Lecture 15 Flashcards
Hormone control of puberty
The arcuate nucleus of the hypothalamus produces the neuropeptide kisspeptin. This initiates puberty and maintains reproductive ability by triggering the release of GnRH
GnRH is a hypothalamic hormone that causes the anterior pituitary to produce gonadotrophic hormones.
GnRH causes the hypothalamus to produce FSH and LH (gonadotropic hormones)
UP TO HERE IS THE SAME FOR MALES AND FEMALES
These cause the gonads to release Test or estradiol
Male sexual behaviour
Men resemble other mammals in their behavioral responsiveness to test
Normal levels - fertile
Without it, sooner or later, sex stops
Dominant monkeys have sex for longer
Without test, castrated mice don’t bang. Will again if you inject test
Men taking GnRH antagonists have less androgens and low sex drive
Female sexual maturation
Estrogen - sex hormones released by ovaries that causes maturation of physical features of females
Estradiol - principle estrogen of many mammals including humans
Hormone control of female reproductive cycles
Menstrual cycle
Female reproductive cycle of humans and promotes
Sexual behaviour is influence by ovarian hormones but can happen at any time
Estrous cycle
Mammals that are not primates Do not menstruate Reabsorb their endometrium Only active during estrus part of cycle Is "in heat"
Human female sexual behavior
not much of an influence on female behavior
Big studies show some in sexual deire but small
Rodent female sex behavior
Responsive to males in heat
All hormone dependent
Big change
Hormones influence willingness/eagerness to mate and capacity as males cannot mate with those not on heat
Males ignore rats without ovaries but will be interested if she is given injections of estradiol and progesterone
Estradiol followed by progesterone does 3 things to female rats
Proceptivity: Eagerness to copulate - seeks out male and entices him
Receptivity: Ability and willingness to copulate - accept advances via lordosis
Attractiveness: Physiological and behavioral qualities that attract the male. Pheromones’ (odors) are onw way. Proceptive behavior is another
Hormonal control of sexual behaviour
Organizational effects of hormones on the body is over at birth but on brain lasts a few weeks
So we can masculinize or feminize rodent brains by altering signaling after birth after development of organs is complete
Castrate males at birth stops further androgen signaling - they develop some female behaviors
If they are injected with estradiol and progesterone as adults, they try to get other males to bang them
Introduction of females’ hormones in non-castrated adults does nothing
Give adult rats female hormones
Hormone treatment
At birth When grown Resulting sec behavior
None E + P Female: yes M: no
None test F: no M: no
Test E+P F:no M:no
Test test F:no Male: yes
Test early on defeminizes female brains so they wont do sex behaviour when given EP later
Test early on masculinizes brains so they will do male sex behavior when given test later
Congenital Adrenal Hyperplasia
Adrenal gland put out too much androgens before and after birth
In males, no drama. Females can get masculinized sex organs in brain and body
Higher likelihood of identifying as a man and being into girls
Higher prevalence of homosexuality’s and trans
This isn’t the main thing though. Other peptides act in the brain. We do not know which
Male female brain configurations
if there are 50 sexually dimorphic areas
scan 100 ppl
only 5% have all of them
Most are mosaics
Why? Cos signaling is super different
Important pathways for female behavior
VMH
GABA neurons in the medial amygdala
gets sensory input but unprocessed, doe not know what it is, just responds to it automatically
Activates the ventromedial nucleus of the hypothalamus (VMH)
Electrical stimulation facilitates female sexual behavior
Injections of estradiol and progesterone here cause sexual behavior even if animal has no ovaries
Female with bilateral VMH will not do lordosis even with estradiol and progesterone
Important pathways for male behavior
GABA on amygdala
MEDIAL PREOPTIC AREA
Electrical stimulation = male behavior
In the mPOA is the SEXUALLY DIMORPHIC NUCLEUS
much larger in males than females
Lesioning the mPOA of females’ does not impact sex but they ignore their offspring
:lesioning males mPOA changes sex behavior but not parenting
Pair bonding
5% of mammal species are fairly monogamous pair bonders
2 proteins: vasopressin and oxytocin
Some species of prairie vole form pair bonds and some don’t
Blocking or activating oxytocin receptors on the ventral forebrain influences who they pair with and when
Introducing oxytocin receptors to the non-pair bonding species makes them pair bond
Regulation of priorities
Falling in love/becoming a drug addict
Nucleus accumbens in the ventral forbrain has oxytocin, vasopressin, dopamine and serotonin activity
When activated the right way, changes priorities and how you value things
Can cause love and addiction
If not, more coldly cognitively evaluate a situation
Pheromones’ (mechanism)
Transmit chemical signals from one animal to another
Odors in humans are learned apart from maybe lavender and rotten fish
In animals more innate
Have a VOMERONASAL ORGAN
finds chemicals
is in nasal cavity
humans do not have a functional VNO
Removal of the VNO, the vomeronasal nerve disrupts the effects of pheromones’
Pheromones (effects)
Lee-Boot effect - female mice housed together (no male urine) estrous cycles slow and eventually stop
Whitten effect - Synchronization of menstrual or estrous cycles of females which occurs only in the presence of male urine (may have advantages for childcare if all give birth at once)
Vandenbergh Effect - Earlier onset of puberty seen in females housed with males: Pheromones’ in male urine
Bruce effect - Females terminate permanency following scent of an unfamiliar male (male eats other males offspring, better to abort and have his kids)
Pheromones’ in humans
VNO non functional
Women together synchronize period to within a day or two
Women in regular contact with men show shorter cycles than women without men
Maybe
2 ideas of emotion research
Mammals have common ancestor so we can use them to study emotions
Cannot know if an animal is just behaving or of they are experiencing emotion
Dopamine signaling experiments
All drugs of abuse increase dopamine so people thought it was the pleasure hormone
Intra-cranial self-stimulation in rats sees them doing it again and again
But in humans, dopamine does not increase pleasure
Do animals like dopamine or CRAVE it
Humans crave when dopamine messed with. Perhaps this is not a pleasure hormone
Frequency of amygdala stimulation
If GABA stimulation at 5 a second = horny
20x = attack!
Change frequency , change behavior. Do they feel horny or angry or just ACT?
If we stimulate with glutamate, pull back and stop socializing. Depression? Or just the action?
Old ideas about emotional expression
6 faces/emotions
Recognition via face is generally automatic, rapid and accurate
More time = no improvement over initial thought
Facial expressions serve a social function
Broadcast emotions and allow us to decide who to trust etc
Innate, natural and unlearned
No cultural or linguistic barrier
36 month old babies mimic facial emotions
Isolated tribes can read westerners and vice versa
No differences in facial expressions in congenitally blind people
New ideas about emotional expression
BUT overstated
Expressions are not super specific - the same facial expression can convey different emotions and different facial expressions can convey the same emotion
Inferring emotions from the face is not very reliable. The same emotion is not reliably expressed through nor perceived from a common set of facial movements
The generalizability (contextual and cultural effects) of deducing emotions from faces is not well studies.
Emotional experiences do not reduce to 6 emotions but 25 unique blends. They do not manifest in prototypical facial-muscle configurations alone but in multimodal behavioral expressions such as voice, touch, posture, gaze and head/body movements
Not just face
