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84 Cards in this Set

  • Front
  • Back

testosterone

masculinize fetus --> make it more male-like


defeminize fetus --> make it less female-like

LH and FSH

stimulation of ovulation in females


spermatogenesis in males

organization effects (hormone effects)

- structural


- prenatal / sensitive period


- PERMANANT / irreversible


- masculinization / defeminization

activational effects (hormone effect)

- act on existing structure / after organi differntiation


- no sensitive period


- temporary / irreversible --> you can undo the effect

sexual dimorphism

differences between males and females




- anatomical


- physiological


- behavioral


- cognitive




- qualitative


- quantitative

No Y chromosome

go to default sex = female

gonad

- undifferentiated until 6 weeks


- contains gonad


- both wolffian duct, mullerian duct

gonad with Y chromosome

turn into testis

gonad without Y chromosome

turn into ovary

SRY

on y chromosome


--> initiate sexual differentiation process

When SRY expressed

1) secretion of hormones: AMH and testosterone

2) AMH --> regression of Mullerian ducts


3) testosterone --> induces wolffian ducts to form epididymis, vas deferens, and seminal vesicles

testosterone

masculinization


--> induces wolffian ducts to form epididymis, vas deferens, and seminal vesicles


--> internal sex organ

AMH

defeminization


--> causes mullerian ducts to regress


--> internal sex organ

When no SRY is expressed

1) no AMH and no T


2) no AMH --> mullerian ducts form fallopian tubes, uterus, and inner vagina


3) no Testosterone -->

5 alpha reductase

converts testosterone to DHT

DHT

forms male external organ


--> induces skin to form scrotum, tubercles to form penis

No DHT

form female external organ


--> skin form labia and outer vagina, tubercle forms clitoris

differentiation of brain

dependent on fetal androgens


1) masculinization: induction of male characteristics --> estradiol


2) defeminization: suppression of female characteristics

testosterone effects on male-typical behavior

require both organizational and activational effect


1) organization effect: injecting testosterone before day 10


2) activational effect: injecting testosterone in adulthood

prenatal exposure and masculinization

higher prenatal exposure (more males around) --> more prenatal estrogen --> more male-like behaviors

aromatase

converts testosterone to estradiol

alpha-fetoprotein (a-FP)

binds to extracellular estradiol and prevents entry into cell


--> reason why females are not masculinized

aromatization hypothesis

1) testosterone from testes enters cell


2) aromatase converts testosterone to estodial


3) affects gene expression




--> extracellular estrogen bound by a-FP and can't enter into cells

sexually dimorphic nucleus (SDN)

larger in male than female


testosterone determines the size of SDN

mPOA

SDN (sexually dimorphic nucleus) in male

VMH

SDN (sexually dimorphic nucleus) in female

sex assignment

1) form of external genitals

2) social factors - reaction of others




ex) putting pink cloths and bow on new born female baby



early gender identity

1) organization of nervous system


2) social factors, further reaction




3-4 years

puberty

sex steroids have activational effect

adult gender identity

1) both steroid dependent and independent


2) change in body and brain with influence of pubertal hormones


3) social factors

androgen insensitiy

- XY


- No androgen receptors - 5a-DHT doesn't do anything for you


- still have testes (still have testosterone)


- wolffian duct


- no external male sex organ




- female @ birth


- female @ puberty


- gender identity: female

5a-reductase deficiency

- XY


- no enzyme


- still have testes (still have testosterone)


- wolffian duct


- no external male sex organ




- female @ birth


- variable @ puberty


- gender identity: either

congenital adrenal hyperplasia

- XX


- no enzyme needed for adrenals


- ovaries


- mullerian




- variable @ birth


- variable @ puberty


- gender identity: female with masculine tendencies

male development requires...

testosterone secreted from the fetal testes during a sensitive period of development

why study sexual reproductive behavior
1) most species reproduce sexually

2) important for reproductive success


3) highly conserved


4) modulated by steroid hormones - neural circuit can be easily identified


5) tied to motivation and reward system

purpose of reproductive behavior

1) propagation of parental genes


2) maximize survival of offspring

advantage of sexual reproduction

genetic variability

why sexual reproduction in stable environment?

higher chance for offspring to survive (fewer predator, food availability)

paradox of sexual reproduction

- why recombination if the goal is to pass your gene?


- to evade parasite that track a host speices

morphology can explain differences in sex role (T/F)

false: morphology alone can't fully explain differences in sex roles

Robert Trivers

an investment in an offspring which decreases your chance of investing in other future offspring


- female invest more --> choosy

variation in the competition of mates can occur because of...

1) differences in parental investment (Robert Trivers)


2) operational sex ratio

operational sex ratio

the ratio of sexually receptive males to females at any given time. usually male biased




ex) a lot of pollen - male biased; less pollen - female biased

sexual selection

- different from natural selection


- maximize reproductive success, not necessarily individual survival success




- intersexual/intrasexual selection




ex) male peacocks will be easily spotted by predators

dominance hierarchy

- killing your own kind to have reproductive success

Coolidge effect

- certain animals quickly rejuvenated when they have access to a new female for copulation




- multiple partners

birds - monogamous or promiscuous?

mostly monogamous

mammals - monogamous or promiscuous?

mostly promiscuous

Neural control in reproductive behaviors

1) sensory control - arousal


2) cortical input


3) spinal cord - performance


4) autonomic nervous system - performance of reproductive behavior


5) limbic system

Autonomic nervous system in reproductive behavior

- performance of reproductive behavior


1) parasympathetic: "point" --> erection


2) sympathetic: "shoot" --> ejaculation, muscular contraction

limbic system in reproductive behavior

- reward and motivation


1) dopaminergic


2) mesolimbic

pheromonal control

- outside of body to affect other individual


- VNO receptor: separate olfactory organ for pheromone


- projects to accessory olfactory bulb

Lordosis

- happens only one day out of 4 day cycle


- hormonal and physical stimulation


- estrogen and progesterone

male reproductive behavior

1) testosterone is required


2) dosage doesn't matter - as long as it is there


--> testosterone puts the right state, but directly causing the behavior

environment effects on reproductive behavior

1) pheromone - to synchronize cycles


2) insufficient energy - shuts off pulse generator, reducing sexual behavior


3) stress - inhibit pulse generator


4) seasonal control


5) effects of plastics and pesticides


--> BPA can mimic estrogen - bad for pregnancy

receptivity

willingness to be mounted


- hormonally prime


- rodents show lordosis posture

proceptive behavior

- solicitation

ex) female mice hop and dart, "ear wiggling" to attract males


pacing

- females maximize timing of intromission to maximize progesterone by pacing


- high progesterone increases the number of offspring

estradiol vs. progesteron

1) differential time courses


2) estradiol alone produces receptivity


3) estrogen induces progestin receptors


4) estrogen and progesterone initially maximize lordosis and produces proceptive behavior


5) biphasic effect of progesterone (sequential inhibition)

what does estrogen do to the brain?

1) changes gene expression


2) changes neural activity/neural connectivity


--> neuroplasticity

estrogen and mating behavior

1) ovariectomy - reduce sexual behavior


2) hormone replacement - restores sexual behavior


3) hormone fluctuation --> behavior


4) transgenic knockout of hormone receptors --> inhibition of sexual behavior

estrogen and neural pathway

VMH --> PAG --> MRF --> spinal cord --> motor neuron --> lordosis

estrogen and neural connectivity

alters connectivity - specifically dendritic spines

conditional mating strategies

individual can change its mating tactic according to the conditions it confronts


ex) horseshoe crabs, scarab beetles, scorpionfly

sperm competition

- male-male competition


- prevent other males sperm from fertilizing female's egg

mate guarding

prevent other males from gaining access to females


ex) whale - male inject a plug into female's vagina, blocking other males sperms

females in sperm competition

females put a plug on a male --> can't ejaculate

chase-away selection

exploitative of preexisting sensory biases


ex) female crabs prefer males with long large claws that they can't do anything with


- no benefit to the female

MPOA (medial preoptic area)

- SDN (sexually dimorphic neurons)


- fires when by sexually stimulating smells (estrous rat urine) only in presence of testosterone


- no testosterone --> no neural activity

Key neural circuit

Olfactory bulb (OB) --> MeA --> BST ---> MPOA

peripheral sensory information circuit

CTF (central tegmental field) --> MeA --> MPOA

two outputs from MPOA

1) ventral tagmental area (VTA) --> reward circuitry


2) brain stem --> motor output

Which brain region in quail is analogous to MPOA in rats

POM

DA and Opioid in sexual excitement

- Opioid activity in VTA


- DA activity in N Acc

DA and Opioid in preparatory behavior

- increased DA activity in N Acc --> appetitive behavior

DA and Opioid in intromissions

- sustained DA activity in N Acc and POA


--> consummatory behavior


- anticipation and preparation

DA and Opioid in post-ejaculatory interval

- increased opioid activity in POA


- inhibition of DA activity in N Acc


DA and MPOA

1) somatomotor - male typical behavior


2) appetitive behavior - reward, reinforcement


3) genital responses - erection and ejaculation

DA and Nigrostriatal

- male typical behavior - motor response

DA and Mesolimbic

- appetitive behavior


- reward, reinforcing behavior

APO

- apomorphine: non-selective DA receptor agonist

APO experiments

1) ER-alpha knockout mice - low male sexual behavior --> APO (DA) reinstates the sexual behavior


2) Long-term castrated rats --> systemic APO restores copulation; APO microinjections into mPOA increases the number of mounts


3) quails --> ICV injection of APO or DA inhibits male sexual behavior