Reproductive Behavior

Question 1

compare and contrast asexual and sexual reproduction.

Answer 1

Asexual reproduction in some animals (parthenogenisis)
All eggs genetically identical to mother
Came from sexual reproduction but these animals lost the ability to sexually reproduce
Vast majority of vertebrates sexually reproduce
Sexual reproduction produces more genetic variation
In hopes that one will survive better

Question 2

why are female gametes larger than male gamete?

Answer 2

Females gametes/ eggs carry the organelles for the reproduction, so larger gamete, limited by number gametes
Sperm generally carries DNA, have flagellum
Male gametes are smaller and designed for motility to find the eggs, smaller than female gametes, limited in number of mates.

Question 3

precursors to female and male internal structures?

Answer 3

Mullerian ducts are precursors to female internal structures

Wolffian ducts are precursors to male internal structures

Question 4

what causes differentiation into male genitals?

Answer 4

Gene on the male’s Y chromosome the SRY gene (sex determining region on the Y chromosome causes those differentiating gonads to develop into testes, the sperm producing organs
Testes produce androgens (hormones more abundant in males) and increases the growth of testes which would then produce more androgens
Androgens cause wolffian ducts to develop into seminal vesicles (stores semen) and the vas deferens (ducts from testes to penis)
Testes produce mullerian inhibiting hormone (MIF) that causes mullerian ducts to degenerate
Male testes produce more androgens than estrogens (hormone abundant in females)

Question 5

what causes differentiation in external genitals?

Answer 5

In mammals differentiation of external genitals depends mainly on T
High levels of T causes external genitals to develop male pattern and low levels leads to a female pattern
First trimester is the human sensitive period for genital formation
Male developing testes secrete testosterone , certain enzymes convert it into dihydrotestosterone - very effective at promoting penis growth: if dihydrotestosterone levels is high enough the tiny genital tubercle grows and develops into a penis but if levels are low, the tubercle develops into a clitoris
Depending on levels of T and dihydrotestosterone , the embryo develops either a scrotum or labia

Question 6

what causes differentiation into female genitals?

Answer 6

do not have the SRY gene, their gonads develop into ovaries and their wolffian ducts degenerate
Ovaries do not produce MIH- females’ mullerian ducts develop and mature into oviducts, uterus, and upper vagina
Female ovaries produce more estrogens than androgens

Question 7

prominent androgens and estrogens

Answer 7

Prominent androgen =testosterone
Prominent estrogen = estradiol
have similar effects in some ways and opposing effects in others

Question 8

progesterone

Answer 8

Progesterone- another prominent female hormone- prepares uterus for implantation of a fertilized ovum and promotes the maintenance of pregnancy
Progesterone released by the corpus luteum in the ovary peaks a bit later -different from rodents; to create a good place for the egg to develop- progesterone stimulates uterine development

Question 9

genes and sex differences

Answer 9

Y and x chromosomes control some biological differences independently of hormones
Y chromosome has many sites that alter the expression of genes on other chromosomes
Genes on X and Y chromosomes produce effects beyond those that we can trace to androgens and estrogens

Question 10

sexual selection

Answer 10

genes that make an individual more appealing to the other sex will increase the probability of reproduction

Question 11

Male sexual behavior- dopamine mesocorticolimbic system

Answer 11

Appetitive (motivation)- sex drive, libido courtship
E.g. vocalizations, movement in search of mates
Consummatory- copulatory behavior
Sexual attraction is largely driven olfactory & auditory
Mounting (latency)
Intermount (interval)
Intromission (insertion of penis) number
Ejaculation (number)
Ultrasonic vocalizations esp after copulation and self grooming

Sensitive to Environmental context & testing paradigm

Question 12

testosterones effects on male sexual behavior

Answer 12

T is essential for male sexual arousal, and acts partly by increasing the sensitivity in the penis
Sex hormone bind to receptors that increase responses in parts of the hypothalamus, including the ventromedial nucleus, the medial preoptic area (MPOA) and the anterior hypothalamus
T primes the MPOA and several other brain regions to release dopamine
MPOA neurons release dopamine strongly during sexual arousal
Both men and women with high T levels are more likely than average to seek additional partners
Decreases in T levels generally decrease male sexual activity
Androgen do not “cause male sexual behavior, but rather androgens change the probability that male sexual behavior will be elicited within a particular context- like a dimmer not a switch

Question 13

dopamine effects on male sexual behavior

Answer 13

in moderate concentrations, dopamine stimulates mostly type D1 and D5 receptors which facilitate erection of the penis in the male and sexually receptive postures in the female
in higher concentrations of dopamine, dopamine stimulates type D2 receptors which lead to orgasm
dopamine stimulates sexual activity, the neurotransmitter serotonin inhibits it by blocking dopamine release.
many antidepressant drugs increase serotonin activity, and one of their side effects is decreased sexual arousal

Question 14

inability to have an erection is likely due to

Answer 14

Low T is not usual basis for impotence, the inability to have an erection (usually caused by impaired blood circulation, especially in older men

Question 15

how does viagra work

Answer 15

The drug sildenafil (Viagra) increases male sexual ability by prolonging the effects of nitric oxide which increases blood flow to the penis and blood flow to the brain

Question 16

activational effects

Answer 16

Activational effects- after reproductive maturity, transient modification behavior, usually after puberty (day 40-50 in rats)- can be both genomic and non-genomic
Genomic effects are mediated by effects in transcription and tend to be longer lasting
Non-genomic effects are quite rapid and do not involve transcription and translation and can involve second messengers
Temporary effects continuing only while a hormone is present or shortly beyond
Current hormones influence the degree of sex drive
Bursts of hormone during pregnancy produces temporary effects on emotional arousal , aggressive behavior and learning and cognition
Organizing effects set the stage for activating effects

Question 17

organizational effects

Answer 17

Organizational effects - early development, long lasting structural effects and often epigenetic in nature, small increase in testosterone after birth to masculinization the brain
Hormones injected early in life have much stronger effects
Sensitive period in early development (e.g. first trimester of pregnancy for humans, sex hormones determine whethter the body develops into female or male genitals and alters certain aspect of brain development)
Organizational effects during puberty: breast development on women, facial hair and penis growth in males, changes in voice, and male-female differences in the anatomy of certain parts of the hypothalamus; some of the differences in brain anatomy between males and females increases during this time
Organizing effects set up the female hypothalamus such that later hormones can activate the menstrual cycle

Question 18

distinction between organizational and activational effects

Answer 18

Distinction between organizing and activating effects is not absolute, hormones often produce a combination of temporary and longer-lasting effects

Question 19

how can we test the effects of T and other hormones

Answer 19

Remove testes, give back testosterone
Slow release implants: Silastic capsule-silicon implants- made of silicon, tubing filled with crystalline testosterone and sealed; the longer the tube, the more testosterone- way of administering testosterone without injection and lasts for weeks in the system for longer and less stressful effects.
ICB administration- brain or part of exposed to androgen, received in the ventricle

Question 20

Testosterone

Answer 20

Testosterone crosses BBB quite easily and effects all around body as it is a small lipophilic molecule

Question 21

aromatase

Answer 21

Aromatization in specific brain regions is crucial
Important for male sexual behavior which is counter-intuitive since it creates estrogens
Converts androgen (testosterone) into estrogen (estradiol) the estradiol then binds to estrogen receptors which has effects on gene expression (genomic effects)

Question 22

in castrated male rats, what did T and E2 administration, and aromatase inhibitor (block activity of enzyme) show?

Answer 22

systemic T, androstenedione-weak androgen precursor to testosterone (also restoration to male sexual behavior), and E2 (estradiol) restore appetitive and consummatory behaviors
T+ aromatase inhibitor (block activity of enzyme)
Reduction in male sexual behavior

Question 23

how do you increase amount of aromatase, inhibit aromatase in the brain, and locate it?

Answer 23

Increase amount of aromatase with viral vector to over express aromatase
inhibit neurons containing aromatase with optogenetics
Located aromatase in brain- in situ hybridization- mRNA
Look for aromatase protein using immunohistochemistry
Take tissue and homogenize i test tube and add radiolabeled testosterone and see active aromatase that produces radiolabeled estradiol

Question 24

how are rats masculinized?

Answer 24

In male rats, testosterone begins masculinizing the external genitals during the last several days of pregnancy and first few days after birth and continues masculinizing at declining rate for the next month

Question 25

female rats injected with T

Answer 25

Female rat is injected with testosterone during last few days of pregnancy or after birth is partly masculinized, just as if her own body had produced the T: exhibiting larger cliterous and shows male sexual behavior and thus, early T promotes male patterns and inhibits female patterns

Question 26

male rats given estrogen

Answer 26

Injecting male with estrogens produces little effects on his external anatomy but if he lacks androgen receptors, he develops female typical pattern of anatomy and behavior

Question 27

cause of low androgen receptors

Answer 27

could be an outcome of castration, genetic deficiency of an androgen receptors, or prenatal exposure to drugs that interfere with androgen response (e.g. alcohol, weed, haloperidol- antipsychotic drug, phthalates- common in manufactured products and cocaine)- amount of interference depends on type of drug and amount of exposure, even aspirin interferes with male pattern of development

Question 28

effects of phthalates

Answer 28

Phthalates inhibit T production: sons of women with high phthalate levels showed less interest in typical boys toys and more interest in typical girls toys and suggests that prenatal hormones especially T alter the brain in many ways that influence differences between boys and girls activities and interest

Question 29

prostate glands

Answer 29

gland that produces a fluid accompanies and protects sperm cells when ejaculated during intercourse

Question 30

females lacking estradiol

Answer 30

Female that lack estradiol during early life develops rather normal female external anatomy but does not develop normal sexual behavior or normal internal anatomy; even if she is given estradiol injections , she will show little sexual response to anyone; estradiol is essential for female development

Question 31

sexual differentiation in the brain for rats in terms of estrodiol and T

Answer 31

Rats Early development (shortly before or after birth) the blood contains high levels of alpha-fetoprotein that binds to circulating estradiol and prevents from entering cells; Female brain is not exposed to estradiol at this time male T is free to enter the hypothalamus where the enzyme converts much of it to estradiol, and exerts masculinizing effects at this time For early developing rodents, T is a way of getting estradiol to the hypothalamus

Question 32

prolactin

Answer 32

Mammalian mother delivers her babies, she increases her secretion of oxytocin and prolactin which promote milk production and several aspects of maternal behavior Prolactin inhibits sensitivity to leptin, promoting feeding Man's testosterone level declines and his prolactin level increases when a baby is born but only if the man has a close relationship with the mother and only in societies where men contribute to infant care Men with lower T levels and higher prolactin levels spend more time playing with and caring for their children but these are correlational data

Question 33

vassopressin

Answer 33

Vasopressin synthesized by the hypothalamus and secreted by the posterior pituitary gland Vasopressin is important for social behavior in many species partly by facilitating olfactory recognition of other individuals Males with highest vasopressin levels show highest levels of sexual fidelity to their mates Low vasopressin levels, mate and then ignore the female and her young Men with genes for less active forms of vasopressin receptor are less likely to marry, more likely to have marital conflicts or threat of divorce- less likely to show altruistic behavior Women with the less active form of the receptor were less attentive to their young children Female rats ignore or avoid baby rats mainly because of aversion of the odor

Question 34

animals with plenty of T, if aromatase is inhibited

Answer 34

there is a gradual decrease in appetitive sexual behavior

Question 35

Non-genomic (rapid) effects of estrogens on male appetitive sexual behavior Single s.c. injection of vehicle control ( C) or vorozole (VOR) an aromatase inhibitor Half of VOR- treated subjects received E2 concurrently After 30 min (shorter than previous test), measured time at window

Answer 35

Vorozole rapidly decreases time at window With estradiol- more time at window, if anything higher than control, possibly because estradiol dose was higher Suggesting estradiol as non-genomic effects

Question 36

Other ways to test non-genomic effects

Answer 36

Give estradiol that is conjugated (connected) to a large protein and thus cannot cross cell and cannot bind to the receptors of the nucleus but could bind to receptor at the plasma membrane- and thus still have a rapid effect Other studies have given an inhibitor of transcription (low dose for short amount of time to not kill the cell) and shown that estrogens can have an effect on behavior or some effect on brain even with the presence of inhibitor

Question 37

autoradiography

Answer 37

using radiolabeled hormones (testosterone or estradiol), and injecting into animals that has been gonadectomized (removing endogenous hormones) doesn’t compete with regular production of testosterone. The tissue is then sectioned and applied to autoradiographic film and develop the film to expose where there is radioactivity. Not as sensitive as immunohistochemistry In Situ Hybridization or PCR to look for mRNA for the receptors

Question 38

Social behavior network

Answer 38

Pattern of activation is important for various behaviors Important for all kinds of behavior regulated by network Interconnected parts of the brain Cfos protein is expressed after some stimulus, indirect way of looking at neuronal activation

Question 39

Male rat had sex and they looked for cfos in the brain 90 mins later- animal killed

Answer 39

There was a lot of activation in the medial amygdala and preoptic area Less activation in the anterior hypothalamus which is more activated by aggressive behavior This is a way of mapping out neuronal activation, following different social behavior

Question 40

Circuit for male sexual behavior

Answer 40

mPOA- medial preoptic area, and medial amygdala that have a lot of aromatase and are part of the social behavior network- important for male reproductive behavior Ventral tegmental area and the midbrain and spinal cord Neurons in the spinal cord are important for erecting the penis and ejaculation, not so much in humans but there are androgens in the motor neurons Testosterone facilitates the release of dopamine in the mPOA and other areas which stimulates behavior

Question 41

hypogonadal men

Answer 41

men with low levels of testosterone- could be a problem in the hypothalamus, pituitary, testes

Question 42

how can T be measured in the plasma

Answer 42

immunoassay

Question 43

DHT

Answer 43

DHT can also reinstate sexual behaviors in hypogonadal men DHT does not get converted into estrogen DHT is longer lasting version of T DHT has little effect on sexual behavior in castrated rodents But has effect in humans

Question 44

effects of E2 on hypogonadal men

Answer 44

E2 is not effective in hypogonadal men in contrast to castrated rodents and quail where there is an effect Clear species differences

Question 45

estrous cycle

Answer 45

component of female rodent sexual behavior Estrous cycle- 4 days long- dark bar (lights off) Ovulate at night (progesterone levels peak just before ovulation) During behavioral estrus (showing receptive behavior also when estrogen levels peak) , highest levels of: Attractivity: to test, 2 females are tied on opposite chambers and male can go back and forth between chambers. Assess time male spends in each chamber or in the middle. Males are more attracted to females in behavioral estrus driven largely by olfaction

Question 46

proceptivity

Answer 46

Female initiation of copulation Sexual Motivation E.g., in female rats, willingness to cross electrified grid to mate with male, lever pressing for access to male In rats, hopping and darting, ear wiggling Female rhesus monkeys will press a lever (e.g. a ratio of 250 times) in order to gain access to a male monkey Operant conditioning Faster lever pressed, more motivation Time taken to complete lever pressing was shorter

Question 47

how to test proceptivity

Answer 47

Progressive Ratio Test: increases lever presses for door to open; at what point do they stop pressing the button, higher the break point, the more motivated for quantification

Question 48

receptivity

Answer 48

Responsiveness to male initiation E.g. lordosis/consummatory behavior lordosis - 4 point scale LQ= lordosis quotient (0 to 100%) - number of times female lordosis divided by number of times male mounts Lordosis is estrogen sensitive Ovariectomy (OVX) greatly reduces receptivity in rats In some primates, OVX females remain receptive (decreases by not that much) Estradiol promote lordosis behavior

Question 49

Social behavior network after sex for female rats after lordosis Pattern of of activity

Answer 49

Ventromedial hypothalamus | Midbrain ventrotecmental area with lots of dopaminergic neurons

Question 50

ERs in female animal brain

Answer 50

Autoradiography: E2 concentration cells in hypothalamic, limbic, and mesencephalic structures Animals are ovariectomized and injected with radiolabeled estradiol ERs in vlVMH (ventral lateral VMH) are critical for female sexual behavior

Question 51

vlVMH lesion? infuse estrogen receptor agonist? In ovariectomized animals, if infused estradiol specifically to vlVMH?

Answer 51

Lesion vlVMH- reduction in lordosis Infuse estrogen receptor antagonist- prominent reduction in lordosis In ovariectomized animals, if infused estradiol specifically to vlVMH- increases in lordosis

Question 52

Endocrine Regulation of Receptivity in female rodents

Answer 52

E2 + PROG sequentially is more effective in inducing lordossis than E2 alone; although estradiol works slowly In OVX rats sexual behavior can be restored by E2 followed by PROG treatment Mimics the estrous cycle Strong female sexual behavior In rats, PROG treatment is 2 days after E2 Testing is 4 hours after PROG

Question 53

brain responsiveness/sensitivity to progesterone

Answer 53

Progesterone receptors fluctuate throughout the cycle: appear then disappear Use track tracer; anterograde, to see connections between brain regions Lots of progesterone receptors in the VMH Estrogen affects neurons at the VMH and in the periaqueductal grey

Question 54

how does lordosis in rats occur?

Answer 54

Estrogen affects neurons at the VMH and in the periaqueductal grey VMH Regions then project these neurons in periaqueductal grey to the medulla then the spinal cord(important for lordosis posture)

Question 55

anterograde and retrograde tracers

Answer 55

Inject anterograde tracers in the VMH to see which regions it projects to; retrograde tracers in the periaqueductal grey, then we see cell bodies labelled in the VMH which confirms the connection

Question 56

menstrual cycle

Answer 56

hypothalamus and pituitary interact with the ovaries to produce the menstrual cycle, a periodic variation in hormones and fertility over the course of about 28 days After end of menstrual period, the anterior pituitary releases follicle-stimulating hormone (FSH) which promotes the growth of a follicle in the ovary Follicle nurtures the ovum (egg cell) and produces several types of estrogen including estradiol Towards middle of menstrual cycle, the follicle builds up more and more receptors to FSH so even though he actual concentration of FSH is decreasing , its effect on follicle increase The follicle produces increasing amounts of estradiol; increased release of estradiol causes increased release of FSH and a sudden surge of luteinizing hormone (LH) from the anterior pituitary FSH and LH combine to cause the follicle to release an ovum Remnant of the follicle release the hormone progesterone which prepares the uterus for implantation of a fertilized ovum Progesterone also inhibits further release of LH If pregnant, estradiol and progesterone levels continue to increase and if not pregnant, both hormones decline , the lining of the uterus is cast off (menstruation) and cycle begins again LH and FSH are hormones released by the anterior pituitary and peak right before ovulation to stimulate ovulation Estradiol also peaks at around ovulation

Question 57

Periovulatory period

Answer 57

time when ovulation occurs; when egg is released into the fallopian tubes Women’s estradiol levels peak sharply during the periovulatory period, days around the middle of the menstrual cycle when fertility is the highest Women not taking birth control pills initiate sexual activity more often during the periovulatory period than at other times of the month Unmarried women flirt with an appealing man more during this period than other times Women during the periovulatory period become more likely than usual to wear red or pink, colors that most men consider sexy

Question 58

sexual desire in women

Answer 58

Administering enough estradiol to return it to normal levels increases sexual desire Increasing testosterone can increase a women’s sexual desire but only if administered levels far beyond what a women would produce naturally Sexual desire correlated strongly with changes in levels of estradiol not T In female rats, a combination of estradiol and progesterone is the most effective combination for enhancing sexual behavior Estradiol increases the sensitivity of the pudendal nerve which transmits tactile stimulation front he vagina and the cervix to the brain

Question 59

Birth control pills

Answer 59

Birth control pills prevent pregnancy by interfering with the usual feedback cycle between the ovaries and pituitary Not always negative feedback, some cases positive feedback; the estradiol coming from the ovary stimulates the release of gonadotropins from the pituitary which then stimulates estradiol production- birth control pills prevent this Birth control pills can cross the blood brain barrier as these steroid hormones are lipophilic and binds to receptors wherever in the brain Alters ovulation and behavior

Question 60

combination pill

Answer 60

The combination-pill contains an estrogen and progestin Prevents the surge of FSH and LH (gonadotropins) that would release an ovum The estrogen-progesterone combination thickens the mucus of the cervix, making it harder for sperm to reach the egg, and prevents and ovum, if released from implanting in the uterus

Question 61

human attracitvity

Answer 61

Men prefer scent of ovulating women Some evidence that humans can detect these hormonal scents Got men to smell armpit of t-shirt of women at different points in cycle; asked to rate the smell

Question 62

Human Proceptivity

Answer 62

Testosterone levels in the blood are associated with proceptivity Cyclicity of behavior is gone with birth control pills There is a peak in initiation during ovulation Sexual interest peaks at the periovulatory period and influences behavior in many ways generally without the women’s conscious recognition of the effect

Question 63

Human receptivity

Answer 63

Studies suggest women are more sexually receptive during the periovulatory period (around the time estimating ovulation)- similar to rodent work, less likely to get pregnant

Question 64

difference between sex and gender differences

Answer 64

Differences that result from biological differences are generally referred to as sex differences Differences that result from people’s thoughts about themselves as male or female are generally referred to as gender differences

Question 65

hermaphrodites

Answer 65

Hermaphrodite has anatomy intermediate between male and female or show a mixture of male and female anatomies A true hermaphrodite has some testicular tissue and some ovarian tissue One way for this to happen is for a woman to release 2 ova each fertilized by a different sperm then fuse instead of becoming twins; if one had a XX chromosome and the other had a XY, the resulting child would have some XX cells and some XY cells True hermaphrodites are rare and some are fertile as either male or female but none are fertile as both

Question 66

intermediate appearance commonly due to

Answer 66

atypical hormone pattern A genetic male with low levels of T or a deficiency of T receptors may develop a female or intermediate appearance A genetic female who is exposed to more T than the average female can be partly masculinized

Question 67

congenital adrenal hyperplasia (CAH)

Answer 67

overdevelopment of of the adrenal gland from birth Ordinarily the adrenal gland has a negative feedback relationship with the pituitary gland as the pituitary secretes adrenocorticotropic hormone (ACTH) which stimulates the adrenal gland Cortisol, one of hormones from the adrenal gland, feeds back to decrease the release of ACTH. some people have a genetic limitation in their ability to produce cortisol; if the pituitary fails to receive much cortisol as a feedback signal, it continues secreting more ACTH causing the adrenal gland to secrete more and more of its other hormones including testosterone In genetic male, the extra T causes little effect Genetic females with this condition develop various degrees of masculinization of their external genitals (the ovaries and other internal organs are less affected)

Question 68

intersex

Answer 68

A person whose sexual development is intermediate Some are given surgery to alter their external genital appearance An estimated 1 in 100 children in US is born with some degree of gential ambiguity and 1 in 2000 has enough ambiguity to make its male or female status uncertain

Question 69

traits of girls with CAH

Answer 69

Girls with CAH played with boys toys more than most other girls did but less than the average for boys; when the children tested with parents, the CAH girls were intermediate between the other 2 groups Girls with CAH perform slightly better than most other girls do on spatial and mechanical skills, on which boys generally do better than girls A study of girls with CAH in adolescence found that on average their interests are intermediate between those of typical male and female adolescents Girls with CAH have a difficult sexual adjustment, especially if they were subjected to clitoris reduction surgery

Question 70

Testicular feminization

Answer 70

certain individuals with an XY chromosome pattern produce normal amounts of androgens including testosterone but the lack the receptor that enables those chemicals to activate genes in a cell’s nucleus Cells do not respond to androgens Smaller size penis to genitals like those of a typical female in which no one has any reason to suspect the person is anything other than female until puberty breasts develop and hips broaden but she does not menstruate because her body has internal testes instead of ovaries and a uterus; the vagina is short and leads to nothing but skin; pubic hair is sparse or absent because it depends on depends on androgens in females and males Psychologically she develops as a typical female

Question 71

Cloacal exstrophy

Answer 71

genetic males are born with a very small penis which is a defect of the pelvis development; despite their small penis, they have typical male levels of T in prenatal development Males with cloacal exstrophy who are reared as girls all develop typical male interests, many or most demand assignment as males and nearly all develop sexual interest towards women

Question 72

dihydrotestosterone

Answer 72

Dihydrotestosterone is more effective than T for masculinizing the external genitals

Question 73

Certain genetic males fail to produce 5-alpha- reductase 2

Answer 73

an enzyme that converts T to dihydrotestosterone These individuals appear to be female though have some swollen clitoris and somewhat lumpy labia They are considered girls and reared as a girl but their brains have been exposed to male levels of T during early development At puberty the T levels increase sharply and even without the conversion to dihydrotestosterone, the result is the growth of a penis and scrotum enough to be clearly male

Question 74

Sex differences in human Brain

Answer 74

Differences in the hypothalamus, cortical area, pituitary glands, parts of the spinal cord and elsewhere Female hypothalamus generate a cyclic pattern of hormone release whereas males release hormones more readily SCN bigger in women Estradiol acts by different routes in different parts of the hypothalamus

Question 75

VMH

Answer 75

In part of the ventromedial hypothalamus, estradiol activates an enzyme called PI3 kinase that increases the release of glutamate from presynaptic neurons, and causes postsynaptic neurons to increase their dendritic branching The ventromedial hypothalamus contributes to aggressive and sexual behavior and feeding

Question 76

In Arcuate nucleus and the anteroventral periventricular nucleus, estradiol increases ____ production, which acts on the astrocytes to decrease dendritic spines which results in shrinkage of these areas for males; remain large for females because low levels of___ in early in life

Answer 76

GABA, estradiol

Question 77

T acts on_____directly instead of by conversion to estradiol

Answer 77

hypothalamus

Question 78

Sex differences in play

Answer 78

Children who show the greatest pattern for boy typical activities at age 3 usually show the greatest amount of boy typical activities at age 13; same with females c Girls who had been exposed to higher levels of T in prenatal life showed slightly higher preference for boys toys

Question 79

Sexual Orientation in gay men

Answer 79

Most men discover their sexual orientation earlier in developments They do not “choose” Generally occurs later in women Biological predisposition might be stronger for men than women

Question 80

homosexual genetics

Answer 80

No single gene has been identified Some studies reported that homosexual men had higher incidence of homosexual men had higher incidence of homosexual relatives (uncles) on maternal side than paternal side Implications; X chromosome gene involved but no replications But other studies have not confirmed this pattern

Question 81

homosexual Early Hormonal influences

Answer 81

Sexual orientation is not correlated with adult hormone levels (testosterone, estradiol, etc) Adult homosexual men and women have hormone levels are similar to those of adult heterosexual men and women

Question 82

Youngs experiment on sexual behavior (mounting) with hormones Hypothesis: hormones in early development important for reproductive behavior in adulthood

Answer 82

Adult males respond to T manipulations Adult females do not respond to T manipulations and or overactomy- no mounting Lordosis Prenatal T treatment reduced lordosis in response to estradiol and progesterone in adulthood Prenatal T treatment increased mounting; strong role of hormones in development Natural increase in T in males in early development Early hormones in conjunctions with hormones in adulthood is very important for sexual behavior

Question 83

Prenatal stress- rats Random assignment of pregnant mothers Last week of pregnancy only Control or stress (2 hours of restraint per day in tube) No pain just psychologically painful Examined sexual behavior of offspring as adults

Answer 83

Daughters: no group differences in sexual behavior Sons: mounting in response to male and lordosis with female Stress could affect HPA axis and effect testosterone levels Early life influences seemed to be more affected for sons for later behavior Most males that were subjected to either prenatal stress or alcohol developed male sexual behavior in addition to these female sexual behaviors, but those that were subject to both alcohol and stress had decreased male sexual behaviors

Question 84

what happens to Mother’s immune system when pregnant

Answer 84

Mother’s immune system suppressed when pregnant so moms immune system does not attack the fetus

Question 85

why do Homosexual men have more older biological brothers regardless of number of other siblings

Answer 85

Key is how many previous times the mother gave birth to a son as the mothers’ immune system sometimes reacts against the protein in a son and then attacks the subsequent son enough to alter their development Later born homosexual men tend to be shorter on average Mother’s immune system might respond more strongly to a protein in the male fetus from Y chromosome Mom’s immune response may respond greater to males than female fetuses Has not been replicated

Question 86

prenatal stress on brain

Answer 86

Prenatal stress and alcohol may alter brain development through several routes Stress releases endorphins which antagonize the effects of T on the hypothalamus Stress also elevates levels of certain adrenal hormones (corticosterone in rats, cortisol in human) that decrease testosterone release Long term effects of either prenatal stress or alcohol include several changes in the structure of the nervous system, making the affected males anatomy closer to that of females Genetic or epigenetic factors contribute as well as prenatal environment and alter experiences

Question 87

sexual orientation and Brain Anatomy

Answer 87

the right hemisphere is a few percent larger in heterosexual males Heterosexual women and homosexual men have more widespread connections in the left amygdala compared to the right amygdala Heterosexual males, the right amygdala has more widespread connections connections and the size of hemispheres The anterior commissure is larger in heterosexual women than in heterosexual males, while in homosexual males the anterior commissure is at least as large as the heterosexual womens perhaps even slightly larger Smaller third interstitial nucleus of the anterior hypothalamus (INAH 3- a subdivision of a subdivision of the preoptic hypothalamus): generally more than twice as large in heterosexual men as in women. This area has more cells with androgen receptors in men

Question 88

__________ can change brain anatomy

Answer 88

Persistent behaviors

Question 89

INAH 3

Answer 89

(small area) is in human within POA - preoptic area, area thought to be involved in sexual behavior, part of social behavior network important in social behavior including sexual behavior Found that mean volume of INAH-3 was larger in heterosexual men than in heterosexual women or gay men who were about equal But there were a substantial amount of variation among individuals Nissl stain- post mortem tissue This study is correlational study

Question 90

critisms of LeVays INAH3 study

Answer 90

These structures are difficult to see in Nissl-stained sections- borders are not distinct All the gay men have AIDS which is a limitation as the difference may arise from AIDS rather than sexuality He measured region volume only, not cell number or gene expression etc. Inadequate sexual histories of subjects- made presumptions about sexuality of people

Question 91

``` mating systems define: polygyny polyandry social monogamy genetic monogamy ```

Answer 91

Polygny (male mates with multiple females) Polyandry (female mates with multiple males)- rarer, some bird species Monogamy (male-female pair) Social monogamy- live in pairs, although they might mate outside of the pair; many birds Genetic monogamy- mate strictly within the pair; some birds and fish Tested by observations, genetic testing of offsprings

Question 92

Prairie Voles

Answer 92

Long term pair bond; show monogamy Vasopressin- hormone released by the posterior pituitary; small (9amino amino acids) non-monogamous Males: higher expression in lateral septum (LS) - part of social behavior network Monogamous males: higher expression in ventral pallidum (VP)- different brain area that is ventral to the lateral septum In females; the oxytocin receptors are different rather than the vasopressin receptors Correlation between pattern of receptor of AVP and sexual behavior Increase V1aR in VP (ventral pallidum) of adult non-monogamous males meadow voles used viral vector to upregulate the amount of V1a : Shifts behavior- partner preference, does not make them monogamous in 3 chamber test Does not become monogamous But remembers the female mated with and prefers the previously mated female

Question 93

oxytocin

Answer 93

Pituitary hormone oxytocin is important for reproductive behavior: oxytocin stimulates contractions of the uterus during delivery of a baby and it stimulates the mammary gland to produce milk; promote maternal behavior, social approach, and pair bonding Sexual pleasure also releases oxytocin especially at orgasm a state of relaxation shortly after orgasm as a result of oxytocin release

Question 94

Viewing photos of your beloved activates the _____ and other areas important for memory and cognition What we call love combines motivation, emotions, memories, and cognition

Answer 94

hippocampus

Question 95

oxytocin administration

Answer 95

Oxytocin passes directly from the nasal cavity to the brain and exerts effects about half an hour later oxytocin did not increase attraction to everyone, but just to someone already loved Oxytocin enhanced man’s fidelity to his partner, decreasing his willingness to face the temptation of another attractive woman Oxytocin helps people who have trouble recognizing faces and people who can recognize faces but have trouble identifying their emotional expressions Oxytocin increases trust towards your in group members but could not increase, decrease, or have no effect on trust toward other people, depending on what you think of those people increases attention to important social cues