Laura L Carruth

Georgia State University, Atlanta, Georgia, United States

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Publications (20)64.7 Total impact

  • Laura L. Carruth · Mahin Shahbazi ·
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    ABSTRACT: Estrogens, including the biologically potent estradiol (E2), are involved in a variety of actions that affect physiology, cognition and behavior. Estrogens feature prominently in regulation of female reproduction physiology and behavior, but they also play a role in brain sexual differentiation, memory, feeding behavior and affective behaviors. While estrogens can be gonadally derived, they can also function as a neurosteroid and be synthesized de novo in the central nervous system via the enzyme aromatase. Estradiol synthesized in this manner is important in rapid E2 signaling. The actions of estrogens require the presence of a receptor. As a steroid, E2 can freely enter a cell and interact in the traditional manner via ligand-activated receptors to directly initiate transcription or it can initiate signal transduction pathways via extranuclear receptors. Sites of action in the mammalian brain include hypothalamus, amygdala, hippocampus, cerebral cortex, midbrain, pituitary gland, cerebellum and brainstem.
    Estrogen Effects on Traumatic Brain Injury, 01/2015: pages 11-28; , ISBN: 9780128014790
  • Mahin Shahbazi · Pedro Jimenez · Luis A. Martinez · Laura L. Carruth ·
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    ABSTRACT: Early developmental stress can have long-term physiological and behavioral effects on an animal. Developmental stress and early corticosterone (Cort) exposure affect song quality in many songbirds. Early housing condition can act as a stressor and affect the growth of nestlings and adult song, and improvements in housing condition can reverse adverse effects of early stress exposure in rodents. However, little is known about this effect in songbirds. Therefore, we took a novel approach to investigate if housing condition can modify the effects of early Cort exposure on adult song in male zebra finches. We manipulated early housing conditions to include breeding in large communal flight cages (FC; standard housing condition; with mixed-sex and mix-aged birds) versus individual breeding cages (IBC, one male–female pair with small, IBC-S, or large clutches, IBC-L) in post-hatch Cort treated male birds. We found that Cort treated birds from IBC-S have higher overall song learning scores (between tutor and pupil) than from FC but there is no difference between these groups in the No-Cort treated birds. When examining the effects of Cort within each housing condition, overall song learning scores decreased in Cort treated birds from flight cages but increased in birds from IBC-S compared to controls. Likewise, the total number of syllables and syllable types increased significantly in Cort treated birds from IBC-S, but decreased in FC-reared birds though this effect was not statistically significant. These findings suggest that the effects of early Cort treatment on learned features of song depend on housing condition.
    Hormones and Behavior 03/2014; 65(3). DOI:10.1016/j.yhbeh.2014.01.010 · 4.63 Impact Factor
  • John L. Pecore · Mandy L. Kirchgessner · Laura L. Carruth ·
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    ABSTRACT: Informal learning environments often host teachers for learning opportunities, but little is known about the impact of these experiences on teacher professional development (PD). This article describes a unique collaborative PD experience between zoological park personnel and university faculty, examining the impact on teacher content knowledge, attitudes, and classroom lessons. Our findings suggest that the PD improved science content, but made no impact on already high attitudes toward science. In light of the high level of self-reported satisfaction and high frequency of teacher lesson plan use, we propose that the PD had other positive outcomes such as pedagogical knowledge and authentic learning experiences.
    The Clearing House 11/2013; 86(6):238-245. DOI:10.1080/00098655.2013.826527
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    ABSTRACT: Male rat copulation is mediated by estrogen-sensitive neurons in the medial preoptic area (MPO) and medial amygdala (MEA); however, the mechanisms through which estradiol (E(2)) acts are not fully understood. We hypothesized that E(2) acts through estrogen receptor α (ERα) in the MPO and MEA to promote male mating behavior. Antisense oligodeoxynucleotides (AS-ODN) complementary to ERα mRNA were bilaterally infused via minipumps into either brain area to block the synthesis of ERα, which we predicted would reduce mating. Western blot analysis and immunocytochemistry revealed a knockdown of ERα expression in each brain region; however, compared to saline controls, males receiving AS-ODN to the MPO showed significant reductions in all components of mating, whereas males receiving AS-ODN to the MEA continued to mate normally. These results suggest that E(2) acts differently in these brain regions to promote the expression of male rat sexual behavior and that ERα in the MPO, but not in the MEA, promotes mating.
    Hormones and Behavior 05/2012; 62(1):50-7. DOI:10.1016/j.yhbeh.2012.04.018 · 4.63 Impact Factor
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    ABSTRACT: To strengthen the US scientific workforce, we aim to recruit and retain talented students in science, technology, engineering, and math (STEM) fields, to enhance success among students from groups underrepresented in STEM fields, and to diversify the scientific workforce to mirror the US population. Given that opportunities for authentic research may support STEM advancement, we seek to maximize the number of students involved in research. Our Behavioral Research Advancements in Neuroscience (BRAIN) research program tests the hypothesis that a team-based collaborative-learning model not only provides research opportunities for more students, but also produces outcomes at least as positive as a traditional one-on-one apprenticeship model. We examined scientific research selfefficacy as a critical construct for measuring student outcomes and predicting student progress toward STEM careers. Here we provide descriptive portraits of four women who participated in BRAIN, integrating quantitative survey data with analysis of pre- and post- semistructured interviews. Although selected for different self-efficacy trajectories in the quantitative surveys, all four women described increased self-efficacy in interviews and emphasized mastery experiences as a source of self-efficacy. Two women illustrate one general outcome from the program: women overcame initially lower scientific research self-efficacy, matching self-efficacy among men by mid-program. The overarching study suggests that both team-based research and apprenticeships can raise scientific research self-efficacy, which predicts STEM career success. Therefore, this collaborative model provides a structure for authentic research at institutions that may lack available mentors, and yet aim to improve opportunities for diverse undergraduate groups to pursue STEM careers.
    Journal of Women and Minorities in Science and Engineering 01/2012; 18(3):273-293. DOI:10.1615/JWomenMinorScienEng.2013004491
  • Mahin Shahbazi · Manfred Schmidt · Laura L Carruth ·
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    ABSTRACT: Stress has long lasting effects on physiology, development, behavior, reproductive success and the survival of an individual. These effects are mediated by glucocorticoids, such as corticosterone, via glucocorticoid receptors (GR), however the exact mechanisms underlying these effects are unknown. GR have been widely studied in mammals but little is known about GR in other vertebrate groups, especially songbirds. We investigated the distribution, quantity, and subcellular-localization of GR-immunoreactive (GRir) neurons in the brains of male zebra finches on P10 (post-hatch day 10, song nuclei formed), and in adulthood (post-hatch day 90 or older) using immunohistochemistry. GRir neurons were widely distributed in the brains of male zebra finches including two song nuclei HVC (acronym is a proper name) and RA (nucleus robustus arcopallii) and brain regions including HP (hippocampal formation), BSTl (lateral part of the bed nucleus of the stria terminalis), POM (nucleus preopticus medialis), PVN (nucleus paraventricularis magnocellularis), TeO (optic tectum), S (nucleus of the solitary tract), LoC (Locus coeruleus). Distribution did not vary at the two age points examined, however there were significant differences in staining intensity. Subcellular GR-immunoreactivity patterns were classified as cytoplasmic, nuclear, or both (cytoplasmic and nuclear) and there were significant differences in the overall number of GRir neurons and neurons with both nuclear and cytoplasmic staining in P10 and adult brains. However, there were no significant differences in the percentage of subcellular GR immunoreactivity patterns between P10 and adults. Our study of GRir neuronal distribution in the zebra finch brain may contribute towards understanding of the complex and adverse effects of stress on brain during two different stages of life history.
    General and Comparative Endocrinology 12/2011; 174(3):354-61. DOI:10.1016/j.ygcen.2011.09.017 · 2.47 Impact Factor
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    Laura L. Carruth ·

    CBE life sciences education 11/2011; 11(2):135-136. DOI:10.1187/cbe.12-01-0015 · 1.89 Impact Factor
  • Barney A Schlinger · Laura Carruth · Geert J de Vries · Jun Xu ·

    Hormones and Behavior 06/2011; 60(1):1-3. DOI:10.1016/j.yhbeh.2010.11.009 · 4.63 Impact Factor
  • Kelli A Duncan · Laura L Carruth ·
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    ABSTRACT: The majority of songbird species have sexually dimorphic neuronal circuits for song learning and production and these differences are paralleled by sex differences in behavior, with only males singing or singing at a higher rate than females. Therefore songbirds serve as an excellent model for studying the mechanisms that influence the sexually dimorphic development of the brain and behavior. Past research focused on the actions of steroid hormones or their receptors in the development of these sex differences. This review examines the distribution and action of steroid receptor coactivators in the songbird brain; more specifically the actions of RPL7, SRC-1, and CBP on the song control system. Coactivators enhance the transcriptional activity of the nuclear steroid receptors with which they associate, and therefore may play a role in modulating the development of sex differences in the brain and behavior. The actions of these proteins may help elucidate the hormonal mechanisms that underlie song nuclei development and steroid activated singing behavior in adulthood.
    Frontiers in Neuroendocrinology 01/2011; 32(1):84-94. DOI:10.1016/j.yfrne.2010.11.001 · 7.04 Impact Factor
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    Kelli A Duncan · Pedro Jimenez · Laura L Carruth ·
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    ABSTRACT: Coactivator proteins, such as steroid receptor coactivator-1 (SRC-1) greatly enhance gene expression by amplifying steroid-induced transcription regulated by receptors such as estrogen receptor. These proteins may also play a role in the development of sex differences in central nervous system as well the maintenance of the sexually dimorphic behaviors in adulthood. One well-studied sexually dimorphic behavior is singing in songbirds such as the Australian zebra finch (Taeniopygia guttata). Song learning and production is controlled by the song control system, a collection of sexually dimorphic nuclei found in the avian telencephalon. While the actions of steroid hormones on song nuclei development has been under debate, steroids, such as testosterone, influence singing behavior in adulthood. We hypothesize that the differential expression of coactivators in male and female brains aid in organizing the song nuclei during development and function in adulthood to aid in activating the song control nuclei to induce singing behavior. The distribution of SRC-1-immunoreactive neurons was localized in the brains of male and female zebra finches on the day of hatch (P1) and in adults. In adults SRC-1 immunoreactive cells are found in the four main song control nuclei as well as other steroid sensitive brain regions. We found that SRC-1 is sexually dimorphic in the adult zebra finch telencephalon, suggesting that coactivators may play a role in the maintenance of sexually dimorphic behaviors including singing.
    General and Comparative Endocrinology 11/2010; 170(2):408-14. DOI:10.1016/j.ygcen.2010.10.021 · 2.47 Impact Factor
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    Kelli A Duncan · Pedro Jimenez · Laura L Carruth ·
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    ABSTRACT: The brain and behavior of the Australian zebra finch (Taeniopygia guttata) are sexually dimorphic. Only males sing courtship songs and the regions of the brain involved in the learning and production of song are significantly larger in males than females. Therefore the zebra finch serves as an excellent model for studying the mechanisms that influence brain sexual differentiation, and the majority of past research on this system has focused on the actions of steroid hormones in the development of these sex differences. Coregulators, such as coactivators and corepressors, are proteins and RNA activators that work by enhancing or depressing the transcriptional activity of the nuclear steroid receptor with which they associate, and thereby modulating the development of sex-specific brain morphologies and behaviors. The actions of these proteins may help elucidate the hormonal mechanisms that underlie song nuclei development. Research described in this review focus on the role of estrogen receptor coactivators in the avian brain; more specifically we will focus on the role of RPL7 (ribosomal protein L7; also known as L7/SPA) on sexual differentiation of the zebra finch song system. Collectively, these studies provide information about the role of steroid receptor coactivators on development of the zebra finch song system as well as on sexual differentiation of brain.
    Psychoneuroendocrinology 07/2009; 34 Suppl 1:S30-8. DOI:10.1016/j.psyneuen.2009.04.023 · 4.94 Impact Factor
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    Kelli A Duncan · Laura L Carruth ·
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    ABSTRACT: Sex differences in the zebra finch (Taeniopygia guttata) brain are robust and include differences in morphology (song control nuclei in males are significantly larger) and behavior (only males sing courtship songs). In zebra finches, hormonal manipulations during development fail to reverse sex differences in song nuclei size and suggest that the classical model of sexual differentiation is incomplete for birds. Coactivators act to initiate transcriptional activity of steroid receptors, and may help explain why hormonal manipulations alone are not sufficient to demasculinize the male zebra finch brain. The present study investigated the expression and localization of L7/SPA (an estrogen receptor coactivator) mRNA and protein expression across the development of zebra finch song nuclei from males and females collected on P1 (song nuclei not yet formed), P10 (posthatch day 10, song nuclei formed), P30 (30 days posthatch, sexually immature but song nuclei formed and birds learning to sing), and adult birds (older than 65 days and sexually mature). Northern blot analysis showed a significant sex difference in P1 and adult L7/SPA mRNA expression while Western blot analysis also showed enhanced expression in the male brain at all age points. Both in situ hybridization and immunohistochemistry demonstrated that L7/SPA mRNA and protein were located in the song nuclei as well as expressed globally. Elevated coactivator expression may be a possible mechanism controlling the development of male song control nuclei, and coactivators such as L7/SPA may be important regulators of the masculinizing effects of estradiol on brain sexual differentiation.
    Developmental Neurobiology 12/2007; 67(14):1852-66. DOI:10.1002/dneu.20539 · 3.37 Impact Factor
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    Andrea M Zardetto-Smith · Keli Mu · Laura L Carruth · Kyle J Frantz ·
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    ABSTRACT: Brains Rule! Neuroscience Expositions, funded through a National Institute on Drug Abuse Science Education Drug Abuse Partnership Award, has developed a successful model for informal neuroscience education. Each Exposition is a "reverse science fair" in which neuroscientists present short neuroscience teaching modules to students. This study focuses on results of assessments conducted with neuroscientist presenters during Expositions at two sites, Atlanta, Georgia and Corpus Christi, Texas. The effects of participating in the Expositions on presenters' perceptions of their own presentation and communication skills were evaluated, as was the potential for increased active participation by neuroscientists in future outreach programs. In four of the five Expositions studied, pre- versus post-event surveys demonstrated significant changes in presenters' perceptions of their own abilities to explain neuroscience concepts to children. Over the course of an Exposition, presenters learned to fit their approaches to conveying neuroscience concepts to fifth through eighth graders and learned to link information they presented about the brain and nervous system to children's past experiences to improve comprehension. The present data suggest that Brains Rule! Neuroscience Expositions are effective in improving communication and teaching skills among neuroscience professionals and contribute to professional stewardship by increasing motivation to participate in future informal education programs.
    CBE life sciences education 02/2006; 5(2):158-66. DOI:10.1187/cbe.05-09-0116 · 1.89 Impact Factor
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    ABSTRACT: Undergraduate students may be attracted to science and retained in science by engaging in laboratory research. Experience as an apprentice in a scientist's laboratory can be effective in this regard, but the pool of willing scientists is sometimes limited and sustained contact between students and faculty is sometimes minimal. We report outcomes from two different models of a summer neuroscience research program: an Apprenticeship Model (AM) in which individual students joined established research laboratories, and a Collaborative Learning Model (CLM) in which teams of students worked through a guided curriculum and then conducted independent experimentation. Assessed outcomes included attitudes toward science, attitudes toward neuroscience, confidence with neuroscience concepts, and confidence with science skills, measured via pre-, mid-, and postprogram surveys. Both models elevated attitudes toward neuroscience, confidence with neuroscience concepts, and confidence with science skills, but neither model altered attitudes toward science. Consistent with the CLM design emphasizing independent experimentation, only CLM participants reported elevated ability to design experiments. The present data comprise the first of five yearly analyses on this cohort of participants; long-term follow-up will determine whether the two program models are equally effective routes to research or other science-related careers for novice undergraduate neuroscientists.
    CBE life sciences education 02/2006; 5(2):175-87. DOI:10.1187/cbe.05-09-0119 · 1.89 Impact Factor
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    ABSTRACT: The brain is a truly fascinating structure! It controls the body and allows everyone to think, learn, speak, move, feel, remember, and experience emotions. Although the brain is a single organ, it is very complex and has several regions, each having a specific function. These functionally diverse regions work together to allow for coordination of behavior. This article discusses the "Build-a-Brain Project" wherein students design and model the brain of an imaginary animal. The lesson presented in this article uses easily identifiable characteristics, such as proportion of brain to body mass, relative size of specific brain structures, complexity of cerebrum and cerebellum, and differential development of the frontal cortex. The depth and breadth of the science content can be easily varied to meet the needs and abilities of a wide range of participants. This project can be conducted in one hour, including the time to review the major brain structures. Students should be given approximately 15 minutes to design and build their brains and time should be allotted for their presentations. This project fits in well with a life science curriculum and contributes to a visual arts curriculum. (Contains 2 figures and lists 4 online resources.)
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    Laura L Carruth · Ingrid Reisert · Arthur P Arnold ·
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    ABSTRACT: Sex differences in the brain are caused by differences in gonadal secretions: higher levels of testosterone during fetal and neonatal life cause the male brain to develop differently than the female brain. In contrast, genes encoded on the sex chromosomes are not thought to contribute directly to sex differences in brain development, even though male (XY) cells express Y-chromosome genes that are not present in female (XX) cells, and XX cells may have a higher dose of some X-chromosome genes. Using mice in which the genetic sex of the brain (XX versus XY) was independent of gonadal phenotype (testes versus ovaries), we found that XY and XX brain cells differed in phenotype, indicating that a brain cell's complement of sex chromosomes may contribute to its sexual differentiation.
    Nature Neuroscience 11/2002; 5(10):933-4. DOI:10.1038/nn922 · 16.10 Impact Factor
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    Laura L Carruth · Richard E Jones · David O Norris ·
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    ABSTRACT: Pacific salmon (genus Oncorhynchus) exhibit an interesting and uncommon life-history pattern that combines semelparity, anadromy, and navigation (homing). During smoltification, young salmon imprint on the chemical composition of their natal stream water (the home-stream olfactory bouquet or "HSOB"); they then migrate to the ocean where they spend a few years feeding prior to migrating back to their natal freshwater stream to spawn. Upstream migration is guided by the amazing ability to discriminate between the chemical compositions of different stream waters and thus identify and travel to their home-stream. Pacific salmon demonstrate marked somatic and neural degeneration changes during home-stream migration and at the spawning grounds. The appearance of these pathologies is correlated with a marked elevation in plasma cortisol levels. While the mechanisms of salmonid homing are not completely understood, it is known that adult salmon continuously utilize two of their primary sensory systems, olfaction and vision, during homing. Olfaction is the primary sensory system involved in freshwater homing and "HSOB" recognition, and will be emphasized here. Previously, we proposed that the increase in plasma cortisol during Pacific salmon home-stream migration is adaptive because it enhances the salmon's ability to recall the imprinted memory of the "HSOB" (Carruth, 1998; Carruth et al., 2000b). Elevated plasma concentrations of cortisol could prime the hippocampus or other olfactory regions of the brain to recall this memory and, therefore, aid in directing the fish to their natal stream. Thus, specific responses of salmon to stressors could enhance reproductive success.
    Integrative and Comparative Biology 07/2002; 42(3):574-81. DOI:10.1093/icb/42.3.574 · 2.93 Impact Factor
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    ABSTRACT: Kokanee salmon (Oncorhynchus nerka kennerlyi ), a landlocked subspecies of sockeye salmon, exhibited hypothalamic-pituitary interrenal (HPI, adrenal homologue) axis activation and an increase in plasma cortisol concentration up to 639 +/- 55.9 ng/ml in association with upstream migration in the upper Colorado River even though they were not exposed to a change in salinity and lengthy migration. Kokanee salmon were collected at various stages of migration and concomitant sexual maturation. The pattern of cortisol elevation in kokanee is similar to that in ocean-run sockeye salmon (O. nerka nerka). The presence of plasma cortisol elevation in an upstream migrating, landlocked Pacific salmon suggests that stressors previously considered to cause the cortisol increase, such as long-distance migration and changes in salinity, may not be primary causes of the HPI axis activation.
    Comparative Biochemistry and Physiology Part C Toxicology & Pharmacology 10/2000; 127(2):123-31. DOI:10.1016/S0742-8413(00)00140-7 · 2.30 Impact Factor
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    Laura L. Carruth · R. G. Bowker ·
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    ABSTRACT: Several papers have suggested that the Freshwater Cichlid Crenicara punctulata is capable of protogynous sex change. These studies provide behavioral data and descriptive details of external morphology but lack information about gonadal histology, which is essential for definitive evidence of sequential hermaphroditism. Therefore, this study was designed to determine whether C. punctulata is a sequential hermaphrodite. The present study included a behavioral experiment, an isolation/transformation experiment, as well as a detailed analysis of gonadal structure. The behavioral experiment established social hierarchies in four groups of juvenile female C. punctulata. The hypothesis that the dominant female in each group would be the only individual to develop male secondary sexual characteristics in that group was verified. The isolation experiment tested the hypothesis that female C. punctulata would change sex without the presence of conspecifics. After social isolation, females that were previously dominant among a group of females in a male harem developed male secondary sexual characteristics. Histological analysis revealed that these individuals possessed testes, whereas all dominant females examined possessed mature ovaries. The results from behavioral, isolation, and histological portions of this project strongly suggest that C. punctulata is a protogynous sequential hermaphrodite, at least in captivity.
    Copeia 02/2000; 2000(1):71-82. DOI:10.1643/0045-8511(2000)2000[0071:FCCPIA]2.0.CO;2 · 1.03 Impact Factor
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    Laura L. Carruth · Richard E. Jones · David O. Norris ·
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    ABSTRACT: This study tested the hypothesis that neurons in olfactory regions of the kokanee salmon brain contain glucocorticoid receptors. Distribution and neuronal number of glucocorticoid receptor-like immunoreactive (GRir) neurons were identified in the kokanee salmon brain using immunohistochemistry with an antibody to GR (polyclonal rabbit anti-human, dilution 1:1500; and monoclonal mouse, dilution 5 micrograms/ml). Distribution of GRir neurons similar to the mammalian pattern was observed in the brains of sexually immature (n = 8; 4 female and 4 male) as well as spawning (n = 8; 4 female and 4 male) salmon. Olfactory-related areas containing GRir positive neuronal bodies included the internal cell layer of the olfactory bulb, ventral-lateral and lateral parts of the dorsal telencephalon (homologue of the mammalian hippocampus), ventral area of the telencephalon (homologue of the mammalian amygdala), glomerulosus complex of the thalamus, the preoptic area, and inferior lobe of the hypothalamus. The pattern of GRir neuronal distribution in sexually immature and spawning fish was similar. However, spawning fish brains, compared to sexually immature brains, exhibited a significantly greater GRir neuronal number in several olfactory regions in paired immunohistochemical runs. There also were differences in intraneuronal location of GRir in olfactory regions, with staining being predominantly cytoplasmic in sexually immature fish but nuclear in spawning fish. These results are consistent with a role for cortisol in olfactory-mediated homing in kokanee salmon. Although GRir were identified in many nonolfactory regions, the focus of this study is on GRir present in brain regions involved in olfaction.
    General and Comparative Endocrinology 02/2000; 117(1):66-76. DOI:10.1006/gcen.1999.7391 · 2.47 Impact Factor

Publication Stats

394 Citations
64.70 Total Impact Points


  • 2002-2015
    • Georgia State University
      • • Center for Behavioral Neuroscience
      • • Neuroscience Institute
      • • Department of Biology
      Atlanta, Georgia, United States
  • 2000-2002
    • University of California, Los Angeles
      • Brain Research Institute
      Los Ángeles, California, United States
    • University of Colorado at Boulder
      • Department of Integrative Physiology
      Boulder, Colorado, United States