Chapter 11
Emotion
Emotions as response patterns
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Consists of 3 types of components:
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Behavioral – consists of muscular movements that are appropriate to
the situation that elicits them
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Autonomic – facilitate the behaviors and provide quick mobilization of
energy for vigorous movement
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e.g. dog defending its territory, growls and assumes aggressive posture
e.g. heart rate increase
Hormonal – reinforce the autonomic responses
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e.g. hormones secreted by the adrenal medulla (epinephrine and NE) further
increase blood flow to muscles
Fear
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Research with lab animals
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The integration of the 3 components of fear appears to be controlled by
the amygdala
Various nuclei of the amygdala become active when emotionally
relevant stimuli are presented
Major regions of the amygdala
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Medial nucleus – receives sensory input, including info about the presence
of odors, and relays it to the medial basal forebrain and hypothalamus
Lateral nucleus (LA) – receives sensory info from the primary
somatosensory cortex, assc. Cortex, thalamus and hippocampal formation;
sends projections to basal, accessory basal, and central nucleus of the
amygdala
Central nucleus (CE) – region of the amygdala that receives sensory info
from the basal, lateral, and accessory basal nuclei and projects to a wide
variety of regions in the brain; involved in emotional responses; damage to
the CE results in a reduction or abolishment of a wide range of emotional
behaviors and physiological responses
Fear
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Research with lab animals (con’t)
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CE important for aversive emotional learning
 Conditioned emotional response – a classically conditioned response
that occurs when a neutral stimulus (e.g. bell) is followed by an aversive
stimulus (e.g. shock); usually included autonomic, behavioral, and
endocrine components such as changes in heart rate, freezing, and
secretion of stress-related hormones
 However, if an organism can learn a coping response (a response that
terminates, avoids, or minimizes an aversive stimulus), the emotional
responses will not occur
 CE necessary for development of a conditioned emotional response
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Research with humans
Lesions of the amygdala decrease people’s emotional responses
 Damage to the amygdala interferes with the effects of emotions on
memory
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Anger and aggression
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Species-typical behaviors
Many related to reproduction (e.g. gain access to mate)
Threat behaviors – a stereotypical species-typical behavior that
warns another animal that it may be attacked if it does not flee or
show a submissive behavior; displayed more often than actual
attacks
Defensive behaviors – a species-typical behavior by which an
animal defends itself against the threat of another animal
Submissive behaviors – a stereotyped behavior shown by an animal
in response to threat behavior by another animal; serves to prevent
an attack
Predation – attack of one animal directed at an individual of another
species on which the attacking animals normally preys
Anger and aggression
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Neural control of aggressive behavior
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Particular muscle movements an animal makes in attacking or
defending itself are programmed by neural circuits in the brain stem
 Activity of these circuits controlled by hypothalamus and amygdala
 Defensive behavior and predation can be elicited by stimulating the
periaqueductal gray (PAG) of the cat’s midbrain
 The activity of serotonergic synapses inhibits aggression; while
destruction of serotonergic axons in the forebrain facilitates aggressive
attack
 5-HT does not simply inhibit aggression however, it appears to exert a
controlling influence on risky behaviors
 In human subjects, depressed rates of 5-HT release are associated with
aggression and other forms of antisocial behavior
 Functional imaging studies found an association b/t differences in the
genes responsible for production of 5-HT transporters and the reaction
of people’s amygdala to the viewing of facial expressions of negative
emotions
Anger and aggression
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Many investigators believe that impulsive violence is a consequence
of faulty emotional regulation
The prefrontal cortex plays an important role in recognizing the
emotional significance of complex social situations and in regulating
our responses to such situations
Orbitofrontal cortex – region of the prefrontal cortex at the base of
the anterior frontal cortex; its inputs provide it with info about what is
happening in the env’t and what plans are being made by the rest of
the frontal lobes, and its outputs permit it to affect a variety of
behaviors and physiological responses
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e.g. Phineas Gage – damage to orbitofrontal cortex caused change in
personality
Hormonal control of aggressive
behavior
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Many instances of aggressive behavior are in some way related to
reproduction; thus many forms of aggressive behavior are affected by
hormones
Aggression in males
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Inter-male aggressiveness begins around the time of puberty, suggesting that the
behavior is controlled by neural circuits that are stimulated by androgens
 Early androgenization has an organizational effect that stimulates the
development of testosterone-sensitive neural circuits that facilitate inter-male
aggression
 Males able to discriminate sex of another animal by pheromones in order to not
attack females, only other males
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Aggression in females
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Although not as common as in males, inter-female aggression appears to also be
facilitated by testosterone
 While in the womb, female mouse fetuses that are situated b/t two male fetuses
have significantly higher levels of testosterone
Hormonal control of aggressive
behavior
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Maternal aggression
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Most parents who actively raise their offspring will vigorously defend them
against intruders
 Usually begins during pregnancy; stimulated by progesterone (like nest building)
 However, if offspring are removed (e.g. via experimenter), or if the mother’s
nipples are surgically removed, will not display aggressive behaviors; this is due
to the necessity of either the pups’ odors or suckling stimuli
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Effects of androgens on human aggressive behavior
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Boys > girls
Socialization definitely effects this difference, but does biology too?
Prenatal androgenization increases aggressive behaviors in all species that have
been studied, including primates
Difficult to study lack of androgens in human subjects; thus, data with androgens
in humans not very reliable
Primary social effect of androgens may be not on aggression but on dominance
However, CORRELATION does not imply CAUSATION!
Hormonal control of aggressive
behavior
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Effects of androgens on human aggressive behavior
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Synthetic hormones given to patients with abnormally low levels of
testosterone (hypogonadal syndrome) does not increase
aggressiveness
 However, athletes who take steroids (which include natural androgens)
reported to be more hostile and aggressive; although may be other
reasons besides androgens for these behaviors
 Alcohol consumption may interact with the effects of androgen; alcohol
intake increases inter-male aggression in dominant squirrel monkeys,
but only during mating season
Communication of emotions
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Many species of animals, including our own, communicate their
emotions to others by means of postural changes, facial
expressions, and nonverbal sounds; they all serve useful social
functions
Facial expression of emotions
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Darwin suggested that human expressions evolved from similar
expressions in other animals; he said that they are innate, unlearned
responses consisting of a complex set of movements, principally of the
facial muscles
 People in different cultures use the same patterns of movement of facial
muscles to express a similar emotional state
 Display rules – a culturally determined rule that modifies the expression
of emotion in a particular situation
Communication of emotions
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Neural basis of the communication of emotions
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Recognition
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The ability to display one’s emotional state by changes in expression is
useful only if other people are able to recognize them
Emotional expressions greater when others present
Right hemisphere more important than left in comprehension of emotions;
found a left-ear and left-visual field advantage in recognition of emotionally
related stimuli
When a message is heard, the right hemisphere assesses the emotional
expression of the voice while the left hemisphere assesses the meaning of
the words
Patients with R hemisphere lesions have no trouble making emotional
judgments about particular situations, but were impaired in judging the
emotions conveyed by facial expressions or hand gestures (“Your house
seems empty without her” vs. “He scowled”)
Most severe damage to the ability to recognize facial emotional expressions
was caused by damage to the somatosensory cortex of the R hemisphere
Communication of emotions
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Neural basis of the communication of emotions
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Recognition (con’t)
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A possible explanation for this may be that when we see a facial expression
of an emotion, we imagine ourselves making that expression
Indeed, patients with R hemisphere damage had both somatosensory
impairments and impairments in recognition of emotions
Amygdala plays a special role in emotional responses; also, patients with
amygdala lesions have an impairment in recognizing facial expressions,
especially those of fear; however, can still recognize emotions in tone of
voice
Gaze (i.e. the direction the other person/animal is looking) is important when
recognizing facial expressions; helps interpret whether or not expression is
aimed at you
Damage to basal ganglia disrupts a person’s ability to recognize expressions
of disgust
Communication of emotions
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Neural basis of the communication of emotions
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Expression
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Automatic and involuntary
Genuinely happy smiles involve the contraction of a muscle near the eyes, the lateral
part of the orbicularis oculi
Facial expressions follow real emotions; difficult to express fully without any emotion
Volitional facial paresis – difficulty in moving the facial muscles voluntarily; caused by
damage to the face region of the primary motor cortex or its subcortial connections
Emotional facial paresis – lack of movement of facial muscles in response to emotions
in people who have no difficulty moving these muscles voluntarily; caused by damage
to the insular prefrontal cortex, subcortical white matter of the frontal lobe, or parts of
the thalamus
Anterior cingulate cortex may be involved in the muscular movements that produce
laughter; damage to this area impairs ability to understand and be amused by jokes
R hemisphere not only helps in recognizing emotion, but also more important for
expressing them; when people show emotions, the left side of face usually makes a
more intense expression
Communication of emotions
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Neural basis of the communication of emotions
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Expression (con’t)
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Wada test – a test that is often performed before brain surgery; verifies the
functions of one hemisphere by testing patients while the other hemisphere
is anesthetized
R hemisphere plays a role in “primary” emotions; i.e. negative emotions
Amygdala not involve in emotional expression
Feelings of emotions
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The James-Lange theory
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A theory of emotion that suggests that behaviors and physiological
responses are directly elicited by situations and that feelings of
emotions are produced by feedback from these behaviors and
responses
 Our own emotional feelings are based on what we find ourselves doing
and on the sensory feedback we receive from the activity of our muscles
and internal organs
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e.g. if we find ourselves trembling, we experience fear
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However, critiques say that internal organs are relatively insensitive,
and could not respond quickly, so feedback from them could account for
our feelings of emotions
 Theory difficult to verify experimentally
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Feedback from simulated emotions
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Feedback from the contraction of facial muscles can affect people’s
moods and alter the activity of the ANS