Affective Neuroscience
Leah Somerville, PhD
Sackler Institute for Developmental Psychobiology
Weill Medical College of Cornell University
What is emotion?
• “one of the most significant things ever
said about emotion may be that
everyone knows what it is until they are
asked to define it”
– Joseph LeDoux (1996)
What is emotion?
• Emotion = reflects a kind of motion outward
• An inferred complex sequence of reactions to
a stimulus including cognitive evaluations,
subjective changes, autonomic and neural
arousal, impulses to action, and behavior
designed to have an effect (functional) upon
the stimulus that initiated the complex
sequence (Plutchik, 1982)
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Inferred
Reaction
Functional
***Cognitive appraisal, feeling, and action***
Today’s agenda
1. What are emotions and do they have a
purpose?
2. How does we study emotions in the
laboratory?
3. What brain circuits support emotional
processes?
4. How does emotion go awry in
psychiatric conditions?
What are emotions and do
they have a purpose?
A brief History of Affective
Neuroscience
• The Expression of the Emotions in Man and
Animal, Charles Darwin (1872)
– Emotions are similar across species and cultures.
James-Lange Theory of emotion
(late 1800s)
Physiology  Appraisal
“My heart is pounding, so I must be afraid.”
Cannon-Bard Theory of emotion
(1920s)
Appraisal  Physiology
“I feel afraid, so my heart pounds.”
Where these theories fall short
• J-L: Assumes there is
a unique physiological
signature to each
emotion.
• C-B: Physiological
responses are
generated so quickly,
it’s unlikely that we
could have perceived
the emotion first.
Schachter Two Factor Theory
(Schachter and Singer, 1962)
Physiology + Context  Feeling and action
Schachter & Singer’s classic
study
• Shot of adrenaline to participants
– Explained as having arousing
side effects or not mentioned
• Placed in room with happy or angry
confederate
• Participants with no explanation for
arousal experienced happiness or
anger
There is still debate about what an emotion “is”, but
nowadays it is agreed on that it involves interactions
between physiology, feeling, and context.
Adaptive purpose of emotions
• Emotions induce motivation
Spring us into action
Lower sensory thresholds
Facilitates learning
- enhance memory
- modulates appropriate
approach/avoidance behavior
- the arousal associated with
emotions facilitates performance
(to a certain extent)
Yerkes-Dodson law
How do we study emotions?
Affective Neuroscience
Toolbox
• Animal models (especially fear)
• Lesion studies
• Psychophysiology
– Heart Rate
– Skin conductance (ANS arousal)
• Neuroimaging:
– fMRI (Hemodynamic response)
• Various other electrophysiology
techniques
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Electroencaphalography
Magnetoencephalography
Single unit recordings
Transcranial magnetic stimulation
How to study emotion in the lab?
• Tapping into emotional experiences and perception
– Make people emotional in the lab
– Mood inductions
– Paradigms that induce fear or anxiety (threat-of-shock) or other
emotions (displaying evocative imagery)
– Measure responses to emotional cues (facial expressions)
• Tapping into emotional regulation and the outcome of
experiencing emotion
– Induce emotion  measure subjects’ ability to dampen
– Measure how emotions facilitate secondary behaviors (memory,
action)
• Directly test individuals who experience emotional
dysregulation
– Psychiatric illnesses involving fear, anxiety, depression
Understanding the
neurobiology of emotions
Functional Neuroanatomy of Emotion
Anterior Cingulate
Dorsomedial
Prefrontal
Cortex
Orbital
Nucleus Accumbens
Amygdala
Ventral Pallidum
Dalgleish, 2004
Hypothalamus
Appraisal
Experience
Action
The Amygdala
Hippocampus
Amygdala
© BrainConnection.com
The amygdalae are almond shapes bodies located in bilateral medial temporal lobe.
Klüver-Bucy Syndrome (1939)
• Bilateral removal of temporal cortex in monkeys.
• Drastic Change in behavior:
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Loss of emotional reactivity,
Hypersexuality,
Orality,
Disrupted social behavior,
Falling in social standing.
• Weiskrantz (1956) bilateral lesions of amygdala produced
similar behavioral changes.
• Improved methods (ibotenic acid lesions) showed that central
site is amygdala (e.g. Murray et al., Behavioral Neuroscience, 1996)
Pavlovian Conditioning
Conditioned
Stimulus (CS)
Unconditioned
Stimulus (US)
Conditioned
Response
Fear Conditioning
Defensive Behavior
ANS arousal
Hypoalgesia
Reflex potentiation
Stress hormones
Ledoux, 1995
Auditory
fear
conditioning
Information
about the CS is
integrated with
information
about the US
within the
amygdala.
Phelps and Ledoux, 2005
Fear conditioning in humans
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LaBar et al., 1998
Insights on the role of the
amygdala in appraising
emotions from Patient SM
S. M.
Insights on the role of the
amygdala in appraising
emotions from Patient SM
Adolphs et al. 1994
Adolphs et al.,
1995
• Subject with bilateral
amygdala lesions was
asked to draw facial
expressions of
emotions.
Amygdala lesions disrupt
physiological responding to
conditioned cues in humans
Labar et al., 1998
Processing emotional cues in the environment
Something really bad is going on near us, and you’d
do well to find out what I know
Amygdala and healthy adults
• Amygdala responses to fearful faces in normal humans (Breiter et
al., 1996).
•(Breiter et al., 1996)
Rapid processing in humans
33 (17) msec
Whalen, P. J. et al. J. Neurosci. 1998;18:411-418
Copyright ©1998 Society for Neuroscience
Whalen et al., 2004
Amygdala response habituates
Breiter et al., 1996
However, the role of the
amygdala in emotion
processing is even more
complicated than we thought
Resolving emotional
ambiguity
Facilitating learning
What conclusions can we draw
about the role of the amygdala in
emotional processing?
• An intact amygdala is necessary for the
acquisition and expression of fear (animal, lesion
patients)
• In humans, the amygdala carries the more
general role of detecting and learning about
important information in the environment.
– motivational salience account
Appraisal
Experience
Action
Emotions serve an important
function, but we also need to be
able to put on the brakes.
On the outside
On the
Inside
Emotion regulation
• The capacity to modify an emotional
experience
– 2 examples
• Fear extinction
• Active reappraisal
Functional Neuroanatomy of Emotion
Anterior Cingulate
Dorsomedial
Prefrontal
Cortex
Orbital
Nucleus Accumbens
Amygdala
Ventral Pallidum
Dalgleish, 2004
Hypothalamus
Fear extinction
Conditioned
Response
Fear extinction
Extinction and the MPFC
• The ventromedial prefrontal cortex is critical to
emotion regulation
• Enables new learning of a
positive interpretation of the
once-negative stimulus
• Dampens amygdala response
via direct inhibitory gating
• Behavior: no response to
previous fear cue
Animal findings
Milad & Quirk, 2002
Lesions to rodent infralimbic cortex prevent the retention of
extinction memories
Human findings
VMPFC recruitment facilitates retention of extinction memory
VMPFC and regulation of
reward approach
Bechara et al., 2005
Behavioral Results
(Bechara et al., 1999)
$100 wins
$50 wins
Skin Conductance Results
(Bechara et al., 1999)
Results
• Healthy control participants developed:
– “Hunches” about how to maximize wins.
– Showed elevated SCR responses in anticipation of
outcomes after poor choices.
• Patients with ventromedial PFC damage:
– Performed poorly on task (risky/low payoff
choices).
• Did not maximize wins and losses.
– Did not show elevated SCR responses after poor
choices.
Kim et al., 2003
Kim et al., 2003
Emotion regulation via Cognitive Reappraisal
Ochsner et al., 2002; 2004
Ochsner et al., 2002
Amygdala activity modulated by regulation strategy
Ochsner et al., 2004
The story isn’t so simple – VMPFC may
also be involved in reappraisal
• Other studies have
used similar
paradigms to show
the VMPFC
engaged while
actively
downregulating
emotion
• Extinction == learning a new
interpretation of a previously aversive
cue
VMPFC
• Reappraisal == using cognitive
strategies to actively ‘spin’ a new
interpretation of a previously aversive
VMPFC, VLPFC
cue
Emotions & Psychopathology
• The symptoms of many psychiatric illnesses
involve inappropriate emotional responses
and/or ineffective emotion regulation
PTSD, phobias : Hyperresponsive emotional
appraisal? Failure to extinguish?
Depression : Failure to reappraise?
This field is still a work-in-progress!
Anxiety disorders and
engagement of emotion circuitry
Meta-analysis Etkin & Wager, 2007
PTSD: failure to extinguish?
PTSD:
Hyper-responsive
amygdala
Hypo-responsive
VMPFC
Summary by Milad et al., 2006
Depression: failure to
reappraise?
Johnstone et al., 2008
Take-home points
• Emotions are complex reactions involving feelings, physiological
reactions, and contextual interpretations.
• The generation and experience of emotion is primarily modulated
through interactions between subcortical and cortical brain structures
including the amygdala and subregions of the prefrontal cortex.
• The amygdala plays a critical role in emotional learning and generating
appropriate responses to environmental cues.
• The VMPFC and VLPFC interact with subcortical structures like the
amygdala to modulate emotional responses.
• Dysfunctional subcortical-cortical interactions play an important role in
the pathophysiology of many psychiatric illnesses.