Chapter 10: Emotion The Limbic System Amygdala — Drives emotions

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The Limbic
System"
Chapter 10: !
Emotion!
Limbic = “border” between
forebrain and brainstem"
Amygdala — Drives emotions!
Amygdala Anatomy!
• Almond-shaped nucleus buried in the temporal lobe"
" "
control center for emotions."
" "
"
• single-unit recordings and fMRI show cells that are
responsive to emotional situations/stimuli"
• lesions decrease the number/intensity of emotions and their
physiological effects (e.g., ulcers)"
• stimulation evokes behavioral effects of strong emotional
states (e.g., fear or rage)"
Most important
for emotional
response to
aversive stimuli—
needed for
learning and
memory"
12 different nuclei"
5 important for emotions"
Central amygdala projects to …"
The Orbital and Medial
Prefrontal Cortex!
Genetic/Evolutionary Aspects"
of Facial Expressions!
• regulate emotions according to the circumstances"
• lesions cause erratic emotions"
" Phineas Gage"
(Video)"
Happiness
Sadness
• or a loss of emotions "
" (e.g., passivity; no longer bothered by pain)"
Fear
! Frontal lobotomy – a surgical
procedure that isolates orbitofrontal cortex
from the rest of the limbic system."
Neural
Circuits for
Facial
Expressions!
Anger
Orbito prefrontal
cortex + hypothalamus"
(Duchenne Smile:
includes eye squint)"
Lesion in right
hemisphere!
Lesion in left
hemisphere!
Disgust
Volitional facial paresis "
(RH lesion/LH paralysis) "
(a) only right side of face responds
when making volitional smile"
(b) Genuine smile works fine"
Emotional facial paresis!
(LH lesion/RH paralysis)"
(c) Has muscle strength to move
muscles on both sides of mouth"
(d) Genuine smile only engages left
side of face"
Right hemisphere dominance for
production of facial expressions!
So, left side of face shows expressions first"
R
"
L"
Amygdala and
hypothalamus
inputs to PAG!
Central
Nucleus"
Basal
Nucleus"
Neuropharmacological basis
of aggression"
Testosterone
increases aggression"
Dorsal PAG"
Medial
Hypothalamus"
• tectum"
" • superior colliculi" "
"
"
(colliculus = “little hill”)"
" "
controls eye movement to visual targets"
" • inferior colliculi"
" "
auditory processing"
• tegmentum"
" • periaqueductal gray matter"
" "
pain regulation"
" "
species-typical motor sequences"
" "
"
fighting, mating, etc."
" • red nucleus and substantia nigra"
" "
motor control"
" • reticular formation"
" "
sleep/arousal, attention, movement"
Amygdala"
Medial
Nucleus"
The Midbrain (Mesencephalon)!
Ventral PAG"
Lateral
Hypothalamus"
(Fig 10.4 from book; study done in cats)"
Defensive Rage"
Predation"
Excitation"
Inhibition"
(video)"
Birth position and aggression in
female rats!
0M, 1M, 2M females"
Increases in aggression
in 2M females relative
to 0M and 1M rats."
Neuropharmacological basis
of aggression"
Serotonin !
(5-HT, 5-hydroxytryptamine)
decreases aggression"
Thought to be due to
increases in prenatal
androgens."
Subjective Feelings of Emotion:
The James-Lange Theory!
Subjective feeling"
How we feel depends on
interpretation of the physical
changes (autonomic,
behavioral) that occur in
body as response to an
emotional event."
James-Lange Theory!
Environmental event
triggers behavioral,
autonomic, and
endocrine response."
Feedback from
responses produces
feelings of emotions."
With feelings, we are “self observers.”"
Subjective Feelings of Emotion:
The Cannon-Bard Theory!
Mimicry of emotions!
•#Support for JamesLange theory"
•#Even mimicking emotion
makes you feel emotion."
•#“Method” acting"
•#… if you want to feel
happier — try smiling!?"
happy"
An emotional event
simultaneously evokes the
feeling of the emotion and
the physical changes that
accompany it."
sad"
(This happens to be picture of baby
and mom, but studies were done on
two adults.)"
surprised"
Subjective Feelings of Emotion:
Schachter#s Cognitive Theory!
The physical changes
evoked by an
emotional event are
attributed to the
prevailing
environmental
conditions, leading to
an emotional feeling
that corresponds."
Misattribution of Arousal!
The outcome of Schachter and Singer#s study on the attribution of emotions. Subjects who were
misinformed or uninformed about the cause of their arousal felt either angry or euphoric, depending on whether a
confederate was angry or euphoric."
Capgras Delusion!
•#Mentioned in Ramachandran NOVA video."
•#Occurs when the emotional processing pathway
fails to produce the normal jolt of recognition in
response to a familiar person."
Cortical “who?” recognition pathway
ends in the frontal area with the
conscious acknowledgement that a
person is familiar.
CONSCIOUS AND
UNCONSCIOUS RECOGNITION
"
"
"
Visual Coretx
Emotional recognition
pathway passes through
limbic structures which give a
feeling of familiarity.
"
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