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Emotion and the nervous system immunity, and health Biological origins of emotion. Emotion and Health Chapter 8. Emotion and the Nervous System.

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emotion and health chapter 8
Emotion and the nervous system

immunity, and health

Biological origins of emotion

Emotion and HealthChapter 8
emotion and the nervous system
Emotion and the Nervous System
  • Emotion is an increase or decrease in physiological activity that is accompanied by feelings that are characteristic of the emotion, and often accompanied by a characteristic behavior or facial expression.
    • Sympathetic nervous system activation is the most obvious component of an emotional response.
      • This system prepares the body for “fight or flight”.
      • The sympathetic nervous system also stimulates the adrenals to release hormones, particularlycortisol.
    • After arousal, the parasympathetic nervous system reduces activity and conserves and restores energy.
    • Muscular activation is involved in the external expression of emotion.
emotion and the nervous system1
Emotion and the Nervous System
  • James-Lange Theory
    • Emotional experience results from the physiological arousal that precedes it.
    • Different emotions are the result of different patterns of arousal.
    • William James: “We feel sorry because we cry, angry because we strike, afraid because we tremble.”
  • Schacter and Singer’s Cognitive Theory
    • Physiological arousal contributes only to the emotion’s intensity.
    • The identity of the emotion is based on the cognitive assessment of the situation.
  • Neither theory has won out, but they have led to insights.
emotion and the nervous system2
Emotion and the Nervous System
  • Facial Feedback in Emotion
    • Paul Ekman demonstrated that posed expressions could produce the intended emotion, and a distinct pattern of physiological arousal.

Figure 8.2: Some of Ekman’s posed emotions

emotion and the nervous system3
Emotion and the Nervous System
  • Posing facial expressions also affects how we interpret the environment.
    • A stimulus is more painful when making a sad face.
    • Cartoons are rated as more amusing during induced smiling.
    • Women who have had facial muscles paralyzed with botox and are unable to frown report less negative mood.
    • When these women attempt to imitate angry expressions they produce less amygdala activity than other women.

emotion and the nervous system4
Emotion and the Nervous System
  • Feedback from facial emotions may help us understand others’ emotions.
    • Mirror neurons are neurons that respond both when we engage in a specific act and while observing the same act in others.
    • This may be why observing emotions in others activates our own brain’s emotional areas.
    • The degree of activation is related to the person’s score on a measure of empathy.

emotion and the nervous system5
Emotion and the Nervous System
  • We mimic others’ emotional expressions, which may contribute to our emotional empathy.
    • Interfering with the muscles required for mimicking facial expressions impairs the ability to recognize emotions in photos.
    • Autistic children’s mimicry is delayed, and they have difficulty understanding others’ emotions.

emotion and the nervous system6
Emotion and the Nervous System
  • The Limbic System
    • This network of structures arranged around the upper brain stem carries out several functions in emotion.
    • The hypothalamus has primary control over the autonomic nervous system, and produces a variety of emotional expressions.

Figure 8.4:

The limbic system

emotion and the nervous system7
Emotion and the Nervous System
  • Septal stimulation produces a sense of pleasure, accompanied by sexual fantasies and arousal.
  • The amygdala plays a role in fear.
  • Disgust has been located in the insular cortex and basal ganglia.
  • The anterior cingulate cortex is believed to combine emotional, attentional, and bodily information to bring about conscious emotional experience.

emotion and the nervous system8
Emotion and the Nervous System
  • The Prefrontal Cortex
    • Prefrontal cortex is the final destination for much of the brain’s information about emotion before action is taken.
    • The prefrontal cortex is necessary for making judgments about behavior and its consequences.
      • People who sustain damage to this area later in life show an understanding of moral and social rules in hypothetical situations but are unable to apply the rules in their own lives.
      • People who sustain damage early in life never learn these rules and, at best, are motivated only to avoid punishment.
    • Abnormalities in this area are associated with aggression, depression, and schizophrenia.
emotion and the nervous system9
Emotion and the Nervous System
  • Amygdala
    • The amygdala is involved primarily in negative emotions.
    • However, it also participates in memory formation, especially when emotion is involved.
    • The amygdala’s role in fear and anxiety has been most thoroughly researched.
      • Fearis an emotional reaction to a specific immediate threat.
      • Anxietyrefers to apprehension about a future, and often uncertain, event.
    • Rats and people with amygdala damage are unusually trusting.
    • Anxiety-reducing drugs act on receptors in the amygdala.
emotion and the nervous system10
Emotion and the Nervous System
  • The hemispheres have different emotional functions.
    • The left frontal area is more active during positive emotions, and the right is more active during negative emotion.
    • People with damage to the left hemisphere often express more anxiety and sadness about their situation.
    • Those with right-hemisphere damage are more likely to be unperturbed or even euphoric, even when their arm or leg is paralyzed.
    • Autonomic responses to emotional stimuli (facial expressions, emotional scenes) are greater when the stimuli are presented to the right hemisphere.
    • Patients with right-hemisphere damage have trouble recognizing emotion in facial expressions and tone of voice.
stress immunity and health
Stress, Immunity, and Health
  • Stress is a demanding condition in the environment and it is the individuals’ internal response to that situation.
    • The stress response includes activation of the sympathetic nervous system, largely under hypothalamic control.
    • The resulting increases in heart rate, blood flow, and respiration rate help the person deal with the situation.
    • Stress also activates thehypothalamic-pituitary-adrenal axis, a group of structures that help the body cope with stress.

stress immunity and health1
Stress, Immunity, and Health
  • The hypothalamus activates the pituitary gland, which stimulates the adrenal glands to


    • epinephrine and norepinephrine,

which increase output from the

heart and liberate glucose from

the muscles for energy;

    • cortisol, which provides a sustained

release of energy for coping with

prolonged stress.

Figure 8.11: The hypothalamic-pituitary-

adrenal cortex axis

stress immunity and health2
Stress, Immunity, and Health
  • Brief stress increases activity in the immune system.
    • The cells and cell products of the immune system:
      • kill infected and malignant cells;
      • protect the body against foreign substances, including bacteria and viruses.
    • The are two major types of immune cells:
      • Leukocytes, or white blood cells recognize invaders by the unique proteins that every cell has on its surface and kills them.
      • Natural killer cellsattack and destroy certain kinds of cancer cells and cells infected with viruses.
stress immunity and health3
Stress, Immunity, and Health
  • Chronic stress:
    • interferes with memory, appetite, and sexual desire and performance;
    • depletes energy and causes mood disruptions;
    • compromises the immune system.
      • Six years after the Three Mile Island nuclear accident, residents showed increased stress, impaired concentration, and impaired immune response.
      • Studies confirm simultaneous impairment of immunity and health during stress.

stress immunity and health4
Stress, Immunity, and Health
  • Heart attacks
    • increased fivefold after a Los Angeles area earthquake;
    • increased in Germany during the 2006 World Soccer Cup;
    • increase following daylight saving time changes.

Figure 8.14: Cardiac deaths on the

day of an earthquake

stress immunity and health5
Stress, Immunity, and Health
  • Stress can also lead to brain damage or long-term brain changes.
    • Hippocampal volume was reduced in Vietnam combat veterans suffering from posttraumatic stress disorder and in victims of childhood abuse.
    • Cortical tissue was reduced in torture victims.
    • Gray matter was reduced in the brains of people who had been in the vicinity of the 9/11 terrorist attacks in New York City.
    • There is some evidence the damage due to stress is caused by cortisol—perhaps due to increased receptor sensitivity.
hippocampal damage in a stressed monkey figure 8 15
Hippocampal Damage in a Stressed MonkeyFigure 8.15

Compare the number of cells between the arrows in the control monkey (left) and a monkey that died of apparent stress (right).

stress immunity and health6
Stress, Immunity, and Health
  • Stress effects vary with social and personality variables.
    • Death rate is lower among people with social support.
    • Stress and stress hormones were lower among Three Mile Island residents who had social support.
    • Personality characteristics have been associated with cardiac risk and cancer survival.
    • Relaxation training increased T cells in HIV patients and was associated with reduced death rates in the elderly.

stress immunity and health7
Stress, Immunity, and Health
  • Even social/personality influences such as these have a physiological basis. For example:
    • The association between HIV levels and introversion may be due to the link between introversion and norepinephrine level.
    • Flu antibodies increased more following vaccinations in subjects who had higher activity in the left hemisphere—which is associated with

positive emotions.

Figure 8.16: Post-vaccine antibody levels

in relation to hemispheric activity level

stress immunity and health8
Stress, Immunity, and Health
  • Pain as an Adaptive Emotion
    • Pain is a major health problem, but it is also adaptive, warning us of injury and motivating us to avoid harm.
    • People with congenital insensitivity to pain injure themselves repeatedly and die from untreated conditions.
    • The effect of pain depends on how it is viewed, as seen in:
      • U. S. women’s more intense pain experience during childbirth;
      • injured soldiers’ refusal of morphine;
      • ritual self torture in some religions.

stress immunity and health9
Stress, Immunity, and Health
  • Pain becomes an emotion in the anterior cingulate cortex.
    • Activity increases there, but not in the somatosensory cortex, as pain unpleasantness increases.
    • This distinction probably explains the pain response in some pain insensitivity disorders and in lobotomy patients.

Figure 8.19: Painful heat stimulates both the somatosensory area (on left) and the anterior cingulate cortex (near midline).

biological origins of aggression
Biological Origins of Aggression
  • Aggression is behavior that is intended to harm.
    • Animal researchers distinguish two types of aggression.
      • In predatory aggression, an animal attacks and kills its prey.
      • Affective aggression is characterized by its emotional arousal.
        • Offensive aggression:unprovoked attack on another animal.
        • Defensive aggression: response to threat, motivated by fear.

biological origins of aggression1
Biological Origins of Aggression
  • Human aggression is less clearly categorized than aggression in animals.
  • Some researchers distinguish between reactive and proactive aggression in humans.
    • Reactive aggression is impulsive, provoked, and emotional.
    • Proactive aggression is premeditated, unprovoked, and relatively emotionless.

biological origins of aggression2
Biological Origins of Aggression
  • The Role of Hormones
    • Aggression increases in female monkeys around the premenstrual period, when estrogen and progesterone are low.
    • A similar phenomenon in some women,premenstrual syndrome, may be reduced by progesterone.
    • Testosterone levels are higher in males convicted of violent crimes, as well as in aggressively dominant female prisoners.

biological origins of aggression3
Biological Origins of Aggression
  • These studies are correlational, and there is no evidence that aggression is affected by manipulation of testosterone or by variations of testosterone in disorders.
    • Critics argue that aggression increases testosterone.
    • Testosterone increases after winning a sports event, watching one’s team win, and even receiving the MD degree.

biological roots of aggression
Biological Roots of Aggression
  • In the cat, aggression follows these two pathways:
    • Defensive : medial amygdala → medial hypothalamus → dorsal periaqueductal gray
    • Predatory : lateral amygdala → lateral hypothalmus →

ventral periaqueductal gray

  • In humans:
    • Tumors in the hypothalamus or septal area can cause aggression.
    • Seizure activity in the amygdala increases aggression.
    • Murderers have higher activity in the amygdala and hypothalamus.
    • Lesioning the amygdala reduced aggression in 33% to 100% of patients in various studies.
biological origins of aggression4
Biological Origins of Aggression
  • Reactive and proactive aggression appear to involve different patterns of brain functioning.
    • Murderers with reactive aggression have reduced activity in the prefrontal cortex.
      • Less gray matter in the prefrontal cortex is associated withantisocial personality disorder.
      • These individuals behave recklessly, violate social norms by engaging in antisocial acts, and are sexually promiscuous.
    • Proactive aggression is associated with psychopathy, which is characterized by lack of remorse. They have:
      • less autonomic response to stress
      • and impaired amygdala function.
biological origins of aggression5
Biological Origins of Aggression
  • Serotonin inhibits aggression; low serotonin activity is specifically associated with reactive or impulsive aggression.
    • Levels of 5-HIAA, a metabolite of serotonin, are lower in reactive violent offenders than in those who planned their crimes.
    • People with reactive aggression have less serotonin activity in the prefrontal cortex and in the anterior cingulate gyrus.
    • The short allele of the SLC6A4 gene:
      • reduces serotonin;
      • is associated with hyperreactivity to fear stimuli in the amygdala, a characteristic of impulsive aggression.
biological origins of aggression6
Biological Origins of Aggression
  • Alcohol is involved in 62% of violent crimes; evidence indicates it is a facilitator of aggression.
  • However, alcohol appears to influence aggression only in people who also have low serotonin levels, such as early-onset alcoholics, who tend to be impulsively aggressive.
    • Alcohol initially increases serotonin activity, then depletes it below the original level.
    • The alcohol abuser is caught in a vicious cycle as alcohol consumption increases both aggression and the craving for more alcohol.
    • Drugs that inhibit serotonin reuptake (such as the antidepressant fluoxetine), reduce both aggression and craving for alcohol.
biological origins of aggression7
Biological Origins of Aggression
  • About 50% of the variability in aggression can be attributed to genetics, leaving room for the environment to play a significant role.
    • Individuals who have experienced neglect or deprivation during childhood are more likely to be aggressive as adults.
    • The impact of early experiences may depend on genetic factors such as the gene for the enzyme MAO, which breaks down serotonin.
      • People with the MAOA-L allele have reduced levels of MAO. This increases serotonin levels, which causes a compensatory reduction in serotonin sensitivity.
genes and early experiences influence violence figure 8 22
Genes and Early Experiences Influence ViolenceFigure 8.22
  • This allele produces aggression only in males who have been subjected to childhood abuse or neglect.
  • Women are less affected because the MAOA-L allele is usually opposed by the MAOA-H allele on the other X chromosome.
biological origins of aggression8
Biological Origins of Aggression
  • Information about genetic and biological links with aggression is now being considered in courtrooms as mitigating evidence.
  • An Italian court reduced the murder sentence of AbdelmalekBayout based on his genetic profile.
    • Bayout has five genes linked to aggression, but the court was particularly influenced by the fact that he has the MAOA-L allele.
    • Scientists surveyed urged caution in using genetic information to make legal decisions, because we lack a full understanding of how genes affect a particular individual.