Sex differences in the effects of visual contact and eye contact in negotiations

"Previous research has proposed that the ability to see others would benefit negotiations. We argue that this view is too narrow and that the impact of visual contact on negotiated agreements depends on the meaning individuals ascribe to either its presence or absence. Based on previous research showing that females are more likely to understand others in the presence of visual contact while males understand others better in the absence of visual contact, we explore how visual contact, eye contact, and sex affect the quality of negotiated agreements in a meta-analysis (Study 1) and a laboratory experiment (Study 2). The two studies combined show that because direct communication via the face facilitates a shared understanding for two unacquainted females, their agreements are of higher quality when they have visual contact compared to when they do not (Study 1), and if they have visual contact, their agreements are better when they have eye contact than when they do not (Study 2). Because communication via the face increases discomfort between two unacquainted males, their agreements are of higher quality when they do not have visual contact (Study 1), and if they do have visual contact, their agreements are better when they have no eye contact than when they do (Study 2)." [author's abstract

Sex differences in the neurokinin B system in the human infundibular nucleus.

CONTEXT: The recent report that loss-of-function mutations in either the gene encoding neurokinin B (NKB) or its receptor (NK3R) produce gonadotropin deficiencies in humans strongly points to NKB as a key regulator of GnRH release. OBJECTIVES: We used NKB immunohistochemistry on postmortem human brain tissue to determine: 1) whether the human NKB system in the infundibular nucleus (INF) is sexually dimorphic; 2) at what stage in development the infundibular NKB system would diverge between men and women; 3) whether this putative structural difference is reversed in male-to-female (MtF) transsexual people; and 4) whether menopause is accompanied by changes in infundibular NKB immunoreactivity. METHODS: NKB immunohistochemical staining was performed on postmortem hypothalamus material of both sexes from the infant/pubertal period into the elderly period and from MtF transsexuals. RESULTS: Quantitative analysis demonstrated that the human NKB system exhibits a robust female-dominant sexual dimorphism in the INF. During the first years after birth, both sexes displayed a moderate and equivalent level of NKB immunoreactivity in the INF. The adult features emerged progressively around puberty until adulthood, where the female-dominant sex difference appeared and continued into old age. In MtF transsexuals, a female-typical NKB immunoreactivity was observed. Finally, in postmenopausal women, there was a significant increase in NKB immunoreactivity compared to premenopausal women. CONCLUSION: Our results indicate that certain sex differences do not emerge until adulthood when activated by sex steroid hormones and the likely involvement of the human infundibular NKB system in the negative and positive feedback of estrogen on GnRH secretion

Sexual differentiation of the human brain

Sex differences in the structures of human hypothalamus and adjacent brain structures have been observed that seem to be related to gender, to gender problems such as transsexuality, and to sexual orientation, that is, heterosexuality and homosexuality. Although these observations have yet to be confirmed, and their exact functional implications are far from clear, they open up a whole new field of structural-functional relationships in human brain research.Biomedical Reviews 1997; 7: 17-32

Distribution of Non-Persistent Endocrine Disruptors in Two Different Regions of the Human Brain

Non-persistent endocrine disrupting chemicals (npEDCs) can affect multiple organs and systems in the body. Whether npEDCs can accumulate in the human brain is largely unknown. The major aim of this pilot study was to examine the presence of environmental phenols and parabens in two distinct brain regions: the hypothalamus and white-matter tissue. In addition, a potential association between these npEDCs concentrations and obesity was investigated. Post-mortem brain material was obtained from 24 individuals, made up of 12 obese and 12 normal-weight subjects (defined as body mass index (BMI) > 30 and BMI < 25 kg/m2, respectively). Nine phenols and seven parabens were measured by isotope dilution TurboFlow-LC-MS/MS. In the hypothalamus, seven suspect npEDCs (bisphenol A, triclosan, triclocarban and methyl-, ethyl-, n-propyl-, and benzyl paraben) were detected, while five npEDCs (bisphenol A, benzophenone-3, triclocarban, methyl-, and n-propyl paraben) were found in the white-matter brain tissue. We observed higher levels of methylparaben (MeP) in the hypothalamic tissue of obese subjects as compared to controls (p = 0.008). Our findings indicate that some suspected npEDCs are able to cross the blood–brain barrier. Whether the presence of npEDCs can adversely affect brain function and to which extent the detected concentrations are physiologically relevant needs to be further investigated.Jana V. van Vliet-Ostaptchouk is supported by a Diabetes Funds Junior Fellowship from the Dutch Diabetes Research Foundation (project no. 2013.81.1673). This work was supported by the National Consortium for Healthy Ageing (NCHA) (NCHA NGI Grant 050-060-810), and the European Union’s Seventh Framework program (FP7/2007-2013) through the BioSHaRE-EU (Biobank Standardization and Harmonization for Research Excellence in the European Union) project, grant agreement 261433, and by the Danish Center on Endocrine Disrupters and the International Center for Research and Research Training in Endocrine Disruption of Male Reproduction and Child Health (EDMaRC)

Volumetric parcellation methodology of the human hypothalamus in neuroimaging: Normative data and sex differences

There is increasing evidence regarding the importance of the hypothalamus for understanding sex differences in relation to neurological, psychiatric, endocrine and sleep disorders. Although different in histology, physiology, connections and function, multiple hypothalamic nuclei subserve non-voluntary functions and are nodal points for the purpose of maintaining homeostasis of the organism. Thus, given the critical importance of hypothalamic nuclei and their key multiple roles in regulating basic functions, it is important to develop the ability to conduct in vivo human studies of anatomic structure, volume, connectivity, and function of hypothalamic regions represented at the level of its nuclei. The goals of the present study were to develop a novel method of semi-automated volumetric parcellation for the human hypothalamus that could be used to investigate clinical conditions using MRI and to demonstrate its applicability. The proposed new method subdivides the hypothalamus into five parcels based on visible anatomic landmarks associated with specific nuclear groupings and was confirmed using two ex vivo hypothalami that were imaged in a 7 T (7 T) scanner and processed histologically. Imaging results were compared with histology from the same brain. Further, the method was applied to 44 healthy adults (26 men; 18 women, comparable on age, handedness, ethnicity, SES) to derive normative volumes and assess sex differences in hypothalamic regions using 1.5 T MRI. Men compared to women had a significantly larger total hypothalamus, relative to cerebrum size, similar for both hemispheres, a difference that was primarily driven by the tuberal region, with the sex effect size being largest in the superior tuberal region and, to a lesser extent, inferior tuberal region. Given the critical role of hypothalamic nuclei in multiple chronic diseases and the importance of sex differences, we argue that the use of the novel methodology presented here will allow for critical investigations of these disorders and further delineation of potential treatments, particularly sex-specific approaches to gene and drug discoveries that involve hypothalamic nuclei