Week 13- Neuroscience of Sex and Love Flashcards
Research methods and limitations
volunteer bias, natural setting, funding, researcher bias (not many researchers interested, may be influenced by worldviews)
Masters & Johnson- Four phases of sexual response
Excitement phase
Increased heart rate, respiration rate, blood pressure, muscle tension
Male penis engorged with blood- becomes erect
Plateau phase
Arousal is maintained for several minutes
Testes rise in scrotum in preparation for ejaculation
Vaginal lubrication increases
Orgasm
Rhythmic contractions in penis accompanied by ejaculation of seminal fluid containing sperm
Resolution
Arousal decreases, return to previous state
Visual stimulation
Males more responsive than females
And more dopamine activation
Unique activation of amygdala
Tactile stimulation- erogenous zones, dopamine
Some receptors activate more dopamine than other types (erogenous zones)
Hormone levels as a moderator
Mouth, anus, genitals (Mosby, 2001)
Female
Olfactory stimulation & pheromones
Olfactory stimulation
Humans can detect 10,000 odors via different combinations of active neurons in olfactory lobe
Pheromones- breakdown products of hormones
Issue of perfumes
Detection
Better in women when ovulating, preference more dramatic
Gay men better than straight men or straight women
Males prefer female pheromones around ovulation
Arousal signalling (PVN- oxytocin- activates posterior pituitary (oxytocin released in blood stream, hormone) and spinal nerves (acts as neurotransmitter, facilitates blood flow to genitals), blood pressure increases until orgasm
Parasympathetic system activated, increased arousal
Periventricular nucleus of hypothalamus (PVN)
Oxytonergic
Connects to posterior pituitary and spinal nerves
Posterior pituitary
Oxytocin released in blood stream (hormonal signalling)
Oxytocin to spinal nerves (acting as a neurotransmitter)
Blood flow to genitals
Role of autonomic regulation in human sexual behavior
Parasympathetic- arousal and erection
Sympathetic- ejaculation
Too rapid transition (more common in males)- premature ejaculation
Failure of transition (more common in female)- inability to reach orgasm
Role of mesolimbic system and dopamine in human sexual behavior
Mesolimbic activity
VTA- dopamine- Nucleus Accumbens
Or anticipation of pleasure?
Drugs that increase dopamine also increase sexual behavior
Receptors: D1 Parasympathetic activation Erection, arousal Linked to faithfulness/maintenance of attachment D2 Sympathetic activation Ejaculation Linked to pair bonding/formation of attachment
Activity of neocortex in orgasm
Neocortex deactivation
Feelings of release
Changes in self-awareness
Altered appreciation of space and time
What is a difference specific to females? males? (in regard to human sexual behavior)
Females don’t require an orgasm to reproduce (but men do); Ventromedial hypothalamus (VMH)
Increased activity
Receptors for estrogen, progesterone
Midbrain
Hormonal aspects
Spinal pathways- Lordosis reflex- back arching
Male: Medial preoptic area of hypothalamus
Testosterone, androgen receptors
Sexual performance
Amygdala
Sexual motivation
Weird role- more likely for males than females to confuse sexuality with aggression
Refractory period
Oxytocin and vasopressin- roles
Oxytocin: Increased after orgasm Feelings of calmness and well-being; Acts as neurotransmitter Formation of attachment/pair-bond During sex- formation of attachment If you introduce nasal oxytocin, people become more trusting Majority has to do with nursing Monogamous sexual attachment an evolution of the biology of mother-offspring attachment? Vasopressin Male oxytocin- formation of pair-bond The more, the faster Vasopressin stimulates dopamine neurons Making monogamy more likely Genetic variation Variations in autism
