MCDB 3650
Class 13
Emotion and behavior
Good-based model of Choice: value ascribed
in the orbitofrontal cortex; action
(attention, motor output, etc) follows the
value
Humans with orbitofrontal lesions often have
eating disorders, risk-seeking, gambling, and
abnormal social behavior
Suggest we need individual neurons in the
OFC to encode value, to make “rational”
choices
•  When we make a choice, if we “think too much”, then we
don’t like choice that was made
•  If asked to explain why choosing something, also are later
unhappy with choice
“fast” part of our brain (not the prefrontal cortex) picks
unconsciously
“slow” part of our brain (prefrontal cortex) weighs options,
chooses consciously
If distracted, prefrontal cortex can be inhibited
i.e., I choose cake if I’m trying to hold something else in
my mind, but an apple if not distracted
Interes'ng reading Thinking Fast and Slow, by Daniel Kahneman Questions of Morality
On Radiolab, several questions about
morality were posed to people. Most
people were aligned on their answers
suggesting that morality is a fundamental
construct of the human condition
Some questions seemed easy
Some were harder. What made them
harder ? What “got in the way” of making a
quick decision?
Making Moral Decisions
•  When we are making these tough moral decisions,
different parts of are brain are ‘battling’ it out
–  the more developed part of the brain (prefrontal cortex) uses
logic—weighs consequences of loss of life
–  the more animalistic part of the brain (limbic system) says no,
(don’t kill your baby, don’t push a person)—”gut reaction”
“triune brain”
reptilian brain
limbic system
neocortex
Emotion
Physiological emotion: the autonomic nervous system
Increased heart rate
Increased blood flow/sweating
Visceral reaction (gastrointestinal response)
vs.
Feeling emotion (subjective)
Conscious awareness of the emotion
Papez circuit (early 1900s)
Removal of cortex with
preservation of
posterior hypothalamus:
“Sham rage”
“preprogrammed”
rage pathway?
Physiological emotion
Reticular formation: cardiovascular function,
respiration, swallowing, sleep/wake brain state,
and other widespread visceral motor and somatic
motor responses)
Hypothalamus: coordinator of emotional behavior:
input to the reticular formation
Output to the Autonomic nervous system
(smooth muscle, glands)
Sympathetic N.S.
Sympathetic: speeds up heart rate (Norepinephrine): physiological component of
emotional response
Parasympathetic (e.g. digestion, decrease heart rate): neurons in brainstem, long
projections to target muscles, uses Acetylcholine
Physiological responses happen in response to
input BEFORE you are consciously aware of
stimuli
but, injections of Norepinephrine, which
stimulate the sympathetic NS, can produce a
variety of behaviors/emotions depending on
context.
So, emotion results only partly from the
physiological response
Conscious component: feelings
The limbic system
Orbitofrontal and medial prefrontal
cortex, basal ganglia, thalamus,
amygdala
Remove medial temporal lobe
(includes good chunk of the limbic
system) in monkeys
Hyperactivity, hypersexuality, but
no excitement anger or fear
The cornerstone of the limbic
system is the amygdala
Emotional experience: feelings
The amygdala
links
Prefrontal cortical regions
that process sensory
information (awareness)
with
hypothalamus and brain stem
effector systems (expression
of emotional behavior)
and
memory (hippocampus)
Areas of the brain involved in emo2onal responses and reward responses are linked to decision making behavior (nucleus accumbens, VTA, substan' nigraa) The amygdala is involved in association of auditory
and aversive stimuli:
conditioned fear response in rats
(sound)
Consciousness
(pain)
Reticular formation
automatic freezing
behavior
Cut “1”: still elicit freezing behavior
Cut “3”; no freezing behavior
Hypothalamus
(blood pressure)
Amygdala can produce a response without
involvement of the cortex
Fear and the amygdala in humans
Amygdala lesion
I’m handing out three different
sets of data about emotional
processing
Please explore the data, draw
some conclusions, and be ready to
tell the rest of the class about it
Emo'onal influences on percep'on ADen'on and emo'on Emo'onal Regula'on What happens when emotional
regulation goes awry?
People with an absence of emotionà more
violent?
Or is it an excess of emotion?
Different kind of emotion?
Morality?
Frontal Lobe
•  The frontal lobe communicates with the emotional
brain(amygdala and hypothalamus)
•  Thus, thought to be involved in helping people
make “good” decisions in emotionally charged
situations
Impulse murderers have lower levels of metabolic
activity in the frontal cortex, while
criminals who have committed premeditated murder
have normal frontal cortex activity
Differences in emotional processing: lack of
control from frontal cortex?
16 apprehended offenders (“unsuccessful
psychopaths”)
13 “successful psychopaths” (not caught)
“Unsuccessful” subjects had
22.3 percent lower gray matter
in prefrontal cortex among (when
compared to controls)
imbalance in left vs right hippocampus
decreased frontal lobe activity
“Successful” criminals were normal in
these areas
Some correlations in repetitively
violent people
•  Lower activity in frontal cortex
•  Low resting heart rate
•  Lack of fear, or indifference in childhood
–  Suggesting problems in the amygdalamirror neuron connections
(on the other hand, extreme shyness can
translate into depression in adulthood)
Other factors: neurotransmitter
levels?
Fluctuation in serotonin may be important:
-- levels are low in animals when they are threatened
-- high in animals with dominant status
Serotonin inhibits secretion of stomach acid and
stimulates smooth muscle (physiological responses) but
also acts in many sites throughout the brain, on many
different serotonin receptors
Is there a connection between violence and serotonin levels?
People with depression have lower levels of serotonin
--Serotonin levels are measured by concentration of 5hydroxyindoleacetic acid (5-HIAA) in cerebrospinal
fluid (produced when serotonin is broken down by
monoamine oxidase, MAO)
-- Thus, low levels of serotonin could be
shortage of serotonin or
lack of MAO (in which case serotonin levels
might actually be high)
Women generally have lower levels of serotonin; men
have higher levels
Clinically depressed individuals have higher
blood flow in amygdala, orbitofrontal cortex
Other interesting things to consider:
Left and Right hemisphere
Damage to posterior frontal and anterior parietal
lobes on right side
Ø  Loss of expression of emotion
But not the person s subjective feeling of the emotion
(a lesion in the same place on the left side leads to
Broca s aphasia!)
•  Left hemisphere: positive emotions
•  Right hemisphere: negative emotions
•  Incidence of depression in patients with lesions of
the left hemisphere is much higher than in patients
with lesions of right hemisphere (lesions in right
hemisphere lead to cheeriness !)
General differences in activity between men and women
Left amygdala active when women feel disturbed
Right amygdala active when men feel disturbed