Chapter 5

Emotion

Contents
5.1 Emotion as Response Patterns: a. Neutral Control of
Emotional Response Patterns, b. Perception of Stimuli
Emotional Response

5.2 Expression and Regression of Emotion: Facial

Expression of Emotions, Neural Basis of
Communications of Emotions – Studies with Normal
Subjects, Studies of People with Brain Damage
 Emotion

Emotions are reactions that human

beings experience in response to
events or situations. It is a physical
and mental states brought on by
neurophysiological changes,
variously associated with thoughts,
feelings, behavioral responses and
a degree of pleasure or displeasure.
 Behavioral components: consists of
muscular movements that are appropriate
to the situation that elicit them.

a. Emotions as Autonomic components: facilitate the

Response behaviors and provide quick mobilization
Patterns of energy for vigorous movement.

Hormonal components: reinforce the

autonomic responses by the secretion of
two types of hormones from Adrenal
medulla- epinephrine, and
norepinephrine.
 Neural Control of
Emotional Response
Patterns

The amygdala plays a special role in physiological

and behavioral reactions to objects and situations
that have special biological significance.

Amygdala – The amygdala (the amygdaloid

complex) is located in the temporal lobes, consists
of several nuclei with different functions.
According to Turner and Herkenham (1991), the
major divisions of amygdala are –
i. Corticomedial group
ii. Basomedial group
iii. Central necleus
iv. Basolateral group
 The role of the amygdala in
organizing emotional responses
produced by aversive stimuli

i. When threatening increases, the production of Fos

protein increases (Pascoe and Kapp, 1985;
Campeau et al., 1991).
ii. When the central amygdala is stimulated by means
of electricity or amino acid, the animal shows
physiological and behavioral signs of fear and
agitation (Davis, 1992b) and produces stress
induced illness (Henke, 1982).
iii. Damages to the central nucleus reduces a wide
range of emotional behaviors and physiological
responses, blood levels of stress hormones are
lowered, less likely to develop ulcers or other form
of stress induced illness (Coover, Murison, and
Jellestad, 1992; Davis, 1992b; LeDoux, 1992).
The role of the central nucleus of the
amygdala in the development of
classically conditioned emotional
responses
LeDoux (1988) destroyed two regions –
lateral hypothalamus and the caudal
periaqueductal gray matter.
LeDoux and his colleagues (1992) have They found that lesions of the lateral
studied these responses in rats by pairing hypothalamus interfered with the change
and auditory stimulus with a brief in blood pressure and lesions of the
electrical shock delivered to the feet. caudal periaqueductal gray matter
interfered with freezing.
b. Perception of The amygdala does not decide
Stimuli with by itself to produce an emotional
Emotional response. Several kinds od
Significance stimuli from the very simple to
the very complex can produce
emotional reaction.
 i. Simple Stimuli: The Thalamus

Most emotional reaction, specially those

associated with defensive or aggressive
behaviors, have been around for a long time.
Lesions of primary auditory cortex do not
disrupt the learning or expression of
conditioned emotional response but lesions
of thalamus do (LeDous et al., 1984).
Destruction of MGM or the connection
between MGM and amygdala prevents rats
from learning a conditioned emotional
responses (Iwata et al., 1986; LeDoux et al.,
1986)
 ii. Complex Stimuli: Sensory Association
Cortex

Most of the emotional reaction involve more

complex stimuli, for example, the sight of a
particular person with whom we have had
unpleasant encounter.
The temporal pole of the amygdala receives
information from the visual, auditory, and
somatosensory association cortex.
A study by Downer (1951) showed the
importance of these connection.
Downer operated on a monkey-
- destroying the amygdala on the left side of the
brain and cutting the - corpus callosum
- anterior commissure, and
- optic chiasm.
The basolateral amygdala receives information
from the hippocampus as well as from the
thalamus and neocortex and this connection
appears to inform the amygdala when the animal
has encountered a dangerous situation.

Phillips and LeDoux (1992) found that

hippocampal lesions had no effect rats ability to
acquire a conditioned emotional response to a
tone. The animal showed no signs of fear when
they were placed in the apparatus where they
received several foot shocks.
 Social Situation: The Orbitofrontal cortex

Perceiving the meaning of social situation is obviously more

complex than perceiving individual stimuli. It involves
experiences and memories, inferences and judgments. This
skills are no localizes in any one part of the cerebral cortex,
but one region of the brain – the orbitofrontal cortex plays
special roles.

Orbitofrontal cortex is located at the base of the frontal

lobe.
It receives direct input from – the dorsal thalamus, temporal
cortex and ventral tegmental area and indirect inputs from –
amygdala and olfactory system.
Its outputs go to several brain regions – the cingulate cortex,
hippocampal formation, temporal cortex, lateral
hypothalamus, and amygdala.
The orbitofrontal cortex plays an important
role in emotional behavior is shown by the
effects of damage to this region.
In the mid 1800
Facial Expression of Emotions:
Innate Response

Charles Darwin (1872/1965) suggested that human

expressions of emotion have evolved from similar
expressions in other animals. He said that emotional
expressions are innate, unlearned responses consisting
of a complex set of movements of the facial muscle.

Research by Ekman and his colleagues (Ekman and

Friesen, 1971; Ekman, 1980) tends to confirm the
Darwin’s hypothesis that facial expression of emotion
uses an innate, species-typical repertoire of
movements of facial muscle.
 Neural Basis of Communication of
Emotions: Studies with Normal Subjects

Effective communication is a two way process.

Kraut and Johnston (1979) observed people in circumstances that

would be likely to make them happy and found that they were
more likely to smile when other people were present than when
they were alone.
Johnston et al. (1991) found that ten-month old children showed
this tendency.

Evidence indicate that recognizing other people’s emotional

expression and producing our own expressions involve particular
neural mechanism.
 Recognition of Other People’s Emotion

We recognize other people’s feelings by

means of visual and auditory.

Bryden, Ley and colleagues have found that

the right hemisphere plays a more important
role then left hemisphere in comprehension
of emotion.

Ley and Bryden (1979) prepared cartoon

drawings of five different people, each
displaying one of the five facial expressions,
ranging from negative to neutral to positive.

Ley and Bryden (1982) also investigated

perception of tone of voice.
 Expression of Emotion

When people show emotions with their

facial muscle, the left side of the face
usually makes a more intense
expression.

Sackhein and Gur (1978) study on

facial expression of emotion.

Moscovitch and Olds (1982) study on

facial expression of emotion.
 Neural Basis of Communication of Emotions Studies:
People with Brain Damage

Facial expression of emotion appear to be organized in

the brain stem but controlled by the frontal lobes.
The best evidence for this proposition comes from a
syndrome known as pseudobulbar palsy, caused by the
damage to the pathway between the motor cortex of the
frontal lobes and the cranial nerve nuclei of the lower
pons and medulla that control the facial muscles.
 Recognition of other People’s Emotions

Damage to the right hemisphere (especially

the caudal part) appears to impair the
recognition of emotions being expressed by
other people.
For example- Heilman, Scholes, and Watson,
(1975) study .
Heilman, Watson, and Bowers, (1983) study.

Visual and auditory recognition of emotions

also appears to be more of a right hemisphere
function than a left hemisphere function.
For example- DeKosky et al. (1980) study
Bowers and Heilman (1981) study
 Expression of Emotion

Left hemisphere lesion do not usually impaired

vocal expression of emotion.
For example- a person with Wernicke’s aphasia
usually modulates his or her voice according to
mood even though the words he or she says
make no sense.

Buck and Duffy (1980) study.