Download - Emotion - Neurophysiology
Emotion -Neurophysiology
What is emotion?
The James-Lange TheoryThe physiological changes are emotion, if they are removed, the emotion will go with them.Seems like a backward idea
The Cannon-Bard TheoryEmotional experience can occur independently of emotional expressionEmotions can be experienced even if physiological changes cannon not be sensedThere is not a reliable correlation between the experience of emotion and the physiological state of the body
A comparison of two theories
Neural Basis of Emotion
Limbic Systeman “emotion system” lyingon the medial wall of the brain that links the cortexwith the hypothalamus
the mediator of emotiona flawed and inadequate theory of the emotionalbrain
Neural basis of fear
Fear conditioningA form of Pavlovian(classical) conditioningInvolves 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
Cellular Mechanism Involved in Fear Conditioning
CS-US ConvergencePhysiological Plasticity induced by CS-US pairingLTP and The AmygdalaPharmacological Similarity of LTP and Fear Conditioning
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
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.
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
LTP and The Amygdala
LTP ( long-term potentiation )Several properties
- experience dependent and synapse specific- cooperativity- associativity- stable and long lasting
Amygdalacrucial site of conditioningplays a central role in neural circuit of fear conditioning
amygdala
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
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.
Conditioned Fear and Instrumental Action
lesions of the amygdala interfere with the acquisition of avoidance responsessepto-hippocampal system is importantamygdala 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
Implication of the Neural Basis of Fear for Understanding Emotion
Cognitive-emotional interactions
Conscious versus unconscious processes in emotion
Volitional control emotion
Cognitive-emotional interactions
Dependence of emotional processing (appraisal) on cognitionIf 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 .
Emotional influences on cognition
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amygdala influences on cortical cognitive processing
SENSORY CORTEX
(PRIMARY)
SENSORY CORTEX
(ASSOCIATION)
PERIRHINAL CORTEX
HIPPOCAMPAL FORMATION
N.BASAUS
AMYGDALA
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
Conscious VS Unconscious Processes in Emotion
fear from running away
or
run from the bear out of fear (conscious emotion)
Volitional Control Emotion
Emotional respondents-effortless and automatic-are controlled by unconscious appraisalprocesses
-include behavioral and visceral responses-are not learned
Emotional operant-are learned through instrumental conditioning procedure
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.