1
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Becegato M, Silva RH. Female rodents in behavioral neuroscience: Narrative review on the methodological pitfalls. Physiol Behav 2024; 284:114645. [PMID: 39047942 DOI: 10.1016/j.physbeh.2024.114645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Revised: 07/19/2024] [Accepted: 07/22/2024] [Indexed: 07/27/2024]
Abstract
Since the NIH 'Sex as biological variable' policy, the percentage of studies including female subjects have increased largely. Nonetheless, many researchers fail to adequate their protocols to include females. In this narrative review, we aim to discuss the methodological pitfalls of the inclusion of female rodents in behavioral neuroscience. We address three points to consider in studies: the manipulations conducted only in female animals (such as estrous cycle monitoring, ovariectomy, and hormone replacement), the consideration of males as the standard, and biases related to interpretation and publication of the results. In addition, we suggest guidelines and perspectives for the inclusion of females in preclinical research.
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Affiliation(s)
- Marcela Becegato
- Behavioral Neuroscience Laboratory, Department of Pharmacology, Federal University of São Paulo, São Paulo, Brazil
| | - Regina H Silva
- Behavioral Neuroscience Laboratory, Department of Pharmacology, Federal University of São Paulo, São Paulo, Brazil; MaternaCiência, Federal University of São Paulo, São Paulo, Brazil.
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2
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Quintana GR, Pfaus JG. Do Sex and Gender Have Separate Identities? ARCHIVES OF SEXUAL BEHAVIOR 2024; 53:2957-2975. [PMID: 39105983 PMCID: PMC11335805 DOI: 10.1007/s10508-024-02933-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 06/07/2024] [Accepted: 06/09/2024] [Indexed: 08/07/2024]
Abstract
The largely binary nature of biological sex and its conflation with the socially constructed concept of gender has created much strife in the last few years. The notion of gender identity and its differences and similarities with sex have fostered much scientific and legal confusion and disagreement. Settling the debate can have significant repercussions for science, medicine, legislation, and people's lives. The present review addresses this debate though different levels of analysis (i.e., genetic, anatomical, physiological, behavioral, and sociocultural), and their implications and interactions. We propose a rationale where both perspectives coexist, where diversity is the default, establishing a delimitation to the conflation between sex and gender, while acknowledging their interaction. Whereas sex in humans and other mammals is a biological reality that is largely binary and based on genes, chromosomes, anatomy, and physiology, gender is a sociocultural construct that is often, but not always, concordant with a person' sex, and can span a multitude of expressions.
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Affiliation(s)
- Gonzalo R Quintana
- Departamento de Psicología y Filosofía, Facultad de Ciencias Sociales, Universidad de Tarapacá, Arica, Arica y Parinacota, Chile
| | - James G Pfaus
- Department of Psychology and Life Sciences, Charles University, Prague, 18200, Czech Republic.
- Center for Sexual Health and Intervention, Czech National Institute of Mental Health, Klecany, Czech Republic.
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3
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Joel D, Smith CJ, Veenema AH. Beyond the binary: Characterizing the relationships between sex and neuropeptide receptor binding density measures in the rat brain. Horm Behav 2024; 159:105471. [PMID: 38128247 DOI: 10.1016/j.yhbeh.2023.105471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 10/30/2023] [Accepted: 12/09/2023] [Indexed: 12/23/2023]
Abstract
Sex differences exist in numerous parameters of the brain. Yet, sex-related factors are part of a large set of variables that interact to affect many aspects of brain structure and function. This raises questions regarding how to interpret findings of sex differences at the level of single brain measures and the brain as a whole. In the present study, we reanalyzed two datasets consisting of measures of oxytocin, vasopressin V1a, and mu opioid receptor binding densities in multiple brain regions in rats. At the level of single brain measures, we found that sex differences were rarely dimorphic and were largely persistent across estrous stage and parental status but not across age or context. At the level of aggregates of brain measures showing sex differences, we tested whether individual brains are 'mosaics' of female-typical and male-typical measures or are internally consistent, having either only female-typical or only male-typical measures. We found mosaicism for measures showing overlap between females and males. Mosaicism was higher a) with a larger number of measures, b) with smaller effect sizes of the sex difference in these measures, and c) in rats with more diverse life experiences. Together, these results highlight the limitations of the binary framework for interpreting sex effects on the brain and suggest two complementary pathways to studying the contribution of sex to brain function: (1) focusing on measures showing dimorphic and persistent sex differences and (2) exploring the relations between specific brain mosaics and specific endpoints.
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Affiliation(s)
- Daphna Joel
- School of Psychological Sciences and Sagol School of Neuroscience, Tel-Aviv University, Tel-Aviv, Israel.
| | - Caroline J Smith
- Department of Psychology and Neuroscience, Boston College, Chestnut Hill, MA, USA.
| | - Alexa H Veenema
- Neurobiology of Social Behavior Laboratory, Department of Psychology & Neuroscience Program, Michigan State University, East Lansing, USA.
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4
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Becher E, Oertelt-Prigione S. The Impact of Sex and Gender in Medicine and Pharmacology. Handb Exp Pharmacol 2023; 282:3-23. [PMID: 37594607 DOI: 10.1007/164_2023_688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/19/2023]
Abstract
Sex and gender play a pivotal role in health and disease. Differences can be identified in symptoms, biomarkers, lifetime experiences of diseases, incidence, prevalence, therapeutic options, health-related behavior, and resiliency. However, awareness of sex and gender differences in medicine is still limited. Systematic implementation of sex and gender-sensitive research is not yet the norm, resulting in gaps in evidence especially in the diagnosis and treatment of diseases in women. For decades research has predominantly included male persons and animals, leading to a lack of information about symptoms in female individuals or the classification of their symptoms as "atypical". Currently, the inclusion of female participants in clinical marketing access trials is mandatory. However, this does not automatically translate into sex-disaggregated analyses potentially limiting the discovery of sex-specific targeted therapeutic schemes. Consistent consideration of sex and gender in planning, conducting, analyzing, and dissemination of pharmacological research projects is an important prerequisite for closing the gender data gap. Targeted implementation strategies might help to include sex and gender aspects in different parts of the health system and thereby support the improvement of health care for all patients. Health economic aspects could be a further drive for the implementation of sex- and gender-sensitive medicine.The current chapter focuses on the role of sex and gender in biomedical research and, consequently, their potential role in pharmacology. We will explore the commonly used terminology in the field, the historical development of sex and gender-sensitive medicine (SGSM), the relevance of sex and gender to research and clinical practice and conclude with an outlook on future developments in the field.
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Affiliation(s)
- Eva Becher
- Sex- and Gender-Sensitive Medicine Unit, Medical Faculty OWL, Bielefeld University, Bielefeld, Germany
| | - Sabine Oertelt-Prigione
- Sex- and Gender-Sensitive Medicine Unit, Medical Faculty OWL, Bielefeld University, Bielefeld, Germany.
- Gender Unit, Departement of Primary and Community Care, Radboud University Medical Center, Nijmegen, The Netherlands.
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5
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Rioux C, Paré A, London-Nadeau K, Juster RP, Weedon S, Levasseur-Puhach S, Freeman M, Roos LE, Tomfohr-Madsen LM. Sex and gender terminology: a glossary for gender-inclusive epidemiology. J Epidemiol Community Health 2022; 76:jech-2022-219171. [PMID: 35725304 DOI: 10.1136/jech-2022-219171] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 06/07/2022] [Indexed: 01/05/2023]
Abstract
There is increased interest in inclusion, diversity and representativeness in epidemiological and community health research. Despite this progress, misunderstanding and conflation of sex and gender have precluded both the accurate description of sex and gender as sample demographics and their inclusion in scientific enquiry aiming to distinguish health disparities due to biological systems, gendered experiences or their social and environmental interactions. The present glossary aims to define and improve understanding of current sex-related and gender-related terminology as an important step to gender-inclusive epidemiological research. Effectively, a proper understanding of sex, gender and their subtleties as well as acknowledgement and inclusion of diverse gender identities and modalities can make epidemiology not only more equitable, but also more scientifically accurate and representative. In turn, this can improve public health efforts aimed at promoting the well-being of all communities and reducing health inequities.
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Affiliation(s)
- Charlie Rioux
- Department of Psychology, University of Manitoba, Winnipeg, Manitoba, Canada
- Children's Hospital Research Institute of Manitoba, Winnipeg, Manitoba, Canada
- Department of Psychology, University of Calgary, Calgary, Alberta, Canada
| | - Ash Paré
- School of Social Work, McGill University, Montreal, Quebec, Canada
| | - Kira London-Nadeau
- Department of Psychology, Université de Montréal, Montreal, Quebec, Canada
- Sainte-Justine Hospital Pediatric Research Centre, Montreal, Quebec, Canada
| | - Robert-Paul Juster
- Department of Psychiatry and Addictology, Université de Montréal, Montreal, Quebec, Canada
- Montreal Mental Health University Institute Research Centre, Montreal, Quebec, Canada
- Centre on Sex*Gender, Allostasis, and Resilience, Montreal, Quebec, Canada
| | - Scott Weedon
- Department of English, Texas Tech University, Lubbock, Texas, USA
| | | | - Makayla Freeman
- Department of Psychology, University of Calgary, Calgary, Alberta, Canada
- Department of Educational and Counselling Psychology and Special Education, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Leslie E Roos
- Department of Psychology, University of Manitoba, Winnipeg, Manitoba, Canada
- Children's Hospital Research Institute of Manitoba, Winnipeg, Manitoba, Canada
| | - Lianne M Tomfohr-Madsen
- Department of Psychology, University of Calgary, Calgary, Alberta, Canada
- Department of Educational and Counselling Psychology and Special Education, The University of British Columbia, Vancouver, British Columbia, Canada
- Department of Pediatrics, University of Calgary, Calgary, Alberta, Canada
- Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada
- Libin Cardiovascular Institute of Alberta, Calgary, Alberta, Canada
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6
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Rey RA. Are We Prepared to Abandon the Idea of Sex Binarism? A Biomedical Perspective. Biomed Hub 2022; 7:48-53. [DOI: 10.1159/000522409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 02/01/2022] [Indexed: 11/19/2022] Open
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Schmitt CA, Garrett EC. De-Scent with Modification: More Evidence and Caution Needed to Assess Whether the Loss of a Pheromone Signaling Protein Permitted the Evolution of Same-Sex Sexual Behavior in Primates. ARCHIVES OF SEXUAL BEHAVIOR 2021; 50:2301-2307. [PMID: 31741251 DOI: 10.1007/s10508-019-01583-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Revised: 10/30/2019] [Accepted: 11/02/2019] [Indexed: 06/10/2023]
Affiliation(s)
- Christopher A Schmitt
- Department of Anthropology, Boston University, 232 Bay State Road, Boston, MA, 02215, USA.
- Department of Biology, Boston University, Boston, MA, USA.
| | - Eva C Garrett
- Department of Anthropology, Boston University, 232 Bay State Road, Boston, MA, 02215, USA
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8
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Joel D. Beyond sex differences and a male-female continuum: Mosaic brains in a multidimensional space. HANDBOOK OF CLINICAL NEUROLOGY 2021; 175:13-24. [PMID: 33008521 DOI: 10.1016/b978-0-444-64123-6.00002-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
In the last two decades, the 60 years old view that in utero exposure to testosterone irreversibly masculinizes the brain of males away from a default female form has been replaced by a complex scenario according to which sex affects the brains of both females and males via multiple mechanisms, which are susceptible to internal and external factors. These observations led to the "mosaic" hypothesis-the expectation that the degree of "maleness"/"femaleness" of different features within a single brain would not be internally consistent. Following a short review of the animal studies providing the basis of the mosaic hypothesis, I describe three studies conducted in humans that assessed internal consistency in regional volume, cortical thickness, and connectivity as revealed by magnetic resonance imaging (MRI); in neuronal numbers in the postmortem hypothalamus; and in changes in regional volume and cortical thickness (assessed with MRI) following exposure to extreme real-life stress. The conclusion from these studies, that human brains are largely composed of unique mosaics of female-typical and male-typical features, was supported by recent findings that the brain "types" typical of women are also typical of men, and vice versa. Lastly, I discuss criticism of the mosaic hypothesis and suggest replacing the framework of a male-female continuum with thinking about mosaic brains residing in a multidimensional space.
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Affiliation(s)
- Daphna Joel
- School of Psychological Sciences and Sagol School of Neuroscience, Tel-Aviv University, Tel-Aviv, Israel.
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9
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Joel D. Uncovering and Challenging the Binary Framework. PSYCHOLOGICAL INQUIRY 2021. [DOI: 10.1080/1047840x.2021.1930768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Daphna Joel
- School of Psychological Sciences and Sagol School of Neuroscience, Tel-Aviv University, Tel-Aviv, Israel
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10
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DuBois LZ, Shattuck-Heidorn H. Challenging the binary: Gender/sex and the bio-logics of normalcy. Am J Hum Biol 2021; 33:e23623. [PMID: 34096131 DOI: 10.1002/ajhb.23623] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Revised: 04/08/2021] [Accepted: 05/18/2021] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND We are witnessing renewed debates regarding definitions and boundaries of human gender/sex, where lines of genetics, gonadal hormones, and secondary sex characteristics are drawn to defend strict binary categorizations, with attendant implications for the acceptability and limits of gender identity and diversity. AIMS Many argue for the need to recognize the entanglement of gender/sex in humans and the myriad ways that gender experience becomes biology; translating this theory into practice in human biology research is essential. Biological anthropology is well poised to contribute to these societal conversations and debates. To do this effectively, a reconsideration of our own conceptions of gender/sex, gender identity, and sexuality is necessary. METHODS In this article, we discuss biological variation associated with gender/sex and propose ways forward to ensure we are engaging with gender/sex diversity. We base our analysis in the concept of "biological normalcy," which allows consideration of the relationships between statistical distributions and normative views. We address the problematic reliance on binary categories, the utilization of group means to represent typical biologies, and document ways in which binary norms reinforce stigma and inequality regarding gender/sex, gender identity, and sexuality. DISCUSSION AND CONCLUSIONS We conclude with guidelines and methodological suggestions for how to engage gender/sex and gender identity in research. Our goal is to contribute a framework that all human biologists can use, not just those who work with gender or sexually diverse populations. We hope that in bringing this perspective to bear in human biology, that novel ideas and applications will emerge from within our own discipline.
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Affiliation(s)
- L Zachary DuBois
- Department of Anthropology, University of Oregon, Eugene, Oregon, USA
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11
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Saguy T, Reifen-Tagar M, Joel D. The gender-binary cycle: the perpetual relations between a biological-essentialist view of gender, gender ideology, and gender-labelling and sorting. Philos Trans R Soc Lond B Biol Sci 2021; 376:20200141. [PMID: 33612000 PMCID: PMC7934953 DOI: 10.1098/rstb.2020.0141] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/02/2020] [Indexed: 01/24/2023] Open
Abstract
Gender inequality is one of the most pressing issues of our time. A core factor that feeds gender inequality is people's gender ideology-a set of beliefs about the proper order of society in terms of the roles women and men should fill. We argue that gender ideology is shaped, in large parts, by the way people make sense of gender differences. Specifically, people often think of gender differences as expressions of a predetermined biology, and of men and women as different 'kinds'. We describe work suggesting that thinking of gender differences in this biological-essentialist way perpetuates a non-egalitarian gender ideology. We then review research that refutes the hypothesis that men and women are different 'kinds' in terms of brain function, hormone levels and personality characteristics. Next, we describe how the organization of the environment in a gender-binary manner, together with cognitive processes of categorization drive a biological-essentialist view of gender differences. We then describe the self-perpetuating relations, which we term the gender-binary cycle, between a biological-essentialist view of gender differences, a non-egalitarian gender ideology and a binary organization of the environment along gender lines. Finally, we consider means of intervention at different points in this cycle. This article is part of the theme issue 'The political brain: neurocognitive and computational mechanisms'.
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Affiliation(s)
- Tamar Saguy
- Baruch Ivcher School of Psychology, The Interdisciplinary Center (IDC), Herzliya, Israel
| | - Michal Reifen-Tagar
- Baruch Ivcher School of Psychology, The Interdisciplinary Center (IDC), Herzliya, Israel
| | - Daphna Joel
- School of Psychological Sciences, Tel-Aviv University, Tel-Aviv, Israel
- Sagol School of Neuroscience, Tel-Aviv University, Tel-Aviv, Israel
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12
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Dump the "dimorphism": Comprehensive synthesis of human brain studies reveals few male-female differences beyond size. Neurosci Biobehav Rev 2021; 125:667-697. [PMID: 33621637 DOI: 10.1016/j.neubiorev.2021.02.026] [Citation(s) in RCA: 148] [Impact Index Per Article: 49.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 01/01/2021] [Accepted: 02/16/2021] [Indexed: 12/21/2022]
Abstract
With the explosion of neuroimaging, differences between male and female brains have been exhaustively analyzed. Here we synthesize three decades of human MRI and postmortem data, emphasizing meta-analyses and other large studies, which collectively reveal few reliable sex/gender differences and a history of unreplicated claims. Males' brains are larger than females' from birth, stabilizing around 11 % in adults. This size difference accounts for other reproducible findings: higher white/gray matter ratio, intra- versus interhemispheric connectivity, and regional cortical and subcortical volumes in males. But when structural and lateralization differences are present independent of size, sex/gender explains only about 1% of total variance. Connectome differences and multivariate sex/gender prediction are largely based on brain size, and perform poorly across diverse populations. Task-based fMRI has especially failed to find reproducible activation differences between men and women in verbal, spatial or emotion processing due to high rates of false discovery. Overall, male/female brain differences appear trivial and population-specific. The human brain is not "sexually dimorphic."
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13
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Joel D. Beyond the binary: Rethinking sex and the brain. Neurosci Biobehav Rev 2021; 122:165-175. [PMID: 33440198 DOI: 10.1016/j.neubiorev.2020.11.018] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 11/12/2020] [Accepted: 11/14/2020] [Indexed: 01/06/2023]
Abstract
The paper reviews the relations between sex and brain in light of the binary conceptualization of these relations and the challenges posed to it by the 'mosaic' hypothesis. Recent formulations of the binary framework range from arguing that the typical male brain is different from the typical female brain to claiming that brains are typically male or female because brain structure can be used to predict the sex category (female/male) of the brain's owner. These formulations are challenged by evidence that sex effects on the brain may be opposite under different conditions, that human brains are comprised of mosaics of female-typical and male-typical features, and that sex category explains only a small part of the variability in human brain structure. These findings led to a new, non-binary, framework, according to which mosaic brains reside in a multi-dimensional space that cannot meaningfully be reduced to a male-female continuum or to a binary variable. This framework may also apply to sex-related variables and has implications for research.
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Affiliation(s)
- Daphna Joel
- School of Psychological Sciences and Sagol School of Neuroscience, Tel-Aviv University, Tel-Aviv, Israel.
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14
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DuBois LZ, Gibb JK, Juster RP, Powers SI. Biocultural approaches to transgender and gender diverse experience and health: Integrating biomarkers and advancing gender/sex research. Am J Hum Biol 2020; 33:e23555. [PMID: 33340194 DOI: 10.1002/ajhb.23555] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 11/06/2020] [Accepted: 12/02/2020] [Indexed: 12/14/2022] Open
Abstract
Transgender and gender diverse (TGD) people are increasingly visible in U.S. communities and in national media. With this increased visibility, access to gender affirming healthcare is also on the rise, particularly for urban youth. Political backlash and entrenchment in a gender binary, however, continue to marginalize TGD people, increasing risk for health disparities. The 2016 National Institute of Health recognition of sexual and gender minority people as a health disparities population increases available funding for much-needed research. In this article, we speak to the need for a biocultural human biology of gender/sex diversity by delineating factors that influence physiological functioning, mental health, and physical health of TGD people. We propose that many of these factors can best be investigated with minimally invasively collected biomarker samples (MICBS) and discuss how to integrate MICBS into research inclusive of TGD people. Research use of MICBS among TGD people remains limited, and wider use could enable essential biological and health data to be collected from a population often excluded from research. We provide a broad overview of terminology and current literature, point to key research questions, and address potential challenges researchers might face when aiming to integrate MCIBS in research inclusive of transgender and gender diverse people. We argue that, when used effectively, MICBS can enhance human biologists' ability to empirically measure physiology and health-related outcomes and enable more accurate identification of pathways linking human experience, embodiment, and health.
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Affiliation(s)
- L Zachary DuBois
- Department of Anthropology, University of Oregon, Eugene, Oregon, USA
| | - James K Gibb
- Department of Anthropology, University of Toronto, Ontario, Canada
| | | | - Sally I Powers
- Psychological and Brain Sciences, University of Massachusetts Amherst, Amherst, Massachusetts, USA
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15
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Trejo-Sánchez I, Pérez-Monter C, Huerta-Pacheco S, Gutiérrez-Ospina G. Male Ejaculatory Endophenotypes: Revealing Internal Inconsistencies of the Concept in Heterosexual Copulating Rats. Front Behav Neurosci 2020; 14:90. [PMID: 32670030 PMCID: PMC7332778 DOI: 10.3389/fnbeh.2020.00090] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 05/14/2020] [Indexed: 12/17/2022] Open
Abstract
Distinct manifestations of sexual behavior are conceived as separate phenotypes. Each sexual phenotype is assumed to be associated with a characteristic brain. These notions have justified the phenotyping of heterosexual copulator males based upon their ejaculation's latencies (EL) or frequencies (i.e., cumulative ejaculation number; EN). For instance, men and male rats showing premature, normal or retarded ejaculation are assumed to be distinctive endophenotypes. This concept, nonetheless, contradicts past and recent evidence that supports that sexual behavior is highly variable within each sex, and that the brain sexual functional morphology represents an intricate sexual phenotypic mosaic. Hence, for ejaculatory male endophenotypes to be considered as a valid biological concept, it must show internal consistency at various levels of organization (including genetic architectures), after being challenged by intrinsic and/or extrinsic factors. We then judged the internal consistency of the presumed ejaculatory endophenotypes by assessing whether copulatory behavior and the expression of copulation relevant genes and brain limbic structures are specific to each of the presumed EL- or EN-ejaculatory endophenotypes. To do this, copulating male rats were first phenotyped in groups consistently displaying short, average or long ejaculation latencies or very high, high, average, low or very low EN, based in their copulatory performance. Then, the internal consistency of the presumed EL- or EN-endophenotypes was tested by introducing as covariates of phenotyping other copulatory parameters (e.g., number of intromissions) in addition to EL or EN, or by analyzing the expression levels of genes encoding for estrogen receptor alpha, progesterone receptor, androgen receptor, aromatase, DNA methyl-transferase 3a and DNA methyl-transferase 1 in the amygdala, medial preoptic area, ventromedial hypothalamus and olfactory bulb. We found that even though there were group-level differences in all the variables that were studied, these differences did not add-up to create the presumed EL- or EN-ejaculatory endophenotypes. In fact, the extensive overlapping of copulatory parameters and expression levels of copulation relevant genes in limbic structures across EL- or EN-phenotyped copulating male rats, is not consistent with the hypothesis that distinct ejaculatory endophenotypes exist and that they are associated with specific brain characteristics.
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Affiliation(s)
- Itztli Trejo-Sánchez
- Laboratorio de Biología de Sistemas, Instituto de Investigaciones Biomédicas, Departamento de Biología Celular y Fisiología, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Programa de Doctorado en Ciencias Biomédicas, Unidad de Posgrado, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Carlos Pérez-Monter
- Departamento de Gastroenterología, Instituto Nacional de Ciencias Médicas y Nutrición “Salvador Zubirán”, Mexico City, Mexico
| | - Sofía Huerta-Pacheco
- Consejo Nacional de Ciencia y Tecnología, Ciencia Forense, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Gabriel Gutiérrez-Ospina
- Laboratorio de Biología de Sistemas, Instituto de Investigaciones Biomédicas, Departamento de Biología Celular y Fisiología, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Coordinación de Psicobiología y Neurociencias, Facultad de Psicología, Universidad Nacional Autónoma de México, Mexico City, Mexico
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16
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Massa MG, Correa SM. Sexes on the brain: Sex as multiple biological variables in the neuronal control of feeding. Biochim Biophys Acta Mol Basis Dis 2020; 1866:165840. [PMID: 32428559 DOI: 10.1016/j.bbadis.2020.165840] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 05/05/2020] [Accepted: 05/13/2020] [Indexed: 12/21/2022]
Abstract
Neuronal interactions at the level of vagal, homeostatic, and hedonic circuitry work to regulate the neuronal control of feeding. This integrative system appears to vary across sex and gender in the animal and human worlds. Most feeding research investigating these variations across sex and gender focus on how the organizational and activational mechanisms of hormones contribute to these differences. However, in limited studies spanning both the central and peripheral nervous systems, sex differences in feeding have been shown to manifest not just at the level of the hormonal, but also at the chromosomal, epigenetic, cellular, and even circuitry levels to alter food intake. In this review, we provide a brief orientation to the current understanding of how these neuronal systems interact before dissecting selected studies from the recent literature to exemplify how feeding physiology at all levels can be affected by the various components of sex.
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Affiliation(s)
- Megan G Massa
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA, United States of America; Laboratory of Neuroendocrinology of the Brain Research Institute, University of California, Los Angeles, CA, United States of America; Neuroscience Interdepartmental Doctoral Program, University of California, Los Angeles, CA, United States of America.
| | - Stephanie M Correa
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA, United States of America; Laboratory of Neuroendocrinology of the Brain Research Institute, University of California, Los Angeles, CA, United States of America.
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17
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The neurobiology of sex differences during language processing in healthy adults: A systematic review and a meta-analysis. Neuropsychologia 2020; 140:107404. [DOI: 10.1016/j.neuropsychologia.2020.107404] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 12/26/2019] [Accepted: 02/17/2020] [Indexed: 11/21/2022]
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18
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Abstract
In the past decennia, our understanding of the sexual differentiation of the mammalian brain has dramatically changed. The simple model according to which testosterone masculinizes the brain of males away from a default female form, was replaced with a complex scenario, according to which sex effects on the brain of both females and males are exerted by genetic, hormonal, and environmental factors. These factors act via multiple partly independent mechanisms that may vary according to internal and external factors. These observations led to the "mosaic" hypothesis-the expectation of high variability in the degree of "maleness"/"femaleness" of different features within a single brain. Here, we briefly review animal data that form the basis of current understanding of sexual differentiation; present, in this context, the results of co-analyses of human brain measures obtained by magnetic resonance imaging or postmortem; discuss criticisms and controversies of the mosaic hypothesis and implications for research; and conclude that co-analysis of several (preferably, many) features and going back from the group level to that of the individual would advance our understanding of the relations between sex and the brain in health and disease.
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Affiliation(s)
- Daphna Joel
- School of Psychological Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Alicia Garcia-Falgueras
- Netherlands Institute for Neuroscience, Amsterdam, An Institute of the Royal Netherlands Academy of Arts and Sciences, KNAW, Amsterdam, the Netherlands
| | - Dick Swaab
- Netherlands Institute for Neuroscience, Amsterdam, An Institute of the Royal Netherlands Academy of Arts and Sciences, KNAW, Amsterdam, the Netherlands
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19
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Fausto-Sterling A. Gender/Sex, Sexual Orientation, and Identity Are in the Body: How Did They Get There? JOURNAL OF SEX RESEARCH 2019; 56:529-555. [PMID: 30875248 DOI: 10.1080/00224499.2019.1581883] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
In this review, I explore theoretical and empirical approaches to the development of gender/sex and sexual orientation (SO). Leaving behind the nature versus nurture opposition, I look at both identities as deeply embodied. My approach intertwines sex, gender, orientation, bodies, and cultures without a demand to choose one over the other. First, I introduce basic definitions, focusing on how intertwined the concepts of sex and gender really are. I affirm recent trends to consider a new term-gender/sex-as the best way to think about these deeply interwoven bodily traits. I introduce several literatures, each of which considers the processes by which traits become embodied. These points of view offer a basis for future work on identity development. Specifically, and selectively, I provide insights from the fields of phenomenology, dyadic interaction and the formation of presymbolic representations in infancy, and dynamic systems in infant development. I consider how thinking about embodied cognition helps to address intersubjectivity and the emergence of subjective identity. Next, I review what we currently know about the development of complex sexual systems in infancy and toddlerhood. Finally, I discuss the few existing theories of SO development that consider the events of infancy and childhood.
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20
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Cornblath EJ, Tang E, Baum GL, Moore TM, Adebimpe A, Roalf DR, Gur RC, Gur RE, Pasqualetti F, Satterthwaite TD, Bassett DS. Sex differences in network controllability as a predictor of executive function in youth. Neuroimage 2019; 188:122-134. [PMID: 30508681 PMCID: PMC6401302 DOI: 10.1016/j.neuroimage.2018.11.048] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 10/10/2018] [Accepted: 11/26/2018] [Indexed: 01/06/2023] Open
Abstract
Executive function is a quintessential human capacity that emerges late in development and displays different developmental trends in males and females. Sex differences in executive function in youth have been linked to vulnerability to psychopathology as well as to behaviors that impinge on health, wellbeing, and longevity. Yet, the neurobiological basis of these differences is not well understood, in part due to the spatiotemporal complexity inherent in patterns of brain network maturation supporting executive function. Here we test the hypothesis that sex differences in impulsivity in youth stem from sex differences in the controllability of structural brain networks as they rewire over development. Combining methods from network neuroscience and network control theory, we characterize the network control properties of structural brain networks estimated from diffusion imaging data acquired in males and females in a sample of 879 youth aged 8-22 years. We summarize the control properties of these networks by estimating average and modal controllability, two statistics that probe the ease with which brain areas can drive the network towards easy versus difficult-to-reach states. We find that females have higher modal controllability in frontal, parietal, and subcortical regions while males have higher average controllability in frontal and subcortical regions. Furthermore, controllability profiles in males are negatively related to the false positive rate on a continuous performance task, a common measure of impulsivity. Finally, we find associations between average controllability and individual differences in activation during an n-back working memory task. Taken together, our findings support the notion that sex differences in the controllability of structural brain networks can partially explain sex differences in executive function. Controllability of structural brain networks also predicts features of task-relevant activation, suggesting the potential for controllability to represent context-specific constraints on network state more generally.
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Affiliation(s)
- Eli J Cornblath
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA; Department of Bioengineering, School of Engineering and Applied Sciences, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Evelyn Tang
- Department of Bioengineering, School of Engineering and Applied Sciences, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Graham L Baum
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA; Department of Bioengineering, School of Engineering and Applied Sciences, University of Pennsylvania, Philadelphia, PA, 19104, USA; Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Tyler M Moore
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Azeez Adebimpe
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - David R Roalf
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Ruben C Gur
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Raquel E Gur
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Fabio Pasqualetti
- Department of Mechanical Engineering, University of California, Riverside, CA, 92521, USA
| | - Theodore D Satterthwaite
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Danielle S Bassett
- Department of Bioengineering, School of Engineering and Applied Sciences, University of Pennsylvania, Philadelphia, PA, 19104, USA; Department of Physics & Astronomy, College of Arts and Sciences, University of Pennsylvania, Philadelphia, PA, 19104, USA; Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA; Department of Electrical and Systems Engineering, School of Engineering and Applied Sciences, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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21
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Abstract
Sex-biased power structures are common in human and nonhuman primate societies. “Female dominance” is a term applied to a wide range of female-biased power structures. However, the full extent of this variation remains obscure because an adequate vocabulary of power has not been adopted consistently. Female power occurs throughout primates and other animals, even in male-dominant societies, but the legacy of patriarchy persists in primatologists’ use of language and implicit assumptions about intersexual power. While explanations for the occurrence of female power can be accommodated within existing ethological theory, many hypotheses seeking to explain the evolution of female power are narrowly focused on particular taxa. Theories about primate social evolution would benefit from a synthesis of the disparate literature on power, increased emphasis on intersexual social relationships, and comparative studies that include the full behavioral diversity of primates and other mammals.
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Affiliation(s)
- Rebecca J. Lewis
- Department of Anthropology, University of Texas at Austin, Austin, Texas 78712, USA
- Ankoatsifaka Research Station, Kirindy Mitea National Park, Morondava 619, Madagascar
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22
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Joel D, Persico A, Salhov M, Berman Z, Oligschläger S, Meilijson I, Averbuch A. Analysis of Human Brain Structure Reveals that the Brain "Types" Typical of Males Are Also Typical of Females, and Vice Versa. Front Hum Neurosci 2018; 12:399. [PMID: 30405373 PMCID: PMC6204758 DOI: 10.3389/fnhum.2018.00399] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 09/14/2018] [Indexed: 12/22/2022] Open
Abstract
Findings of average differences between females and males in the structure of specific brain regions are often interpreted as indicating that the typical male brain is different from the typical female brain. An alternative interpretation is that the brain types typical of females are also typical of males, and sex differences exist only in the frequency of rare brain types. Here we contrasted the two hypotheses by analyzing the structure of 2176 human brains using three analytical approaches. An anomaly detection analysis showed that brains from females are almost as likely to be classified as “normal male brains,” as brains from males are, and vice versa. Unsupervised clustering algorithms revealed that common brain “types” are similarly common in females and in males and that a male and a female are almost as likely to have the same brain “type” as two females or two males are. Large sex differences were found only in the frequency of some rare brain “types.” Last, supervised clustering algorithms revealed that the brain “type(s)” typical of one sex category in one sample could be typical of the other sex category in another sample. The present findings demonstrate that even when similarity and difference are defined mathematically, ignoring biological or functional relevance, sex category (i.e., whether one is female or male), is not a major predictor of the variability of human brain structure. Rather, the brain types typical of females are also typical of males, and vice versa, and large sex differences are found only in the prevalence of some rare brain types. We discuss the implications of these findings to studies of the structure and function of the human brain.
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Affiliation(s)
- Daphna Joel
- School of Psychological Sciences, Tel Aviv University, Tel Aviv, Israel.,Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Ariel Persico
- School of Computer Science, Tel Aviv University, Tel Aviv, Israel
| | - Moshe Salhov
- School of Computer Science, Tel Aviv University, Tel Aviv, Israel
| | - Zohar Berman
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Sabine Oligschläger
- Max Planck Research Group for Neuroanatomy and Connectivity, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.,Faculty of Life Sciences, University Leipzig, Leipzig, Germany.,International Max Planck Research School NeuroCom, Leipzig, Germany
| | - Isaac Meilijson
- School of Mathematical Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Amir Averbuch
- School of Computer Science, Tel Aviv University, Tel Aviv, Israel
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23
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Skewes L, Fine C, Haslam N. Beyond Mars and Venus: The role of gender essentialism in support for gender inequality and backlash. PLoS One 2018; 13:e0200921. [PMID: 30040839 PMCID: PMC6057632 DOI: 10.1371/journal.pone.0200921] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 07/05/2018] [Indexed: 11/18/2022] Open
Abstract
It has been argued that gender essentialism impedes progress towards greater gender equality. Here we present a new gender essentialism scale (GES), and validate it in two large nationally representative samples from Denmark and Australia. In both samples the GES was highly reliable and predicted lack of support for sex-role egalitarianism and support for gender discrimination, as well as perceived fairness of gender-based treatment in the Australian sample, independently of two established predictors (i.e., social dominance orientation and conservative political orientation). In addition, gender essentialism assessed by the GES moderated some manifestations of the backlash effect: high essentialists were more likely to respond negatively towards a power-seeking female political candidate relative to a male candidate. Given the implications for possible workplace interventions, further work could usefully explore whether gender essentialism moderates other well-established forms of gender bias.
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Affiliation(s)
- Lea Skewes
- School of Culture & Society, Interacting Minds Centre, Aarhus University, Aarhus, Denmark
| | - Cordelia Fine
- School of Historical & Philosophical Studies, The University of Melbourne, Victoria, Australia
| | - Nick Haslam
- Melbourne School of Psychological Sciences, The University of Melbourne, Victoria, Australia
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24
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Joel D, McCarthy MM. Incorporating Sex As a Biological Variable in Neuropsychiatric Research: Where Are We Now and Where Should We Be? Neuropsychopharmacology 2017; 42:379-385. [PMID: 27240659 PMCID: PMC5399245 DOI: 10.1038/npp.2016.79] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 05/17/2016] [Accepted: 05/23/2016] [Indexed: 11/09/2022]
Abstract
Understanding the multiplicity of ways in which sex can alter the brain is essential to crafting policies and treatments that are beneficial for all human beings. This is particularly true for the field of neuropsychopharmacology, as many neuropsychiatric disorders exhibit gender bias in the frequency, severity, or response to treatment. The goal of this circumspective is to provide two views on the current state of the art of the relations between sex and the brain, relations that are studied almost exclusively by comparing females and males on specific end points, from gene expression to behavior. We start by suggesting a framework for defining what is being measured and what it means. We suggest that 'sex differences' can be classified on four dimensions: (1) persistent vs transient across the lifespan; (2) context independent vs dependent; (3) dimorphic vs continuous; and (4) a direct vs an indirect consequence of sex. To accurately classify a sex difference along these dimensions, one may need to compare females and males under varied conditions. We next discuss current data on the mechanisms of sexual differentiation of the brain and on sex differences in the brain to conclude that the brain of each male and female is a mosaic of relative masculinization, feminization, and sameness, which theoretically could produce an infinite variety of individuals. We also raise the possibility that sex differences in the brain are canalized, which may act to both enhance and restrain variation between males and females. We end by discussing ways to consider sex when studying neuropsychiatric disorders.
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Affiliation(s)
- Daphna Joel
- School of Psychological Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel,School of Psychological Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel, Tel: +972 3 640 8996, Fax: +972 3 640 9547, E-mail:
| | - Margaret M McCarthy
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, Maryland, USA
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25
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Abstract
Swayed by the clear distinction between male and female genitalia, the question of how far these categories extend into human biology has attracted humans for centuries. This question is sometimes being framed as whether the effects of sex are restricted to the genital organs or penetrate the entire organism. Here I argue that the two questions are not equivalent and that whereas the answer to the question, how far sex penetrates the body, is – deep down to the level of every cell, the answer to the question, how far the categories, “male” and “female”, do, is – probably nowhere beyond the genitals. That the two questions are often used interchangeably reflects the prevailing conceptualization of sex as a dichotomous system or process that exerts profound effects on other systems (e.g., the brain), leading to sexual dimorphism (i.e., two forms, male versus female) also of these systems. Here I discuss the question of whether the effects of sex result in dimorphic systems, focusing on the case of sex effects on the brain. I show that although there are sex/gender differences in brain and behavior, humans and human brains are comprised of highly variable ‘mosaics’ of features, some more prevalent in females, others more prevalent in males.
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26
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Reply to Del Giudice et al., Chekroud et al., and Rosenblatt: Do brains of females and males belong to two distinct populations? Proc Natl Acad Sci U S A 2016; 113:E1969-70. [PMID: 26984490 DOI: 10.1073/pnas.1600792113] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
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27
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Reply to Glezerman: Why differences between brains of females and brains of males do not "add up" to create two types of brains. Proc Natl Acad Sci U S A 2016; 113:E1972. [PMID: 26957593 DOI: 10.1073/pnas.1600791113] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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28
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Joel D, Fausto-Sterling A. Beyond sex differences: new approaches for thinking about variation in brain structure and function. Philos Trans R Soc Lond B Biol Sci 2016; 371:20150451. [PMID: 26833844 DOI: 10.1098/rstb.2015.0451] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/14/2015] [Indexed: 12/21/2022] Open
Abstract
In the study of variation in brain structure and function that might relate to sex and gender, language matters because it frames our research questions and methods. In this article, we offer an approach to thinking about variation in brain structure and function that pulls us outside the sex differences formulation. We argue that the existence of differences between the brains of males and females does not unravel the relations between sex and the brain nor is it sufficient to characterize a population of brains. Such characterization is necessary for studying sex effects on the brain as well as for studying brain structure and function in general. Animal studies show that sex interacts with environmental, developmental and genetic factors to affect the brain. Studies of humans further suggest that human brains are better described as belonging to a single heterogeneous population rather than two distinct populations. We discuss the implications of these observations for studies of brain and behaviour in humans and in laboratory animals. We believe that studying sex effects in context and developing or adopting analytical methods that take into account the heterogeneity of the brain are crucial for the advancement of human health and well-being.
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Affiliation(s)
- Daphna Joel
- School of Psychological Sciences, Tel-Aviv University, Ramat Aviv, Tel-Aviv, Israel Sagol School of Neuoroscience, Tel-Aviv University, Ramat Aviv, Tel-Aviv, Israel
| | - Anne Fausto-Sterling
- Department of Molecular Biology, Cell and Biochemistry, Brown University, Providence, RI, USA
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29
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Forger NG. Epigenetic mechanisms in sexual differentiation of the brain and behaviour. Philos Trans R Soc Lond B Biol Sci 2016; 371:20150114. [PMID: 26833835 DOI: 10.1098/rstb.2015.0114] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/12/2015] [Indexed: 11/12/2022] Open
Abstract
Circumstantial evidence alone argues that the establishment and maintenance of sex differences in the brain depend on epigenetic modifications of chromatin structure. More direct evidence has recently been obtained from two types of studies: those manipulating a particular epigenetic mechanism, and those examining the genome-wide distribution of specific epigenetic marks. The manipulation of histone acetylation or DNA methylation disrupts the development of several neural sex differences in rodents. Taken together, however, the evidence suggests there is unlikely to be a simple formula for masculine or feminine development of the brain and behaviour; instead, underlying epigenetic mechanisms may vary by brain region or even by dependent variable within a region. Whole-genome studies related to sex differences in the brain have only very recently been reported, but suggest that males and females may use different combinations of epigenetic modifications to control gene expression, even in cases where gene expression does not differ between the sexes. Finally, recent findings are discussed that are likely to direct future studies on the role of epigenetic mechanisms in sexual differentiation of the brain and behaviour.
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Affiliation(s)
- Nancy G Forger
- Neuroscience Institute, Georgia State University, Atlanta, GA 30307, USA
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30
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Levine SC, Foley A, Lourenco S, Ehrlich S, Ratliff K. Sex differences in spatial cognition: advancing the conversation. WILEY INTERDISCIPLINARY REVIEWS. COGNITIVE SCIENCE 2016; 7:127-55. [DOI: 10.1002/wcs.1380] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Revised: 09/30/2015] [Accepted: 12/09/2015] [Indexed: 01/10/2023]
Affiliation(s)
- Susan C. Levine
- Department of Psychology University of Chicago Chicago IL USA
| | - Alana Foley
- Department of Psychology University of Chicago Chicago IL USA
| | - Stella Lourenco
- Department of Psychology University of Chicago Chicago IL USA
| | - Stacy Ehrlich
- Department of Psychology University of Chicago Chicago IL USA
| | - Kristin Ratliff
- Department of Psychology University of Chicago Chicago IL USA
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31
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Abstract
Whereas a categorical difference in the genitals has always been acknowledged, the question of how far these categories extend into human biology is still not resolved. Documented sex/gender differences in the brain are often taken as support of a sexually dimorphic view of human brains ("female brain" or "male brain"). However, such a distinction would be possible only if sex/gender differences in brain features were highly dimorphic (i.e., little overlap between the forms of these features in males and females) and internally consistent (i.e., a brain has only "male" or only "female" features). Here, analysis of MRIs of more than 1,400 human brains from four datasets reveals extensive overlap between the distributions of females and males for all gray matter, white matter, and connections assessed. Moreover, analyses of internal consistency reveal that brains with features that are consistently at one end of the "maleness-femaleness" continuum are rare. Rather, most brains are comprised of unique "mosaics" of features, some more common in females compared with males, some more common in males compared with females, and some common in both females and males. Our findings are robust across sample, age, type of MRI, and method of analysis. These findings are corroborated by a similar analysis of personality traits, attitudes, interests, and behaviors of more than 5,500 individuals, which reveals that internal consistency is extremely rare. Our study demonstrates that, although there are sex/gender differences in the brain, human brains do not belong to one of two distinct categories: male brain/female brain.
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32
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McCarthy MM, Pickett LA, VanRyzin JW, Kight KE. Surprising origins of sex differences in the brain. Horm Behav 2015; 76:3-10. [PMID: 25917865 PMCID: PMC4620061 DOI: 10.1016/j.yhbeh.2015.04.013] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Revised: 03/22/2015] [Accepted: 04/06/2015] [Indexed: 11/22/2022]
Abstract
This article is part of a Special Issue "SBN 2014". Discerning the biologic origins of neuroanatomical sex differences has been of interest since they were first reported in the late 60's and early 70's. The centrality of gonadal hormone exposure during a developmental critical window cannot be denied but hormones are indirect agents of change, acting to induce gene transcription or modulate membrane bound signaling cascades. Sex differences in the brain include regional volume differences due to differential cell death, neuronal and glial genesis, dendritic branching and synaptic patterning. Early emphasis on mechanism therefore focused on neurotransmitters and neural growth factors, but by and large these endpoints failed to explain the origins of neural sex differences. More recently evidence has accumulated in favor of inflammatory mediators and immune cells as principle regulators of brain sexual differentiation and reveal that the establishment of dimorphic circuits is not cell autonomous but instead requires extensive cell-to-cell communication including cells of non-neuronal origin. Despite the multiplicity of cells involved the nature of the sex differences in the neuroanatomical endpoints suggests canalization, a process that explains the robustness of individuals in the face of intrinsic and extrinsic variability. We propose that some neuroanatomical endpoints are canalized to enhance sex differences in the brain by reducing variability within one sex while also preventing the sexes from diverging too greatly. We further propose mechanisms by which such canalization could occur and discuss what relevance this may have to sex differences in behavior.
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Affiliation(s)
- Margaret M McCarthy
- Department of Pharmacology, Program in Neuroscience and Program in Molecular Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
| | - Lindsay A Pickett
- Department of Pharmacology, Program in Neuroscience and Program in Molecular Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Jonathan W VanRyzin
- Department of Pharmacology, Program in Neuroscience and Program in Molecular Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Katherine E Kight
- Department of Pharmacology, Program in Neuroscience and Program in Molecular Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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33
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Santalucia P, Franchi C, Djade CD, Tettamanti M, Pasina L, Corrao S, Salerno F, Marengoni A, Marcucci M, Nobili A, Mannucci PM. Gender difference in drug use in hospitalized elderly patients. Eur J Intern Med 2015. [PMID: 26209883 DOI: 10.1016/j.ejim.2015.07.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
PURPOSE The aims of this study were to evaluate whether or not there are gender differences in drug use at hospital admission and prescription at discharge and to evaluate the effect of hospitalization on medication patterns in the elderly. METHOD In-patients aged >65years included in the REPOSI registry during a recruitment period of 3years (2008-2010-2012) were analyzed in order to evaluate drug use at hospital admission and prescription at discharge according to gender. RESULTS A total of 3473 patients, 52% women and 48% men, were considered. Polypharmacy (>5 drugs) is more frequent in men both at hospital admission and discharge. At hospital discharge, the number of prescriptions increased in both sexes at all age groups. Neuropsychiatric drugs were significantly more prescribed in women (p<0.0001). At admission men were more likely to be on antiplatelets (41.7% vs 36.7%; p=0.0029), ACE-inhibitors (28.7% vs 24.7%; p=0.0072) and statins (22.9% vs 18.3%; p=0.0008). At discharge, antiplatelets (43.7% vs 37.3%; p=0.0003) and statins (25,2% vs 19.6%; p<0.0001) continued to be prescribed more often in men, while women were given beta-blockers more often than men (21.8% vs 18.9%; p=0.0340). Proton pump inhibitors were the most prescribed drugs regardless of gender. At discharge, the medication pattern did not change according to gender. CONCLUSION Our study showed a gender difference in overall medications pattern in the hospitalized elderly. Hospitalization, while increasing the number of prescriptions, did not change drug distribution by sex.
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Affiliation(s)
- Paola Santalucia
- Scientific Direction, Foundation IRCCS Cà Granda Ospedale Maggiore Policlinico, Milan, Italy; Department of Neuroscience, IRCCS, Istituto di Ricerche Farmacologiche "Mario Negri", Milan, Italy.
| | - Carlotta Franchi
- Department of Neuroscience, IRCCS, Istituto di Ricerche Farmacologiche "Mario Negri", Milan, Italy
| | - Codjo D Djade
- Department of Neuroscience, IRCCS, Istituto di Ricerche Farmacologiche "Mario Negri", Milan, Italy
| | - Mauro Tettamanti
- Department of Neuroscience, IRCCS, Istituto di Ricerche Farmacologiche "Mario Negri", Milan, Italy
| | - Luca Pasina
- Department of Neuroscience, IRCCS, Istituto di Ricerche Farmacologiche "Mario Negri", Milan, Italy
| | - Salvatore Corrao
- Dipartimento Biomedico di Medicina Interna e Specialistica, University of Palermo, Palermo, Italy
| | - Francesco Salerno
- Internal Medicine I, Policlinico IRCCS San Donato, University of Milan, Milan, Italy
| | - Alessandra Marengoni
- Geriatric Unit Spedali Civili, Department of Clinical and Experimental Sciences, University of Brescia, Brescia Italy
| | - Maura Marcucci
- Foundation IRCCS Cà Granda-Ospedale Maggiore Policlinico, Geriatrics, Milan, Italy; Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Alessandro Nobili
- Department of Neuroscience, IRCCS, Istituto di Ricerche Farmacologiche "Mario Negri", Milan, Italy
| | - Pier Mannuccio Mannucci
- Scientific Direction, Foundation IRCCS Cà Granda Ospedale Maggiore Policlinico, Milan, Italy
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34
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van Anders SM. Beyond Sexual Orientation: Integrating Gender/Sex and Diverse Sexualities via Sexual Configurations Theory. ARCHIVES OF SEXUAL BEHAVIOR 2015; 44:1177-213. [PMID: 25772652 DOI: 10.1007/s10508-015-0490-8] [Citation(s) in RCA: 225] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 09/12/2014] [Accepted: 12/25/2014] [Indexed: 05/10/2023]
Abstract
Sexual orientation typically describes people's sexual attractions or desires based on their sex relative to that of a target. Despite its utility, it has been critiqued in part because it fails to account for non-biological gender-related factors, partnered sexualities unrelated to gender or sex, or potential divergences between love and lust. In this article, I propose Sexual Configurations Theory (SCT) as a testable, empirically grounded framework for understanding diverse partnered sexualities, separate from solitary sexualities. I focus on and provide models of two parameters of partnered sexuality--gender/sex and partner number. SCT also delineates individual gender/sex. I discuss a sexual diversity lens as a way to study the particularities and generalities of diverse sexualities without privileging either. I also discuss how sexual identities, orientations, and statuses that are typically seen as misaligned or aligned are more meaningfully conceptualized as branched or co-incident. I map out some existing identities using SCT and detail its applied implications for health and counseling work. I highlight its importance for sexuality in terms of measurement and social neuroendocrinology, and the ways it may be useful for self-knowledge and feminist and queer empowerment and alliance building. I also make a case that SCT changes existing understandings and conceptualizations of sexuality in constructive and generative ways informed by both biology and culture, and that it is a potential starting point for sexual diversity studies and research.
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Affiliation(s)
- Sari M van Anders
- Department of Psychology, University of Michigan, 530 Church St., Ann Arbor, MI, 48105, USA,
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Expanding the Role of Gender Essentialism in the Single-Sex Education Debate: A Commentary on Liben. SEX ROLES 2015. [DOI: 10.1007/s11199-015-0474-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Affiliation(s)
- Cordelia Fine
- Melbourne School of Psychological Sciences, Melbourne Business School & Centre for Ethical Leadership, University of Melbourne, Australia.
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Junger J, Habel U, Bröhr S, Neulen J, Neuschaefer-Rube C, Birkholz P, Kohler C, Schneider F, Derntl B, Pauly K. More than just two sexes: the neural correlates of voice gender perception in gender dysphoria. PLoS One 2014; 9:e111672. [PMID: 25375171 PMCID: PMC4222943 DOI: 10.1371/journal.pone.0111672] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Accepted: 10/03/2014] [Indexed: 01/28/2023] Open
Abstract
Gender dysphoria (also known as “transsexualism”) is characterized as a discrepancy between anatomical sex and gender identity. Research points towards neurobiological influences. Due to the sexually dimorphic characteristics of the human voice, voice gender perception provides a biologically relevant function, e.g. in the context of mating selection. There is evidence for a better recognition of voices of the opposite sex and a differentiation of the sexes in its underlying functional cerebral correlates, namely the prefrontal and middle temporal areas. This fMRI study investigated the neural correlates of voice gender perception in 32 male-to-female gender dysphoric individuals (MtFs) compared to 20 non-gender dysphoric men and 19 non-gender dysphoric women. Participants indicated the sex of 240 voice stimuli modified in semitone steps in the direction to the other gender. Compared to men and women, MtFs showed differences in a neural network including the medial prefrontal gyrus, the insula, and the precuneus when responding to male vs. female voices. With increased voice morphing men recruited more prefrontal areas compared to women and MtFs, while MtFs revealed a pattern more similar to women. On a behavioral and neuronal level, our results support the feeling of MtFs reporting they cannot identify with their assigned sex.
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Affiliation(s)
- Jessica Junger
- Department of Psychiatry, Psychotherapy and Psychosomatics, Medical School, RWTH Aachen University, Aachen, Germany
- Jülich Aachen Research Alliance-Translational Brain Medicine, Jülich, Germany
- * E-mail:
| | - Ute Habel
- Department of Psychiatry, Psychotherapy and Psychosomatics, Medical School, RWTH Aachen University, Aachen, Germany
- Jülich Aachen Research Alliance-Translational Brain Medicine, Jülich, Germany
| | - Sabine Bröhr
- Department of Psychiatry, Psychotherapy and Psychosomatics, Medical School, RWTH Aachen University, Aachen, Germany
| | - Josef Neulen
- Department of Gynaecological Endocrinology and Reproductive Medicine, Medical School, RWTH Aachen University, Aachen, Germany
| | - Christiane Neuschaefer-Rube
- Department of Phoniatrics, Pedaudiology and Communication Disorders, Medical School, RWTH Aachen University, Aachen, Germany
| | - Peter Birkholz
- Department of Phoniatrics, Pedaudiology and Communication Disorders, Medical School, RWTH Aachen University, Aachen, Germany
| | - Christian Kohler
- Department of Psychiatry, Neuropsychiatry Division, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Frank Schneider
- Department of Psychiatry, Psychotherapy and Psychosomatics, Medical School, RWTH Aachen University, Aachen, Germany
- Jülich Aachen Research Alliance-Translational Brain Medicine, Jülich, Germany
| | - Birgit Derntl
- Department of Psychiatry, Psychotherapy and Psychosomatics, Medical School, RWTH Aachen University, Aachen, Germany
- Jülich Aachen Research Alliance-Translational Brain Medicine, Jülich, Germany
| | - Katharina Pauly
- Department of Psychiatry, Psychotherapy and Psychosomatics, Medical School, RWTH Aachen University, Aachen, Germany
- Jülich Aachen Research Alliance-Translational Brain Medicine, Jülich, Germany
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Rippon G, Jordan-Young R, Kaiser A, Fine C. Recommendations for sex/gender neuroimaging research: key principles and implications for research design, analysis, and interpretation. Front Hum Neurosci 2014; 8:650. [PMID: 25221493 PMCID: PMC4147717 DOI: 10.3389/fnhum.2014.00650] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 08/04/2014] [Indexed: 01/17/2023] Open
Abstract
Neuroimaging (NI) technologies are having increasing impact in the study of complex cognitive and social processes. In this emerging field of social cognitive neuroscience, a central goal should be to increase the understanding of the interaction between the neurobiology of the individual and the environment in which humans develop and function. The study of sex/gender is often a focus for NI research, and may be motivated by a desire to better understand general developmental principles, mental health problems that show female-male disparities, and gendered differences in society. In order to ensure the maximum possible contribution of NI research to these goals, we draw attention to four key principles-overlap, mosaicism, contingency and entanglement-that have emerged from sex/gender research and that should inform NI research design, analysis and interpretation. We discuss the implications of these principles in the form of constructive guidelines and suggestions for researchers, editors, reviewers and science communicators.
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Affiliation(s)
- Gina Rippon
- Aston Brain Centre, School of Life and Health Sciences (Psychology), Aston UniversityBirmingham, West Midlands, UK
| | - Rebecca Jordan-Young
- Department of Women’s, Gender and Sexuality Studies, Barnard College, Columbia University in the City of New YorkNew York, NY, USA
| | - Anelis Kaiser
- Department of Social Psychology, Institute of Psychology, University of BernBern, Switzerland
| | - Cordelia Fine
- Melbourne School of Psychological Sciences, Melbourne Business School, and Centre for Ethical Leadership, University of MelbourneCarlton, VIC, Australia
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Joel D, Yankelevitch-Yahav R. Reconceptualizing sex, brain and psychopathology: interaction, interaction, interaction. Br J Pharmacol 2014; 171:4620-35. [PMID: 24758640 DOI: 10.1111/bph.12732] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2013] [Revised: 03/22/2014] [Accepted: 03/26/2014] [Indexed: 01/08/2023] Open
Abstract
In recent years there has been a growing recognition of the influence of sex on brain structure and function, and in relation, on the susceptibility, prevalence and response to treatment of psychiatric disorders. Most theories and descriptions of the effects of sex on the brain are dominated by an analogy to the current interpretation of the effects of sex on the reproductive system, according to which sex is a divergence system that exerts a unitary, overriding and serial effect on the form of other systems. We shortly summarize different lines of evidence that contradict aspects of this analogy. The new view that emerges from these data is of sex as a complex system whose different components interact with one another and with other systems to affect body and brain. The paradigm shift that this understanding calls for is from thinking of sex in terms of sexual dimorphism and sex differences, to thinking of sex in terms of its interactions with other factors and processes. Our review of data obtained from animal models of psychopathology clearly reveals the need for such a paradigmatic shift, because in the field of animal behaviour whether a sex difference exists and its direction depend on the interaction of many factors including, species, strain, age, specific test employed and a multitude of environmental factors. We conclude by explaining how the new conceptualization can account for sex differences in psychopathology.
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Affiliation(s)
- D Joel
- School of Psychological Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
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Cahill L. Equal ≠ the same: sex differences in the human brain. CEREBRUM : THE DANA FORUM ON BRAIN SCIENCE 2014; 2014:5. [PMID: 25009695 PMCID: PMC4087190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
While advances in brain imaging confirm that men and women think in their own way and that their brains are different, the biomedical community mainly uses male animals as testing subjects with the assumption that sex differences in the brain hardly matter. This month's Cerebrum highlights some of the thinking and research that invalidates that assumption.
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Affiliation(s)
- Janet Shibley Hyde
- Department of Psychology, University of Wisconsin, Madison, Wisconsin 53706;
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