PHD, Kent State University, 2024, College of Arts and Sciences / School of Biomedical Sciences

Many neurochemicals that affect social behavior also play a role in mediating bone development and metabolism. In primates, higher levels of neuropeptide Y and serotonin in humans and chimpanzees, compared to monkeys, are associated with decreased levels of aggression and increased social competence, respectively. Additionally, apes have higher levels of acetylcholine (ACh) and lower levels of dopamine, corresponding to internally driven and autonomous social behavior. Humans, conversely, have relatively low ACh and high dopamine, corresponding to externally driven social behavior and social conformity. ACh is specifically associated with the control of internally versus externally motivated behaviors in the striatum and is also known to promote osteoblastogenesis, bone formation, and to also inhibit bone resorption. However, the relationship between neurochemicals in the brain, bone, and behavior has, to date, remained relatively unexplored. In this dissertation, I investigate potential relationships among ACh concentrations and bone architecture by examining rats of differing levels of domestication and also among primates. I show that, in wild-caught and laboratory-raised rats, skeletal ACh concentrations, trabecular spacing, cortical bone density, and cortical area are lower in laboratory-raised rats, while bone volume is higher. Additionally, skeletal ACh may account for 40.8% of variation in trabecular spacing and 35.5% of variation in bone volume among rats. Though the difference in skeletal ACh among groups was consistent with expectations, our other findings largely contrast with currently available literature, warranting further research into the relationship between skeletal and neural ACh. I also show that, while in a highly limited primate sample, there is no relationship between skeletal and neural ACh concentrations, the methods used to explore this relationship could be used in future studies. Lastly, I show that in exploring the relationship between (open full item for complete abstract)

MA, Kent State University, 2024, College of Arts and Sciences / Department of Anthropology

Guenons are a diverse group of Old World monkeys in the family Cercopithecidae, consisting of six genera and many distinct species. Guenons exhibit a vast array of phenotypic, behavioral, and genetic variation; however, hybridization has been observed to occur between distinct species, implying that the genetic boundaries between species are semi-permeable. Due to advances in genomic technologies, introgression among many species has been readily detected. Introgression of the X-chromosome – while less frequent than autosomal introgression – has also been demonstrated among guenons. Here, we tested data from multiple guenon species and clades to assess the general strength of introgression across the X-chromosome and to identify regions exhibiting distinct signals of interspecific gene flow. We also performed functional enrichment analyses and SNP effect prediction to determine whether gene content or SNP location may have played a role in facilitating introgression of particular X-chromosomal regions. The majority of our tests indicate that X-chromosome introgression has occurred, and signals are identified within specific windows of sequence. Few windows with strong introgression signals exhibited enrichment in genes of specific functions; however, several frequently introgressing windows demonstrated enrichment in genes associated with transcriptional regulation, RNA-mediated gene silencing, and X-chromosome inactivation. The implications of introgression of these regions and insights into guenon evolution are discussed.

Doctor of Philosophy, The Ohio State University, 2024, Anthropology

The microbiome plays a critical role in primate health and is shaped by many environmental factors. In Human Immunodeficiency Virus (HIV) and Simian Immunodeficiency Virus (SIV), gut epithelial damage, and microbial translocation from the gut to systemic circulation are key determinants of disease progression and are also associated with increased viral loads and CD4+ T-cell depletion. However, in natural SIV host species such as sooty mangabeys (Cercocebus atys), the gut barrier remains intact, and microbial translocation does not occur despite high levels of viral replication. Moreover, disease progression to AIDS is not commonly observed. This phenomenon has promoted interest in the microbial communities that play a role in maintaining gut homeostasis in SIV. This dissertation examines the role of sooty mangabey ecology, behavior, immunity, and the gut and oral microbiome in sooty mangabey resistance to developing AIDS. First, I identify a robust “field-friendly” method (i.e., without freezing or refrigeration) for preserving viral RNA, specifically SIV, in primate fecal samples. Characterizing viral prevalence and shedding in natural hosts is critical to understanding infection and transmission risks within and between primate species. My results indicate that DNA/RNA shield is an optimal “field-friendly” buffer for preserving SIV RNA in fecal samples over time and may also be effective for preserving other RNA viruses in feces. Second, I report results from an analysis of the gastrointestinal microbial communities derived from fecal samples of seven cercopithecids living in the Ivory Coast's Tai Forest. Gut microbiota fundamentally contribute to an animal's overall health and immune function. Study taxa were Cercocebus atys (Sooty mangabey), Cercopithecus campbelli (Campbell's monkey), Cercopithecus diana (Diana monkey), Cercopithecus petaurista (Lesser spot-nosed monkey), Colobus polykomos (Black and white colobus), Piliocolobus badius (Western red colobus) (open full item for complete abstract)

Doctor of Philosophy, The Ohio State University, 2024, Anthropology

Across three articles, this dissertation analyzes patterns of dental defect formation and childhood physiological stress within the population of Neolithic Catalhoyuk (ca. 7100-5950 BCE), in order to contribute to a better understanding of biological, temporal, and social variation within this important early “megasite” community. Article one addresses biological questions with important methodological implications regarding the impact of linear enamel hypoplasia (LEH) defects on inter- and intra-population variability in relationships between incremental enamel microstructures. Relationships between perikymata (PK) periodicity and distribution were tested from high-definition epoxy replicas and histological thin-sections of unworn mandibular canines (n = 15) with high LEH prevalence from Catalhoyuk. Findings re-affirm the existence of significant inter-population variability and suggest that high LEH prevalence likely increases PK distribution variability and weakens relationships with periodicity. PK distribution-based methods may nevertheless help narrow likely periodicity ranges and improve microstructure-based chronological age estimation accuracy even in highly LEH-impacted samples. To better understand relationships between population aggregation and physiological stress in early human settlements, Article two tests whether LEH prevalence or timing change significantly over time alongside population levels at Neolithic Catalhoyuk. LEH defect frequency scores (n = 109), defect-per-individual (DPI, n = 44), and defect initiation age (DIA, n = 44) were collected from epoxy canine replicas. LEH measures did not differ significantly by sex or age-at-death, nor did they significantly change over time in parallel with population size. Developmental stress episodes were very common (DPI: all defects M = 11, pronounced defects M = 6; DIA: all defect M = 3.9 years, pronounced defects M = 4.0 years), with 100% of observable individuals experiencing at least one de (open full item for complete abstract)

BS, Kent State University, 2023, College of Arts and Sciences / Department of Anthropology

The endocannabinoid system plays an important role in social behaviors across a variety of species. Recently, the distribution of cannabinoid receptor 1 (CB1) was linked to the mating patterns of voles (i.e., monogamy versus non-monogamy) (Simmons et al., 2021). This raises the question of whether a similar mechanism exists in primates. The goal of the present study was to address that question by examining the relationship between CB1 density and mating patterns in monogamous (owl monkey, marmoset) and non-monogamous (capuchin) New World monkeys. Our study found that CB1 axon length density was higher in the monogamous species than the promiscuous in layer III of the anterior cingulate cortex. Our study suggests a potential correlation between monogamy and CB1 in New World monkeys. More research is needed to determine the extent of this trend in other primate species.

PHD, Kent State University, 2023, College of Arts and Sciences / School of Biomedical Sciences

External jaw morphology has been linked to diet and feeding behavior in primates, where biomechanical significance of condylar trabeculae is still being evaluated. Thus, the structural variation of condylar trabeculae remains largely unknown. I investigate trabecular architecture of the mandibular condyle to assess size-related variation, relationship to feeding behavior, and deterioration secondary to edentulism. I used µCT images of mandibular condyles of adult strepsirrhine primates, adult and neonatal callitrichid primates, and of elderly edentulous and dentate humans. For the non-human primates, the entire trabecular volume was processed using Avizo 8.0 to remove cortical bone. For the human samples, cubed sections were used and compared to cubed sections from the twelfth thoracic vertebra and the distal radius. VOIs were imported into BoneJ for measurement of trabecular parameters. When appropriate, phylogenetic comparative methods were used to address issues of phylogenetic non-independence. Similar to nonhuman primate postcranial bones, the mandibular condyle of strepsirrhine primates exhibits negatively allometric scaling with no alterations in the two features which should most affect load resistance: bone volume fraction and degree of anisotropy. This suggests primate trabecular architecture appears to have generalized scaling trends and trabeculae do not appear to undergo size-related increases in load resistance abilities. This study is the first evidence that the trabeculae of the mandibular condyle scale similarly to those of the postcranium. I compared ontogeny of condylar trabeculae of the tree-gouging common marmoset (Callithrix jacchus) and the non-gouging cotton-top tamarin (Saguineus oedipus). Several growth trends suggest the marmoset does not have a superior load resistance ability than its nongouging relative: bone volume fraction decreased in the marmoset while increasing in the tamarin; spacing increased and connectivity decreased in (open full item for complete abstract)

Doctor of Philosophy, The Ohio State University, 2022, Anthropology

Although prior anthropological research has established that our skeletal biology is influenced by our cultural background, the interplay between growth and development and cultural practices is not well understood. This study aims to contribute to this topic by determining the relative influence of biodemographic variables and cultural stressors on the adult morphology of the skeletal foot. To meet this objective, three aspects of tarsals and metatarsals, robusticity, osteoarthritis, and entheseal changes, were analyzed in the context of biodemographic and occupation data for recent modern humans. The sample utilized for this project is comprised of 28 individuals born pre-1950 (11 men and 17 women) and 43 born post-1950 (32 men and 11 women) from the William M. Bass Donated Skeletal Collection at the University of Tennessee-Knoxville Forensic Anthropology Center. The effects of age, sex, stature, body mass index (BMI), tibial robusticity, occupation, and period of birth on the pedal skeleton were determined via a suite of statistical tests, including linear regression, Spearman rank-order correlation, Welch two-sample t-tests, Wilcoxon rank sum tests, ANCOVAs, and Levene's tests. The results indicate that the foot morphology of individuals born before 1950 differs significantly from the foot morphology of individuals born after 1950. Specifically, metatarsal robusticity, entheseal changes, and osteoarthritis decreased over time. These temporal trends may be attributed to an increase in sedentism in the past 100 years. In addition, age, sex, stature, BMI, and tibial robusticity have statistically significant relationships with pedal morphological variables. Of these, sex has the greatest influence on metatarsal robusticity, while age has the greatest influence on entheseal changes and osteoarthritis. Metatarsal robusticity, entheseal changes, and osteoarthritis all have statistically significant relationships with period of birth, but only osteoarthritis (of MT5) h (open full item for complete abstract)

Master of Arts, The Ohio State University, 2022, Anthropology

The Inhibitory Cascade Model (ICM) is a model of molar development positing that molar tooth germs influence one another's growth by a balance of activator and inhibitor molecules as they form in series. Previous research on mammals has generally validated the model, but conformation of human molars to ICM predictions has been questioned. Previous work on humans has also not assessed the extent to which population variation in molar proportions conforms to ICM predictions. Here, two different human population samples are assessed based on expectations of the ICM. Both are expected to exhibit a pattern of decreasing size across molar series, as has been shown to be the most frequent pattern in previous studies for humans. However, the two populations are predicted to differ in terms of molar size ratios given that one population sample (Seminole Nation) derives from an ancestry group that exhibits high frequencies of third molar agenesis, while the other (Gullah-Geechee) does not. If the ICM influences differences in third molar agenesis between peoples of Native American vs. African ancestry, then it is expected that molar sizes will decrease across the molar row to a greater extent in the Seminole than they do in the Gullah. Such a difference, though not definitively demonstrating a role for the ICM in third molar agenesis, would be consistent with the possibility that in the Seminole, there is greater inhibition of growth across the molar row than there is in the Gullah. Buccolingual (BL), mesiodistal (MD), and area (BL x MD) dimensions of the teeth were analyzed. Frequencies of size proportion relationships for molar areas were analyzed, with attention to patterns consistent with ICM expectations. Molar size ratios for the BL and MD dimensions as well as for areas were compared for the two population samples in simple and multiple linear regression models. Across the entire sample set, there is a clear pattern aligned with expectations of the ICM, with greatest (open full item for complete abstract)

Bachelor of Arts (BA), Ohio University, 2022, Anthropology

Anthropology is the study of humans with four subbranches: cultural, biological, linguistic, and archaeological. Bioarchaeology is a subfield of biological anthropology and studies human skeletal remains in order to understand people's lives in the past. This is very similar to forensic anthropology, but forensics tries to interpret skeletal remains to aid law enforcement in finding their identity and possible cause of death. Bioarchaeologists study human skeletons to understand their osteological health and quality of life based on bone lesions and pathologies. Skeletons are also studied to interpret significant historical periods and events, such as famines. The goal for this project is to attempt to assess if there are bone remodeling patterns consistent with specific time periods and associated economic changes such as those that occurred during the Industrial Revolution. To answer this question, this project drew skeletal data from Ohio State University's European Module Skeletal Database (Steckel et al. 2019). The European Module project focused on health in the past and aggregated a large number of previously excavated and analyzed skeletal datasets. This large bioarcheology project resulted in a freely downloadable database with over 15,000 human skeletons ranging from Anglo-Saxon to modern time periods (0 CE to roughly 1850 CE) from 6 continents. The sample population chosen for this project is a dataset containing 621 female skeletons who were buried within the geographic area of modern United Kingdom. The researcher hypothesizes the changes in occurrence of degenerative joint disease (DJD) and diffuse idiopathic skeletal hyperostosis (DISH) in the female skeletons could indicate a major shift in socio-economic patterns, specifically during United Kingdom's Industrial Revolution.

Doctor of Philosophy, The Ohio State University, 2022, Anthropology

To deliver the level of care infants need for survival, the Homo genus evolved to engage in cooperative breeding. In fact, a large cross-cultural review found that most cultures have a set of structured postpartum practices to protect women and infants during the immediate postpartum—all requiring social support. Cooperative breeding researchers have focused on non-maternal support to older offspring and on infant outcomes, without regard for the vulnerable immediate postpartum or the reciprocal mother-infant impact. Considering the well-being of the infant without consideration for that of the mother, or vice versa, limits understanding of this integrated system. By including maternal mental health in the immediate postpartum, my project served to advance the cooperative breeding model, thereby providing a conceptual framework to further understand the development of postpartum depression. Finally, cooperative breeding models have examined social support primarily in terms of its presence or absence overlooking the fact that practices vary locally and recipients will thus expect and value different forms of support. Postpartum depression afflicts approximately 13% of women globally, with exceptionally high rates in Latin America. While it often resolves with only minor impact on subsequent quality of life, it does not always do so. In addition to creating serious mental health consequences for mothers, postpartum depression can result in serious and sometimes fatal results for infants. Despite our species' expectation of postpartum social support, very few studies have examined the relationship between mental health and postpartum practices, and among the few that have, there are methodological limitations that I addressed in this dissertation. My study objectives were: (1) describe the local cultural model of postpartum social support in Coatepec, Veracruz, Mexico; (2) determine the congruence of women's postpartum experiences with their cultural expecta (open full item for complete abstract)

Master of Arts, The Ohio State University, 2022, Anthropology

Data on longevity and mortality are essential for understanding life-history patterns and managing captive animal populations. This is particularly true for long-lived taxa such as nonhuman primates. I used the most comprehensive dataset on captive chimpanzee demography to evaluate life-history patterns in a retired metapopulation of captive former biomedical research (CFBR) chimpanzees. The study synthesized over 51,000 life-years of data recorded between April 15, 1923, and September 16, 2014, representing a total of 2,349 individuals. My goal was to assess the metapopulation's current age-sex composition, estimate rates of survivorship, mortality, and life expectancy, and compare the CFBR metapopulation to other chimpanzee populations of interest. Results indicated that the contemporary metapopulation is declining in size and increasingly geriatric. The median life expectancy of the entire metapopulation was 32.6 years (males 29.1, females 36.1). For chimpanzees who reached one year of age, the median life expectancy increased to 34.9 years (males 31.0, females 38.8). Survival probability was influenced by both sex and birth type. Females exhibited greater survivorship than males (regression coefficient = -0.34, z = -5.74, p<0.001), which is consistent with sexual selection theory and the notion that males engage more regularly in aggressive, competitive, and risky behaviors than females. Additionally, wild-born individuals exhibited greater survivorship than captive-born individuals (regression coefficient = -0.55, z = -5.89, p<0.001). This result should be treated cautiously, as ascertainment and early-life mortality selection biases likely exaggerated wild-born survivorship. Analyses of life expectancy over time showed continual increases in both median age of living individuals and median age at death, suggesting the CFBR metapopulation has yet to reach its full aging potential in a post-research environment. Finally, I found a seasonal trend in mortality suc (open full item for complete abstract)

PHD, Kent State University, 2022, College of Arts and Sciences / School of Biomedical Sciences

The human ilium is significantly shorter and broader than are those of all other primates. In addition, it exhibits an anterior inferior iliac spine that emerges via a secondary center of ossification. It is also unique to hominins. Here we track the ontogeny of the ilium in human and subadult primate ossa coxae. We find that its ontogeny is exclusive among primates from anlagen to adulthood and that the fusion of the anterior inferior iliac spine is a capstone event of a unique growth process that repositions the anterior gluteal muscles for control of pelvic drop during upright walking. This novel growth process is therefore a hominin synapomorphy that can be used to assess the presence of bipedal locomotion in extinct taxa. We recently reported that a unique physis modulates broadening of the hominin ilium and shortening of its isthmus. We report here the discovery of a large, constant vascular foramen which lies close to the novel growth plate and serves as a central structure in the hominin ilium's vascular network. No likely homologues appear in Old World Monkeys but are sometimes present in African great ape pelves. However, the human foramen (the Anterior Iliac Foramen) is significantly larger than the same individual's nutrient foramen, and when corrected for body size, the human anterior iliac foramen is substantially larger than are those of apes. Those of Pan and Gorilla do not differ significantly from one another when so corrected, establishing that a small foramen is primitive and that its enlarged state is derived in hominins. This likely reflects amplification of the blood supply to the novel hominin physis during growth. Its presence in hominin fossil ilia can therefore provide evidence of iliac ontogenetic specialization for bipedality. The unique presence of this synapomorphy provides robust evidence that non-saltatory bipedality is a singular adaptation restricted to hominins, and that it has occurred only once in known primates.

Doctor of Philosophy, The Ohio State University, 2021, Anthropology

Identifying dietary signals in extant primate dental features has significant implications for inferring diet in fossil primates (including hominins) and can reveal potential disconnects between extant primates' dental features and current diets. Consumption of hard foods (durophagy) in modern primates has been linked to features that protect teeth against cracks and crack propagation: large tooth size, low-crowned, “bunodont” teeth, thick enamel, and unevenly distributed enamel. In broad terms, this dissertation seeks to systematically test associations between hard object feeding and various enamel features (tooth size, tooth shape, and enamel thickness distribution) in both premolars and molars across a range of primates, taking into account phylogeny. In so doing, this dissertation provides insight into how closely these features track the evolution of durophagy. Most previous studies have been limited to a small number of measurements taken on molars from a limited number of species, without taking into account phylogenetic relationships. Primate groups are closely related and share an evolutionary history and thus there is a chance that the traits associated with durophagy may have more to do with phylogenetic history than with the novel adoption of durophagous diets within a clade. The ultimate aim of this dissertation is to elucidate whether (or not) there are dental features that are consistently associated with durophagy that might allow paleoanthropologists to reliably infer the evolution of durophagous behavior in the past. Given the noted evolvability of enamel thickness, variables associated with enamel thickness were hypothesized to be most frequently associated with durophagy. Tooth size, cusp shape, and enamel distribution were recorded on more than 600 histological and virtual 2D slices of premolars and molars from primates, fossil hominins, and modern human populations. A protocol for accurately reconstructing worn enamel cusp tips was created a (open full item for complete abstract)

MA, Kent State University, 2021, College of Arts and Sciences / Department of Anthropology

Neurodevelopment and brain aging varies between species and across the lifespan of all mammals. The brain undergoes significant changes through fetal development, early life development, and through aging and senescence even in the absence of pathology. Animal models are commonly used to learn more about the development and aging of the human brain however little is known about the development and aging of one of humans' closest evolutionary relatives, chimpanzees. The objective of this study was to determine age and/or species related effects on neuron density (Nv), glia density (Gv), and glia to neuron ratio (G:N) in Brodmann's area 9 (BA9) of the prefrontal cortex (PFC) using direct comparative methods in stereology to compare Nv, Gv, and G:N between age cohorts within-species and between-species in humans and chimpanzees. We found that there were no age-related effects on Nv, Gv, or G:N ratio within species across the lifespan but there were differences between species in Nv and Gv with chimpanzees having increased cell densities of both types. Additionally, there were significant differences between the developmental and young adult human cohorts in Gv with the young adult cohort having decreased Gv as compared to the developmental group. Additional analysis revealed differences in the way that cell densities changed across the lifespan between species indicating that aging has different effects on the PFC of the human brain in comparison to the chimpanzee brain. However, this research sample was limited with few young individuals in the chimpanzee sample restricting our ability to detect early age-related patterns in chimpanzees or between species in the younger cohorts.

MA, Kent State University, 2021, College of Arts and Sciences / Department of Anthropology

The aims of this study are to show that bone development within the diaphysis is not controlled by mechanical forces as believed by those who follow Wolff's Laws of bone formation. Rather its design comes from genomic controls and this will be able to be seen in the physical shape of the bone. It is proposed that the morphology of the bone is simply the wake of the growth plate's temporary form, and it is genomic influences which are the primary guidance. By making cross sectional comparisons of tibia, it should be seen that the shape of the diaphysis conforms to a standard form. That form should be dictated by the shape of the base of the physis during growth. To accomplish this, subadult tibias will be 3D scanned, cross sectioned, and compared to immature growth plates to assess whether the shape of the physis at different stages of growth and development is present in a fully formed adult bone.

MA, Kent State University, 2021, College of Arts and Sciences / Department of Anthropology

Researchers have examined the potential physical and behavioral effects in individuals diagnosed with alcoholism, a chronic disease in which an individual experiences intense cravings for alcohol, an inability to limit consumption, and a continuation of consumption despite negative legal, professional, interpersonal, or physical consequences (Michael and Bengston, 2018). This study aims to determine whether there are common indicators of pathology and associated morbidity in individuals with a cause of death reported as alcoholism verses those with a cause of death reported as pneumonia, by the presence of fractures, their states of healing, and also dental disease. We use this comparison of samples to assess whether there exists a difference between chronic stressors that affect morbidity verses the swift, fast-acting effects of infectious disease in a skeletal collection predating the advent of antibiotics and vitamin supplementation. This study was conducted using the Hamann-Todd Human Osteological Collection housed at the Cleveland Museum of Natural History, the largest historical aggregation of modern human skeletons, comprised of individuals who likely lived through the 1918 Influenza pandemic, national Prohibition, rapid industrialization, and the start of the Great Depression. The results of this study have predominantly corresponded to previous research that examined the association between chronic alcohol consumption and fracture incidence: That chronic alcoholics are more likely to exhibit fractures than the control group, and these fractures are observed most often in the craniofacial region, ribs, upper limb, and vertebrae. There was a statistically significant association between cause of death and fracture incidence (individuals in the alcoholism group were over twice as likely to exhibit a fracture than individuals in the pneumonia group) and the association between ancestry and fracture incidence was also statistically significant (European-derived (open full item for complete abstract)

Master of Arts, The Ohio State University, 2021, Anthropology

Accentuated Striae (AS) are enamel growth disruptions visible as thick dark lines in histological slides of enamel, paralleling normal growth lines known as brown striae of Retzius. They have been used as indicators of stress in archaeological, forensic, and primate studies within the field of biological anthropology. This research investigates whether there is a relationship between the manifestation of AS and (1) socioeconomic status (SES) differences between two Ohio populations, and (2) several physiological attributes of the sample. Deciduous teeth were collected from 48 individuals representing two populations with known disparities in overall stress exposure (high-SES sample from affluent neighborhoods in Central Ohio; low-SES sample from primarily rural Appalachian Ohio). Histological slides of enamel were created, and the presence of AS was observed in each tooth using a Nikon polarizing transmitted light microscope with Cannon digital camera. AS prevalence was compared between samples and contrasted with several demographic and physiological health measures (gestation length, birth mode, sex of infant, gestational diabetes). AS were observed among the low-SES sample (31%), but not among the high-SES sample (0%) (chi-square test; p=0.007). There are no associations between AS and any other assessed measure (p>0.05 for all comparisons). These results support the hypothesis that AS and non-specific population stress are related, thereby reinforcing AS as a valid indicator for reconstructing past population health

MA, Kent State University, 2001, College of Arts and Sciences / Department of Anthropology

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MA, Kent State University, 2020, College of Arts and Sciences / Department of Anthropology

In order for any type of social relationship to form, social recognition and social memory must be maintained as they provide the foundation on which social relationships are built. Oxytocin (OT) has been correlated to a variety of other prosocial behaviors such as pair bonding, social recognition memory, and trust in a wide variety of species. Serotonin plays a role in regulating OT levels and expression, acting on OT by way of 5HT receptors that are located in the PVN and SON. Together, OT and serotonin work in concert to affect social behavior in primates and rodents, which relies on intact social recognition ability. The hippocampus plays a vital role in social recognition and OT and 5HT act within this region to influence memory and social behaviors. Previous research discovered that OT manipulation to male prairie voles on the first day of life altered serotonin expression in adult brain regions involved in social behaviors, especially aggression. The current project will build on these findings by evaluating whether early exposure to OT or its antagonist alters serotonin within the hippocampus of prairie voles. We expect that there will be differences in the amount of serotonin based on the treatment of either high OT, low OT, OTA, or the saline control in regions of the hippocampus. However, our results indicated that OT manipulation does not have an effect on serotonin expression in the adult hippocampus.

PHD, Kent State University, 2020, College of Arts and Sciences / School of Biomedical Sciences

The roles of glia in cognition, pathology, and brain evolution are becoming increasingly clear, although our understanding is far from complete. The goal of this research was to further our understanding of glia through a comparative study of mammalian brains utilizing immunohistochemical and stereological techniques. Glia density and the ratio of glia to neurons increases with overall brain size, likely reflecting an increase in neuronal energy expenditure. This finding led to the assumption that the number of astrocytes, a glia subtype involved in regulating metabolism, will also increase with brain size. To test this assumption, we quantified glia density (Gv), astrocyte density (Av), and astrocyte soma volume (SV) in layer I and white matter in the frontal cortex of 10 mammalian species of varying brain weights. We found that Av, SV, and Av to Gv (Av/Gv) significantly increases in layer I as brain weight increases. Within primates, humans have a significantly greater Av, SV, and Av/Gv in layer I. These results indicate an expansion of layer I astrocytes with increasing brain size. Astrocytes specifically regulate neuronal metabolism through the astrocyte-neuron lactate shuttle via two important transporters, excitatory amino acid transporter two (EAAT2) and glucose transporter one (GLUT1). Since the human brain is metabolically more expensive compared to those of other primate species, we hypothesized that these transporters would have increased in humans compared to three other catarrhine primates. We found that humans have a greater EAAT2 density, GLUT1 vessel volume, and GLUT1 area fraction compared to baboons and chimpanzees, but did not differ from macaques. Therefore, EAAT2 and GLUT1 are not related to the increased energetic demands of the expanded human brain. In addition, aquaporin 4 (AQP4) which plays a role in astrocyte migration and water homeostasis was examined among macaques, baboons, chimpanzees, and humans. We found through a qualitative examina (open full item for complete abstract)