11: Emotion and Meaning

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11 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 AB disadvantageous you lose over time
• 100 per win, occasional huge losses (e.g. up to
  1250)
• Net loss
• Decks CD 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 AB
  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 LP argue they have different
  patterns of memory decay.
• 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.

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A Amygdalas 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
• 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.

lt- 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
• Pick 1903 reduplicative paramnesia
• Misidentifies familiar places as replica
• Capgras Syndrome 1923
• Familiar people described as doppelgangers
• visual but not emotional recognition
• Frégoli Syndrome 1927
• 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

• HR 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 HR

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Pain asymbolia

• Patients 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 brains response to bodies
  reaction.
• Stimulus (bump in night) -gt Arousal (heart races)
  -gt Emotion (fear)
• Canon
• Stimulus (bump in night) -gt Arousal (heart races)
  Emotion (fear)
• Schachters Two-Factor Theory (1962)
• Stimulus (bump in night) -gt Arousal (heart races)
  Cognitive Label (Im afraid)-gt 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)