Emotions, Aggression and Stress

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Emotions, Aggression and Stress

• Theories of Emotion
• Emotion and Evolution
• Individual Variability
• Brain Substrates of Emotion
• Brain, Hormones and Aggression
• Stress and Body
• Stress and Disease

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What are Emotions?

• Subjective
• Objective displays
• 4 main aspects
• Feelings
• Action
• Physiological arousal
• Motivational programs

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Theories of Emotion

• James-Lange Theory
• Perception of stimulus immediately affects
  autonomic system
• Canon-Bard Theory
• Sensory stimulus goes BOTH to thalamus
  hypothalamus
• Thalamus regulates how we feel / emotional
  response
• Hypothalamus triggers the autonomic responses
• These responses happen simultaneously
• Schachters Cognitive Theory
• Emotions are not just stimulus-driven but are
  largely due to the brains appraisal of all the
  stimulus, the situation and autonomic responses
  (this appraisal / memory formation helps person
  to temper future emotional responses)

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Emotive Expressions

• Paul Ekman (8 basic emotions)
• Anger
• Sadness
• Happiness
• Fear
• Disgust
• Surprise
• Contempt
• Embarrassment
• Cultural validity
• Quasi-universality hypothesis of facial
  expressions
• Culture-prescribed rules for interpretation of
  expressions
• Facial expressions facial muscles, facial and
  trigeminal nerves and CNS pathways

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Emotions from Comparative / Evolutionary Viewpoint

• Darwin
• Emotional expressions in various species
• Facial musculature and nerves
• Use for communication evolutionary advantage
• Developmental
• Infants
• 0-3 months (joy, happiness, sadness)
• 4-6 months (anger, surprise)
• 7-8 months (fearfulness)
• Individual response stereotypy early
  distinction maintained
• Individual response fingerprint
• Physiological response fingerprint

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Brain Circuitry of Emotions

• Decorticate rage (isocortex removal)
• Cortex inhibits emotional responsiveness
• Papez neural circuit
• Mammillary bodies, anterior thalamus, cingulate
  cortex, hippocampus, fornix, (amygdala) limbic
  system
• Kluver-Bucy syndrome
• Temporal lobectomy taming, hyperphagia,
  hypersexuality
• Amygdala
• Self-stimulation / brain reward
• MFB / Nucleus Accumbens / Locus coeruleus,
  forebrain
• Dedicated brain circuit Fear responding /
  amygdala

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Brain Regions - Emotion

• Medial prefrontal cortex / anterior cingulate
  cortex
• Establishing a representation of emotional state
• Insula cortex
• Processing visceral information
• Amygdala (temporal lobe)
• Performing complex sensory discrimination of
  emotional stimuli
• Retrieving emotion-laden memories
• Posterior cingulate cortex
• Regulating autonomic responses

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Rodent Brain and Basic Emotions

• Seeking / expectancy
• NAcc-VTA mesolimbic mesocortical outputs,
  lateral hypothalamus-periaqueductal gray
• Fear
• Central / lateral amygdala-medial hypothalamus,
  dorsal periaqueductal gray
• Panic
• Anterior cingulate bed nucleus of stria
  terminalis dorsomedial thalamus dorsal
  periaqueductal gray
• Happiness / play
• Dorsomedial hypothalamus parafascicular area
  ventral periaqueductal gray

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Hemispheric Processing of Emotion

• Right hemisphere
• Discern others emotions
• Left side of face more expressive than right
• Processing emotional stimuli
• Left ear advantage for processing emotion tone
• Right ear advantage for understanding the meaning
• Emotional syndromes
• Indifference right parietal lobe
• Major depression left frontal lobe left BG
• Pathological laughing/crying bilateral
  hemispheric lesions, multiple sites
• Mania right basotemporal, right orbitofrontal
  region

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Aggression

• Predatory, feeding, sexual, maternal
• Androgens
• Circulating (i.e., puberty) increase aggression
• Seasonal changes mirrors aggression variability
• Correlational confounds
• 5-HT negatively correlated with aggression
• Aberrant EEG patterns, temporal lobe seizures and
  increased violence
• Small prefrontal cortex, reduced activity

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Stress

• General adaptation syndrome
• Alarm reaction, adaptation stage, exhaustion
  phase
• Uncertainty or unpredictability most egregious
• Endocrine responses
• Hypothalamus (corticotropin-releasing hormone
  (CRH)) anterior pituitary (adrenocorticotropic
  hormone (ACTH)) adrenal (cortisol)
• Testosterone levels recover more rapidly in
  dominant males, subordinates have more prolonged
  increase in cortisol levels (Sapolksy)
• Impact on immune system
• Emotional state influences immune system
• NE autonomic fibers innervate immune system
  organs
• Hypothalamic neurons monitor signaling proteins
  (regulate B lymphocytes)
• Vagus nerve regulates immune system response by
  relaying signaling protein levels to brain
• Immunosuppression evolutionary advantage
• Depression and grief decrease immune response
  stress lowers healing / immune response
• Prolonged stress (Type A), cardiovascular disease
  and hostility and cardiovascular disease

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Take Home Message

• Theories of Emotion
• Emotion and Evolution
• Individual Variability
• Brain Substrates of Emotion
• Brain, Hormones and Aggression
• Stress and Body
• Stress and Disease