Donna L. Maney - US grants

Songbirds possess a talent rare among non-human animals: the ability to learn complex vocalizations. The system of brain regions that controls the learning and production of song has become perhaps the most popular model for studying the neural basis of a complex learned behavior. Despite this popularity, few researchers have investigated how the song system is connected to and affected by brain regions outside it. Song is produced only in specific social contexts, and is undoubtedly controlled in part by a distinct network of brain regions involved in the regulation of social behavior in general. Here, the PI proposes to map this "social behavior network" in songbirds and explore how it affects song and its perception. Neuroanatomical methods will be used to identify connections among these regions, and to determine which brain cells and proteins in the network participate in song and other social behaviors. By connecting brain areas that mediate social behavior with those processing social information, the project effectively merges cognitive and affective neuroscience. The results will help us understand how the brain perceives social cues as well as how it organizes and implements an appropriate social response. The PI's multi-disciplinary approach offers exciting pedagogical opportunities to train new scientists in a variety of laboratory and field techniques, and challenges students to ask questions on many levels, from molecular to evolutionary. The teaching plan emphasizes writing skills, and includes development of new writing-intensive courses in the sciences. The PI hopes to help train future scientists to communicate effectively, not only with each other, but also with the public.

The white-throated sparrow has generated a great deal of interest among behavioral biologists because it occurs in two ""morphs"", or types, that have different social behavior. Dozens of behavioral studies, conducted in both field and laboratory settings, have established that individuals with a white stripe on the crown tend to be more aggressive, whereas birds with a tan stripe exhibit more parental care. By conducting the studies in this project, the neurochemical reasons why white birds are more aggressive than tan birds will be revealed. Because the steroid hormone testosterone is higher in white than tan males, investigating the biological ways in which testosterone may alter aggression and thus cause behavioral differences between morphs is an essential feature of this project. The approach used by the PI is powerful because it will comprehensively examine both behavior and neurochemistry in the same individuals, thus enabling detailed study of individual variation. Because the biological basis of aggressive behavior is similar in most vertebrate animals, the results from these studies will facilitated a better understanding of the neurochemical underpinnings for aggression in tens of thousands of species, including humans. A graduate student will receive training in behavioral biology, neuroscience, and molecular biology, and will thus be well prepared for career that integrates all three fields. The PI will also mentor several undergraduate students, and will encourage them to present their findings at national meetings and in published journal articles.

DESCRIPTION (provided by applicant): Social behaviors that impact human health, including risk-taking, aggression, and parental care, have a neuroendocrine basis that is both biologically based and well conserved across vertebrates. Animal models, particularly those in which definitive neuroendocrine and genetic links to social behavior have been described, are therefore valuable systems in which to study the hormones and genes that influence human social behavior. Ideally, such models would be easily studied in their natural habitats, reasonably similar to humans in their social behavior, genetically tractable, and inexpensive to work with. We have been studying the neuroendocrine and genetic bases of social behavior in an exceptionally promising model, the white-throated sparrow (Zonotrichia albicollis). This songbird, which is native to North America, has generated a great deal of interest among behavioral biologists because of a plumage polymorphism that predicts many aspects of an individual's social behavior. Dozens of behavioral studies conducted in the animals'natural habitat have established that individuals with a white-stripe (WS) on the crown are more competitive and aggressive, and birds with a tan stripe (TS) engage in more parental care. The color polymorphism is associated with a structural rearrangement on chromosome 2;all of the WS individuals have a copy of the rearranged chromosome (2m), whereas those of the TS morph are homozygous for the wild-type chromosome. We are currently mapping the 2m chromosome and have identified a set of promising neuroendocrine genes that are located within the rearrangement and may therefore contribute toward the behavioral phenotype and thus to risk-taking, aggression, and parenting. These genes, which include a gonadal steroid receptor, a steroidogenic enzyme, and a serotonin receptor subtype, are already suspected to play a role in social behavior in vertebrates, including humans. Here, we propose to evaluate these genes by identifying those (1) whose expression mirrors the behavioral polymorphism;(2) that may have organizational effects on the development of polymorphic behavior;and (3) that have been directly altered by the chromosomal arrangement in ways that may alter gene expression or function. Overall, the white-throated sparrow represents a unique and valuable opportunity for studies of the biological bases of social behavior because the behavioral differences between the morphs are already well-documented in free-living and laboratory populations, and the chromosomal inversion has been definitively linked to the behavioral polymorphism. Because the genes and pathways that regulate social behavior are conserved across species, the results of these studies will be applicable to understanding the mechanisms underlying aggressive and parental behavior in humans. PUBLIC HEALTH RELEVANCE: Social behaviors that impact human health, including competitive aggression and parental care, are in part influenced by hormones and gene expression. Here, we will study these influences in an animal model with a natural polymorphism that provides a unique opportunity to characterize the processes underlying aggression and parenting.

A Summer School of Behavioral Neuroendocrinology has been operating successfully at Michigan State University since 2005. The program will relocate in 2010 to Emory University. Leaders in the field will be brought to Emory's campus from all over the U.S. to discuss topics such as sex differences in behavior and the nervous system, the effects of hormones on brain structures and processes, and the neuroendocrinology of stress. Participants will receive training in writing, data archiving and bioinformatics, and the analysis of hormone-dependent behaviors. The course is intended for undergraduates (or people who have recently received their undergraduate degree) who are contemplating applying to graduate school. The aim is to give trainees an appreciation for behavioral neuroendocrinology as a discipline as well as a sense of what it is like to have a career in science. One important aspect of the course is that the trainees interact with professors and graduate students who are accomplished scientists. Following the one-week course, trainees attend the annual meeting of the Society for Behavioral Neuroendocrinology (SBN) to consolidate what they have learned and to expand their social contacts within the field. Attending the SBN meeting is an excellent way for trainees to find graduate programs and faculty mentors with matching interests. A mixture of students who have expressed interest in a career in science will be brought together, and recruitment efforts will target underrepresented minorities. Thus, the overall goal is to increase the strength and the diversity of the applicant pool in this area of science nationwide.

Research on the genetic basis of social behavior has proceeded slowly because of a general lack of interdisciplinary expertise in both genomics and behavior. This project is a collaboration between a PI trained in molecular biology and genetics and a co-PI trained in the analysis of social behavior and its hormonal mechanisms. New high-throughput sequencing methods enable the detailed study of the genetic basis of social behavior in a variety of carefully chosen species, even in the absence of a completely sequenced genome. A songbird model, the white-throated sparrow, is used to characterize genes involved in aggression. This species exhibits a plumage polymorphism that correlates with many aspects of social behavior. Individuals with a white stripe (WS) on the crown are more aggressive and have higher song rates than individuals with a tan stripe (TS). The plumage polymorphism is linked to a chromosomal rearrangement, presenting a unique opportunity to study the relationship between genes and social behavior. This project uses the powerful and exciting technology of next-generation sequencing to identify genes in the brain that vary in expression with relation to both plumage morph and aggressive behavior. Once identified, the expressions of these genes are mapped in the brain to help clarify their role in behavior. Gene sequences are analyzed to identify variation in protein sequence that is linked to plumage morph. These results provide extensive information on the expression, sequence, and distribution of genes linked to aggression.

Intellectual Merit:

Genome-wide association studies have identified a vast array of single nucleotide polymorphisms that are weakly associated with phenotypes but which explain very little variation. The link between genetic polymorphisms and behavioral constructs such as "aggression" is still lacking, largely because of a failure to consider the intermediary steps that happen at the levels of gene transcription and protein function. Progress in this field will require an understanding not only of whether gene sequences contribute to behavior, but how they do so. The behavioral sciences would thus benefit from the expertise of researchers trained to address these questions. In this project, a PI with a background in molecular biology joins a psychology department and integrates genomics techniques and resources into the study of social behavior.

It is essential that studies intended to elucidate the mechanisms driving social behavior be conducted in a way that allows animals to interact in their natural environment. Behavioral studies on laboratory-housed animals often do not represent naturalistic conditions, and can produce results that are not biologically relevant. This study links genes and social behavior using animals that are observed and collected in their natural habitat. Although social behavior is complex and predicted to involve many genes, only a few genes have been definitively linked to social behavior. These results greatly contribute to our knowledge base of gene expression in the brains songbirds, an important model useful for studying the relationship between genes and behavior.

Broader Impacts:

The PI develops and teaches a course, aimed at psychology graduate students interested in genetics-based approaches, which emphasizes basic gene function, the use of genomics databases, and the interpretation of associations between polymorphisms and behavior. Ultimately the course encourages psychology students to integrate genetic approaches in to their research in a powerful way. The PI's other activities include mentoring undergraduates, making presentations at underserved K-12 schools, and mentoring high school students and teachers from underrepresented groups.

DESCRIPTION (provided by applicant): The Institute On Neuroscience Summer Research Immersion. Engaging outstanding high school students in authentic and rewarding laboratory research may attract them to research careers. An intensive summer research experience provides an ideal environment for students to experience hands-on, inquiry-based science learning, which will likely enhance their content knowledge, technical skills, and confidence in their ability to conduct scientific research (scientific research self-efficacy). In turn, science elf-efficacy predicts intent to persist in science-related academic and career paths. Likewise for high school teachers, participating in summer research may improve knowledge, skills, and teaching efficacy, ultimately affecting commitment to teaching and retention in teaching careers. Moreover, by translating research experiences into inquiry-based learning opportunities for future students, teachers can exponentially increase the distribution of knowledge and skills acquired in a summer program. Thus, we will facilitate integration of students and teachers into neuroscience research teams through our program called ION/Teach. Our first aim is to engage high school students and teachers in an intensive summer research program, called the Institute on Neuroscience & Teaching (ION/Teach). A diverse group of students and teachers will start the summer with a week-long seminar on basic neuroscience concepts and methods, then engage in seven weeks of mentored lab research with active investigators at metro-Atlanta universities. Weekly professional development workshops will focus on topics such as scientific communication, college prep, and ethical conduct of research. Teacher participants will translate their summer research into standards-based lesson plans. The summer research experience will culminate in a research symposium. Our second aim is to use the ION/Teach program as a basis to test the hypothesis that participation in authentic laboratory research can improve externally demonstrable research skills (e.g. neuroscience content knowledge, competency at the bench or in the clinic, and scientific communication), and/or internal constructs associated with success in science or teaching careers (e.g. research or teaching self-efficacy, low science anxiety, science identity). Beyond individual outcomes for participants, the effectiveness of lesson plan development by the teacher participants will be monitored by assessment instruments that probe student learning outcomes in their classrooms. This research will fill a gap in current knowledge about how best to prepare young people to help address current biomedical, behavioral, and clinical research needs. For teachers, our results will also help identify ways to enhance retention in science classrooms. Ultimately, this project will produce not only students and teachers with research skills and dispositions toward successful careers, but also education research data for dissemination to the international science education community.

DESCRIPTION (provided by applicant): The underlying genetic basis of variation in social behavior is of intense interest, yet only a handful of genes have been linked to specific social behaviors in vertebrates. Thus, there is a strong need to identify populations, human or otherwise, in which there is clear linkage between genes and social behavior. In the proposed project, resources will be developed to take advantage of a uniquely suited model, the white-throated sparrow. Males and females of this abundant North American songbird occur in two plumage morphs that differ with respect to the presence of a chromosomal rearrangement (ZAL2m) that predicts responses to social threat. Birds of the white-striped (WS) plumage morph (ZAL2m/ZAL2) respond to a territorial intrusion with high levels of vocal aggression, whereas birds of the tan-striped (TS) morph (ZAL2/ZAL2) respond with relatively little or no vocal aggression. The morphs also differ with respect to the formation of social attachments and parental provisioning rates; the phenotypes are thus characterized by a suite of correlated complex traits with a discrete genetic basis. The long-term goal of this research program is to fully exploit this unique model organism, which resembles humans with respect to many aspects of social behavior, to link gene expression and complex behavior in ways never before possible. Limited gene flow between the ZAL2 and ZAL2m haplotypes has led to the genetic differentiation of the rearranged chromosomal region, resulting in the accumulation of single nucleotide polymorphisms and other changes. The primary objective of this proposal is to assess the impact of these genetic forces on the genome and brain transcriptome, thus laying the groundwork to identify molecular mechanisms of behavioral dysregulation in future studies. We will combine the experience of two PIs: one with expertise in the behavioral neuroendocrinology of wild sparrows and the other in genome evolution. In Aim 1, we will identify and evaluate sequence differences between the two haplotypes, which will reveal a large number of potential functional polymorphisms that can then be explored experimentally. In Aim 2, we will use Next Generation techniques to sequence total mRNA from individuals for whom reactive aggression was quantified in a natural setting. We will then use weighted gene coexpression network analysis (WGCNA) of the mapped and quantified reads to identify modules of highly correlated genes associated with morph and reactive aggression. Together, the two aims will reveal candidate mechanisms underlying social strategies. This exploratory project will focus on responses to social threat, which are difficult to study in humans in a naturalistic setting. All behavioral manipulations and measurement will be conducted in the animals' natural habitat, making this project highly innovative. The project is significant because many mental disorders-including autism, depression, bipolar disorder and schizophrenia are characterized by dysregulated responses to social threat and because reactive aggression is often comorbid with risk-taking, substance abuse, and criminal behavior. Thus an understanding of the mechanisms underlying response to social threat is important for human health.

? DESCRIPTION (provided by applicant): Early disruption of social reward can have devastating effects on the development of skills such as initiation of joint attention and vocal communication. Because most existing animal models of social reward focus on adults, a new model is needed for understanding early critical periods of social development in juveniles. The objective of the proposed work is to fill that gap by establishing an animal model of early social reward in juveniles interacting with caregivers. To achieve this goal, the research team will develop an assay to quantify and interrelate social motivation, social preferences, and vocal development in young zebra finches. The rationale for this approach is as follows: First, even before they begin to sing, young zebra finches are highly motivated to hear adult song and will key-press for access to it. Thus, social motivation can be easily quantified. Second, song learning in juveniles is contingent upon social bids (e.g., key presses to hear song) and can also be quantified using established methods, allowing the team to test for relationships between social motivation and vocal learning. Third, young finches prefer to learn song from caregivers rather than unfamiliar adults, providing the opportunity to understand how early social experience dictates social preferences and how those preferences drive vocal learning. In Aim 1, the team will develop an assay to obtain densely sampled, longitudinal data on these processes over the entire trajectory of sensorimotor vocal development. A key innovation of this aim will be to use novel computational methods, originally developed to understand the contributions of social orienting to vocal development in human children, to show the relationships among social motivation, social preferences, and vocal development in this new animal model. Aim 1 will produce a tool to assess the behavioral effects of pharmacological manipulations and gene knockdown within social reward pathways, allowing precise characterization of the relevant neural circuits. To begin capitalizing on the new assay, in Aim 2 the team will test the effects of oxytocin receptor (OTR) blockade on the development of social preferences and vocal learning. The central hypothesis underlying these aims is that OTR signaling early during development, contingent with social interactions with a caregiver, directs juveniles to attend preferentially to that caregiver. As a result, juveniles will more accurately copy that caregiver's vocalizations. A second key innovation is that the project will expand our understanding of oxytocin to include critical periods of social development as well as learning-both of which are potentially rich but grossly underdeveloped areas of research. The new assay will make it possible to model juvenile-initiated social bids in the context of parent-offspring interactions, as well as the relationship between social reward and the development of vocal communication. Because this species has a short generation time and can be maintained in relatively large numbers, the assay will provide new, important opportunities for understanding the neural mechanisms underlying early social reward and the developmental sequelae of its disruption.

The evolution of behavior relies on changes at the level of the genome, yet few vertebrate behaviors can be traced directly to specific gene sequences. In this project, the research team will use a naturally-occurring animal model, the white-throated sparrow, to connect behavior with gene sequence in a concrete way. In this species, 50% of the birds have an unusual chromosome that makes them more aggressive. The chromosome is therefore an excellent tool for understanding how individual variation in gene expression contributes to variation in behavior. The team recently showed that animals with the unusual chromosome have higher expression of a type of steroid receptor in some areas of the brain. Here, the research group determines the genetic mechanisms, at the molecular level, that cause some birds to express more of these receptors than others. In so doing, the team demonstrates how responsiveness to steroid hormones is encoded in the genome. The work lends itself well to education and outreach because it illustrates basic biological concepts in a common backyard bird. Thus, it serves to integrate multiple units of a typical biology course in a way that is accessible to students. High school teachers are recruited to participate in the research and to develop lesson plans about genetics, hormones, brain anatomy, and social behavior. The PI also mentors high school students, undergraduates, and graduate students in the lab. More than 75% of the PI's mentees at Emory have been underrepresented minorities or women.

The evolution of behavior relies on changes at the level of the genome, yet few vertebrate behaviors can be traced directly to genetic sequences. In the white-throated sparrow (Zonotrichia albicollis), a chromosomal inversion segregates with an aggressive behavioral phenotype, offering a rare opportunity to connect genes and behavior in a concrete way. The inversion has captured the gene ESR1, which encodes estrogen receptor alpha (ERalpha). The research team recently showed that the local expression of ERalpha in the brain depends on the presence or absence of the inversion and that variation in ERalpha expression predicts the effect of genotype on territorial aggression. The research group uses in vitro reporter assays, bisulfite sequencing, and allele-specific quantitative PCR to identify the genetic and epigenetic mechanisms that contribute to variation in expression of ERalpha. The effects of selective ERalpha ligands on aggressive behavior in animals of each genotype is used to determine whether variation in ERalpha expression and function is causal for variation in territorial aggression. Because the team uses tissue from behaviorally characterized, free-living animals, the molecular and behavioral levels are integrated in the same animals to allow novel connections. The results provide an interdisciplinary, integrated model of how genetic change leads to phenotypic change. The work lends itself well to education and outreach because it illustrates basic biological concepts in a common backyard bird.