1. Emotion: PAIN, stress and aggression
CHAPTER 8
Emotion:
PAIN, stress and aggression

2. Stress, Immunity, and Health
Conditions in the environment that makes unusual demands on the organism,
Often include: threat, failure, or bereavement.
Stress also refers to internal condition
your response to a stressful situation.
You respond with aggression, depression, illness

3. Stress, Immunity, and Health
The stress response includes:
Activation of the sympathetic branch of the autonomic nervous system
Largely under the control of the hypothalamus.
The result:
Increases in heart rate, blood flow, and respiration rate
Kick person into fear/flight/fright
Help the person deal with the stressful situation.
Stress is supposed to be a short term reaction to an immediate threat, NOT a prolonged response.

4. Stress, Immunity, and Health
Stress activates the hypothalamic-pituitary-adrenal axis
Group of inter-related structures that help the body cope with stress.
The hypothalamus activates the pituitary gland
Pituitary gland in turn releases hormones that stimulate the adrenal glands
Adrenal glands then release stress hormones:
Epinephrine,
Norepinephrine,
Cortisol (and other corticosteroids).
Epinephrine, Norephinphrine
increase output from the heart
liberate glucose from the muscles for additional energy
Cortisol smooths muscles; reduces inflammation and pain
allows for greater muscle effort

5. Figure 8.11 The Hypothalamus-Pituitary-Adrenal Cortex Axis

6. Stress, Immunity, and Health
The hormone cortisol increases energy levels but acts much slower than epinephrine and norepinephrine
Allows Conversion of proteins to glucose
Increases fat availability
Result is increased metabolism.
Cortisol provides a more sustained release of energy than the sympathetic nervous system does, for coping with prolonged stress.
In turn: this allows for greater muscle activation; suppresses pain system….great for short term!

7. Stress, Immunity, and Health
Humans are better equipped to deal with brief stress than with prolonged stress.
Chronic stress can interfere with:
Memory
Appetite (increase or decrease)
Sexual desire and performance
Energy: depletes energy stores
Cause mood disruptions.
Although brief stress enhances immune activity, prolonged stress compromises the immune system.

8. Stress, Immunity, and Health
The cardiovascular system is particularly vulnerable to prolonged stress.
Stress increases blood pressure,
Prolonged high blood pressure can damage the heart or cause a stroke.
Sudden cardiac death:
Stress causes excessive sympathetic activity
Sends the heart into fibrillation: contracting so rapidly that it pumps little or no blood.
Extreme stress can also lead to brain damage.
Hippocampal volume was reduced in Vietnam combat veterans suffering from posttraumatic stress disorder
Also found in victims of childhood abuse,
Cortical tissue reduced in torture victims.
Evidence suggests damage is caused by long term raised levels of cortisol.

9. Figure 8.14 Increase in cardiac deaths on the day of an earthquake
Increase in cardiac deaths on day of an earthquake (involving people NOT hurt in earthquake)

10. Stress, Immunity, and Health
Stress can also damage the brain
Cortisol-related damage to hippocampus and gray matter
Altered sleep cycles due to stress also cause illness

11. Stress, Immunity, and Health
Whether stress has a negative impact on health depends on a variety of factors:
Initial health status
Social support
Personality
Attitude.
Social and personality influences must work through physiological mechanisms
Unfortunately: social/personality have been seldom assessed in physiological studies.
Looks like our social interactions may be critical for dealing with stress

12. Is pain homeostatic?
The pain pathway has rich interconnections with the limbic system
In limbic system, pain becomes an emotional phenomenon.
Pain activates
Somatosensory areas
Anterior cingulate cortex: intimately connected with other limbic structures.
If pain continues:
Recruits activity in prefrontal areas
Prefrontal area = pain is evaluated and responses to the painful situation are planned.

13. Figure 8.18 PET scan of brain during pain stimulation
The bright area near the midline is the cingulate gyrus; the one to the left is the somatosensory area. The four views were taken simultaneously at different depths in the same brain.
Figure PET scan of brain during pain stimulation
The bright area near the midline is the cingulate gyrus; the one to the left is the somatosensory area. The four views were taken simultaneously at different depths in the same brain.

14. Function of pain Is pain important?
Provides feedback regarding body state
Is a signal to STOP a particular behavior
Gives clues to damage to body parts
People with congenital insensitivity to pain are born unable to sense pain.
They injure themselves repeatedly
not motivated to avoid dangerous situations,
Can even die from untreated conditions like a ruptured appendix because they process the sensation of pain

16. Pain = emotional stressor
In pain insensitivity disorders, it is the emotional response that diminished
Not sensation of pain: The person can recognize painful stimulation
Simply aren’t bothered or distressed by the pain
The same is true for people who underwent prefrontal lobotomy
Once used to manage untreatable pain.
When questioned, the patients reported still felt “little” pain but “big” pain gone.
Still had sensory aspect of pain, but not emotional
Chronic pain induces stress.
We are not hard wired to experience constant pain
Pain should be feedback to brain to “do something different”
Chronic stress produces even further brain changes

17. Biological Origins of Aggression
Aggression: behavior that is intended to harm.
Often the result of stressors
Not surprising that stressed people are more aggressive!
Basic kinds of aggression:
Predatory aggression occurs when an animal attacks and kills its prey.
Territorial aggression: aggression to defend territory
Maternal/Paternal aggression: protection of young
Pain induced aggression: induced by pain
Affective aggression is characterized by its emotional arousal

18. Biological Origins of Aggression
Aggression can be further subdivided:
Offensive Aggression: An unprovoked attack on another animal.
Defensive aggression: occurs in response to threat and is motivated by fear.
Approach/Avoidance: May show offensive aggressive behaviors as way of avoiding defensive aggression
Human aggression is less clearly categorized.

19. Testosterone and aggression
In nonprimate mammals:
Aggression enhanced by testosterone in males
Enhanced by both testosterone and estrogen in females.
In primates: Aggression related to testosterone levels
Both male AND female primates:
Aggressiveness increases in female monkeys during the premenstrual period:
Estrogen and progesterone at lowest;
Ratio of testosterone to estrogen/progesterone at highest.
Studies have also reported a doubling of crimes and violent crimes in women during this period.

20. Biological Origins of Aggression
In women:
Progesterone reported to reduce PMS-related aggressiveness:
Some data suggests is due to decreased levels of a metabolite of progesterone: allopregnanolone,
However: may impair woman’s anxiety response to stress.

21. Biological Origins of Aggression
Males:
Some relationship between testosterone and violence in male prison inmates.
Appears to be some relation between testosterone and aggression in human males
Social factors are stronger, however
In humans: aggression is largely learned

22. Biological Origins of Aggression
No clear evidence that aggression in humans directly affected by:
Manipulation of testosterone levels
By disorders that increase/decrease testosterone.
Some increase in XYY men, XXY women, but not a strong correlation
Appears to have a stronger learned component
That is, we learn to be aggressive; remember and respond to cues rather than hormones

23. Biological Origins of Aggression
We know more about brain structures involved in feline aggression and their connections than in any other animal.
The defensive pathway begins in the medial nucleus of the amygdala: When react to defensive aggression triggering stimuli:
Medial nucleus of amygdala activates medial hypothalamus,
From there Dorsal part of the periaqueductal gray area in the brain stem.
Control of predatory attack flows from
The lateral nucleus and the central nucleus of the amygdala 
lateral hypothalamus 
ventral periaqueductal gray.
In cats: innate stimuli elicit defensive and predatory behaviors

24. Biological Origins of Aggression
Research on human aggression is understandably constrained in terms of types of research:
Ethical constraints
Rely on correlational studies, world outcomes
What do we know?
Tumors can cause aggression if they are in the hypothalamus or the septal region.
Seizure activity in the area of the amygdala or speficic locations of hypothalamus increase aggression,
Damage to the amygdala reduces aggression
The prefrontal cortex is critical in restraining aggression.

25. Aggression and neurotransmitters
Which neurotransmitter plays the strongest role?
Serotonin inhibits aggression:
Probably through its effects in the amygdala, hypothalamus, periaqueductal gray, and prefrontal area
Remember, is inhibitory;
Shutting off anxiety circuits
Shutting down “acting out” behaviors .

26. Aggression and neurotransmitters
Low serotonin activity is specifically associated with impulsive aggression.
Dopamine may be paired with aggressive stimuli
Learn a drive towards/reinforces aggressive behavior

27. Aggression and depression
Interaction of hormones and neurotransmitters important for eliciting aggression
Higley and his colleagues (1996): High testosterone and low serotonin interact to produce aggression.
Monkeys with low 5-HIAA levels were impulsive.
Took dangerously long leaps among the treetops more often
When engaged in aggression, more likely to accelerate into greater violence.
The most aggressive monkeys had both low 5-HIAA and high testosterone levels.
Bottom line:
As humans, we learn to be aggressive situationally
Can be exacerbated with hormone or neurotransmitter disruptions

28. Take home message:
Pain is an emotional response with learned components
Can produce stress
Produces autonomic arousal
Produces emotional response
Stress is a biological reaction, but learning plays a vital role
Aggression is hardwired in the brain, but we learn WHEN to be aggressive (are aggressive situationally)
Stress, pain, aggression all linked to depression: Depletion of serotonin
All of these “emotional” behaviors can be exacerbated with hormone or neurotransmitter disruptions resulting from environmental stressors.
Degree to which one has coping skills is critical to controlling pain and aggression.