Cortisol and oxytocin are hormones that impact human behavior. Cortisol is released during stress and helps regulate the body's stress response. Short-term stress and cortisol release is normal, but chronic stress can weaken the hippocampus and frontal lobe over time. Oxytocin is involved in bonding and trust. Studies found oxytocin levels increased in newly formed couples and predicted relationship success later. Oxytocin also improved couple communication and lowered stress when administered. It plays an important role in social bonding for many species.

1. Hormones
The Chemicals of Stress and
Love.

2. I.B. Learning Outcome
 B7- Using one or more examples, explain
functions of two hormones in human
behavior.
 I can explain the difference between a
neurotransmitter and hormone.
 I can explain the impact that oxytocin and
cortisol have on human behavior.

3. Hormones
 Chemical substances, secreted by organs
called glands, that affect the functioning
of other organs.

4. Hormones vs.
Neurotransmitters
 Neurotransmitters are released in the
brain
 Hormones are released by glands in the
body.
 When hormones are active in the brain,
they serve as neurotransmitters.
 Assume cortisol and oxytocin are hormones.

5. Stress Questions
 What are stressors in your life?
 What is it like when you are under stress? Is
there a difference between short-term
and long-term stress?
 How do you deal with stress?

6. Stress: Fight or Flight
1. Oh geez…ZOMBIE!!!!!
2. Eyes and Ears send information to the
A(HHH!!)mygdala.
1. If danger, Amygdala sends a message
to the Hypothalamus.
2. Hypothalamus sends signal to the
Adrenal Gland to release epinephrine.
3. Epinephrine increases heart rate, lung
capacity increase. Ready for action.
4. If danger continues, the body releases
cortisol. This allows the body to regain
energy lost from the adrenaline burst
and return to homeostasis.

7. Example #1: Cortisol
 Stress hormone
 Produced in adrenal gland
 Designed to return the body to homeostasis
following a stressful event.
 Some cortisol is good.
 Chronic stress and continual release of
cortisol is bad.

8. McEwen et al. (2006)
 Learning Outcome: B8: Environment &
Physiology
 Aim: To determine the impact of chronic stress
on neural structure
 Method:
 Control: Rats in cages with two other rats.
 Treatment: Rats who were placed in highly
stressful restraints for 6 hour each day for 21
days.
 On the 22nd day, all rats were euthanized and
their brains dissected.

9. McEwen et al. (2006)
Continued
 Findings: The treatment rats had weakened
dendrites in their frontal lobes and
hippocampus. They also had stronger neural
connections in their amygdala.
 Conclusions: Chronic stress brought about by
isolation weakens the frontal lobe and
hippocampus, while strengthening the
amygdala.
 Critical Thinking?

10. Hippocampus Neurons

11. Bremner et al. (2003)
 Learning Outcome: B8, B10, (B5, B7)
 Aim: To investigate whether prolonged
stress (PTSD) reduces the volume of the
hippocampus.
 Method:
 Participants: War veterans and female
adults who were sexually abused as
children. (Some had PTSD, but not all)
 Took MRI scans of brains and had
participants take a memory test.

12. Bremner et al. (2003)
continued
 Finding: Veterans with the most memory
problems had the smallest hippocampus.
 The Hippocampus of PTSD suffers was
smaller than a control group.
 Conclusions: Chronic stress reduces the
volume of the hippocampus and impairs
memory.
 Critical Thinking:
 Small Sample Size
 Small Hippocampus leads to PTSD?

13. Newcomer et al (1999)
 Learning Outcome: B7 & B9
 Hormone: Cortisol
 Aim: To determine the role of cortisol on
memory.
 Method: Double-Blind study that had asked
three groups to take varying levels of cortisol
over a four day period and tested their ability
to remember verbal information.
1. High Level: Tablet of 160 mg Cortisol each
day…simulates a major stressful event.
2. Low Level: Tablet of 40 mg of Cortisol each
day…Simulated a minor stressful event.
3. Placebo: Tablet with no active ingredient.

14. Newcomer et al. (1999)
continued
Findings:
 The High Level group performed worse
on the memory test than the Low Level
group.
 The Low Level group showed no
memory decrease when compared
with the placebo group.
Conclusions: High Levels of cortisol
have a negative impact on a
person’s ability to recall verbal
data.

15. Love Discussion Questions
 How is being in love similar to addiction?
 What advice would you have for
someone who is in love? Heartbroken?
 Does this change the way you think about
love? Human behavior?
 Would “Love Drugs” be ethical? Would
you want to take them?
 Would you be interested in seeing how
you or your partner reacts on a biological
level to you? Why or why not?

16. Example #2: Oxytocin
 Released by the pituitary gland.
 Only exists in mammals.
 Acts primarily as a neurotransmitter.
 Involved in building bonds, trust, and
generosity.
 The coolest hormone ever!

17. Feldman et al. (2012)
 Hormone: Oxytocin
 Aim: To investigate the role of Oxytocin in
early relationships in young adults.
 Method:
 Measured the oxytocin levels of 120 young
adults (60 couples of 3 months) and 43
singles.
 Measured oxytocin levels of the same
participants six months later.

18. Feldman et al. (2012)
 Findings:
 Oxytocin levels were higher for the new couples
than the single individuals.
 High Oxytocin levels at the first test correlated
with couples staying together after 6 months.
 High Oxytocin predicted more affectionate
touch, reciprocity, positive emotions, and
worries about the partner and relationship.
 Conclusion: Oxytocin plays a key role in the
formation of new romantic relationships
among young adults.
 Critical Thinking:
 Did not test Oxytocin before falling in love...
 Ecological Validity?

19. Ditzen (2013)
 Hormone: Oxytocin
 Aim: To determine the impact of oxytocin
on couples’ communication.
 Method: Had couples either spray
oxytocin or a placebo up their nose and
engage in a high stress conversation.

20. Ditzen (2013) Continued
 Findings:
 Oxytocin improved communication and
lowered levels of cortisol.
 Women: showed less social stress
 Men: showed more social stress and were
more engaged in the conversation (Eye
contact, smiling, etc.)
 Conclusions: Oxytocin impacts the ways
that couples communicate.

21. Nakajima et al. (2014)
 Aim: To determine the role of oxytocin in
female rats interest levels in male rats.
 Method: Gave a group of female rats a
chemical that blocked the receptor sites
of oxytocin in the frontal lobe.
 Finding: The females showed almost no
interest in males and even showed equal
attention to a LEGO block.
 Conclusion: Oxytocin is responsible for
sexual interest in female rats.