Research in the Kelly lab combines conceptual and empirical tools from comparative neuroanatomy, developmental psychology, behavioral ecology, and molecular neuroscience to understand the proximate and ultimate causes of social behavior. A unifying theme in our research is to examine plasticity in the neural mechanisms of social behavior and question how neuroplasticity can allow for phenotypic changes on different timescales. Research on neuroplasticity on immediate timescales can elucidate how animals are able to rapidly shift social behaviors, such as moment-to-moment transitions from being affiliative with a partner or offspring to being aggressive to an intruder. Plasticity over development can reveal how some aspects of social behavior are stable within an individual’s lifetime, whereas others are more susceptible to environmental influence. We are keenly interested in the neural mechanisms and behaviors that demonstrate exceptional plasticity throughout the lifetime; organisms never stop developing – rather, there are numerous stages of development characterized by varying degrees of mechanistic plasticity. Lastly, examining plasticity on longer timescales can shed light on the role of neuroplasticity in the evolution of social behavior, and how it might account for the profound behavioral variation demonstrated in the natural world.
The Kelly Lab has three primary lines of research, all with a central goal of investigating the mechanisms underlying social behavior at multiple levels by utilizing different approaches.
Elucidating the mechanisms and environmental influences underlying individual and species differences in social behavior
What are the neural circuits underlying sociality (i.e., reproductive and non-reproductive affiliation) and aggression? How does function within these circuits differ to produce variation in behavior? What types of environmental social stimuli impact the development of behavior and neural function? And how plastic (i.e., flexible) is social behavior and the social brain once animals are adults? To answer questions such as these, the Kelly Lab uses prairie voles (Microtus ochrogaster), African spiny mice (Acomys), and estrildid finches (Estrildidae). Utilizing immediate early gene (IEG) studies, pharmacological manipulation, retrograde labeling in conjunction with IEG analysis, and chemogenetics (i.e., DREADDs), we aim to map the nonapeptide neural circuitry underlying various types of social behavior. Of particular interest, nonapeptides have neuromodulatory capabilities and can communicate with neurons and modulate different brain structures in a multimodal manner – both through a fast, axonal, and focal manner, and in a slow, diffusive, and global fashion. A primary goal of the lab is to understand how these different modes of nonapeptide action serve to maintain stable characteristics of social behavioral phenotype within an individual’s lifetime versus serving to produce rapid behavioral responses to social stimuli in the environment.
Examining neuroplasticity and the functional properties
of the nonapeptide system
This line of research involves establishing a basic framework of how the nonapeptide system functions to allow for plasticity in behavior. We live in an age where we manipulate our physiology with pharmacology for a myriad of different reasons. In fact, studies are currently being conducted in humans that seek to manipulate aspects of social behavior using intranasal OT and VP. However, we know very little about the consequences of manipulating the nonapeptide system. It is likely that manipulation of one node or circuit within a larger system will have downstream consequences. Projects under this line of research in the lab investigate the compensatory capabilities of the nonapeptide system. When one neural node or pathway is manipulated, what are the functional consequences for the rest of the system? If one node in a system is compromised, will other nodes in the system alter their function to compensate? Can the nonapeptide system adapt to and/or become desensitized to manipulation over time? Similarly, are there neural circuits that are more susceptible to environmental influence than others? Using prairie voles and spiny mice, we aim to elucidate compensatory capabilities and the plasticity of the nonapeptide system at genetic, epigenetic, gene expression, and behavioral phenotypic levels.
Applying a comparative approach
to understand social behavior
If we are to truly understand the evolution of social behavior, we must consider the fact that various aspects of social behavior evolved independently many times. Thus, we cannot assume that relevant mechanisms have evolved similarly in all species. In order to build a solid foundation on which we study behavior and the underlying mechanisms, we must consider several important factors. Principally, we must use comparative approaches to examine a diversity of species within and across taxa. Doing so will ultimately determine the fundamental principle components for particular social behaviors. On the other hand, and equally important, we must consider the behavioral ecology of an organism and how this shapes components of social behavior. This approach helps explain the significant species-specific subtleties that govern the same behaviors. A combination of these approaches will ultimately provide a picture of the primary evolutionary drivers for those behaviors, both in terms of identifying unifying principles that generalize across taxa, and the singularities that make animals different. Without a fundamental baseline that captures the similarity across taxa, comparisons lack reference. To this end, our research incorporates the use of multiple social species across taxa.
Teaming up with colleagues who work with a variety of species across numerous taxa and have expertise in different areas of ecology, behavior, endocrinology, and neuroscience can lead to the development of a comprehensive body of work that examines the evolution of behavior that considers the whole organism (i.e., feedback between the brain and the periphery) and its environment in a manner that is often not feasible within a single laboratory. Thus, the Kelly Lab is always open to collaboration – please feel free to reach out to us if you are interested in developing a collaboration.
ANIMALS IN THE LAB
Prairie voles are a well-studied, socially monogamous rodent native to the central and mid-western United States and south-central provinces of Canada. Numerous field studies have resulted in a rich literature on their natural history and behavioral ecology. Importantly, they share some relatively rare, but defining, behaviors with humans – social monogamy and biparental care. Prairie voles have become quite popular for translational social neuroscience and are an emerging model organism for understanding the neurobiology of attachment and bonding (primarily monogamous pair-bonds and parent-offspring bonds). Various molecular tools have been developed for prairie voles over the last decade, so despite prairie voles not representing a traditional laboratory rodent, state-of-the-art technology is available for asking cutting edge questions in this species.
African Spiny Mice
Spiny mice are a new addition to Dr. Kelly’s research. Spiny mice are precocial rodents found throughout Africa, the Middle East, and southern Asia. They are primarily studied for their late-gestational development and their remarkable regenerative abilities (i.e., they can regenerate skin and musculoskeletal tissue). However, a few studies have examined their social structure and revealed that they are communal breeders and socially cooperative. We believe that this genus of mice offers unique opportunities for studying mammalian grouping behavior, cooperative behavior, neurodevelopment, and neuroplasticity.
Mongolian gerbils are a socially monogamous rodent that hail from grasslands and shrublands of China, Mongolia, and Russia. Although gerbils have been used in science since the late 1800s, they are a surprisingly uncommon study organism today. Gerbils are primarily used for examining the auditory system and studying epilepsy. Spiny mice are more closely related to gerbils than mice, and thus Mongolian gerbils serve as a less social relative for comparative studies. An added bonus is that the gerbils are quite friendly and a delight to work with!
Estrildid finches are found throughout the Old World tropics and Australasia. They exhibit an array of social phenotypes, ranging from highly territorial to highly social. Some species are solitary and affiliate only with their pairbond partner whereas other species flock in groups of hundreds. Thus, this family of birds lends itself well to the study of the evolution of sociality. Dr. Kelly’s past research in violet eared waxbills, Angolan blue waxbills, and zebra finches elucidated both convergent and divergent neural mechanisms that modulate grouping behavior. Highly social estrildids, such as zebra finches, are also an excellent model for translational social neuroscience given that they exhibit behaviors similar to humans: communal living, social monogamy, and biparental care. Although the Kelly Lab does not currently have ongoing finch studies at Emory, Dr. Kelly worked with estrildid finches for nearly a decade, and eagerly awaits the day to have the opportunity to return to working with birds – either in the lab or through outside collaborations.