Emotion Lecture 7

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Emotion Lecture 7

• Evaluation and emotional experience

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Role of amygdala in emotional evaluation

• Amygdala has general role in the appraisal of
  danger or threat (Broks et al., 1998).
• Expressions of fear and CS are signals of
  possible or imminent threat
• Amygdala also activated by negative words
• Amygdala especially important for identification
  of and reaction to aversive stimuli (Aggleton
  Young, 2000)
• Adolphs et al. (1995) the amygdala is an
  essential link for responding to stimuli with
  emotional value, especially stimuli that signal
  potential danger or threat.
• Amygdala not isolated, but component of an
  emotional network (LeDoux, 1998)

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Amygdala is component of emotional network

• receives input from cortical sensory areas of
  visual, auditory, somatosensory and gustatory
  modalities
• determine potential danger of stimuli in these
  modalities
• projects back to cortical sensory areas
• amygdala can regulate these cortical areas
• (e.g. focus attention in emotional stimuli)
• direct input from thalamus, but no projection to
  thalamus
• direct input amygdala can regulate sensory
  cortex very quickly (before cortical
  representation are fully built up)
• direct input useful for early warning system
• output to motor systems and hypothalamus
  (autonomic responses) (LeDoux, 2000)

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Two pathways to the amygdala (LeDoux)

• Direct pathway, from thalamus (early warning)
• quick and dirty
• not aware
• Indirect pathway, via cortex
• slower, but more detailed analysis
• aware

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Evidence for direct pathway from affective
blindsight (Morris et al., 2001)

• blindsight patient G.Y.
• increased activation in amygdala
• to fearful faces, but not happy faces, presented
  in blind field
• to fear-conditioned faces in the blind field
• no cortical activation to faces in blind field
• amygdala activated independently of primary
  visual cortex and visual awareness

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Evaluation emotional significance and frontal
lesions

• Skin conductance responses (SCR) (Damasio, 1994
  Tranel, 2000)
• SCR one of physiological responses to emotional
  stimulation
• SCR responses to emotional stimuli
• neutral pictures (landscapes or abstract
  painting) and emotional pictures (disaster
  scenes, mutilations, nudes)
• normal controls and patients with lesions outside
  ventral frontal lobe increase in SCR to
  emotional pictures

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• SCRs and frontal lesions (Damasio, 1994 Tranel,
  2000)
• neutral pictures (landscapes or abstract
  painting) and emotional pictures (disaster
  scenes, mutilations, nudes)
• normal controls and patients with lesions outside
  ventral frontal lobe increase in SCR to
  emotional pictures
• patients with ventral frontal lesions reduced
  response to emotional pictures, no impairment of
  SCR to physical stimuli, e.g startling noises.
• reduced response to psychologically significant
  rather than physically significant stimuli

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Right vs left hemisphere? SCRs and frontal
lesions (Zahn et al., 1999)

• 3 types of pictures sex (nudes), gruesome
  (mutilated bodies), neutral
• SCRs sex gt gruesome gt neutral
• SCRs patients with left frontal lesion gt right
  frontal or bilateral frontal lesions

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SCRs and frontal lesions (Zahn et al., 1999)

• 3 types of pictures sex (nudes), gruesome
  (mutilated bodies), neutral
• SCRs sex gt gruesome gt neutral
• SCRs patients with left frontal lesion gt right
  frontal or bilateral frontal lesions
• confirms previous findings that RH lesions
  attenuate SCRs to emotional stimuli more strongly
  than LH lesions

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SCRs and amygdala lesions (Tranel, 2000)

• 2 patients with bilateral amygdala damage
  presented with significant items
• own name
• emotional pictures (nudes, mutilation, neutral)
• emotional and neutral words
• No differences in SCRs between amygdala patients
  and normal controls to significant stimuli.
• Suggests amygdala not necessary for generating
  these SCRs

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SCRs and emotional experience

• Do reduced SCRs to emotional stimuli reflect
  reduced experience of emotions or changes in
  emotional behaviour?
• Frontal patients
• Subjective reports more patients with ventral
  frontal lesions reported decreased intensity or
  frequency of emotional experiences compared to
  patients with other lesions (Hornak et al., 1996)

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SCRs and emotional experience responses to
emotional pictures RHD lt LHD

• Different effects emotional experience RHD LHD?
  (Gainotti, 2000 Heilman, 2000)
• Catastrophic reactions more frequent after LH
  damage
• feelings of depression and anxiety
• not necessarily a reaction to impairments
• Indifference reactions or euphoria more frequent
  after RH damage
• indifferent, unconcerned about impairments
• Gainotti RHD patients seldom averted eyes from
  distressing pictures, emotional blunting

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• Different reactions RHD and LHD not simply
  response to impairments (in Heilman, 2000)
• Selective inactivation of hemisphere (Wada test,
  sodium amytal)
• LH dysphoric reaction
• RH euphoria or indifference
• in line with

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• Valence theory
• LH dominant for positive emotions
• RH dominant for negative emotions
• OR
• Laterality hypothesis RH dominant for emotion
  processing, regardless of valence
• Attenuated SCRs in RHD to emotional stimuli may
  reflect reduced emotional experience (blunting,
  indifference)
• Relatively normal responses in LH patients
  possible because dominant RH is still intact

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Emotional experience

• Amygdala patients
• Anecdotal evidence knowing no fear
  (Sprengelmeyer et al., 1999)
• bilateral amygdala damage (probably
  long-standing)
• rarely experienced feelings of fear or anger
• thrill seeker

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Emotional experience

• Amygdala patients
• Ratings on Positive and Negative Affect Schedules
  (Anderson Phelps, 2002)
• 10 L, 10 R and 1 bilat. amygdala patients,
  healthy controls
• emotional experiences in past year no
  differences in self-reported experienced
  emotions, including fear, anxiety
• daily fluctuations over 1 month ratings bilat.
  amygdala patient very similar to healthy
  controls ratings
• amygdala not necessary for production emotional
  experience

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Stimulation amygdala can produce emotional
experience - amygdala may be sufficient to
produce experience

• Temporal lobe epilepsy (in Heilman et al., 2000)
• Changes in emotional behaviour and in emotional
  experience
• ictal symptoms (directly related to the seizure
  discharge during the seizure)
• post-ictal (directly after the seizure)
• interictal (between seizures)

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Stimulation amygdala can produce emotional
experience amygdala may be sufficient to produce
experience

• Fear most common ictal emotional experience
• not simply fear of attack, experience seems to
  come by itself
• intensity and duration can vary
• sometimes accompanied by visceral sensations that
  normally go with fear
• e.g. palpitations, pallor
• may be associated with a fearful hallucination or
  memory

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Stimulation amygdala can produce emotional
experience

• Temporal lobe epilepsy (in Heilman et al., 2000)
• Changes in emotional experience
• ictal symptoms (directly related to the seizure
  discharge during the seizure)
• Fear most common ictal emotional experience
• not simply fear of attack, experience seems to
  come by itself
• intensity and duration can vary
• sometimes accompanied by visceral sensations that
  normally go with fear
• e.g. palpitations, pallor
• may be associated with a fearful hallucination or
  memory

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Case J.V. The patient was a girl of 14 when
first seen. At the age of 7 she had a fright when
a man came up behind her. She ran across a meadow
to her brothers. Her mother remembered the story.
.. At 11 years she began to have epileptic
seizures in which she showed fright, screamed and
clung to people. .. During the period of her
fright she saw the above scene a little girl
identified as herself in the same meadow where
the event occurred, and she was filled with
terror lest she be struck or smothered from
behind.
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Stimulation amygdala can produce emotional
experience

• Ictal fear typically associated with
  abnormalities in amygdala (Cendes et al., 1994)
• more amygdala atrophy in patients with ictal fear
• ictal fear could stop after removal portions of
  the amygdala
• Feelings of fear can also be evoked by direct
  electrical stimulation of the brain (in Cendes et
  al., 1994)
• in particular amygdala and hippocampus

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• Ictal fear suggests role amygdala in generation
  of emotional experience (of fear), unlike
  conclusion Anderson Phelps (2002)
• Ictal fear short episode and result of abnormal
  bursts of activity
• Anderson Phelps (2002) Amygdala damage has no
  effect on emotional experience assessed over much
  longer episodes (when there are burst of abnormal
  neural activity)

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References

• Anderson, A. Phelps, E. (2002). Is the human
  amygdala critical fro the subjective experience
  of emotion? Journal of Cognitive Neuroscience,
  14, 709-720
• Broks, P., Young, A.W., Maratos, E.J. et al.
  (1998). Face processing impairments after
  encephalitis Amygdala damage and recognition of
  fear. Neuropsychologia, 36, 59-70.
• Cendes, F., Andermann, F., Gloor, P. et al.
  (1994). Relationship between atrophy of the
  amygdala and ictal fear in temporal lobe
  epilepsy. Brain, 117, 739-746.
• Hornak, J., Rolls, E.T. Wade, D. (1996). Face
  and voice expressions identification in patients
  with emotional and behavioural changes following
  ventral lobe damage. Neuropsychologia, 34,
  247-261.
• Morris, J., de Gelder, B. Weiskrantz, L. Dolan,
  R. (2001). Differential extrageniculostriate and
  amygdala responses to presentation of emotional
  faces in a cortically blind field. Brain, 124,
  1241-1252.
• Sprengelmeyer R, Young AW, Schroeder U,
  Grossenbacher PG, Federlein J, Buttner T,
  Przuntek H. Knowing no fear. Proceedings of the
  Royal Society, London 1999 B266 2451-56.
• Zahn, T., Grafman, J. Tranel, D. (1999).
  Frontal lobe lesions and electrodermal activity
  effects of significance. Neuropsychologia, 37,
  1227-1241.