Outline
Emotional Enhancement of Memory
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Animal Models: One-trial
Avoidance Learning
• Rats placed on a
platform
• When they step down
they receive a shock
• Experimental treatment is
given after learning:
– Electrical brain stimulation
– Pharmacological treatment
– Hormone administration
• Days after treatment,
retention is tested (#
seconds on the platform)
One-trial Avoidance Learning:
Main Findings
Animal models of EEM
EEM model
Human studies
Discussion
The Yerkes-Dodson Law
• Predicts an inverted
U-shaped function
between arousal
and performance .
• There are optimal
levels of arousal for
each task.
• Too little arousal is
detrimental.
• Too much arousal
is detrimental, too.
Summary
Seconds
to step
down
from
platform
First Trial
Epinephrine
injection
(moderate
level)
Endogenous epinephrine
following a more sever
shock (Gold & McCarty,
1981)
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Summary
One-trial Avoidance Learning:
Post-encoding treatment
Seconds
to step
down
from
platform
First Trial
Hippocampal damage Amygdala damage
5 seconds 5 days
5 seconds 5 days
Summary
One-trial Avoidance Learning:
Post-encoding treatment
Seconds
to step
down
from
platform
First Trial
Peripheral b-blockers
5 seconds 5 days
Vagal nerve damage
5 seconds 5 days
Epinephrine doesn’t cross the blood-brain barrier
Mcgaugh 2000
Adrenal Demedullation
Studying Emotion & Memory
• Animal models
• Field studies
– Eye-witness
– “Red outs”
– Childhood abuse
• Laboratory
studies
Passive Avoidance
E: Epinephrine injection;
Active Avoidance
– Simulations
– Experimental
manipulations
• Patient studies
Sal: Saline injection
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Encoding Emotions
Hamman 1999
Encoding Emotions
Hamman 2002
PET study shows increased amygdala activation for positive,
negative, or interesting pictures relative to neutral pictures.
Subliminal Registration
Retrieving emotions
• Backward masking by neutral faces.
• 8/10 participants reported not seeing the
emotional faces.
Whalen 1998
The Subsequent
Memory Effect
The Story Paradigm: Section 1
(Neutral)
• PET study: Cahill et al.
(1996) presented neutral
and emotional films to
participants in the PET
• Imaging studies show
correlation of amygdala
activation with
subsequent memory
after delayed testing
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The Story Paradigm: Section 2
(Critical)
The Story Paradigm: Section 3
(Neutral)
Effects of Amygdala Damage I
Effects of Amygdala Damage II
• Participants
exposed to the
emotional version
of the story.
• Contradictory results
• Patient DR had damage
resulting from operations to
control epilepsy
• Potentially related to
location of damage in the
amygdala
• DR has abnormal perception
of fear – dissociation of
perceptual and mnemonic
consequences of amygdala
damage
• Patient BP has
Urbach-Wiethe
disease
• Memory
measured following
1-week delay.
(Cahill et al., 1995)
Controls
Patient
Effect of Beta-Blockers
Effect of Beta-Blockers
Arousing,
Placebo
• Participants received
beta-blocker treatment
1 hour prior to
encoding.
• Treatment did not
affect emotional
experience.
Neutral,
Placebo
Neutral Neutral Arousing Arousing
Placebo Beta-B Placebo
Beta-B
Arousing,
BetaBlockes
Neutral,
BetaBlockes
Results: Betablockers eliminate
enhancement of
memory for an
emotional portion
of a story (Cahill
et al., 1994)
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Post-encoding induction of arousal
• Clark et al. (1999)
• Stimuli: Neutral
words
• Post-training
vagal stimulation
(3 levels)
• Recognition
memory test
Normalized word
recognition score after 3
levels of vagal nerve
stimulation
Amygdala Effects on Multiple Memory Systems
Spatial task
Cued task
The Modulation Hypothesis
• Animal & human evidence
• Correspondence between animal and
human evidence
• “Converging evidence” from lesion,
pharmacological, and behavioral studies
• New directions – effects on nondeclarative memory
Problems with the Modulation
Hypothesis
• EEM in immediate testing
Hippocampus
Amygdala
Caudate
Packard, Cahill & Mcgaugh 1994
Short/Long-Term Consolidation
Problems with the Modulation
Hypothesis
• EEM in immediate testing
• Memory enhancement specific to
emotional items?
• Cognitive mediation mechanisms
• Serial vs. parallel short and long-term Izquierdo 1998
consolidation
• Each can be disrupted independently of the
other
• McGaugh’s model currently addresses LTM only
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Amygdala and Experience
• “emotion center in
the brain”
• Production in
bilateral amygdala
lesioned patients
• Phenomenology in
bilateral amygdala
lesioned patients
• Amygdala activation
for subliminal
material
Patient Boswell
• 63-year old man
• Extensive bilateral lesions in the MTL (including
hippocampus, PHG and the amygdala) and the
temporal cortex
• No perceptual, language, or motor impairment
• Severely amnesic for 15 years
• Cannot identify or report as familiar the faces of people
(e.g. caregivers) he met since the onset of his amnesia
– either explicitly or implicitly (SCR)
Patient Boswell’s Affective
Memory
Good guy-Bad guy
experiment:
– no explicit knowledge
(free/cued recall),
– but chose the “good guy” as
the person he would go to
for a treat
Good guy-Bad guy followup after 4 years:
– No explicit knowledge
– Clearly chose the “real-life”
good guys more than others
– Generated SCR to good
guy’s face
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