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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 |
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LH and FSH |
stimulation of ovulation in females spermatogenesis in males |
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organization effects (hormone effects) |
- structural - prenatal / sensitive period - PERMANANT / irreversible - masculinization / defeminization |
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activational effects (hormone effect) |
- act on existing structure / after organi differntiation - no sensitive period - temporary / irreversible --> you can undo the effect |
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sexual dimorphism |
differences between males and females - anatomical - physiological - behavioral - cognitive - qualitative - quantitative |
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No Y chromosome |
go to default sex = female |
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gonad |
- undifferentiated until 6 weeks - contains gonad - both wolffian duct, mullerian duct |
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gonad with Y chromosome |
turn into testis |
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gonad without Y chromosome |
turn into ovary |
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SRY |
on y chromosome --> initiate sexual differentiation process |
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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 |
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testosterone |
masculinization --> induces wolffian ducts to form epididymis, vas deferens, and seminal vesicles --> internal sex organ |
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AMH |
defeminization --> causes mullerian ducts to regress --> internal sex organ |
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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 --> |
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5 alpha reductase |
converts testosterone to DHT |
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DHT |
forms male external organ --> induces skin to form scrotum, tubercles to form penis |
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No DHT |
form female external organ --> skin form labia and outer vagina, tubercle forms clitoris |
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differentiation of brain |
dependent on fetal androgens 1) masculinization: induction of male characteristics --> estradiol 2) defeminization: suppression of female characteristics |
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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 |
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prenatal exposure and masculinization |
higher prenatal exposure (more males around) --> more prenatal estrogen --> more male-like behaviors |
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aromatase |
converts testosterone to estradiol |
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alpha-fetoprotein (a-FP) |
binds to extracellular estradiol and prevents entry into cell --> reason why females are not masculinized |
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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 |
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sexually dimorphic nucleus (SDN) |
larger in male than female testosterone determines the size of SDN |
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mPOA |
SDN (sexually dimorphic nucleus) in male |
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VMH |
SDN (sexually dimorphic nucleus) in female |
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sex assignment |
1) form of external genitals
2) social factors - reaction of others ex) putting pink cloths and bow on new born female baby |
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early gender identity |
1) organization of nervous system 2) social factors, further reaction 3-4 years |
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puberty |
sex steroids have activational effect |
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adult gender identity |
1) both steroid dependent and independent 2) change in body and brain with influence of pubertal hormones 3) social factors |
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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 |
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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 |
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congenital adrenal hyperplasia |
- XX - no enzyme needed for adrenals - ovaries - mullerian - variable @ birth - variable @ puberty - gender identity: female with masculine tendencies |
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male development requires... |
testosterone secreted from the fetal testes during a sensitive period of development |
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why study sexual reproductive behavior
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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 |
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purpose of reproductive behavior |
1) propagation of parental genes 2) maximize survival of offspring |
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advantage of sexual reproduction |
genetic variability |
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why sexual reproduction in stable environment? |
higher chance for offspring to survive (fewer predator, food availability) |
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paradox of sexual reproduction |
- why recombination if the goal is to pass your gene? - to evade parasite that track a host speices |
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morphology can explain differences in sex role (T/F) |
false: morphology alone can't fully explain differences in sex roles |
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Robert Trivers |
an investment in an offspring which decreases your chance of investing in other future offspring - female invest more --> choosy |
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variation in the competition of mates can occur because of... |
1) differences in parental investment (Robert Trivers) 2) operational sex ratio |
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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 |
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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 |
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dominance hierarchy |
- killing your own kind to have reproductive success |
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Coolidge effect |
- certain animals quickly rejuvenated when they have access to a new female for copulation - multiple partners |
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birds - monogamous or promiscuous? |
mostly monogamous |
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mammals - monogamous or promiscuous? |
mostly promiscuous
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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 |
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Autonomic nervous system in reproductive behavior |
- performance of reproductive behavior 1) parasympathetic: "point" --> erection 2) sympathetic: "shoot" --> ejaculation, muscular contraction |
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limbic system in reproductive behavior |
- reward and motivation 1) dopaminergic 2) mesolimbic |
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pheromonal control |
- outside of body to affect other individual - VNO receptor: separate olfactory organ for pheromone - projects to accessory olfactory bulb |
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Lordosis |
- happens only one day out of 4 day cycle - hormonal and physical stimulation - estrogen and progesterone |
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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 |
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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 |
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receptivity |
willingness to be mounted - hormonally prime - rodents show lordosis posture |
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proceptive behavior |
- solicitation
ex) female mice hop and dart, "ear wiggling" to attract males |
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pacing |
- females maximize timing of intromission to maximize progesterone by pacing - high progesterone increases the number of offspring |
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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) |
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what does estrogen do to the brain? |
1) changes gene expression 2) changes neural activity/neural connectivity --> neuroplasticity |
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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 |
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estrogen and neural pathway |
VMH --> PAG --> MRF --> spinal cord --> motor neuron --> lordosis |
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estrogen and neural connectivity |
alters connectivity - specifically dendritic spines |
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conditional mating strategies |
individual can change its mating tactic according to the conditions it confronts ex) horseshoe crabs, scarab beetles, scorpionfly |
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sperm competition |
- male-male competition - prevent other males sperm from fertilizing female's egg |
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mate guarding |
prevent other males from gaining access to females ex) whale - male inject a plug into female's vagina, blocking other males sperms |
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females in sperm competition |
females put a plug on a male --> can't ejaculate |
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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 |
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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 |
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Key neural circuit |
Olfactory bulb (OB) --> MeA --> BST ---> MPOA |
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peripheral sensory information circuit |
CTF (central tegmental field) --> MeA --> MPOA |
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two outputs from MPOA |
1) ventral tagmental area (VTA) --> reward circuitry 2) brain stem --> motor output |
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Which brain region in quail is analogous to MPOA in rats |
POM |
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DA and Opioid in sexual excitement |
- Opioid activity in VTA - DA activity in N Acc |
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DA and Opioid in preparatory behavior |
- increased DA activity in N Acc --> appetitive behavior |
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DA and Opioid in intromissions |
- sustained DA activity in N Acc and POA --> consummatory behavior - anticipation and preparation |
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DA and Opioid in post-ejaculatory interval |
- increased opioid activity in POA - inhibition of DA activity in N Acc |
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DA and MPOA |
1) somatomotor - male typical behavior 2) appetitive behavior - reward, reinforcement 3) genital responses - erection and ejaculation |
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DA and Nigrostriatal |
- male typical behavior - motor response |
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DA and Mesolimbic |
- appetitive behavior - reward, reinforcing behavior |
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APO |
- apomorphine: non-selective DA receptor agonist |
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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 |
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