Browsing by Subject "Sex differences"
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Item A role for the medial preoptic area in neuroendocrine modulation of sex differences in reward(2022-08-12) Martz, Julia R.; Dominguez, Juan M.; Gore, Andrea C; Delville, Yvon; Serafine, Katherine MThe medial preoptic area (mPOA), located in the rostral hypothalamus, is an important regulator of motivated behaviors in rats. While its role in naturally rewarding behaviors, such as maternal care and sexual behavior, is well established, its role in drug response is just beginning to be explored. As a major site of neuroendocrine integration with direct connections to the mesolimbic dopamine system, it is not surprising that the mPOA is implicated in the modulation of sex differences in reward responses. Prior work has demonstrated that activation of the mPOA in response to sexual and parental reward differs between males and females, but whether sex differences are present in medial preoptic responses to drugs of abuse is unknown. Here, a role for the mPOA in the regulation of neuroendocrine-induced sex differences in neural and behavioral responses to cocaine is uncovered. Furthermore, while it is known that the mPOA influences the mesolimbic dopamine system through efferent connections with the ventral tegmental area (VTA), whether there are sex differences in the extent and profile of these projections remains unclear. The use of an iontophoretically injected tract-tracer, in conjunction with immunohistochemical techniques, revealed sex differences in mPOA efferents to the VTA. Specifically, projections from the central mPOA to the VTA contain more estrogen receptors and fewer androgen receptors in females, compared to males. Taken together, this work identifies the mPOA as a modulator of neuroendocrine-induced sex differences in downstream reward processing.Item Anxiolytic effects of exogenous intranasal testosterone in humans(2019-07-29) Jin, Shuo; Josephs, Robert A.; Harden, Kathryn P; Pruessner, Jens; Smits, Jasper AHigher levels of testosterone have been associated with fewer anxiety symptoms and greater psychological wellbeing. However, additional research is needed to advance the clinical use of testosterone in mental healthcare. This dissertation aims to investigate the anxiolytic effects of testosterone in men and women through three studies. The first study examines the pharmacokinetic profile of a novel testosterone nasal spray, designed for the safe and rapid delivery of exogenous testosterone in men and women. The second study leverages the utility of this novel spray preparation, and investigates the effect of intranasal testosterone on subjective anxiety during a psychosocial challenge. The final study extends the anxiolytic effects of exogenous testosterone in women, and explores the effect of intranasal testosterone on test anxiety and cognitive performance. Collectively, these three studies aim to contribute to a broader understanding of the anxiolytic effects of testosterone, and with it, the potential for testosterone to act as a novel pharmaceutical in the treatment of anxiety.Item The benefits of advertising status : what conspicuous consumption buys women(2012-05) Cloud, Jaime Marie; Buss, David M.; Loving, Timothy J.; Meston, Cindy M.; Raghunathan, Raj; Tucker-Drob, Elliot M.The primary objectives of the current research were to (1) test the effectiveness of conspicuous consumption as a status-enhancement tactic and (2) examine access to material resources as an interpersonal benefit that incentivizes status striving behavior. The studies that follow investigated the status striving motivations of both men and women; however, this research endeavor was primarily designed to address the paucity of research on female status. In Study 1, a nation-wide sample of participants perceived target women to be higher status when they were depicted conspicuously consuming than when not. Several individual difference variables that predict conspicuous consumption were also identified, many of which related to the attainment of high status. In Studies 2 and 3, conspicuous consumption was shown to increase perceptions of status in face-to-face interactions, further supporting the status signaling function of conspicuous consumption. Study 3 utilized a Dictator Game methodology to test the prediction that participants would share more of a monetary allotment with confederates who were conspicuously consuming than with those who were not. Results indicated that conspicuous consumption did not increase generosity except in male participants who shared more of a monetary allotment with conspicuous consumers, particularly those of the same sex. This sex-specific result is discussed in light of the possibility that conspicuous consumption signals a type of status that is particularly relevant to men (i.e., economic status). In conclusion, I consider the different pathways by which high status individuals receive increased access to resources.Item Differential activation of the vastus medialis and the vastus medialis oblique in individuals with and without patellofemoral pain syndrome(2019-06-18) Peng, Yi-Ling; Griffin , LisaAn imbalance of medial and lateral quadriceps control can lead to patellofemoral pain syndrome (PFPS). The incidence rate of PFPS is twice as high in females than in males. The aims of this research were to investigate sex differences in quadriceps neuromuscular control and motor unit recruitment properties in healthy individuals comparing to those with PFPS. We also investigated optimal leg position and levels of force production to target the vastus medialis oblique (VMO). In Study One, quadriceps surface EMG onset time and amplitude were examined at different submaximal force levels in asymptomatic males and females with and without PFPS. Females showed a 320 ± 70 ms delay in average quadriceps onset time relative to males. The vastus lateralis (VL) and VMO activated together and prior to the vastus medialis (VM) and rectus femoris. A low force (25%MVC) generated the lower VMO:VL ratio compared to 50% and 75% MVC. In order to determine if the VMO was controlled independently of the VM, Study Two examined motor unit recruitment patterns in the VM and VMO in healthy males and females when performing straight leg tasks in two different hip positions. VMO motor units were recruited 2.92 ± 1.28% MVC earlier than VM motor units. Females fired motor units in the vastus medialis complex faster than the males. We found that hip position is a crucial factor influencing motor unit recruitment properties in the vastus medialis complex. In a neutral hip position, motor units in the VM were activated at lower recruitment thresholds and at faster firing rates compared to in lateral hip rotation. Study Three evaluated the effect of PFPS on VM and VMO motor unit recruitment during two different hip positions of straight leg raise in females with and without PFPS. Individuals with PFPS showed an altered control strategy of VMO motor units between the two hip positions compared to healthy individuals. A traditional straight leg raise without hip rotation generated greater VMO motor unit initial firing rates in healthy individuals. However, VMO motor units were recruited at faster rates in lateral hip rotation for individuals with PFPS. The findings from this series of studies indicate that the neuromuscular control strategies of the quadriceps muscle subsections were affected by sex, PFPS, hip position as well as force level. These factors should be taken into consideration when designing rehabilitation protocols.Item Evolution of body size and sexual size dimorphism in the order primates: Rensch's rule, quantitative genetics, and phylogenetic effects(2004) Gordon, Adam Duffy; Kappelman, John W.Rensch’s rule, positive scaling of sexual size dimorphism (SSD) with body size, has been shown to be present in the evolutionary history of Primates. However, in some radiations there is negative or absent scaling of size and dimorphism. Lande’s (1980) quantitative genetics model predicts (1) positive scaling (Rensch’s rule) when selection acts more intensely on male body size than female body size, (2) no scaling when selection acts equally on both sexes, and (3) negative scaling when selection acts more intensely on female body size. Presented here is a combined response model which describes how sex-specific means and relative variabilities of continuous traits respond to sex-specific selection pressures. Model predictions are compared to data from extant primate populations to identify likely sources of unequal sex-specific selection pressures. Evolution of size and dimorphism within primate radiations is discussed in the context of a new conceptual model for the evolution of various scaling patterns of size and SSD. Under sexual selection by male competition or female mate choice, male body size is expected to be the primary target of selection. Under sexual selection by female competition or male mate choice, or natural selection by resource limitation, female body size is expected to be the primary target of selection. Because any of these forces may be in operation at any particular point in time, surveys of recent evolutionary changes in dimorphism capture positive and negative scaling patterns of SSD and size, and thus Rensch’s rule does not emerge. However, the phylogenetic history of living taxa is not representative of all taxa that ever lived, but only of those taxa that have living descendants. Species subject to intense resource scarcity are more likely to go extinct than species that have abundant resources, so phylogenetic history will be biased against the inclusion of resource limited taxa. In the absence of polyandry, positive scaling of size and SSD (Rensch’s rule) is the most likely pattern to emerge in radiations characterized by sexual selection on male size. This conceptual framework is used to study sex-specific body size evolution in Pan and Australopithecus afarensis.Item Friends and lovers : competition for social partners(2019-09-19) Wyckoff, Joy Plumeri; Markman, Arthur B.; Buss, David M; Cormack, Lawrence K; Hofmann, JohannSocial relationships grant access to a variety of resources relevant to survival and reproduction. Such resources include access to mates, resources that influence one's mate value (e.g., social status), and direct or indirect benefits provided by mates themselves. Similar resources exist for non-mating social domains as well (e.g., friendships, kinships, business relationships). However, given constraints on time, energy, and cognitive resources, people can only hold a finite number of individuals in their social networks. Therefore, we must strategically deploy competitive tactics in order to acquire and maintain cooperative social relationships. The strategies and tactics employed in competing for social relationships are explored here through an evolutionary lens. In Chapter 1, I introduce the topic of competition for mating and non-mating relationships from an evolutionary perspective. In Chapter 2, I present two studies demonstrating that people are motivated to share information about a rival when it has greater potential to thwart their rival’s mating attempts. I argue that this pattern of findings is indicative of psychological mechanisms for derogating mating rivals. In Chapter 3, I provide two studies that examine sex differences in reactions to victimization of online aggression, which we predicted from evolved defenses for competitor derogation for mates. In Chapter 4, I apply theories derived from mate competition to study competition for friends and strategies to defend relationships from third-party interlopers (i.e., friend poachers). I develop and validate measures for friend attraction, retention, and poaching. In doing so, I demonstrate that tactics used in competition for friends overlap with those used for mate competition (e.g., competitor derogation) and highlight tactics unique to friendships (e.g., including an interloper in one’s social network).Item Investigating the interplay between early life stress, acute secondary pathogenesis, and chronic hippocampal impairments in young mice with traumatic brain injury(2023-07-27) Parker, Kaila N.; Noble-Haeusslein, Linda J.; Curley, James P; Champagne, Frances A; Gore, Andrea C; Fonken, Laura K; Jones, Theresa AWhile Traumatic brain injury (TBI) is the leading cause of disability in children, it is unclear how early life stress (ELS) may act as a determinant of long-term recovery in brain-injured children. A murine model of ELS preceding TBI at postnatal day (P)21 addressed the following: regionally specific acute pathogenesis of the hippocampus after ELS+TBI, are these early changes predictive of hippocampal damage and impairment at adulthood. Males and females were exposed to ELS (P2-9) with the limited bedding nestlet (LBN) model, randomized to TBI or sham, and euthanized at P22 or adulthood. At P22, ELISAs revealed an upregulation of IL1B, IL-6, TNFα, and IFNγ in both sexes after injury. ELS+TBI elevated IL-1B, IL-10, TNFα, and IFNγ in males compared to TBI. Iba-1 and caspase-3 were evaluated in hippocampal subregions. While TBI increased microglial density in both sexes, ELS+TBI increased microglial density in male CA2 and CA3 but only in the CA3 in females compared to TBI. Quantification of caspase-3 revealed apoptosis in males and females after TBI. ELS + TBI increased apoptosis in CA1 and CA3 in males and females compared to TBI. Adulthood learning and memory were assessed with the NOR and Barnes Maze. Compared to TBI, ELS+TBI reduced novelty preference in females and increased path length to target in both sexes. Hippocampal neuron loss after ELS+TBI was evaluated at adulthood. TBI significantly reduced neurons in all subregions; ELS+TBI reduced neurons in the CA1 region in females only. These findings highlight hippocampal vulnerability after ELS+TBI and ELS prior to a TBI may enhance acute pathogenesis in males. Correlation matrices determined hippocampal acute pathogenesis is predictive of neuronal loss at adulthood and is associated with learning and memory impairments. Males and females were assessed for all outcomes. Both sexes showed similar vulnerability to secondary pathogenesis following TBI and adulthood impairments in learning and memory; males showed greater vulnerability to acute pathogenesis and females showed greater vulnerability to adulthood outcomes. These findings may advocate for opportunities to tailor therapies specific to each sex. Thus, developing pre-clinical biomarkers to predict long-term recovery may continue to bolster care management.Item Lingual fungiform papillae and teh evolution of the primate gustatory system(2009-05) Alport, Laura Jean; Kirk, E. Christopher, 1974-Among humans, the density of lingual fungiform papillae (DFP) is correlated with taste sensitivity. The purpose of this dissertation was to investigate the evolution of the primate gustatory system through a comparative analysis of DFP. This investigation was conducted in three separate studies. The first study took a broad perspective incorporating data from 37 primate species to assess the relationships among DFP, body mass, taste sensitivity, and diet. Among the major findings of this first study: (1) Sucrose sensitivity was negatively correlated with DFP and positively correlated with papilla area. (2) Sucrose sensitivity was not correlated with the percent of leaves or fruit in the diet. (3) DFP and papilla area were correlated with diet. (4) The relationships between fungiform papillae and diet differed among different taxonomic groups. The second study of DFP investigated whether there are sex differences in the DFP of non-human primates, as there are in humans. In all five primate species investigated, females had higher mean DFPs than males. These sex differences were significant in Pan troglodytes and Cebus apella, and not significant in Alouatta palliata, Cercopithecus aethiops, or Varecia variegata. Pan, Cebus, and Homo share large relative brain sizes with associated life history parameters making each offspring very costly. Accordingly it was suggested that sex differences in DFP may be due to the particularly high risk of lacking nutrients or ingesting toxins for females of these three species. The third study was a comparison of phenylthiocarbamide (PTC) taste ability and DFP in humans and chimpanzees. The major questions addressed in this study were (1) Is DFP correlated with PTC phenotype in chimpanzees as it is in humans? (2) Are there sex differences in PTC genotype and phenotype as there are in DFP? Although females had greater DFPs than males, and significantly more females had the genotype for higher PTC taste sensitivity, there was no correlation between DFP and PTC phenotype. Several explanations for the differences between human and chimpanzee results were offered, including small sample sizes for chimpanzees and greater accuracy in determining PTC sensitivity among humans.Item Sex differences in quadriceps alternating muscle activation patterns during fatigue(2021-07-30) Morrison, Drew Terris; Griffin, LisaSynergistic alternating muscle activation (AMA) consists of a period of co-activation (Co-A) and a period of trade-off (TO). Together they form a load-sharing cycle which is a neuromuscular control strategy that attenuates fatigue. However, the structure of AMA interactions of synergistic muscles has only been investigated during low-level contractions of 2.5-10% maximal voluntary contraction (MVC) and has yet to be investigated at moderate force levels (≥ 20% of MVC) and differentiated between the sexes. The purpose of this study was to quantify the activation relationship between pairs of synergistic quadriceps muscles to further understand the patterns (durations of Co-A and TO and frequency of AMA cycles). Surface electromyographic (EMG) data was collected from 16 individuals (8 male, 8 female) from the rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM), and vastus medialis oblique (VMO) during a fatiguing contraction at 20% MVC. Synergistic muscle pairs (VL-RF, VL-VM, VL-VMO, RF-VM, RF-VMO, VM-VMO) were analyzed for Co-A, TO, and AMA frequency during 3 phases of the fatiguing contraction. The synergistic pairs were in Co-A significantly longer than TO during all fatigue phases. Some muscle pairs differed significantly from each other in time spent in each state (Co-A or TO) during the final contraction phase. There was no significant difference in AMA patterns within individual muscle pairs between fatigue phases. There were strong positive and negative correlations between endurance time and Co-A and TO durations respectively for every muscle pair in males during the final two fatigue phases. For the same measures in females, only the RF-VL, RF-VMO, and VL-VM muscle pairs demonstrated a significant negative and positive correlation in the middle fatigue phase for Co-A and TO respectively. AMA was present in both male and female EMG data, but contrary to expectations that AMA cycle frequency would produce significant differences throughout the contraction, the endurance time correlations were where significant differences were present.Item Sexual misperception : individual differences and context effects(2011-05) Perilloux, Carin Jeanne; Buss, David M.; Gosling, Samuel D.; Henderson, Marlone D.; Loving, Timothy J.; Meston, Cindy M.The current research evaluated individual differences and contextual effects on men’s robust sexual overperception bias and on women’s tendency to be misperceived. Study 1 pioneered the use of a “speed-meeting” methodology which allowed for a direct calculation of sexual misperception by comparing measures of actual interest to measures of estimated interest across five interactions. As predicted, men demonstrated a robust sexual over-perception bias, a bias that was influenced by their mating strategy and physical attractiveness. Women, on the other hand, consistently underestimated men’s sexual interest in them, and physical attractiveness was a key predictor of their likelihood of being overperceived. Study 2 replicated the prediction tests from Study 1 and narrowed down the exploratory regression models to the most specific and robust effects, namely mating strategy and physical attractiveness. Study 3 examined the effects of testosterone (T) on men’s sexual misperception by manipulating intrasexual competition in the lab. Men engaged in a computer game, which randomly assigned them to win or lose, against an unseen male competitor. After the game, each participant interacted with a trained female confederate posing as a participant, after which they rated her on multiple traits, including interest in her and his estimate of her interest in him. Salivary assays for T were collected before and after the game, and after interacting with the confederate. The results of the experiment demonstrated that although the competition outcome did not affect men’s T, changes in T during the interaction with the woman predicted men’s sexual misperception. The more attractive the man found her, and the more interested he was in her, the more his T increased during their interaction and the more he overperceived her interest. Taken together, these studies indicate that far from a simple sex difference, men’s overperception bias is predictably nuanced and specific.