Marc Breedlove

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Dr. Marc Breedlove

Stephen Marc Breedlove (born 1954) [1] [2] [ self-published source? ] is the Barnett Rosenberg professor of Neuroscience at Michigan State University in East Lansing, Michigan. [3] He was born and raised in the Ozarks of southwestern Missouri. [2] After graduating from Central High School (Springfield, Missouri) in 1972, [4] he earned a bachelor's degree in Psychology from Yale University in 1976, [2] and a Ph.D. in psychology from UCLA in 1982. [2] He was a professor of psychology at the University of California, Berkeley from 1982 to 2003, [2] moving to Michigan State in 2001. [2] He works in the fields of Behavioral Neuroscience and Neuroendocrinology. He is a member of the Society for Neuroscience [5] and the Society for Behavioral Neuroendocrinology, [6] and a fellow of the Association for Psychological Science (APS) [7] and the Biological Sciences section of the American Association for the Advancement of Science (AAAS). [8]

Contents

Research

In numerous papers, Breedlove has demonstrated that steroid hormones and sexual behavior affect the developing and adult spinal cord and brain. He also reported that the average digit ratio of lesbians is more masculine than that of straight women, [9] a finding that has been replicated in his [10] and many other labs [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] and which indicates that lesbians, on average, are exposed to more prenatal testosterone than are straight women. This finding joins many others that biological influences, such as prenatal testosterone and fraternal birth order, [22] act before birth to affect the later unfolding of human sexual orientation, which is the theme for the documentary project Whom You Love.

He is sole author of two textbooks Principles of Psychology and Foundations of Neural Development and has co-authored textbooks in Biological Psychology and Behavioral Neuroendocrinology. [23] [24] [25] [26]

Breedlove, along with other neuroscientists, researched PTSD being connected to erectile dysfunction. This erectile dysfunction is usually treated by psychotherapy. Breedlove helped to find the receptor that is affected by the PTSD. This was found through a series of stress tests on rats. The receptor is called the gastrin-releasing peptide (GRP) receptor. This receptor is stress-vulnerable and should be targeted in treatment. [27]

He also researched how GRP in the lumbar spinal cord could be stimulated for the purpose of curing erectile dysfunction. It was found that the female rats and the male rats with erectile dysfunction had the same amount of GRP. Once the GRP was stimulated in the male rats, androgen receptors worked, and erectile dysfunction was cured. During the experiment, simple erections, dorsal flips of the penis and cup-like flaring erections of the distal glans were measured in the rats before and after probe stimulation. [28]

Breedlove examined the sex differences in animals to gain an understanding of the sex differences in humans. It was found in rats that the males had more cell numbers in the spinal nucleus of the bulbocavernosus (SNB) than the female rats. These motor neurons appear in both male and female rats, but fade with age in the female rats. Testosterone was also found as the key hormone that is responsible for the differences between males and females. [29]

Breedlove researched the sexual preferences of homosexual men. Using homosexual and heterosexual male participants, it was found that the two groups did not vary according to mating desires. Even though homosexual males cannot reproduce, they, like the heterosexual males, prefer to be with a younger partner. This concludes that both groups' partner references were independent of the evolutionary need for reproduction. [30]

See also

Related Research Articles

<span class="mw-page-title-main">Sexual orientation</span> Pattern of romantic or sexual attraction

Sexual orientation is an enduring personal pattern of romantic attraction or sexual attraction to persons of the opposite sex or gender, the same sex or gender, or to both sexes or more than one gender. Patterns are generally categorized under heterosexuality, homosexuality, and bisexuality, while asexuality is sometimes identified as the fourth category.

<span class="mw-page-title-main">Biology and sexual orientation</span> Field of sexual orientation research

The relationship between biology and sexual orientation is a subject of on-going research. While scientists do not know the exact cause of sexual orientation, they theorize that it is caused by a complex interplay of genetic, hormonal, and environmental influences. However, evidence is weak for hypotheses that the post-natal social environment impacts sexual orientation, especially for males.

<span class="mw-page-title-main">Hypothalamus</span> Area of the brain below the thalamus

The hypothalamus is a small part of the vertebrate brain that contains a number of nuclei with a variety of functions. One of the most important functions is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamus is located below the thalamus and is part of the limbic system. It forms the basal part of the diencephalon. All vertebrate brains contain a hypothalamus. In humans, it is about the size of an almond.

<span class="mw-page-title-main">Digit ratio</span> Ratio of lengths of fingers

The digit ratio is the ratio taken of the lengths of different digits or fingers on a hand.

Sexual dysfunction is difficulty experienced by an individual or partners during any stage of normal sexual activity, including physical pleasure, desire, preference, arousal, or orgasm. The World Health Organization defines sexual dysfunction as a "person's inability to participate in a sexual relationship as they would wish". This definition is broad and is subject to many interpretations. A diagnosis of sexual dysfunction under the DSM-5 requires a person to feel extreme distress and interpersonal strain for a minimum of six months. Sexual dysfunction can have a profound impact on an individual's perceived quality of sexual life. The term sexual disorder may not only refer to physical sexual dysfunction, but to paraphilias as well; this is sometimes termed disorder of sexual preference.

<span class="mw-page-title-main">Paraventricular nucleus of hypothalamus</span>

The paraventricular nucleus of hypothalamus is a nucleus in the hypothalamus, that lies next to the third ventricle. Many of its neurons project to the posterior pituitary where they secrete oxytocin, and a smaller amount of vasopressin. Other secretions are corticotropin-releasing hormone (CRH) and thyrotropin-releasing hormone (TRH). CRH and TRH are secreted into the hypophyseal portal system, and target different neurons in the anterior pituitary. Dysfunctions of the PVN can cause hypersomnia in mice. In humans, the dysfunction of the PVN and the other nuclei around it can lead to drowsiness for up to 20 hours per day. The PVN is thought to mediate many diverse functions through different hormones, including osmoregulation, appetite, wakefulness, and the response of the body to stress.

<span class="mw-page-title-main">Fraternal birth order and male sexual orientation</span> Theory of sexual orientation

Fraternal birth order, also known as the older brother effect, has been correlated with male sexual orientation, with a significant volume of research finding that the more older brothers a male has from the same mother, the greater the probability he will have a homosexual orientation. Ray Blanchard and Anthony Bogaert first identified the association in the 1990s and named it the fraternal birth order effect. Scientists have attributed the effect to a prenatal biological mechanism, since the association is only present in men with older biological brothers, and not present among men with older step-brothers and adoptive brothers. The mechanism is thought to be a maternal immune response to male fetuses, whereby antibodies neutralize male Y-proteins thought to play a role in sexual differentiation during development. This would leave some regions of the brain associated with sexual orientation in the 'female typical' arrangement – or attracted to men. Biochemical evidence for this hypothesis was identified in 2017, finding mothers with a gay son, particularly those with older brothers, had heightened levels of antibodies to the NLGN4Y Y-protein than mothers with heterosexual sons.

<span class="mw-page-title-main">Ventromedial nucleus of the hypothalamus</span> Nucleus of the hypothalamus

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The sexually dimorphic nucleus (SDN) is an ovoid, densely packed cluster of large cells located in the medial preoptic area (POA) of the hypothalamus which is believed to be related to sexual behavior in animals. Thus far, for all species of mammals investigated, the SDN has been repeatedly found to be considerably larger in males than in females. In humans, the volume of the SDN has been found to be 2.2 times as large in males as in females and to contain 2.1 times as many cells. The human SDN is elongated in females and more spherical in males. No sex differences have been observed in the human SDN in either cell density or mean diameter of the cell nuclei. The volume and cell number of the human SDN considerably decreases with age, although the decrease in cell number is both sex and age-specific. In males, a substantial decrease in the cell number of the human SDN was observed between the age of 50–60 years. Cell death was more common in females than males, especially among those older than 70 years of age. The SDN cell number in females can drop to 10-15% of that found in early childhood.

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<span class="mw-page-title-main">Neuroscience and sexual orientation</span> Mechanisms of sexual orientation development in humans

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<span class="mw-page-title-main">Arthur P. Arnold</span> American biologist

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References

  1. ↑ Who, Marquis Who's (November 1995). Who's Who in the West 1996-1997. ISBN   9780837909264.
  2. 1 2 3 4 5 6 Breedlove, S. Marc (18 March 2009). "Curriculum Vitae" (PDF). Retrieved 31 October 2009.
  3. ↑ "Cellular/Molecular Neuroscience Faculty". Michigan State University. 2008. Retrieved 31 October 2009.
  4. ↑ "Neuroscientist and Springfield native shares view on sexual orientation". Archived from the original on 2014-05-02.
  5. ↑ "Donald B. Lindsley Prize in Behavioral Neuroscience".
  6. ↑ "Hormones & Behavior Editorial Board".
  7. ↑ "List of APS Fellows".
  8. ↑ "AAAS Members Elected as Fellows".
  9. ↑ Williams TJ, Pepitone ME, Christensen SE, et al. (March 2000). "Finger-length ratios and sexual orientation" (PDF). Nature. 404 (6777): 455–6. Bibcode:2000Natur.404..455W. doi:10.1038/35006555. PMID   10761903. S2CID   205005405.
  10. ↑ Brown WM, Finn CJ, Cooke BM, Breedlove SM (February 2002). "Differences in finger length ratios between self-identified 'butch' and 'femme' lesbians" (PDF). Archives of Sexual Behavior. 31 (1): 123–7. doi:10.1023/A:1014091420590. PMID   11910785. S2CID   10259939.
  11. ↑ Tortorice JL (2002). Written on the body: butch/femme lesbian gender identity and biological correlates (Ph.D. Dissertation). Rutgers University. OCLC   80234273.
  12. ↑ McFadden D, Shubel E (December 2002). "Relative lengths of fingers and toes in human males and females". Hormones and Behavior. 42 (4): 492–500. doi:10.1006/hbeh.2002.1833. PMID   12488115. S2CID   1360679.
  13. ↑ Hall LS, Love CT (February 2003). "Finger-length ratios in female monozygotic twins discordant for sexual orientation". Archives of Sexual Behavior. 32 (1): 23–8. doi:10.1023/A:1021837211630. PMID   12597269. S2CID   1743441.
  14. ↑ Rahman Q, Wilson GD (April 2003). "Sexual orientation and the 2nd to 4th finger length ratio: evidence for organising effects of sex hormones or developmental instability?". Psychoneuroendocrinology. 28 (3): 288–303. doi:10.1016/S0306-4530(02)00022-7. PMID   12573297. S2CID   21071741.
  15. ↑ Csathó A, Osváth A, Bicsák E, Karádi K, Manning J, Kállai J (February 2003). "Sex role identity related to the ratio of second to fourth digit length in women". Biological Psychology. 62 (2): 147–56. doi:10.1016/S0301-0511(02)00127-8. PMID   12581689. S2CID   38339150.
  16. ↑ Putz, David A.; Gaulin, Steven J. C.; Sporter, Robert J.; McBurney, Donald H. (May 2004). "Sex hormones and finger length: What does 2D:4D indicate?" (PDF). Evolution and Human Behavior. 25 (3): 182–99. doi:10.1016/j.evolhumbehav.2004.03.005. Archived from the original (PDF) on 2010-01-07.
  17. ↑ Rahman Q (May 2005). "Fluctuating asymmetry, second to fourth finger length ratios and human sexual orientation". Psychoneuroendocrinology. 30 (4): 382–91. doi:10.1016/j.psyneuen.2004.10.006. PMID   15694118. S2CID   39896938.
  18. ↑ Kraemer B, Noll T, Delsignore A, Milos G, Schnyder U, Hepp U (2006). "Finger length ratio (2D:4D) and dimensions of sexual orientation". Neuropsychobiology. 53 (4): 210–4. doi:10.1159/000094730. PMID   16874008. S2CID   201838.
  19. ↑ Wallien MS, Zucker KJ, Steensma TD, Cohen-Kettenis PT (August 2008). "2D:4D finger-length ratios in children and adults with gender identity disorder". Hormones and Behavior. 54 (3): 450–4. doi:10.1016/j.yhbeh.2008.05.002. PMID   18585715. S2CID   6324765.
  20. ↑ Grimbos T, Dawood K, Burriss RP, Zucker KJ, Puts DA (2010). "Sexual orientation and the second to fourth finger length ratio: a meta-analysis in men and women". Behav Neurosci. 124 (2): 278–287. doi:10.1037/a0018764. PMID   20364887.
  21. ↑ Breedlove, S.M (2010). "Organizational Hypothesis: Instances of the Fingerpost". Endocrinology. 151 (9): 4116–22. doi:10.1210/en.2010-0041. PMC   2940503 . PMID   20631003.
  22. ↑ Puts DA, Jordan CL, Breedlove SM (July 2006). "O brother, where art thou? The fraternal birth-order effect on male sexual orientation" (PDF). Proceedings of the National Academy of Sciences of the United States of America. 103 (28): 10531–2. Bibcode:2006PNAS..10310531P. doi: 10.1073/pnas.0604102103 . PMC   1502267 . PMID   16815969.
  23. ↑ S. Marc Breedlove (2015). Principles of Psychology. Oxford University Press. ISBN   978-0199329366
  24. ↑ S. Marc Breedlove, and Neil V. Watson (2013). Biological Psychology: An Introduction to Behavioral and Cognitive Neuroscience (7th Ed). Sinauer Associates. ISBN   978-0-87893-927-5
  25. ↑ Neil V. Watson and S. Marc Breedlove(2016). The Mind's Machine: Foundations of Brain and Behavior (2nd Ed). Sinauer Associates. ISBN   978-1-60535-276-3
  26. ↑ Jill B. Becker, S. Marc Breedlove, David Crews and Margaret M. McCarthy (2002). Behavioral Endocrinology, (2nd Ed). MIT Press. ISBN   978-0-262-52321-9
  27. ↑ Sakamoto, H., Matsuda, K., Zuloaga, D. G., Nishiura, N., Takanami, K., Jordan, C. L., & ... Kawata, M. (2009). Stress Affects a Gastrin-Releasing Peptide System in the Spinal Cord That Mediates Sexual Function: Implications for Psychogenic Erectile Dysfunction. PLoS One, 4(1), 1-7. doi:10.1371/journal.pone.0004276
  28. ↑ Sakamoto, H., Matsuda, K., Zuloaga, D. G., Hongu, H., Wada, E., Wada, K., & ... Kawata, M. (2008). Sexually dimorphic gastrin releasing peptide system in the spinal cord controls male reproductive functions. Nature Neuroscience, 11(6), 634-636. doi:10.1038/nn.2126
  29. ↑ Morris, J. A., Jordan, C. L., & Breedlove, S. (2004). Sexual differentiation of the vertebrate nervous system. Nature Neuroscience, 7(10), 1034-1039. doi:10.1038/nn1325
  30. ↑ Gobrogge, K. L., Perkins, P. S., Baker, J. H., Balcer, K. D., Marc Breedlove, S. S., & Klump, K. L. (2007). Homosexual Mating Preferences from an Evolutionary Perspective: Sexual Selection Theory Revisited. Archives Of Sexual Behavior, 36(5), 717-723. doi:10.1007/s10508-007-9216-x

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