Chapter 5 Flashcards
(22 cards)
Define male sexual behavior
Male sexual behavior→ all behaviors necessary to deliver sperm to female gametes
Define sex drive
motivational force propelling individuals to seek sexual union
- ex: nematode worm→ leave resource-rich areas to search for mates
- influenced by hormonal and environmental factors
- tend to be strong in males
Define sexual arousal
Sexual arousal→ hard to define
- originally thought as motivation
- now presence of erected penis in sexual context OR genital blood flow
What are the two phases for male sexual behavior?
Appetitive phase (sex drive)→ behaviors the male uses to gain access to the female/ courtship
- last longer than other phase
Consummatory phase (sexual performance)→ copulation
—>fuzzy boundaries
—>both influence by hormones
What are the effect of androgens on male sexual behavior?
Androgens→ critical for sexual motivation
- castration leads to reduced sexual behavior
- puberty→ increased in sexual interest
—>but don’t directly cause the sexual behavior
- increase likelihood of copulation in presence of appropriate stimuli
—>interact with experience and social context
What is the origin of the word testes?
testiculus→ witness
- Ancient Roman witnesses swore oaths by placing their hands on their testes, symbolizing the link between virility and truth
What is the role of experience on castration?
Role of experience
- sexually inexperienced male rats→ Stop mating within two weeks of castration
- Sexually experienced males→ Show variation; some stop mating quickly, others continue for weeks
What did Pfuger suggest concerning castration in humans?
Pfuger→ Suggested human persistence in sexual behavior post-castration could be explained by unique cognitive facultie
What is the hormonal rejunevation myth?
Brown-Séquard
- testicular extract could make you rejuvenate
- exploited commercially by charlatans
What is the drive theory?
Drive theory→ popular in north American in 1920s
- cause of behaviour is competing drives
- studies to answer questions like “Do animals prioritize sex drive over hunger or thirst?, How much effort will an individual exert to gain access to a mate?”
Which invention allow scientific to study effect of sex steroid hormones during the early 20th century?
early 20th century→ ablation and replacement technique
- allow to study effects of sex steroid hormones
When was crystalline testosterone first identified?
1935
synthetic testo soon produced from cholesterol
What did Beach and Holz-Tucker experiment show?
found that androgen replacement treatment maintains sexual behavior after castration
- dose dependent→ rats needed 100yg/day or greater
What are the different behaviors infleunced by multiple hormones?
Parental behavior in rodents-> prolactin + estradiol, oxytocin and progesterone
Aggression-> testo + cortisol and social context
Sexual behavior-> testo + estradiol
Stress response-> cortisol + norepinephrine, vasopressin
What are some strong evidences showing the strenght of sex drive in humans?
Evidences
- Premarital sex is universal→ In every culture studied, young people engaged in sexual activity despite risks
- Severe punishment does not deter sex drive (ex: Gilbert Islands→ execution)
- discount risks (pregnancy, STDs)
- Roaring Twenties→ sexual liberation despite deadly venereal disease
—>demonstrates that the biological drive for sex often overrides fear and rational decision-making
What are the paradoxical findings concerning the effect of testo on safe sex?
Risky sexual behavior→ paradoxical findings
- testo link with increase sexual activity and greater impulsivity and risky behaviors
- BUT studies suggest higher testo in men have stronger attitudes toward safe sex
—>might be because testo increase sexual confidence leading to better decision making about protection
What are the main reasons for having sex?
Not only for pleasure (proximal cause) or reproduction (ultimate cause)
- more than 237 different motivations including
- Physical pleasure, Emotional connection, Revenge, Social status, Altruism, Spiritual reasons
—>multidimensional sexual motivation→ hormones, social norms and individual psychological factors
What are the statistics of sexual behavior in men?
Sexual behavior emerge after puberty
- average of first masturbation→ 13.5yo
- at 17yo→ 80% masturbated
- first intercourse before 19yo→ 45%in 1940s to 61% in 2003
- peaks in the 20s
- correlates with peak in testosterone
- andropause→ debated in medical circle (around 60s and 70s
What is hypogonadism?
Hypogonadism→ low testosterone
- testo treatment restores sexual behavior
- leuprolide acetate (hormone medication) supresses testo→ reduces sexual activity and used in treatment of sexual offenders
What are the brain mechanisms involved in male sexual behaviors?
mPOA (medial preoptic area)→ electrical stimulation induces penile erection in socially isolated male rhesus monkeys
- different sites produce either erections, mounting or mounting with erections
No critical need for chemosensory cues in primates
- can remove olfactory bulb and still have sexual behavior
Amygdala→ Kluver-Bucy syndrome (bilateral temporal lobe removal) results in
- Docility and fearlessness
- Hypersexuality (indiscriminate mounting)
- Ingestion of inedible material
—>suggest limbic structure regulate sexual behavior
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Steroid hormones
- androgen, estrogen and progestin concentrated in→ hypothalamus, amygdala and hippocampus
- androgen and testosterone seems to change speed and pattern of neural firing
Mirror neurons→ automatic activation before penile erection
- might play a command role in sexual response
What are the parts of the brain showing activation in males when exposed to ovulatory female odors?
- Preoptic area (POA)
- Anterior hypothalamus
- Striatum
- Hippocampus
- Septum
- Periaqueductal gray
- Cerebellum
—>involved in sexual behavior, emotion and reward
Which brain region is activated during an orgasm in a male?
Ventral tegmental area (VTA) activation during orgasm with PET scans
- part of brain’s reward system
- also activated by heroin
