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

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.

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 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.

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 http://www.alifewithoutpain.com/about.php http://www.alifewithoutpain.com/view_clip.php

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

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

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.

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

Figure 8.11 The Hypothalamus-Pituitary-Adrenal Cortex Axis

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!

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.

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.

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)

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

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

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.

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.

Biological Origins of Aggression 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. 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

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

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

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.

Antisocial personality disorders People with antisocial personality disorder: Reckless behavior Violate social norms Commit antisocial acts like fighting, stealing, and using drugs Engage in sexual promiscuity Show little or no remorse for their behavior. Are their brains different? People with antisocial personality disorder are more likely to have reduced prefrontal gray matter. Less inhibitory areas of prefrontal lobe to inhibit limbic/hypothalamic activity Remember prefrontal cortex damage: never learned the “rules”

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

Alcohol and Aggression Why does alcohol (inhibitory drug) increase aggression? Alcohol facilitates aggression by inhibiting the prefrontal cortex Alcohol has greater influence on aggression in people who also have low serotonin levels May be sign of early-onset alcoholics Those who already exhibiting impulsive aggressive behavior. Initially alcohol increases serotonin activity, but then depletes it below the original level. The alcohol abuser is caught in a vicious cycle Alcohol consumption increases aggression due to prefrontal inhibition Alcohol also increases craving for more alcohol Drink to get away from aggressive feelings, but this makes you more aggressive!.

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

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.