and losing their fights, their tendency to join in fights of others that are close by (social facilitation), their tendency to groom when they are anxious, the reduction of their anxiety by grooming, and the increase of anxiety when involved in aggression. Further, we represent the difference in intensity of aggression apparent in egalitarian and despotic macaques. The model reproduces many aspects of support in fights, such as its different types, namely, conservative, bridging and revolutionary, patterns of choice of coalition partners attributed to triadic awareness, those of reciprocation of support and 'spiteful acts' and of exchange between support and grooming. This work is important because it suggests that behaviour that seems to result from sophisticated cognition may be a side-effect of spatial structure and dominance interactions and it shows that partial correlations fail to completely omit these effects of spatial structure. Further, the model is falsifiable, since it results in many patterns that can easily be tested in real primates by means of existing data.
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Affiliation(s)
- Charlotte K Hemelrijk
- Behavioural Ecology and Self-Organization, Centre for Ecological and Evolutionary Studies, University of Groningen, Groningen, The Netherlands.
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Tiddi B, Aureli F, Schino G. Grooming up the hierarchy: the exchange of grooming and rank-related benefits in a new world primate. PLoS One 2012; 7:e36641. [PMID: 22590582 PMCID: PMC3348124 DOI: 10.1371/journal.pone.0036641] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Accepted: 04/04/2012] [Indexed: 11/18/2022] Open
Abstract
Seyfarth's model assumes that female primates derive rank-related benefits from higher-ranking females in exchange for grooming. As a consequence, the model predicts females prefer high-ranking females as grooming partners and compete for the opportunity to groom them. Therefore, allogrooming is expected to be directed up the dominance hierarchy and to occur more often between females with adjacent ranks. Although data from Old World primates generally support the model, studies on the relation between grooming and dominance rank in the New World genus Cebus have found conflicting results, showing considerable variability across groups and species. In this study, we investigated the pattern of grooming in wild tufted capuchin females (Cebus apella nigritus) in Iguazú National Park, Argentina by testing both the assumption (i.e., that females gain rank-related return benefits from grooming) and predictions (i.e., that females direct grooming up the dominance hierarchy and the majority of grooming occurs between females with adjacent ranks) of Seyfarth's model. Study subjects were 9 adult females belonging to a single group. Results showed that grooming was given in return for tolerance during naturally occurring feeding, a benefit that higher-ranking females can more easily grant. Female grooming was directed up the hierarchy and was given more often to partners with similar rank. These findings provide supporting evidence for both the assumption and predictions of Seyfarth's model and represent, more generally, the first evidence of reciprocal behavioural interchanges driven by rank-related benefits in New World female primates.
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Affiliation(s)
- Barbara Tiddi
- Research Centre in Evolutionary Anthropology and Palaeoecology, School of Natural Sciences and Psychology, Liverpool John Moores University, United Kingdom.
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