hormones and behaviour Flashcards
how can hormones influence behaviour
- biological rhythms
- eating and drinking
- reproductive behaviour
- social behavior
- stress
how does the pineal gland act in mammals?
via the cervical ganglia
what does melatonin control
- the timjing of onset of sleep
- breeding conidition in seasonally breeding animals
What does Atrophy mean
shrivel up
how does breeding in hamsters work
- senses longer autumn nights
- pineal gland prolongs nocturnal secretion of melatonin
- hypohtalamus becomes sesnitive to negative feedback effects of gonadal steroids
- less GnRH released
- less gonadotopin released, so gonads atrophy
what is Ghrelin
- Peptide hormone
- 28-amino-acid peptide secreted by cells in stomach epithelium
- stimulates feeding
- stimulates release of growth hormone (GH) from pituitary
- ghrelin-secreting neurons in brain also involved in control of feeding
how does ghrelin levels change
- rise prior to mealtimes and at night
* drop following a meal
what is odd about obese peoples ghrelin levels
• have lower ghrelin before eating
• but following a meal their levels do not drop
→ a ghrelin system unresponsive to feeding and therefore always hungry?
What does Pro-oestrus mean
follicular development and ovulation
what does oestrus mean
receptive period during which fertilisation is most likely to lead to pregnancy
what did Beall & Tracy (2013) find?
- N = 124 normally ovulating women, aged 17–47 (undergrad + community samples)
- asked on-line what colour shirt they were wearing
- classified as high fertility or low fertility based on reported time since last period
wore red or pink more when ovulating
what did miller et al (2007) find?
- recorded tip earnings by dancers in lap-dancing club
* dancers provided information on their menstrual cycle and use of hormonal contraception
What is oxytocin
- a mammalian peptide hormone that acts on the central nervous system
- generally associated with uterine muscle contraction at birth and milk letdown
- also governs a suite of prosocial behaviours as do analogues (e.g. isotocin) in other taxonomic groups
How does oxytocin work with parental care
- female rats bred for high levels of maternal behaviours have more oxytocin receptors in the central nucleus of their amygdala
- female prairie voles that show more maternal behaviour have higher oxytocin receptor density in their nuclear accumbens
- blocking these receptors inhibits maternal behaviour
how does oxytocin work with alloparental care
- neonate (just born) female prairie voles injected with oxytocin are less likely to attack novel stimulus pups
- neonate male prairie voles injected with an oxytocin antagonist show reduced alloparental care
What did Madden & Clutton-Brock (2010) find
- N = 36 meerkats (28 males, 8 females) injected with oxytocin vs saline control
- treatments reversed 3–5 days later
- recorded suite of prosocial behaviours
what did Kosfeld et al (2005) find about trust?
- 2-player economic ‘trust’ game
- investor and trustee each receive 12 monetary units
- investor chooses to send 0, 4, 8 or 12 MU to trustee
- amount sent is tripled by experimenter
- trustee chooses how much of total to send back
- N = 194 healthy male participants
- 3 puffs per nostril of oxytocin vs control (double-blind) 50 mins before playing game
Those who received oxytocin made transfers ~17% higher than control group
What did Zak et al (2007) find about genorosity?
- N = 68 men
- ‘one-shot’ economic game involving a voluntary donation
- given oxytocin vs control via nasal spray
- donations were ~80% higher in oxytocin group
What did Marsh et al (2010) find about social sensitivity
- used well-validated set of photos of facial expression
- blended with neutral expression to create varying emotional intensity
- participants classified expression 35 mins after oxytocin vs control nasal spray
→ oxytocin increases sensitivity to positive emotional expression
Only the happiness condition had a significant difference. Oxytocin has a positive affect on positive emotions. It increases peoples ability to identify happy faces.
Facts about orgasm
- plasma oxytocin increases during orgasm—in males and females
- plasma oxytocin levels increase during self-stimulated orgasm
- oxytocin evokes feelings of contentment, reductions in anxiety and feelings of calmness and security around mate (trust and generosity?)
- may indicate that sex promotes pair bonding
What does the endocrine ssytem and nervous system have in common?
- communication and control systems
- take inputs and effect outputs
- be influenced by prior exposure
