PSYC10003 Lecture Notes - Lecture 11: Fear Conditioning, Classical Conditioning, Somatic Marker Hypothesis
6 Jun 2018
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PSYC10003 – MIND, BRAIN, & BEHAVIOUR 1
BEHAVIOURAL NEUROSCIENCE
Lecture 11 (Week 4 . 2): The Neural Basis of Emotion
Emotion: can refer to the positive or negative feelings we experience in particular situations, or the
physiological / behavioural changes that accompany certain situations
• Are strong motivators & exert influence on how likely we are to behave in particular situations
• Emotional behaviours likely played an important part in the evolution of our CNS
• Darwin: expressions of emotion evolved through natural selection, & some responses evoke similar
emotional states in all species members (same facial expressions → same feelings in all individuals)
• Components of emotional responses:
• Behavioural: muscular changes appropriate to the situation (e.g. aggressive vs submissive dog)
• Autonomic: physiological changes induced by ANS facilitate behavioural responses (heart rate)
• Hormonal: reinforce autonomic changes (adrenal medulla secretes epinephrine, norepinephrine)
• Surgical ablation of cats’ cerebral cortex → excessive aggression (sham rage). If hypothalamus also
removed → sham rage no longer elicited (hypothalamus = expression. Cortex = inhibition / control)
• James Papez suggested a distinct circuit of brain structures assist emotional expression:
hypothalamus, anterior thalamus, cingulate gyrus, fornix, & hippocampus (Papez ciruit)
• Paul McLean added amygdala, orbitofrontal cortex, & some nuclei of basal ganglia (Limbic system)
• Kluver-Bucy syndrome: damage to amygdala (in anterior temporal lobe) → increased &
inappropriate sexual activity, tendency to explore with the mouth, absence of fear, & tame / ‘flat’
• Phineas Gage. Frontal leucotomy. → personality changes attributide to emotional responses
Amygdala: key role in physiological & behavioural reactions of objects &
situations with particular biological significance (pain, food, water, mate, rival).
Crucial in recognition & expression of emotion – facial expressions
• Located in the anterior temporal lobe, & consists of several nuclei:
• Medial nucleus: receives sensory input (including from olfactory system
- odours & pheromones) & relays info to basal forebrain & hypothalamus
• Lateral / basolateral nuclei: receive sensory info from primary sensory
cortex, association cortex, thalamus, & hippocampus, & send axons to
parts of the basal ganglia, thalamus, & central nucleus of the amygdala
• Central nucleus: sends axons to regions of hypothalamus, midbrain, pons, &
medulla responsible for expression of various emotional responses (especially
threatening stimuli)
• Basal nucleus: receives axons from lateral & basolateral nuclei, & sends axons
to other amygdaloid nuclei & to the midbrain
Orbitofrontal cortex: located on ventral surface of frontal lobes. Preceise role is unclear,
but likely crucially involved in regulating ability to evaluate social & emotional info, inhibit inappropriate
responses, & develop plans for acting appropriately – sort of decision making
Feelings associated with emotions:
• James-Lange theory: emotion-inducing stimulus/event triggers appropriate set of physiological
responses & particular behaviours (clench fists/teeth), which the brain receives feedback from via
sensory receptors in the skin, muscle, & internal organs, & which
generates the subjective feeling of emotion. Emotional feelings determined
by interpretation of sensory feedback received from physiological
response to emotion-inducing stimulus
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Document Summary
If hypothalamus also removed sham rage no longer elicited (hypothalamus = expression. Amygdala: key role in physiological & behavioural reactions of objects & situations with particular biological significance (pain, food, water, mate, rival). Crucial in recognition & expression of emotion facial expressions: located in the anterior temporal lobe, & consists of several nuclei, medial nucleus: receives sensory input (including from olfactory system. Orbitofrontal cortex: located on ventral surface of frontal lobes. Preceise role is unclear, but likely crucially involved in regulating ability to evaluate social & emotional info, inhibit inappropriate responses, & develop plans for acting appropriately sort of decision making. Emotion-inducing stimuli has 2 independent effects: feeling of emotion, & physiological effects / behaviour: stanley schachter"s theory: a general state of visceral arousal is necessary to experience emotion, & individucal"s interpretation of the experience is determined by the current enviornmental context, thoughts, & memories.
