Brain And Emotion Flashcards
Brian systems
Prefrontal cortex (hemispheric differences) - Dorsolateral, ventromedial, orbirofrontal
Subcortical structures
- Limbic system, nucleus accumbens, amygdala
Posterior RH
- Perception of expressions
PFC: Emotion memory and recall
Phobics given pictures of aversive stimuli
Results in PFC activation; seems to be location of recall of emotion memories
Emotions are essential for motivation and planning. Need an emotional memory and the PFC seems to be the location of emotional working memory
PFC Hemispheric differences
Davidson emotional films
- Left anterior activated during positive affect - right anterior during negative affect
Sutton et al (1997): Pictures: induced changes in mood
PET scan. Right side increase during negative affect
Left side increase during positive affect and left nucleus accumbens
‘Socially wary’ children more right prefrontal activation (Davidson 2001)
Amygdala - Substantial evidence has an important role in the:
Perception of fear
Feelings of fear
Learning to recognise fear and aversive events (associative aversive learning)
Breiter et al (1996)
The amygdala is activated by perception of fear in the face of another
Morris et al (1996)
Activation in the lef amygdala showed a linear relationship with decreasing intensity of happiness and increasing intensity of fear
Amygala
Stimulating amygdala in animals produces freezing and fear response
Stimulation and seizures focused on the human amygdala frequently produce fear or other emotional responses (Gloor, 1990)
Kluver and Bucy (1937)
Lesion to medial temporal lobe:
Animals placid - lacking emotion
Will approach fear inducing stimuli with no display of anger or fear
Inappropriate sexual behaviour: mounting inanimate objects
Weiskrantz (1956) demonstrated that it was the amygdala within the medial temporal lobe
Klüver-Bucy syndrome
Lesions of amygdala and surround
emotional blunting: displays a flat affect and may not respond appropriately to stimuli
Hyperphagia: extreme weight gain, oral stimulation or exploration and not feeling hungry
Inappropriate sexual behaviour: may be an increase in their sexual activity
Visual agnosia: an inability to visually recognise objects
Urbach-Wiethe Syndrome
Rare
SM
progressive calcification of the amygdala. A few early memories of fear but no fear in adulthood
Is emotional - has other emotions
Personal space .34 metres (Kennedy, 2009)
Amygdala helps create personal space
Is fascinated by sights that terrify others eg haunted house
Exotic pets (spiders, snakes)
Recent SM findings
Tsuchiya et al (2009)
briefly presented fear expressions or fear scenes
Button response - choose which was most fearful. normal response
unlimited time - abnormal response
Kennedy and Adolphs (2011) gaze to eyes improved performance
Interpretation
Initial subconscious detection occurs in other regions and is accurate
Then amygdala directed to gather further evidence eg form eyes to assess the danger
non conscious processes may cause arousal but lack of amygdala prevents correct interpretation
Amygdala and individual differences
- Big individual differences in quality and intensity of amygdala response (blood flow, glucose use) to same stimuli
- Depressed patients with more severe depression had greater blood flow in amygdala (Drevets, 1995)
- Higher dispositional negative affect - higher glucose metabolism
Amygdala questions
Affect in general, negative affect in particular or fear most specifically? (Davidson and Irwin, 1999)
Where is happiness?
Left, Right or both sides equally involved in fear
Adolphs et al 1999
Emotion recognition in nine amygdala patients found that deficits apparent for all the negative emotions
Amygdala deficits may be more general - affecting all the basic negative emotions
Issues
Fear perception hardest
Controls find fear more difficult to recognise than other emotions
Just a product of any generalised brain damage
Adolphs, Tranel and Damasio, 2002
Patient B - bilateral lesions in the insular vortices damage may account for impairments in recognising disgust
Seems unable to feel disgust: ingests items indiscriminately including inedible items. Shows no disgust to food related stimuli (such as pictures of food covered with cockroaches)
Phillips et al (1997)
Two levels of disgust and fear expressions were used
- morphed images containing 75% of the expression and 25% of neutral and 150% caricatures of the expressions
- The baseline condition contained morphs composed of 25% happiness and 75% neutral
Right insula activated in response to expressions of disgust
Winston et al 2002
Trust (in addition to disgust) in the insula
Right insula and amygdala activated for untrustworthy faces
Amygdala and the right insula are activated by untrustworthy faces
The insula is activated in a wide variety of functional imaging studies of emotion
One possible role for the insula is as the basis of ‘gut feelings’ about emotive stimuli. Untrustworthy people cause a gut reaction?
Interim Summary
The amygdala has a large role in processing the emotion of fear (but task difficulty) - Rapcsak et al (2000)
might also process a wide range on negative emotions (and trust)
There’s disgust and trust in my insula and trust fear etc in amygdala
New evidence suggest there are other faster fear pathways that are not involving the amygdala
high and low road (Le Doux, 1994; 1999)
2 routes to an emotional response
- Fast and crude fear response (low road)
- Slower and more sure (high road)
Low road: thalamic-amygdala route very quick effective and very basic analysis of stimuli. very fast emotional (fear) response
High and low road
No need for cognitive appraisal for an emotion to occur
Low road perfect for fast defence mechanism
LeDoux
Intact ‘High road’ is necessary for learning a ear association
Once it is learned the high road is not required for a fear response
Makes many emotions unconscious and difficult to extinguish (eg anxiety and phobias)
Summary
Many brain regions involved in emotions and d
Summary
Many brain regions involved in emotions depends on aspect (perception/experience) of emotion
PFC - negative and positive. Approach - withdrawal. Emotional memories, emotion regulation, coordination prediction
Amygdala - Fear and negative emotions
Insula - disgust and trust
What is an emotion?
Emotional is a state of feeling and experiencing
It has several dimensions including behavioural, physiological and cognitive
