Chapter 12
Biology of Emotion
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What is Emotion?
• Psychologists define emotion in terms of
three components:
– Cognition
– Action
– Feeling
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Emotions, Autonomic Arousal, and the
James-Lange Theory
• Emotional situations arouse the autonomic
nervous system
• Each situation evokes its own special mixture
of sympathetic and parasympathetic arousal
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Emotions, Autonomic Arousal, and the
James-Lange Theory (cont’d.)
• The James-Lange theory of emotion
suggests that autonomic arousal and skeletal
action occurs first in an emotion
• The emotion that is felt is the label that we
give the arousal of the organs and muscle
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Emotions, Autonomic Arousal, and the
James-Lange Theory (cont’d.)
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Emotions, Autonomic Arousal, and the
James-Lange Theory (cont’d.)
• James-Lange theory leads to two predictions:
– People with a weak autonomic or skeletal
response should feel less emotion
– Increasing one’s response should enhance
an emotion
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Emotions, Autonomic Arousal, and the
James-Lange Theory (cont’d.)
• Research indicates the following:
– Paralyzed people report feeling emotion to
the same degree as prior to their injury
– People with “pure autonomic failure” still
report feeling emotion but less intensely
• Pure autonomic failure: output from
autonomic nervous system to body fails
– Suggests other factors are involved in the
perception of emotion
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Emotions, Autonomic Arousal, and the
James-Lange Theory (cont’d.)
• BOTOX blocks transmissions at synapses
and nerve-muscle junctions
• People with BOTOX injections show:
– Slower time in reading unhappy sentences
– Weaker than usual emotional responses
after watching short videos
• Points to body change being important for
feeling an emotion
• However, people with certain types of brain
damage show “normal” responses
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Emotions, Autonomic Arousal, and the
James-Lange Theory (cont’d.)
• According to the James-Lange theory,
emotional feelings result from the body’s
action
• Panic attacks are marked by extreme
sympathetic nervous system arousal (rapid
heartbeat, fast breathing, etc.)
– Only if perceived as occurring
spontaneously
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Emotions, Autonomic Arousal, and the
James-Lange Theory (cont’d.)
• Creating certain body actions may also
slightly influence emotion
– Smiling slightly increases happiness
– Inducing a frown leads to the rating of
stimuli as slightly less pleasant
• Indicates that perception of the body's actions
do contribute to emotional feeling
• However, body’s actions are not required
– Example: Möbius syndrome
–
(see a video here: https://www.youtube.com/watch?v=Qh8vxzLirf4 )
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Brain Areas Associated with Emotion
• Emotional experiences arouse many areas of
the brain
• The limbic system includes the forebrain
areas surrounding the thalamus
– Traditionally been regarded as critical for
emotion
• PET and fMRI studies also suggest many
other areas of the cerebral cortex, especially
the frontal and temporal lobes, are activated
during an emotional experience
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Brain Areas Associated with Emotion
(cont’d.)
• Measurement of evoked responses indicate
the brain is specialized to attend strongly to
facial expressions
• Emotions tend not to be localized in specific
parts of the cortex
• A single emotion increases activity in various
parts of the brain
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Brain Areas Associated with Emotion
(cont’d.)
• Localization in the brain seems to
exist for the emotion of disgust
• The insular cortex is strongly
activated during exposure to
stimuli perceived as “disgusting”
– Also the primary taste cortex
– Also reacts to frightening
stimuli and angry faces, so not
completely dedicated to
disgust
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Brain Areas Associated with Emotion
(cont’d.)
• The two hemispheres of the brain play
different roles in emotion
• Activation of the frontal and temporal areas of
the left hemisphere is associated with
“approach” and the Behavioral Activation
System
– Marked by low to moderate arousal
– Can characterize either happiness or anger
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Brain Areas Associated with Emotion
(cont’d.)
• The Behavioral Inhibition System (BIS) is
associated with increased activity of the
frontal and temporal lobe of the right
hemisphere
– Increases attention and arousal
– Inhibits action
– Stimulates emotions such as fear and
disgust
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Brain Areas Associated with Emotion
(cont’d.)
• Differences in frontal cortex activity relates to
personality
• People with greater activity in the left
hemisphere tend to be happier, more outgoing, and friendlier
• People with greater right hemisphere activity
tend to be socially withdrawn, less satisfied
with life, and prone to unpleasant emotions
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Brain Areas Associated with Emotion
(cont’d.)
• The right hemisphere seems to be more responsive
to emotional stimuli than the left
• Damage to the right temporal cortex causes
problems in the ability to identify emotions of others
• Wada test: One hemisphere at a time was
anesthetized by drug injection into one of the carotid
arteries, which provide blood to the head, used
before certain kinds of brain surgery.
•
See video : https://www.youtube.com/watch?v=SBKc_ncPzOo
• When the right hemisphere is inactived, people do
not experience strong emotions and don’t remember
feeling them
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The Functions of Emotions
• Functions of emotions include:
– Adaptive values (fear leads to escape,
anger lead to attack, etc.)
• Allow us to make quick decisions
• Help us make moral decisions
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The Functions of Emotions (cont’d.)
• The consequences of our decisions have
emotional considerations
• Emotions are an important component to
moral decisions
• Failure to anticipate the unpleasantness of an
event can lead to bad decision making
• Contemplating moral decisions activates the
prefrontal cortex, cingulate gyrus, and
amygdala
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The Functions of Emotions (cont’d.)
• Damage to the prefrontal cortex impairs
decision making
• Leads to impulsive decision-making without
pausing to consider consequences
• Stems from failure to anticipate
unpleasantness of an outcome
– Example: Phineas Gage
• Those with damage to the ventromedial
prefrontal cortex show decreased guilt
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The Functions of Emotions (cont’d.)
• Phineas P. Gage was an
American railroad
construction foreman
remembered for his
improbable survival of an
accident in which a large
iron rod was driven
completely through his
head, destroying much of
his brain's left frontal lobe.
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The Functions of Emotions (cont’d.)
• Damasio (1994) examined a man with prefrontal cortex
damage who expressed almost no emotions.
• Nothing angered him. He was never very sad, even about
his own brain damage. Nothing gave him much pleasure,
• Rational, but he frequently made bad decisions that cost
him his job, his marriage, and his savings.
• When tested in the laboratory, he successfully predicted
the probable outcomes of various decisions, but he
apparently did not anticipate that one action would win him
approval would feel good and trouble would feel bad
• Failure to anticipate the unpleasantness of likely outcomes
leads to bad decisions.
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Attack and Escape Behaviors
• Attack and escape behaviors are closely
related physiologically and behaviorally
• Related with the sympathetic nervous system
(fight-or-flight system)
• Corresponding behaviors are anger and fear
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Attack Behaviors
• Pain, threat, or other unpleasant stimuli can
trigger an attack behavior
• Attack behaviors are associated with
increased activity in the the amygdala
• After experiencing a provocation, people are
more likely to attack for a period of time
afterwards
• An initial attack behavior increases the
probability of a second attack behavior
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Attack Behaviors (cont’d.)
• Environmental factors associated with
increased violent tendencies include:
– Exposure to lead which is harmful to
developing brains.
• Since the banning of lead-based paints
and the rise of unleaded gasoline, the
prevalence of violent crime has declined,
– Witness or victim of violence in childhood
– Living in a violent neighborhood
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Attack Behaviors (cont’d.)
• Twins studies suggest genetic contribution to
the likelihood of violent behavior
• Monozygotic twins resembled each other
much more than dizygotic twins with regard to
violent and criminal behavior
• Attempts to identify a specific gene have
found only a weak effect
– Example: one gene linked to aggression
only found among people with Finnish
ancestry
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Attack Behaviors (cont’d.)
• Hormones also influence aggressive behavior
• Male aggressive behavior is influenced by the
hormone testosterone
• On average, males engage in more
aggressive and violent behaviors than do
females
• Research shows that men with the highest
rates of violent behavior also have slightly
higher testosterone levels
•
Watch video: https://www.youtube.com/watch?v=ZU4urdgp67s
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Attack Behaviors (cont’d.)
• “Triple imbalance hypothesis”: violence depends on
other chemicals besides testosterone, notably cortisol
(stress hormone) and serotonin
– Aggression levels are highest when cortisol levels
are low and testosterone levels are high
• Cortisol increases fear
– Serotonin tends to inhibit violent impulses
– Increased testosterone levels in women, increased
importance of social status, and decreased ability
to recognize angry faces
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Attack Behaviors (cont’d.)
• Testosterone alters the way people respond
to stimuli
– May increase the response of the
amygdala to angry expressions
– Decreases ability of the cerebral cortex to
identify and regulate emotion
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Attack Behaviors (cont’d.)
• Studies also suggest a connection between
aggressive behavior and low serotonin
release.
• Turnover is the amount of a neurotransmitter
that is released, reabsorbed and
resynthesized by neurons
• Valzelli’s (1973) study with male juvenile mice
found that social isolation decreased
serotonin turnover and increased aggressive
behavior
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Attack Behaviors (cont’d.)
• 5-hydroxyindoleacetic acid (5-HIAA) is a
serotonin metabolite found in the
cerebrospinal fluid, blood, and urine that
allows researchers to infer turnover rate
• High levels of 5-HIAA imply much serotonin
release and turnover
• Research with monkeys has demonstrated
that low levels of 5-HIAA increases the
probability of attack on larger monkey
– Few survived past age six
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Attack Behaviors (cont’d.)
• Monkeys with high levels of 5-HIAA were
more likely to survive
• Evolution seems to select for an intermediate
amount of anxiety and aggression
• Evolution might also select for high
aggressive behaviors
– May die young, but are more likely to
achieve a dominant position within the
troop
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Attack Behaviors (cont’d.)
• In human studies, low serotonin turnover has
been linked to:
– People with a history of violent behavior
and violent crime
– People who attempt suicide by violent
means
– Recurrent violent behaviors
• A simple blood test does not enable the
reliable identification
• Not applicable in the “normal” population
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Attack Behaviors (cont’d.)
• Changes in diet can alter serotonin synthesis
• It would seem prudent for anyone with
aggressive or suicidal tendencies to reduce
consumption of aspartame and maize
(American corn)
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Fear and Anxiety
• Proneness to approach, avoidance, and
anxiety varies with the situation
• Amygdala is one of the main areas for
integrating both environmental and genetic
influences and then regulating current levels
of anxiety
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Fear and Anxiety (cont’d.)
• The startle reflex is the extremely fast response to
unexpected loud noises
– Found in young infants
• Auditory information stimulates an area of the pons
that commands the tensing of the neck and other
muscles (because neck is so vulnerable to injury)
– Information reaches the pons within 3 to 8
milliseconds after
– The startle response occurs within two-tenths of a
second
•
See a video: https://www.youtube.com/watch?v=PTz-iVI2mf4
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Fear and Anxiety (cont’d.)
• Current mood or situation can modify the
reaction
• Startle reflex is more strong if already tense
• Cells in the amygdala receive information
from pain, vision, and hearing circuits
• Axons extend to areas in the midbrain that
relay information to the nucleus in the pons
• The relay controls the startle reflex
•
See a video for an example of a startle response: https://www.youtube.com/watch?v=FNlfKBR0uAM
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Fear and Anxiety (cont’d.)
• Output from the amygdala to the
hypothalamus controls autonomic fear
responses such as increased blood pressure.
• Axons extending from the amygdala to the
prefrontal cortex regulate approach and
avoidance responses
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Fear and Anxiety (cont’d.)
• Damage to the amygdala interferes with:
– The learning of fear responses
– Retention of fear responses previously learned
– Interpreting or understanding stimuli with
emotional consequences
• When Toxoplasma gondii parasites enters a rat, it
damages the amygdala. The rat fearlessly
approach a cat, and get eaten by a cat.
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Fear and Anxiety (cont’d.)
• In the early 1900s, studies of monkeys with
Kluver-Bucy syndrome illustrated the effects
of amygdala damage
• Monkeys with this syndrome are calm and
placid and display less than normal fear of
snakes and larger, more dominant monkeys
• Also alters social behaviors in that they have
decreased ability to interpret threat gestures
• Non-damaged monkeys with a vigorously
active amygdala show fear to noise/intruder
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Fear and Anxiety (cont’d.)
• fMRI studies suggest the amygdala responds
strongly to emotional stimuli/facial
expressions
• Activity is strongest when the meaning is
unclear and requires some processing
• Responds more strongly to an angry face
directed toward the viewer and frightened
faces directed elsewhere
• Amygdala also responds to stimuli not
consciously perceived
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Fear and Anxiety (cont’d.)
• People’s tendency for anxiety remains fairly
consistent over time
– College students who reported more unpleasant
emotions showed higher amygdala response than
others one year later
– Soldiers with initial high levels of amygdala
response showed more combat stress
• People with a greater startle response show more
support for military and guns. People with a highly
reactive amygdala are likely to perceive dangers, and
therefore to support strong protection against those
dangers.
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Fear and Anxiety (cont’d.)
• In humans, damage to the amygdala does
not result in the loss of emotion
• Damage to the amygdala impairs the
processing of emotional information
• People with damage recognize the cognitive
aspects of emotions, but not the feeling
aspect
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Fear and Anxiety (cont’d.)
• Urbach-Wiethe disease: rare genetic
condition that causes calcium to build up into
the amygdala until it wastes away
– Case study of SM
– Experiences fearlessness that is
dangerous to her: robberies at gunpoint,
physical assaults, no inhibition when
strangers approach
– Reports feeling angry but not afraid in
response to these incidents
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Fear and Anxiety (cont’d.)
• Amygdala damage also affects the ability to
recognize emotions specifically in
photographs or pictures
– Effect is particularly strong for fear or
disgust
• Amygdala damage does not affect the ability
to recognize fear in real life
– Attention to certain aspects of the face
(eyes versus mouth) may account for the
difference
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Anxiety Disorders (cont’d.)
• Panic disorder: frequent periods of anxiety
and occasional attacks of rapid breathing,
increased heart rate, sweating, trembling, etc.
– More common in women than men; more
common in adolescents and young adults
– Possible genetic component
– Seems to be linked to abnormalities in the
hypothalamus
– Decreased GABA, increased orexin
(maintaining wakefulness and activity)
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May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.
Anxiety Disorders (cont’d.)
• Drugs that increase GABA activity inhibit
panic
• Benzodiazepines are the most commonly used
anti-anxiety drugs
– Examples: diazepam (Valium), alprazolam
(Xanax)
• Benzodiazepines bind to the GABAA receptor,
and facilitate the effects of GABA
• Benzodiazepines exert their effects in the
amygdala, hypothalamus, midbrain, and other
areas
© 2013 Cengage Learning. All Rights Reserved. This edition is intended for use outside of the U.S. only, with content that may be different from the U.S. Edition.
May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.
© 2013 Cengage Learning. All Rights Reserved. This edition is intended for use outside of the U.S. only, with content that may be different from the U.S. Edition.
May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.
Anxiety Disorders (cont’d.)
• Alcohol as an Anxiety Reducer
– Ethyl alcohol has behavioral effects similar
to benzodiazepines
– Alcohol enhances GABA effects
© 2013 Cengage Learning. All Rights Reserved. This edition is intended for use outside of the U.S. only, with content that may be different from the U.S. Edition.
May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.
Concepts of Stress
• Hans Selye (1979) defined stress as the nonspecific response of the body to any demand
made upon it
• Threats on the body activate a general
response to stress called the general
adaptation syndrome
© 2013 Cengage Learning. All Rights Reserved. This edition is intended for use outside of the U.S. only, with content that may be different from the U.S. Edition.
May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.
Concepts of Stress (cont’d.)
• The general adaptation syndrome:
– Alarm stage: increased sympathetic nervous
system activity
– Resistance stage: sympathetic response
declines; adrenal cortex releases cortisol and
other hormones; prolonged alertness
– Exhaustion stage: occurs after prolonged
stress; inactivity, vulnerability, and decreased
energy, tiredness
© 2013 Cengage Learning. All Rights Reserved. This edition is intended for use outside of the U.S. only, with content that may be different from the U.S. Edition.
May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.
Concepts of Stress (cont’d.)
• Sapolsky (1998) argues that the nature of
today’s crises are more prolonged (such as
advancing in a career, paying a mortgage)
• Accounts for widespread stress-related
illnesses and psychiatric problems in
industrial societies
• Long-term, inescapable issues activate the
general adaptation syndrome which is
harmful to our health over time
© 2013 Cengage Learning. All Rights Reserved. This edition is intended for use outside of the U.S. only, with content that may be different from the U.S. Edition.
May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.
Stress and the HypothalamusPituitary-Adrenal Cortex Axis
• Stress activates two systems in the body:
– The sympathetic nervous system: “fight or
flight” response that prepares the body for
brief emergency responses
– The HPA axis: the hypothalamus, pituitary
gland, and adrenal cortex
© 2013 Cengage Learning. All Rights Reserved. This edition is intended for use outside of the U.S. only, with content that may be different from the U.S. Edition.
May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.
© 2013 Cengage Learning. All Rights Reserved. This edition is intended for use outside of the U.S. only, with content that may be different from the U.S. Edition.
May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.
Stress and the HypothalamusPituitary-Adrenal Cortex Axis (cont’d.)
• The HPA axis becomes the dominant
response to prolonged stressors
• Activation of the hypothalamus induces the
pituitary gland to secrete adrenocorticotropic
hormone (ACTH)
• ACTH stimulates the adrenal cortex to
secrete cortisol
• Cortisol helps to mobilize energies to fight a
difficult situation
© 2013 Cengage Learning. All Rights Reserved. This edition is intended for use outside of the U.S. only, with content that may be different from the U.S. Edition.
May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.
Stress and the HypothalamusPituitary-Adrenal Cortex Axis (cont’d.)
• The effects of stress depend on amount and
duration
• Brief or moderate stress improves attention
and memory formation performance on
relatively simple tasks
• It impairs performance that requires complex,
flexible thinking
© 2013 Cengage Learning. All Rights Reserved. This edition is intended for use outside of the U.S. only, with content that may be different from the U.S. Edition.
May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.
Stress and the HypothalamusPituitary-Adrenal Cortex Axis (cont’d.)
• In response to a stressful experience, the
nervous system activates the immune system
• Prolonged stress response is damaging to
the body
• Prolonged increase of cortisol detracts from
the synthesis of proteins of the immune
system
• Prolonged stress of longer than a month
significantly increases the likelihood of illness
© 2013 Cengage Learning. All Rights Reserved. This edition is intended for use outside of the U.S. only, with content that may be different from the U.S. Edition.
May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.
Stress and the HypothalamusPituitary-Adrenal Cortex Axis (cont’d.)
• Prolonged stress can also be harmful to the
hippocampus and can affect memory
• Cortisol enhances metabolic activity in the
body
• When metabolic activity is high in the
hippocampus, the neurons are more sensitive
to damage by toxins or over-stimulation
• Stress also impairs the production of new
hippocampal neurons
© 2013 Cengage Learning. All Rights Reserved. This edition is intended for use outside of the U.S. only, with content that may be different from the U.S. Edition.
May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.
Stress and the HypothalamusPituitary-Adrenal Cortex Axis (cont’d.)
• A variety of ways exist to reduce stress or
control our response to it:
– Breathing routines, exercise, meditation,
distraction, and addressing issues
– Social support from a loved one helps to
reduce stress
• Reduces response in several brain
areas, including the prefrontal cortex
© 2013 Cengage Learning. All Rights Reserved. This edition is intended for use outside of the U.S. only, with content that may be different from the U.S. Edition.
May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.
Post-traumatic Stress Disorder
• Post-traumatic stress disorder (PTSD) occurs
in some people after terrifying experiences
and includes the following symptoms:
– Frequent distressing recollections
– Nightmares
– Avoidance of reminders of the event
– Exaggerated arousal in response to noises
and other stimuli
© 2013 Cengage Learning. All Rights Reserved. This edition is intended for use outside of the U.S. only, with content that may be different from the U.S. Edition.
May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.
Post-traumatic Stress Disorder
(cont’d.)
• Most PTSD victims have a smaller than
average hippocampus
• Severe stress elevated the cortisol secretion
and high cortisol damaged the hippocampus
• PTSD victims show lower than normal
cortisol levels after the trauma
• People with low cortisol levels may be illequipped to combat stress and more prone to
the damaging effects of stress
• The amygdala is essential for the extreme
© 2013 Cengage Learning. All Rights Reserved. This edition is intended for use outside of the U.S. only, with content that may be different from the U.S. Edition.
May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.