Sex: Evolutionary, Hormonal, and Neural Bases
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Questions and Answers

What behavior do female rats display to indicate they are receptive to mating?

  • Singing
  • Nesting
  • Ear-wiggling (correct)
  • Ejaculation

    • What is necessary for the brain to release hormones that support pregnancy in rats?

  • External fertilization
  • Quitting copulatory behavior
  • Single intromission
  • Multiple intromissions (correct)

    • What does the Coolidge effect describe?

  • Increased parental behavior after mating
  • Variations in postcopulatory behavior
  • The faster resumption of mating with a different partner (correct)
  • The quick resumption of mating with the same partner

    • What is a characteristic of the copulatory lock observed in some species?

    <p>The male's penis temporarily swells</p> Signup and view all the answers

    Where does internal fertilization take place?

    <p>Inside the female’s body</p> Signup and view all the answers

    What behavior might occur after copulation in various species?

    <p>Nurturing or parental behaviors</p> Signup and view all the answers

    What behavior do male rats exhibit as part of their mating ritual?

    <p>Building nests</p> Signup and view all the answers

    What was the primary belief of Dr. John Money regarding gender identity?

    <p>It is primarily determined by social learning in childhood.</p> Signup and view all the answers

    What is required for the masculinization of external genitals?

    <p>Conversion of testosterone to dihydrotestosterone</p> Signup and view all the answers

    What significant event affected Bruce Reimer's early life?

    <p>His circumcision was botched, leading to a loss of his penis.</p> Signup and view all the answers

    What was one outcome of the Reimer case on the scientific community's perspective?

    <p>It fostered skepticism about effective treatments for gender assignment in infants.</p> Signup and view all the answers

    What happens in the absence of 5-alpha reductase?

    <p>Masculinization of external genitals does not occur</p> Signup and view all the answers

    Which of the following describes appetitive behaviors in reproductive behavior?

    <p>Establishing, maintaining, or promoting sexual interaction</p> Signup and view all the answers

    What condition was discovered in Caster Semenya?

    <p>5-alpha reductase deficiency.</p> Signup and view all the answers

    Which stage of reproductive behavior follows sexual attraction?

    <p>Appetitive behavior</p> Signup and view all the answers

    What notable characteristic did Caster Semenya possess regarding her chromosomes?

    <p>XY chromosomes.</p> Signup and view all the answers

    How did Brenda Reimer's experience reflect on her social treatment during childhood?

    <p>She was often bullied and teased, which influenced her behavior.</p> Signup and view all the answers

    What factor aids in sexual attraction among species?

    <p>Learned associations and physiological readiness</p> Signup and view all the answers

    Which of the following statements best encapsulates the complexity of sex and gender?

    <p>Both biological and psychological influences play a role in gender identity.</p> Signup and view all the answers

    What action did David Reimer take at age 14 that marked a significant shift in his gender identity?

    <p>Decided to live as a man.</p> Signup and view all the answers

    Which factor is crucial but not entirely determinative of gender identity, according to recent perspectives?

    <p>Hormonal influences during early life.</p> Signup and view all the answers

    Why is there significant reluctance to study the biological aspects of sex and gender?

    <p>Limited funding and interest in the topic.</p> Signup and view all the answers

    What role do pheromones primarily play in reproductive behavior?

    <p>They guide reproductive behavior in many species.</p> Signup and view all the answers

    What is the effect of castration on a male rat?

    <p>Decreases interest in mating behavior</p> Signup and view all the answers

    What is the significance of estrogen in female rats?

    <p>It is necessary for the lordosis response</p> Signup and view all the answers

    How does the amount of testosterone influence the copulatory score in guinea pigs?

    <p>There is a specific threshold of testosterone required</p> Signup and view all the answers

    What role does progesterone play in the reproductive behavior of female rats?

    <p>It increases proceptive and receptive behavior</p> Signup and view all the answers

    What is the function of the ventromedial hypothalamus (VMH) in female rats?

    <p>Regulates the lordosis response</p> Signup and view all the answers

    Which hormone is essential in making a female rat proceptive and receptive when ovaries are absent?

    <p>A combination of estrogen and progesterone</p> Signup and view all the answers

    What happens to the dendritic trees of neurons in the VMH when estrogen levels increase?

    <p>They increase in size</p> Signup and view all the answers

    How does the VMH communicate with other areas of the brain related to reproductive behavior?

    <p>It utilizes a pathway through the periaqueductal gray to the medullary reticular formation</p> Signup and view all the answers

    What role does the medial preoptic area (mPOA) play in male rats?

    <p>It coordinates male copulatory behavior.</p> Signup and view all the answers

    How does the paragigantocellular nucleus (PGN) influence male erection responses?

    <p>It normally inhibits the erection response.</p> Signup and view all the answers

    Which structure detects pheromones that activate male arousal?

    <p>Vomeronasal organ (VMO)</p> Signup and view all the answers

    What is a characteristic difference in sexual response between men and women?

    <p>Men tend to have a refractory phase following orgasm.</p> Signup and view all the answers

    Which phase involves increased blood flow to the vagina and production of lubricating fluid?

    <p>Excitement</p> Signup and view all the answers

    What is indicated by the interplay of hormonal stages, neural systems, and sensory information in reproduction?

    <p>The complexity of reproductive behaviors.</p> Signup and view all the answers

    What defines the hormonal and pheromonal influence on sexual behavior?

    <p>They are essential for determining sexual behavior.</p> Signup and view all the answers

    What distinct feature characterizes human sexual behavior compared to other species?

    <p>High variability and subjective reactions.</p> Signup and view all the answers

    Which brain regions are activated in men when they view unseen cues related to cocaine or sexual images?

    <p>Ventral striatum and amygdala</p> Signup and view all the answers

    What structure is responsible for the release of oxytocin during orgasm?

    <p>Hypothalamus</p> Signup and view all the answers

    What unique finding was observed in women with spinal cord injuries regarding orgasm?

    <p>They can still experience orgasms despite sensory information blockage.</p> Signup and view all the answers

    What is suggested about the difference in sex drives between males and females?

    <p>Males have a stronger sex drive than females on average.</p> Signup and view all the answers

    What complicates the identification of differences in sexual behavior between sexes?

    <p>Diverse cultural factors and socialization influences.</p> Signup and view all the answers

    What trend has been observed regarding the differences within sexes versus between sexes?

    <p>Differences within sexes are larger than those between sexes.</p> Signup and view all the answers

    What potential factor influences women's selectivity in choosing potential romantic partners?

    <p>Socialization and cultural influences.</p> Signup and view all the answers

    What method is commonly used to study brain activation during orgasm?

    <p>Functional MRI (fMRI)</p> Signup and view all the answers

    Study Notes

    Sex: Evolutionary, Hormonal, and Neural Bases

    • Gender determination is complex and not fully understood.

    • Biological and social factors both play a role.

    • 1965 twin case study (Brian and Bruce/Brenda) highlighted the complexity and controversies surrounding gender.

    • Dr. John Money, a proponent of gender identity being primarily determined by social learning in childhood, encouraged the family to treat Brenda as a girl.

    • Brenda, despite being raised as a girl, experienced significant psychological distress related to her gender identity. Later in life, she lived as "David Reimer", underwent gender reassignment surgery and committed suicide at age 38.

    • This case led to skepticism about infant genital reconstructive surgery.

    • Gender and sex also relate strongly to athletic competition.

    • The case of Caster Semenya demonstrated the complexity of sex and gender, along with legal challenges.

    • Semenya has issues with 5-alpha reductase, which affected her external genitalia, leading to her being raised as a girl, and her strong identification as a woman.

    • Without the 5-alpha reductase, she would not have been masculinized, and her sex assigned at birth would have been female.

    • Hormones and neural pathways, including the ventromedial hypothalamic area (VMH) in female rats and the medial preoptic area (mPOA) in male rats are crucial in regulating reproductive behavior.

    • Vomeronasal organ (VMO) detects pheromones, activating male arousal.

    • The Brain regions- including the nucleus accumbens, amygdala, and insula- are involved during human sexual arousal.

    • The amygdala, cingulate cortex, and the nucleus accumbens regions in the brain, along with the hypothalamic areas responsible for oxytocin release, are involved during orgasm.

    • Spinal cord injury does not affect a woman's ability to experience orgasm in some cases.

    • Research on sexual behavior and differences between sexes are fraught with potential confounds and limitations that need considering.

    • The differences between sexes are often smaller than differences seen within the same sex.

    • Hormones and pheromones play a key role in determining sexual behaviors, in humans and other species.

    Sexual Behavior

    • Sexual behavior (especially in humans) exhibits high diversity.
    • Neural circuitry in the brain regulates reproductive behavior. Specific circuits are seen in rodents.
    • Pheromones may affect reproductive behaviors. Menstrual cycles of women living together may synchronize.

    Reproductive Behaviors: Four Stages

    • Reproductive behavior can be divided into four stages:

      • Sexual attraction
      • Appetitive behavior
      • Copulation
      • Postcopulatory behavior

    • Sexual attraction brings males and females together, can be synchronized physiologically(e.g., odors reflecting estrogen levels).

    • Appetitive behaviors include pre-mating activities. Examples include ear wiggling, sniffing, singing, and nest-building in the rat.

    • Copulation involves intromission and ejaculation of sperm.

    • Post-copulation behavior varies by species. Some species have a refractory period, also the importance of hormones and/or pheromones.

    Internal and External Fertilization

    • Internal fertilization takes place within the female body. Fusion results in a zygote.
    • External fertilization occurs outside the female body. (e.g., fish and frogs.)

    The Hallmark of Human Sexual Behavior: Diversity

    • Human sexual behavior varies significantly from other species.
    • Humans report subjective sexual experiences, such as orgasm.
    • The four phases of response are excitement, plateau, orgasm and resolution.
    • Women often have more variety in their sexual responses.
    • Men, unlike women, experience a refractory phase following orgasm.
    • Orgasm in humans involves activity in various brain structures or regions.
    • Hormonal activity within the estrous/ovulatory cycle in female rats is important to reproductive behavior

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    Lecture 17 - Sex and Behavior PDF

    Description

    Explore the complex interplay of biological and social factors in gender determination through significant case studies, including that of Brenda/David Reimer and Caster Semenya. This quiz delves into the implications of gender identity, societal perceptions, and athletic competition, highlighting the need for nuanced understanding in these debates.

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