Lecture 10 - Neurobiology of Emotions Flashcards
What is an emotion
One of the most significant things ever said about emotion may be that everyone knows what it is until they are asked to define it A response of the whole organism
4 level of emotions
Physiological Arousal Anatomical Level Hormonal Level Expressive Behaviours Behavioural Level Conscious Experience Cognitive Level
Evolutionary advantage of emotions
Darwin believed emotions evolved from behaviors: (1) what an animal would do next in a given situation (2) behaviors that are advantageous to the animal “fight or flight” response Automatic response that allows us to survive -> very quick and imperative to survival
Biological meaning of emotions
“fight or flight” response In response to acute stress, the body’s sympathetic nervous system is activated due to the sudden release of hormones 1. Signalling function (we might take action) 2. Promote unique, stereotypical patterns of physiological change and behaviour 3. Provide strong impulse to take action Entire body -> but out of our control Only aware of the effect Cannot control physiological changes Prepares to take action Physiological changes to generate an action Involve many different areas of the body -> in order to make movement, there must be motor response, so it recrutes different areas for response
6 basic emotions
Negative Emotions: moving away from what one doesn’t want Positive Emotions: moving towards what one does want Anger Happiness Surprise Disgust Sadness Fear
James-Lange’s theory
Opposed to the common-sense view Physiology -> Appraisal Stimulus (dog) -> Perception/ Interpretation (danger) -> Specific pattern of automatic arousal (heart races) -> Particular emotion expressed (“My heart is pounding, so I must be afraid”) Stimulus is potential danger -> brain recognises this Only after this -> is emotion expressed (SPSP) Can only express emotion with physiological changes Assumes there is a unique physiological signature to each emotion
Cannon-Bard’s theory
Recognition of emotion and then body’s arousal takes place Appraisal -> Physiology Stimulus (dog) -> Perception/ Interpretation (danger) -> Emotion Experience -> Specific pattern of automatic arousal (heart races) (“I feel afraid, so my heart pounds”) Physiological responses are generated so quickly, it’s unlikely that we could have perceived the emotion first
Schachter-Singer’s theory
Two-factor theory of emotions To experience emotion one must: (1) be physically aroused (2) cognitively label the arousal Stimulus (dog) -> Specific pattern of automatic arousal (heart races) + Cognitive label -> Particular emotion expressed “I am afraid”
Schachter-Singer’s classic study
In a 1962 experiment: A group of 184 male participants was injected with epinephrine (hormone that produces arousal including increased heartbeat, breathing) Epinepherin cause physiological changes (so the changes are due to the hormone not the emotional changes) “a new drug to test their eyesight” Group A = informed the side-effects that the injection might cause Group B = ignored side-effects -> were not told Placed in room with happy or angry confederate Participants with no explanation for arousal experienced happiness or anger trembling, and rapid Participants were then asked how they felt Group A (might cause … as side effects) -> say they did experience some side effects Group B (said nothing) -> happy confederate - said felt happy, angry confederate - said felt angry, didnt know why happy or angry -> just said felt that emotion Experiencing a physiological change causes an assosiation to the emotion
Cognition and emotions
Must cognition precede emotion? Some emotional reactions may occur without conscious thinking Emotions involve bodily responses Bodily responses are very noticeable (butterflies in our stomach when fear arises) but others are more difficult to discern (neurons activated in the brain)
Two dimensions of emotion
Valence and Arousal
Physiology of emotion
Autonomic Nervous System (ANS) controls our arousal
ANS = part of the nervous system responsible for control of the bodily functions not consciously directed: breathing, heartbeat, and digestive processes
ANS -> strongly effect emotions due to effect on ‘fight or flight’ response
Epinephrine regulates a lot of different organs and bodily procedures -> including emotions
High erosal -> increase epinephrine -> increase in breathing, heartbeat etc.
Similarities and differences between emotions and physiological response
Similarities
Physiological responses related to the emotions of fear, anger, love are very similar
Excitement and fear involve a similar physiological arousal
Differences
Brain responses related to the emotions are slightly different “Different” brain areas activated by different emotions
Difficult to tell emotions apart from physiological response but there is differences in brain activation -> but these are not dramatically different
Polygraph (machine used in attempt to detect lies)
Uses the low level physiological changes (percpiration, cardiovascular changes, breathing changes), to detect lies -> answer neutral and target question and look at changes
Control-question technique
Lie detector
Polygraph -> machine used in attempts to detect lies
Physiological Responses:
Perspiration
Cardiovascular changes
Breathing changes
Control-Question Technique -> ANS responses to answers to innocuous questions (Is your mother’s name Betty?) are compared to those of target questions (Did you steal the money?)
50 Innocents
50 Thieves
2/3 of innocent declared guilty
1/4 of guilty declared innocent
(Kleinmuntz & Szucko, 1984) Manchester Police Department
Facial expression of emotions
Ekman and Friesen analyzed hundreds of films and photos of people experiencing various emotions
They concluded that there are 6 primary facial expressions of emotions and all others are mixtures of these
anger fear disgust surprise happiness sadness
Universality of emotions
Study in New Guinea tribe -> Coded in the same way -> found same muscular contractions -> expression of emotion completely cross-cultural
Brain circuits for emotions
Brain circuits for emotions particular brain regions are involved in emotion, but often the same areas seem to be involved in many different emotions electrical stimulation of the septum (in rodents) septum brain self-stimulation
Brain lesion affect emotions
Decorticate cats/dogs (without cortex) respond with unusual aggression to the slightest provocation
Too invasive for humans
Cat -> similar structure
Remove all the cortex -> particularly prefrontal
Keep subcortical structure -> hypothalumus etc
Deliver stimuli -> neutral, should not generate agression -> because removed = inappropriate response
Cortical and subcortical reagon to express emotion
Can still generate behaviour with subcortical, just cannot inhibit response => constant agressive/ anger
Sham rage -> behaviour not appropriate to enviromental stimuli
Papez circuit
Subcortical Circuit of Emotion “destruction of a set of interconnected pathways in the brain would impair emotional processing”
Emotional system on the medial wall of the brain linking cortex with hypothalamus
Neocortex (emotional coloring) <—> Subcortical structures
Cingulate cortex (emotional experience) -> Hipocampus (homeostasis) -fornix-> Hypothalamys (emotional expression) -> Anterior nuclei of the thalamus (most important in emotion recognission) -> Cingulate cortex
Hippocampus (temporal lobe) ->navigation and spatial perception, memory = emotion recognition (can recal emotions and recognise them)
All structures communicate in the process -> each involved in particular part
Cingulate cortex also linked to hippocampus to create a memory of the emotion
Connected together as well as to the neocortex (cortical structure) -> emotional colouring = control/inhibition the behaviours relating to the emotion
Subcortical structures = take into account experiencce and expresses emotion
Cortical = take into account behavioural control etc.
Limbic system: expt. evidence
Temporal Lobe lesion in primates
Kluver-Bucy Syndrome
No fear or aggression after surgery
Lesions restricted to the cerebral cortex do not produce these results à deeper regions of the temporal lobe (including sites within the limbic system) are implicated
Amygdala
Temporal lobe -> memory, auditory proccewssing and emotions
Monkey approached the snake it would
Removing one temporal lobe -> some imparement but not completely due to brain placitity in which other side compensates
Structure in temporal lobe in emotion regulating -> particularly fear
Amygdala
Amygdala = Fear proccessing and regulation
Amygdala appears to be involved in the perception of fear (as opposed to the expression of emotions)
Fear conditioning measured this
Every now and then there is a pleasent/ neutral sound -> mild activation
The start to introduce shock with this -> big response
Then return to just sound -> big response
Amygdala -> take into account what happened before, the sound becomes associated to the potential danger
Without amygdala/ leasion to -> fear conditioning not possible/ cannot experience fear
Lesion in the Amygdala
Female - 1994
Complete bilateral amygdala destruction since late childhood.
No fear perception
No fear recognition (even on faces of others)
Low ANS responses
Also found to invade personal space of others -> came closser to people than the average person -> hence amygdala seems to regulate personal space
Normal in every other way
Fear and panic in humans with bilateral amygdala damage
Cerebral Hemispheres
LH is less involved in perception of emotion
RH is more involved in perception of emotion, specifically facial expression and prosody
(melody of speech that conveys sincerity, sarcasm, etc.)
LH lesion -> Depressive symptoms
RH lesion -> Euphoria symptoms
Presentation of emotional stimuli on the LEFT visual field à faster reaction times and accurate identification
