Transcript c83lnp: Neuropsychology - University of South Carolina

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Emotion and Meaning
• Chris Rorden
www.mricro.com
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Temporal lobectomy
 Brown and Schäfer (1888) reported
behaviour of monkey ‘Tame one’ after
bilateral temporal lobectomy.
 Preop: wild, fierce
 Postop:
– Does not retaliate or escape if slapped,
tame
– Poor memory and intelligence
– Evidence of hearing and seeing, but ‘no
longer clearly understands meaning of
sights, sounds.’
– Does not select raisins from other food in
dish: does not seem to visually recognize
items.
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A: Klüver-Bucy Syndrome
Klüver-Bucy (1938) rediscover Brown
and Schäfer.
– Tameness
– Visual Agnosia
– Hyperorality (examines objects with mouth)
– Compulsive attention to visual stimuli
– Hypersexuality
– Lack of social skills
– Change in diet (eats more meat)
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B: Klüver-Bucy Syndrome
Is KB syndrome unitary (all symptoms, or
none) or do specific focal lesions cause
components:
– Visual Recognition: Inferior Temporal Cortex
Mishkin & Pribham (1954).
– Emotion: Damage to just amygdala
Weiskrantz (1954)
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Role of Amygdala
 Primate amygdala damage:
– Function of amygdala or traversing fibre tracts?
– Exitotoxic lesions [destroy cell bodies, spare fibres]
suggest amygdala plays role in processing emotion.
 For review: Calder et al. (2001).
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A: Amygdala and social judgement
 Adolphs et al. (1998) asked people to judge the
‘approachability’ and ‘trustworthiness’.
– Photographed faces: Patients with bilateral
amygdala damage gave more positive ratings than
controls or patients with unilateral lesions.
– Written biographies: Patients showed similar ratings
to controls.
 Conclusion: words directly evoke information,
do not require amygdala. Unfamiliar faces must
be matched to prior experiences.
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B: Results
Judgements of photographs:
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A: Bechara et al. 1999
Emotional deficits seen following damage
to amygdala and ventromedial frontal
damage.
Are these due to the same functional
deficits? Or are separate processes
involved?
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B: Amygdala patients
5 patients with bilateral amygdala
damage
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C: Ventromedial Frontal patients
5 patients with Ventromedial Frontal
lesions.
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D: Task
 Gambling task
– Decks A&B disadvantageous: you lose over time
 $100 per win, occasional huge losses (e.g. up to $1250)
 Net loss
– Decks C&D advantageous: you win over time
 Only $50 per win, but small losses
 More wins than losses
– Players must play each deck to discover if it is
beneficial or bad.
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E: Behavioural Results
 Controls learn to avoid A & B, both patient groups begin to rely on
them (hoping for big win to counter mounting losses).
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F: Anticipatory SCRs
 Skin conductance responses (SCR, lie detector)
measure of emotional state.
 SCR generated prior to picking a card.
– In controls, bigger SCR prior to picking from the ‘high risk’ deck
– Patients do not show difference between decks in this
anticipatory measure.
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G: SCRs in response to gain/loss
 Controls show strong SCR in response to wins/losses.
Big loss when losing with decks A&B leads to amplified
SCR.
 VMF patients also generate SCR to wins/losses.
 Amygdala patients show little SCR.
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H: Conclusions
Both groups impaired in decision making.
– Surprising for amygdala group: they have
intact frontal lobes.
Amygdala plays role in generating initial
emotional responses.
VMF required to integrate emotional
responses and develop winning
strategies.
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A: Clark et al. 2003
Bechara show Ventromedial frontal
patients choose poorly on the Iowa
gambling task.
Clark et al examine patients with lateral
prefrontal cortex damage
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B: Results
Controls and Left hemisphere patients
learn to avoid disadvantageous decks.
Right patients persist taking more cards
from disadvantgeous deck
 In figure: negative score means more cards from bad
decks than good decks.
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A: Amygdala and visual processing
 Anderson & Phelps (2001) examined visual
performance in patient with bilateral amygdala
damage.
 ‘Attentional Blink’ task:
– Asked to report green words presented in a rapidly
displayed stream of black words.
– Following a target (T1), people tend to miss a
second target (T2) unless there is a long delay.
– This ‘attentional blink’ is reduced if T2 is an
emotionally salient word (like ‘sex’).
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B: Task
Schematic of ‘attentional blink’ task.
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C: Results
 Controls: (open symbols)
– Less attentional blink for  negative than  neutral words.
 Amygdala patient: (filled symbols)
– No difference between  negative and  neutral words.
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D: Conclusions
 Patients with right amygdala damage appear
similar to controls.
 Patients with left damage are similar to bilateral
patient.
 Suggests amygdala not only involved with
memory, but also initial perceptual awareness:
– Amygdala ensures important events receive extra
processing.
– Role in vigilance.
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A: LeBar and Phelps (1998)
Healthy people show stronger skin
conductance responses (SCR, lie
detector) to arousing words.
Healthy people also remember arousing
words more than neutral words.
 Psychological Science (1998), 9, 490-493.
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B: LeBar and Phelps (1998)
Patients with unilateral temporal lobe
damage (including amygdala) show
normal SCRs!
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C: Conclusions
– LeBar and Phelps argue that ‘only control subjects exhibited an increase in
memory for arousing words over time’
– Is the difference due to emotional nature of words, or shoddy memory in
patients?
– Right (RTL) patients show control-like pattern of better performance for
arousing than control words, though L&P argue they have different patterns of
memory decay (Controls remember arousing words, RTL patients forget).
– Left (LTL) patients may be at floor performance.
– Interaction in controls pretty weak.
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Human amygdala damage
Humans with amydala damage
– Poor face recognition, esp. expression.
Adolphs (1995) small number of patients:
– Bilateral damage: poor at fear, anger surprise
– Right damage only: no noticeable impairments
– Left damage only: poor anger and surprise
– Poor memory of emotional material.
– Conceptual understanding of fear intact:
simply recognition impaired.
A: Amygdala’s functional
asymmetry
 Funayama et al. (1997):
 Examine startle response to pictures.
 Controls show startle to negative pictures or
when they see pictures that they have been
told predict bad consequences (e.g. shock)
 Compare unilateral amygdala damage to
heathy responses
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Right temporal lobectomy (RTL)
Left temporal lobectomy (LTL)
 All groups verbally rate pictures similarly
(they agree that the aversive pictures are less
pleasant than the others).
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B: Results
Controls: stronger response to negative
pictures.
LTL patients similar to controls.
RTL patients do not show this pattern.
*
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C: Results 2
RTL and normals show strong response
when image appears that they have been
told signals possible electric shock.
LTL patients do not show this response.
<- SP is a bilateral patient
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D: Conclusion
RTL modulates fear response to
intrinsically aversive images.
LTL modulates fear that results from
linguistic/cognitive representation.
– Aversive nature learned through verbal
instruction.
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Disgust
Emotion of disgust appears related with the
sensation of taste.
Insula and Basal Ganglia:
– Stimulation causes nausea and unpleasant
tastes
– Lesions inhibit learned taste aversions
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Disgust
Calder et al.(2000) describe patient NK:
Left lesion includes Insula and BG
Impaired recognition of disgust.
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Delusional Misidentification Syndromes
 3 DMS:
1. Pick [1903] “reduplicative paramnesia”

Misidentifies familiar places as replica
2. Capgras Syndrome [1923]

Familiar people described as doppelgangers
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visual but not emotional recognition
3. Frégoli Syndrome [1927]
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Person misidentified as someone else with totally
different appearance.
 DMS are rare
–
–
Rare enough to be of little clinical importance
Yet, may still reveal how emotions are processed
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Hirstein and Ramachandran [1997]
H&R postulate that DMS is caused by
disconnection between visual recognition
system and emotional system.
E.G. Capgras syndrome due to
disconnection between fusiform gyrus
[face area] and amygdala [limbic system]
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Hudson and Grace
 71 women suffered lesion to anterior fusiform
gyrus (between face area and amygdala)
– Frégoli Syndrome
 Identified husband as elder sister (who had died 3 years
previously)
 Only visual misidentification (fine on phone)
 Home was ‘replica’ would pack bags to return to ‘real’
home.
 Support for H&R
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Pain asymbolia
Patient’s report they can feel pain, but it
no longer hurts.
Ramachandran (1998): speculates
disconnection of insula from cingulate
(part of limbic system)
– Insula identifies pain
– Cingulate does not receive signal, so
discounts threat
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Emotion and cognition
 James: emotion is the brain’s response to bodies
reaction.
Stimulus (bump in night) -> Arousal (heart races) ->
Emotion (fear)
 Canon:
Stimulus (bump in night) + Emotion (fear) -> Arousal (heart
races)
 Schachter’s Two-Factor Theory (1962)
Stimulus (bump in night) -> Arousal (heart races) +
Cognitive Label (‘I’m afraid’)-> Emotion (fear)
– secrectly give people adrenaline and they report
heightened emotional state. Funny events seem funnier,
frustrating events seem more frustrating.
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Emotion and cognition
Kolb suggests emotionality
decreases after spinal cord
injury. Degree of change
dependent on amount of cord
severed.
This is not a well-replicated
finding. See Nicotra (2006) for
review, Cobos et al (2002)