Karen L. Bales - US grants

Monogamy is a derived trait that occurs in 3 percent of mammals. Peptide hormones, especially oxytocin (OT) have been implicated in the regulation of these traits. OT is especially important early in life, and early exposures are often reflected in the behavior of the adult animal. This research will test the effects of neonatal administration of OT and an OT antagonist on adult expression of monogamous behaviors in a monogamous rodent, the prairie vole (Microtus ochrogaster). This project will also examine the effects of neonatal OT on the classic traits of monogamy in a closely related polygamous vole, the montane vole (Microtus montanus). Finally this project will examine the effects of neonatally administered OT on the number and distribution of estrogen and OT receptors in the brains of male prairie and montane voles. It is predicted that monogamous behaviours and the number of OT receptors will be increased by neonatal OT, while estrogen receptors should be decreased, with effects being more prominent in montane voles. This research has public health implications because of the now routine use of OT and OT antagonists to induce or inhibit labor in pregnant women, and the lack of research on behavioral effects of this procedure.

This project will examine the effects of early social experience on
male parental care in prairie voles (Microtus ochrogaster). Prairie voles are a
monogamous, cooperatively breeding species in which males display high levels
of spontaneous parental and alloparental behavior (taking care of infants not their own). However, the principal investigator has previously observed marked differences in paternal behavior as a function of differential handling during the postnatal period. Experiences during the postnatal period and the availability of neuropeptide hormones, including oxytocin (OT) and arginine vasopressin (AVP), may contribute to the expression of positive behaviors toward pups as well. In this project the researcher will study the neurobiology underlying the effects of varying levels of early experience on male alloparental care. Pups will receive different levels of handling during the first week of life. Later variables measured will include alloparental care and anxiety, as well as long-term changes in peptide receptor systems (OT, AVP, and CRH, corticotropin-releasing hormone), mRNA expression for these receptors, and short-term peptide changes in the brain and blood when exposed to a pup. This project will help us to understand the biology of male parenting.

Prairie voles are a monogamous species of rodent in which males participate in infant care. This project will investigate the effects of early experiences on later male parental care and its underlying neurobiology.

behavioral /social science research tag; positron emission tomography

EMT: Collaborative Research: Primate-inspired Heterogeneous Mobile and Static Sensor Networks

Although previous bio-inspired models have concentrated on invertebrates (such as ants), mammals such as primates with higher cognitive function are valuable for modeling the increasingly complex problems in engineering. Understanding primates? social and communication systems, and applying what is learned from them to engineering domains is likely to inspire solutions to a number of problems.
This research involves studying and modeling modes of group behavior and communication of coppery titi monkeys, rhesus macaques, and other primate models, and applying what the investigators learn to the distributed control of heterogeneous mobile and static sensor networks. The investigators will model the social and communication behavior of these primates, which will provide biological inspiration for solving problems in communication and networking. The phases of this research include: 1) identification, interpretation, and translation of primate behavioral models, 2) assessment of the effectiveness of small and large group formations based on primate grouping models in heterogeneous mobile and static sensor networks, 3) development of bio-inspired message-based communications, and 4) development of bio-inspired behavior-based communications. This research aims to achieve a deeper understanding of effectiveness of bio-inspired communications and networking by studying primates, and to establish interdisciplinary research and education in the fields of biological modeling, sensor networking, and robots control.

Monogamy is characterized by the formation of strong and selective preferences for a specific partner ("pair-bonding"). Pair-bonding is associated with a number of significant changes in both behavior and physiology; however, the mechanisms for these changes are not completely understood. This research will explore a potential cellular mechanism for neural adaptations involved in the social behavior of a monogamous rodent, the prairie vole (Microtus ochrogaster). Specifically, the studies will focus on a unique protein, delta-FosB, which has emerged as a potential molecular 'switch' mediating long-term adaptations in the brain. This protein has been shown to accumulate in the brains of animals that are repeatedly exposed to drugs, food-reinforcement and wheel-running. However, the role of this protein in naturalistic, species-typical behavior is not well characterized. The proposed research consists of three goals: 1) examine delta-FosB accumulation in the brain following the formation and maintenance of a pair bond, 2) explore whether increasing levels of delta-FosB in the brain facilitates pair bond formation in the monogamous prairie vole, and 3) examine region-specific delta-FosB accumulation as a result of social separation (a chronic stressor and model of 'grief'). This study is designed to expand understanding of the evolution and neurobiology of social behavior. This research will also inform our understanding of the biology of attachment, grief and mourning in humans, as social bonds are a critical component of human behavior. Finally, this research will provide training in neuroscience for a female graduate student and multiple undergraduates.

DESCRIPTION (provided by applicant): Offspring receive differential early somatosensory stimulation through parenting and other processes, such as neonatal exposure to novelty. This early somatosensory stimulation is known to have long-term effects on the development of stress reactivity and social behavior. These early differences in somatosensory stimulation may also contribute both to normal and pathological development of sensory function. A wide variety of developmental disorders share many characteristics including a developmental timeline and dysregulation of both social behavior and somatosensory function. The aim of the current proposal is to examine the effects of early environment, in particular the effects of early somatosensory stimulation on later social and sensory behavior, and on the functional organization and size of the primary somatosensory cortex (S1) in a rodent model, the prairie vole (Microtus ochrogaster). First, normal development will be studied in offspring from parents which demonstrate extremes of natural individual variation in somatosensory stimulation. We will then examine offspring from a handling model known to produce deficits in social behavior, and which has been shown to exert its effects through differential early somatosensory stimulation of young. Following weaning, anxiety, social behavior, and sensorimotor gating in the offspring will be examined, as well as the functional organization and size of S1, and its thalamocortical and cortico-cortical connections. Finally, all of these variables will be correlated: early somatosensory stimulation received from parents, later social, anxiety, and sensory behavior, and neuroanatomical organization of S1. PUBLIC HEALTH RELEVANCE: Many developmental disorders exhibit changes in both social behavior and sensory function. This proposal will investigate how environmental factors in early life can lead to changes in behavior and in the function of the somatosensory cortex.

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The primary goal of this research is to further our understanding of the neurobiological basis of social bonding, using a unique non-human primate model. Dysfunctions in social bonding underlie a number of developmental and psychiatric disorders, as well as having long-term consequences for physical and psychological health. In this broader context, we propose to study a species which displays high levels of selective social bonding, the monogamous titi monkey (Callicebus cupreus). This species displays a pair-bond, or selective attachment between males and females, as well as attachment by offspring to their father. Non-human primate models are a valuable addition to rodent models, in being neuroanatomically much closer to humans. In many cases they are also preferable to studying humans directly, because of the greater control possible over individual experience and experimental conditions. Arginine vasopressin (AVP) and oxytocin (OT) are neuropeptide hormones known to be involved in social bonding in rodents. Although there is also evidence for their role in primate social bonding, the directionality of the process is unclear. We propose to distinguish between three models of the relationship between AVP, OT and social bonding: a) Maturational - the formation of social bonds in a monogamous species are the results of irreversible, age-related maturational processes in which changes in the AVP and OT systems (increases in synthesis, changes in receptor binding) set up a predisposition to form a pair-bond;b) Situational - changes in the AVP and OT systems are completely environmental and the direct result of the formation of a pair-bond or parental attachment. In this model, these changes are reversible upon the loss of the attachment figure, and c) Combination - while irreversible maturational changes in AVP and/or OT set the stage for formation of an adult attachment, the formation of a pair-bond then induces further changes and the loss of an attachment figure can "reset" the process. Our previous research in this species shows evidence for both maturational changes (gonadal hormones, Valeggia et al., 1999) and situational changes (adrenocortical response to formation and disruption of attachment bonds, Mendoza et al., 2000). Our overarching hypothesis for the current research is that both processes are combined with respect to neuropeptide regulation of pair-bonding - the proposed "combination" model.

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The objective of this study is to investigate the occurrence and mechanisms of prosocial behavior (affiliation, pair-bonding, parenting, etc.) in a monogamous, non-human primate model, the titi monkey.

DESCRIPTION (provided by applicant): Autism is a common, impairing neurodevelopmental disorder involving deficits in social interaction and social communication. Oxytocin (OT) is a nine amino acid peptide produced in the hypothalamus and stored in the posterior pituitary. OT regulates the formation of close selective social bonds and has been implicated in the social dysfunction found in autism spectrum disorders (ASD). There has been a proliferation of recent research examining the effects of intranasal OT on human behavior, including suggestions for its use as a therapeutic for various psychopathologies involving social deficits, including ASD. Phase 2 trials for use of intranasal OT in autism are underway for children 12-18 years of age (Clinicaltrials.gov identifier: NCT01256060), and OT is already frequently prescribed in the United States to children with ASD. Alarmingly, our preliminary data in animal models show that while administration of intranasal OT has positive effects of social behavior in the short-term, long-term effects at some dosages are negative. Aside from our pilot study, there have been no long-term studies of chronic intranasal OT use in humans or in ANY animal model; that is what we propose to do in this study. The aim of the current study is to examine the developmental effects of chronic intranasal OT administered to two animal models of selective social behavior (prairie voles and titi monkeys), as well as one mouse model of the social deficits of autism. In the rodent models, dosage, frequency, and age of administration will be varied. The immediate social effects of administration, as well as long-term effects on social behavior, repetitive behavior, and anxiety will be explored, as well as changes to the OT and vasopressin systems and functional neural changes in response to social stimuli. In titi monkeys, we will administer the dosage being used in clinical trials and examine the short-term and long-term effects on social behavior, repetitive behavior, and anxiety. Finally, we will examine changes to local cerebral glucose metabolism in titi monkeys treated with chronic intranasal OT or vehicle via PET imaging, with a focus on areas that produce or have receptors for OT.

? DESCRIPTION (provided by applicant): Decades of research have shown that the peptide oxytocin (OT) can act as a potent neuromodulator in a variety of species to influence complex social behaviors, including social bonding, affiliation, and social reward. In a growing number of studies, administering intranasal OT to humans has been shown to affect a suite of social behaviors, such as trust, eye contact, emotion recognition, and pair-bonding-related behaviors. Due to the ability of OT to modulate social function in animals as well as humans, the OT system has been highly implicated in the biology and treatment of autism spectrum disorder (ASD), a condition that is characterized in part by deficits in sociality. ASD affects approximatel 1 in 68 children in the United States (CDC 2014). Recent research has now shown that intranasal OT can improve some aspects of social functioning in patients with ASD. However, it is currently unknown whether differences in the neural distribution of the oxytocin receptor (OXTR) exist between patients with ASD and neurotypical individuals. By locating the neural substrates that are sensitive to OT, we will become better able to understand the mechanisms by which OT can influence human behavior. The aim of this proposal is to employ a novel and pharmacologically optimized method to detect OXTR in brain tissue from patients with ASD and matched control tissue, in order to determine whether neurological changes in the OT system may be part of the biology of ASD. Mapping the locations of OXTR expression in human brain tissue has been a difficult endeavor due to the pharmacological cross reactivity between the OT and vasopressin (AVP) receptor systems. There is a high degree of structural homology between OT and AVP and between OXTR and the vasopressin 1a receptor (AVPR1a), which results in both neuropeptides having a high affinity for each other's receptors. This mixed affinit is particularly high in humans and nonhuman primates, compared to rodents. Similarly, most of the pharmacological tools that are currently available to study these receptors also have a high affinity for both OXTR and AVPR1a in primates. As a result, research on the basic physiology of OXTR and AVPR1a in primates has been markedly hindered, especially the fundamental neuroanatomical research to localize the distributions of these receptors in brain tissue. In order to overcome these limitations on reliably detecting OXTR in primate tissue, Dr. Freeman (co-investigator) has previously designed a reliable, pharmacologically informed protocol for visualizing OXTR in post-mortem primate brain tissue by determining the precise concentrations at which these ligands can be used to selectively occupy one receptor over the other. This pharmacologically optimized modification for OXTR receptor autoradiography is the first reliable technique for identifying OXTR in human and nonhuman primate brain tissue. By using this optimized technique in human brain tissue, we are uniquely capable of specifically identifying OT's neural targets in humans for the first time.

? DESCRIPTION (provided by applicant): This grant application seeks to uncover the molecular and neural networks underlying social attachment behaviors in prairie voles. Humans form attachments at many levels of social interactions, including with spouses, family members, friends, and other members of the community. The neurobiological mechanisms that control the formation and maintenance of social attachment remain poorly understood. This is in part because traditional genetic model systems such as mice, fish, flies, and worms do not exhibit social attachment behavior as adults, precluding the use of powerful molecular genetic approaches to dissect mechanisms underlying social attachment behavior. Prairie voles are small rodents that form an enduring social bond between adults, and they also display other related afflictive behaviors. Pharmacologic studies in prairie voles have implicated vasopressin and oxytocin signaling in the control of social attachment behaviors. However, there are significant limitations of these pharmacological manipulations such that the genetic requirement of specific neuropeptide signaling pathways remains unclear. Progress in uncovering the molecular and neural circuit basis of social attachments in prairie voles has been slowed by the absence of gene targeting techniques as well as by the absence of identification of behaviorally-salient neurons. In this grant application, we propose to develop gene targeting technology in prairie voles, focusing on vasopressin and oxytocin signaling pathways (Aim 1). In Aim 2, we propose to analyze behavioral deficits in social attachment in prairie voles genetically mutant for these signaling pathways. Finally, in Aim 3 we propose developing molecular tools to uncover genetic and neural pathways underlying social attachment in prairie voles. Taken together, our studies will enable gene targeting in prairie voles and elucidate neural mechanisms that control social attachment behavior. Health relatedness: Social attachments are thought to be critical for our mental health and for success in personal and professional interactions. Failure to form or maintain social attachments is often an early indicator of a serious mental illness such as autism spectrum disorder or schizophrenia. Strikingly, vasopressin and oxytocin are also thought to play a critical role in human social attachments, and dysregulated signaling via these neuropeptide pathways has been implicated in autism spectrum disorders. Our proposal seeks to establish the prairie vole as a new mammalian genetic model system and to uncover mechanisms underlying social attachment behavior. These advances may therefore provide a useful model system to study social behaviors relevant to human health and mental illnesses.

Project Summary The neurobiology of social behavior is of crucial importance not only in order to understand our own basic biology, but also for cases in which social behavior is impaired (for example, autism spectrum disorder and schizophrenia). The effects of social support on long-term health are now largely undisputed; and the dangers of loneliness are also increasingly well-recognized. For instance, a recent meta-analysis found that poor social relationships led to 29% increased risk for coronary heart disease, and a 32% increased risk for stroke. Our own prior investigations on the neurobiology of primate social bonds, like many others, have focused on males. Females represent a crucial and under-studied population when it comes to both psychiatric disorders of social behavior and studies of primate pair-bonding. Females are also more likely to be diagnosed with affective disorders, such as major depressive disorder, which may have critically understudied social risk factors, such as social stress. Here we propose a series of investigations into the neurobiological basis of attachment in female titi monkeys, a socially monogamous New World primate, using pharmacology and functional imaging to address fundamental questions about the substrates for sociality. Our overarching hypothesis is that the transition from attachment to parents to attachment to a pair-mate, may rely on neuropeptide receptor function, particularly the neuropeptides oxytocin and vasopressin. We will study these questions in adolescent and adult female titi monkeys. We will use behavioral pharmacology to investigate the effects of oxytocin and vasopressin manipulation on the fundamental traits of an attachment (preference for the partner/parent, distress upon separation, and social buffering). We use functional imaging to examine dynamic changes in glucose uptake in areas that we know to have oxytocin or vasopressin receptors in titi monkeys, in response to manipulations including the presence or absence of an attachment figure. Finally, we will use molecular techniques to examine changes in methylation of the oxytocin and vasopressin receptors across the course of pair-bonding, separation, and buffering from stress.

Decades of research have shown that the peptide oxytocin (OT) can act as a potent neuromodulator in a variety of species to influence complex social behaviors, including social bonding, affiliation, and social reward. Administering intranasal OT to humans affects a suite of social behaviors, such as trust, eye contact, emotion recognition, and pair-bonding-related behaviors. Due to the ability of OT to modulate social function in animals as well as humans, the OT system has been highly implicated in the biology and treatment of several psychiatric conditions that are characterized by deficits in sociality, including autism spectrum disorder, schizophrenia, and social anxiety disorder. Because of this high translational potential for OT to benefit human health, it is crucial that research efforts focus on the fundamental neuroanatomy and physiology of the oxytocin system in the brains of both animals and humans. Thanks to the suite of transgenic tools available, research in mice has contributed considerably to our understanding of the function of OT in the regulation of social behavior. But non-mouse models are increasingly being used, including monogamous rodents as well as nonhuman primates. To complement the elegant behavioral pharmacology being done in these species, rigorous neuroanatomical work is required to characterize the underlying neural circuits. Currently, the most reliable and widely available technique for the visualization of OXTR in brain tissue sections is receptor autoradiography, but this method has some limitations. It only resolves receptors at the gross anatomical level; it is not possible to analyze receptor expression on the cellular scale. The most common technique to visualize receptors on the cellular level is with a method called immunohistochemistry. But because there are no reliable, commercially-available antibodies for OXTR, the field of OXTR research has been left without a widely available and tractable technique to investigate these receptors on the cellular level. Thus, the first aim of our proposal is to advance the field of OT research by developing a novel method for the cellular staining of OXTR in brain tissue. This technique will use a novel biotinylated OXTR ligand provided by our chemist collaborator and will be optimized from prairie voles, titi monkeys, and humans. The second limitation of receptor autoradiography is that it uses an indirect visualization method (radiosensitive film) that doesn't label the tissue directly. Thus, it is impossible to perform co-localization studies with targets of other neurotransmitter systems known to interact with OT/OXTR to modulate social function. Aim 2 seeks to resolve this issue by applying the novel OXTR staining method to the localization of OXTR on dopaminergic neurons in prairie voles. Our decision to start with the dopaminergic system in prairie voles is based on extensive experimental evidence for the interaction between these two systems in the regulation of pair bond formation in this monogamous rodent. By developing a cellular stain for OXTR that is tractable across laboratories and species, a massive opportunity will be created for future studies of OXTR-expressing neurons.

Project Summary Social relationships are crucially important to human health. The effects of social relationships on healthy aging are seen in several systems, including the cardiovascular system, metabolism, emotion, and cognitive function. The effects of social isolation and loneliness have been shown to independently increase risk for stroke, heart disease, and overall mortality. High quality social support, in contrast, can play a positive role in healthy aging including reducing metabolic syndrome and adverse cardiovascular outcomes. Long-term partnerships (such as marriage) are the primary close relationship in many adults, but other types of relationships such as sibling relationships, other family relationships, and friendships, may also support healthy aging. Prairie voles are an excellent rodent model of social relationships, in that they show classic behavioral characteristics of an attachment bond: adult males and females form pair bonds, which are characterized by a preference for the familiar partner, distress upon separation, and the ability of the partner to provide a social buffer against stress. These behavioral characteristics in prairie voles provide researchers with the ability to examine the effects of specific types of affiliative relationships (pair mates, siblings, parent-offspring) in adult males as well as in females. The hormone oxytocin has been established as a foundational mechanism in the neurophysiology of relationship formation, relationship quality and partner loss. Its secretion is stimulated by a wide variety of social stimuli, including social touch, sex and social stress. Its receptor is widespread throughout the body. As such, it presents a potential unifying mechanism for organismal-scale effects of social relationships on the brain and the body. Here we will examine how long-term social relationships influence cardiac, metabolic, cognitive and emotional health across the lifespan. Our general approach is to use prairie voles, both males and females, in differing social conditions (pair-bonded, housed with same-sex sibling, or isolated) to examine the effects of presence of a relationship, type of that relationship, and quality of that relationship on cardiac and metabolic health, behavioral and cognitive health, and longevity. We will longitudinally assess measures of cardiac, metabolic, behavioral, and cognitive function at three timepoints: 6, 18, and 24 months of age. We will assess changes in the OT system across aging, on both brain and peripheral tissues (heart, adipose tissue, and skeletal muscle). Finally, we will explore how relationships change over time, and how loss of a partner affects healthy aging.