Stress 2 Flashcards
What is the Dutch Hunger winter findings with prenatal stress and what is the Dutch hunger winter?
- Nazis pushed back
- Dutch tried to aid allies for liberation
- As punishment, Nazis cut off all food transport
- Typical food consumption: 400-800 calories/ day
- After liberation sudden increase in food
- Effects: cohort of people with increased risk of heart disease, type 2 diabetes aged 50 years
- Pregnancy during famine:
Fetus ‘learns’ that food is scarce
Metabolism of fetus has permanent shift: ‘metabolic imprinting’ - Afterwards, foetus becomes good at storing consumed food, retaining salt from diet
- Developed ‘thrifty’ metabolism
What was Kajantie et al’s Finish study on birthweight?
- Large cohort of study of 421 men born 1924-33
- Birthweight and size was recorded, evaluated cortisol levels aged around 70
- The lower the birthweight (adjusted for height), the higher the basal cortisol levels in adults: particularly for premature birth
- Early exposure to stress programs your stress-reactiveness
What happened when offspring of stressed pregnant rats were placed in stressful situations?
- Test anxiety in new environment:
Food placed in middle of bright cage
Placed in with new rats - Prenatally stressed rats show:
Freezing in bright lights, difficulties learning and take longer to socially interact
All evidence of greater anxiety
Amygdala shows greater glucocorticoid receptor density
What did Plotsky and Meaney find the effects of postnatal stress were?
- Maternal separation of rats
- As adults, rats showed increased glucocorticoid response to stress: greater fearfulness
- Stress in infancy can reduce growth hormones – lower adult height
What was Gunnar’s finding with stress and Romanian orphanages?
- Compared daytime cortisol measured in children from:
Romanian orphanages for >8 months
Romanian orphanages for <= 4 months and were then adopted into Canadian families
Canadian children - Studied at 7-8 years old
- Found that
Early adopted children showed similar cortisol levels to Canadian children
Children in Romanian orphanages for a long amount of time have increased cortisol at all time
What does noradrenaline do, when is it at it’s lowest and highest levels and where does it act?
- Noradrenaline prepares body and brain for action
- Lowest release in sleep, highest during stress
- Acts on amygdala
Where is noradrenaline primarily release in the brain?
From Locus Coeruleus
What does noradrenaline do as a neurotransmitter?
It can enhance formation and retrieval of memory
Which brain structure has a high density of corticosteroid (rats)/cortisol (humans) receptors
Neurons of the hippocampus
What do we see with rats with high levels of stress in early life?
A loss of structure in the hippocampal neurons
What can be done to test the effects of stress on humans?
Expose people to vicious animals, make people endure pain, infect with diseases
What was Nili’s stress experiment exposing people to vicious animals?
- people with snake phobias recruited – put in MRI scanner with snakes on conveyer
- Used toy bear as control
- At each point, participants chose whether to bring the live snake closer – or further away – from them
- Found a fear response with snake
- When choosing to let snake closer you would see increased activity in subgenual activity cortex (when they are being brave)
- Also, when fearful people chose to advance the snake, amygdala activities was reduced (when people gave into their fear amygdala activity was increased)
What was Vuilleumier’s experiment for seeing how the brain recognises threats in the environment and what does this show?
- fMRI study, subjects decided
Are the vertical or horizontal boxes the same
They were shown either faces or houses (faces weren’t relevant to task) - Some faces were neutral, others were fearful
- Participants slower at judging houses if faces happened to be fearful
- Regions active to faces:
Fusiform gyrus - Regions active to houses
Parahippocampal gyrus - When participants were incidentally seeing fearful faces (not involved in task) the amygdala was more active: the limbic structures that detect threat respond and interact with other parts of the brain that regulate stress response
What clinical cases of poor emotion regulation can you examine to find out which brain areas are involved in regulating the stress response?
Post-traumatic stress disorder
Social anxiety disorder
Specific phobia
In Etkin and Wagner’s meta-analysis of fMRI studies across PTSD, social anxiety disorder and specific phobias what did he find?
Increased activation in amygdala (phobia/ social anxiety)
Decreased activity in medial prefrontal cortex (PTSD)
What in the medial prefrontal cortex seems to respond to regulating threats?
the midline of the brain in front of the motor cortex
In examining brain responses to fear which brain regions did Etkin et al find were active when we consciously control our emotional response?
- ‘Bottom-up’ signalling from the amygdala indicates threats in the environment
- ‘top-down’ regulation from the medial pre-frontal cortex prevents this from triggering constant stress-responses
What is how stress affects memory examined by studying?
- examined by studying stress during:
Encoding
Consolidation
Retrieval
Is information encoded during stressful events generally well remembered and what in particular?
Yes, particularly information that is relevant to the stressor
What could dysregulation in stress encoding lead to?
psychological trauma
E.g. post-traumatic stress disorder, characterised by flashbacks
Feeling that traumatic event is recurring
What was Henckens et al’s experiment for stress at encoding and what did they find?
- fMRI study – shown film clips (very violent or neutral) and pictures
- Later asked to remember pictures
- Heart rate recording, pupil dilation tracking, cortisol tracking
- Found increase in cortisol present, greater change in pupil diameter with people that saw violent pictures
- Stressful films led to better memory for pictures
- During stress LOWER activity in hippocampus at encoding = better memory for those pictures
- Poor separation of event info from relevant stimuli may overwhelm hippocampul activity
What did Cahil et al’s find out with with Stress and consolidation?
- Stress enhances consolidation of emotional pictures, but not neutral pictures
- Limbic structure involved with consolidation of emotional memories
What did the Trier test show with stress at retrieval?
Unexpected 5 min talk
Followed by 5 min arithmetic
Combines feeling of peer evaluation with forced failure
- Memory retrieval during stress is impaired – e.g. Guez et al., 2016
- Suggest that systems involved in coding during stress are enhanced by systems to do with retrieval are inhibited
What are the two factors in Lazarus’ cognitive appraisal theory?
- Primary appraisal – is the situation relevant to someone’s needs?
- Secondary appraisal – whether a person has resources and options to cope with the event
