Emotion - Neurophysiology

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  • 1. Emotion - Neurophysiology
  • 2. What is emotion? The James-Lange Theory The physiological changes are emotion, if they are removed, the emotion will go with them. Seems like a backward idea The Cannon-Bard Theory Emotional experience can occur independently of emotional expression Emotions can be experienced even if physiological changes cannon not be sensed There is not a reliable correlation between the experience of emotion and the physiological state of the body
  • 3. A comparison of two theories
  • 4. Neural Basis of Emotion Limbic System an emotion system lying on the medial wall of the brain that links the cortex with the hypothalamus the mediator of emotion a flawed and inadequate theory of the emotional brain
  • 5. Neural basis of fear Fear conditioning A form of Pavlovian(classical) conditioning Involves the presentation of a noxious unconditioned stimulus(US), at the end of the occurrence of a relatively neutral conditioned stimulus(CS) Studies of fear conditioning have successfully indentified the neural system
  • 6. Cellular Mechanism Involved in Fear Conditioning CS-US Convergence Physiological Plasticity induced by CS-US pairing LTP and The Amygdala Pharmacological Similarity of LTP and Fear Conditioning
  • 7. CS-US Convergence Every cell that responded to auditory stimuli also responded to the US The lateral nucleus of the amygdala is a site of CS-US convergence
  • 8. Physiological Plasticity induce by CS-US pairing Plasticity has been found throughout the fear conditioning circuitry: -in the auditory thalamic areas -in the auditory cortex -in the lateral, basolateral and central nuclei of the amygdala.
  • 9. Plasticity in different locations serves different functions: -in sensory structures could make stimulus processing more efficient - in motor systems could make the execution of the responses more efficient -in the amygdala could represent the integrative aspects of learning
  • 10. LTP and The Amygdala LTP ( long-term potentiation ) Several properties - experience dependent and synapse specific - cooperativity - associativity - stable and long lasting Amygdala crucial site of conditioning plays a central role in neural circuit of fear conditioning
  • 11. amygdala
  • 12. Pharmacological Similarity of LTP and Fear Conditioning LTP does not occur if the NMDA channel is blocked, the expression of LTP is not affected by NMDA blockade. Blockade of NMDA receptors in the lateral/basal amygdala interferes with the acquisition but not the expression of Pavlovian fear conditioning to a CS or to contextual stimuli
  • 13. Extinction of Conditioned Fear Extinction of conditioned fear does not occur passively, but is an active process. Cortical lesions can interfere with extinction. Extinction is prolonged by damage to the medial prefrontal cortex.
  • 14. Conditioned Fear and Instrumental Action lesions of the amygdala interfere with the acquisition of avoidance responses septo-hippocampal system is important amygdala is less important and probably unnecessary for the long-term maintenance of well-trained avoidance responses the instrumental aspects of avoidance may require connections between the amygdala and the ventral striatum for their acquisition and expression
  • 15. Implication of the Neural Basis of Fear for Understanding Emotion Cognitive-emotional interactions Conscious versus unconscious processes in emotion Volitional control emotion
  • 16. Cognitive-emotional interactions Dependence of emotional processing (appraisal) on cognition If cognition is defined broadly, emotional processing by the amygdala is highly dependent on cognitive processing. If cognitive processing is defined narrowly, emotion is not necessarily dependent on prior cognitive processing .
  • 17. Emotional influences on cognition SENSORY SENSORY CORTEX PERIRHINAL CORTEX (ASSOCIATIO CORTEX (PRIMARY) N) 1 2 3 HIPPOCAMPA 4 L FORMATION AMYGDALA 5 N.BASAU S amygdala influences on cortical cognitive processing
  • 18. Is emotional processing cognitive processing? Early pioneers of cognitive science did not view emotion as a cognitive Appraisal involves information processing. Therefore emotion is cognition ???
  • 19. Conscious VS Unconscious Processes in Emotion fear from running away or run from the bear out of fear (conscious emotion)
  • 20. Volitional Control Emotion Emotional respondents -effortless and automatic -are controlled by unconscious appraisal processes -include behavioral and visceral responses -are not learned Emotional operant -are learned through instrumental conditioning procedure
  • 21. Conclusion Although the focus on fear conditioning has its limits, it has proven valuable as a research strategy and can help us see emotions in a different light.