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Lecture 3

PSY395 lecture 3.docx

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University of Toronto Mississauga
Emis Akbari

PSY395 (3) Male Sexual Behavior Sexual behavior linked to rewards, motivation such as drinking when you’re thirsty Pleasurable systems converge – similar output – reproduction piggy backed on pleasurable systems 2 kinds of divisions - Mission of sex - Goal of sex Other forms of sexual behavior that has no reproductive end Why we engage in sex? Mutual anogenital sniffing- dogs- “doggie style” Rats – virgins do this more than experienced animals – not so long in duration Mount – failed intromission attempt –to gain access – chase and intromission – female runs away when the male rat mounts and ejaculates “Monkey Style” – primates do from rear but face to face as well- chimp front facing vagina – how sex is played out Human positions during sex are experientially determined – it’s about what you like in humans Population is very variable – as many sexual preferences as there are people Hormones are necessary but almost never sufficient How is the brain wired for sex? Why does everyone want to have sex – brain activity – sexual pleasure experiences – activates neurochemical system in our brain – bonding/intimacy Classical conditioning – associate those features with pleasure Male Sexual Behavior Sex-biology- genetic sex Sexual behavior – gametes brought together Sex drive- motivational force – how powerful that drug is Sexual arousal- sympathetic nervous system activated Sexual desire – craving, wanting Sexual inhibition post orgasm – don’t want more sex- period of satiety – aversed to certain parts of sex – avoiding environments that are not sexually arousing (secondary avoidance) Male Sexual Behavior – Two phases 1. Appetitive Phase – fighting with another male to gain access to a female – advertising behavior to have sex (anticipatory, preparatory) (similar brain areas, similar chemicals underlie these activities in both rats and humans) 2. Consummatory Behavior – actual copulation Post Ejaculatory Interval (PEI)- time between ejaculation and next copulatory bout For rats – if the male rat is with the same female rat –usually waiting period of 5 minutes If a new female – 1 min- ejaculate again – get him going sooner than the old female Absolute refractory period – under what circumstances is he going to initiate sex again – nothing will get him going –need to reset Steroid hormones important for phases Rats – studs and duds Animals- intrinsic motivation towards a stimuli Castration – incision into the scrotum – push out testis –litigate the seminal vesicles until blood flow ceases – block the scrotum Study of Male Sexual Behavior Intact controls – sham surgery – fake surgery as control for the effects of the surgery Male sexual behavior declines over the week Injecting with testosterone – restoration of male sexual behavior Injecting with oil – not any restoration Testosterone given immediately after castration T receptors down regulate if not being used – androgen receptors needed When inject testosterone after down regulation- no changes in behavior but androgen (testosterone) receptors begin to appear again so subsequent testosterone can have effects on the behavior Right after castration – receptors still present – no down regulation Testosterone maintains internal reproductive organs Taking steroid – testosterone doesn’t produce as much – testis begin to shrivel up Testosterone -Summary Hormones important for appetitive and consummatory actions Rat penile erections go away after castration Steroid hormone synthesis – need to know for test Sexual behavior in humans – need to know for test Sertoli cells produce sperm Leydig cells produce testosterone Neuroanatomy of Male Sexual Behavior Projections to the VTA– areas rich in Dopamine neurons – main NT project to the nucleas acumbens ( rewards) Medial PreopticArea Lesion – does not have effect on appetitive behavior but effects on the consummate behavior Makes sex more robust Hormone action – androgen receptors and estrogen Need both these receptors for SB Aromatize exists in areas where there is ER andAR Something with hype and MPOAimportant in sexual behaviors primarily its dopamine Olfactory Input Rodent species because live in olfaction – volatile means readily evaporate at high temperatures VNO- normal nasal region Experience based plasticity – certain types of damage – do nothing as a result of experience Amygdala – sexual/ maternal Rat have quite large amygdala Subnuclei does different things to sexual behavior Basolateral reduce sex motivation but not…. Second order conditioning – as opposed to primary conditioning – Pavlov dog- bell-saliva Walk associated with bell which is associated with food Double dis
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