Lecture 2 stress Flashcards
What is stress?
What are the feelings of stress?
Stress is a response to a perceived aversive or threatening situation
Associated with feelings of being overloaded, wound-up tight, tense and worried
What are the positive effects of stress?
What are the negative effects of stress?
Positive - exciting, motivating, improving alertness & performance
Negative - harmful for health, gives you PTSD, impairing optimal performance
What is a critical condition for stress?
How do people react to this condition?
Lack of control over stressor
Thrill seekers attracted to calculate risks, but with some control
Complete lack of control or the threat of it is generally experienced very negatively
What is acute stress episodic acute stress and chronic stress?
Acute stress - a single event that leads to increased fight or flight response, raising levels of arousal
Episodic acute stress - repeated but independent acute stress
Chronic stress - seemingly endless nad uncontrollable
Why do we use animals to study stress?
For ethical reasons human studies are often correlational or observational.
However, if we want to manipulate hte conditions, we have to use animals in order to have direct measures of effects of different types of stress on biology
What horribles conditions could we subject the rats to?
Conditions - type of stress (constraint, predator odor, separation, elevated platform, social threat), length of exposure, single or repeated
Describe the mechanism of the fight or flight response
Two system mediated by the hypothalamus - HPA system (cortisol) and sympathetic NS (epinephrine)
see slides for graphical detail lol
What are the physical effects of fight or flight response
Heart rate increase, bladder relaxation, tunnel vision, shaking, dilated pupils, flushed face, dry mouth, slowed digestion, hearing loss
What are the acute effect of stress on hte brain?
Fight or flight
The balance between the brain and body is tipped. over. Optimal performance imparired
Difference between moderate stress and high stress
Moderate levels of stress = aroused & optimal functioning of the PFC allowing top-down regulation of thought, actions & emotions
PFC inhibits amygdala
High stress = arousal increases further overwhelming/impairing function of prefrontal cortex & releasing/increasing the influence of emotional responses, habitual action and bodies arousal response.
PFC offline, amygdala dominates
What can weaken PFC mediated inhibitory control to increase substance abuse
Acute uncontrollable stress
Acute stress can also increase amygdala response to increase memory consolidation of stressful events
Acute stress can enhance fear conditioning function of amygdala
What long-term changes are associated with chronic stress?
Amygdala (important in mood) the number & strength of neural connections increases
Behavioural function and activity up
Hippocampus (important for memory storage) number & strength of neural connections reduces (more cell death & less neurogenesis).
Behavioural functino, volume and activity down
Prefrontal cortex (important in “executive function) number & strength of neural connections reduces. Behavioural function, volumne and acitivity down
How to turn a rational man into a beast
Exposure to stressors causes chemical changes in the brain that impair higher cognitive functions why strengthening “primitive” brain reactions. People become more emotionally reactive with impaired rational thinking.
What does impaired emotional and memory function lead to?
Reduced flexible emotinoal processing and reduce separation between memories causing overgeneralization and less capacity to cope iwth new or potential stressful events. Provide an example using myself
Effects of stress on the body
Acute stress - increased energy availability in muscles breaking down fats and protein to glucose
Chronic effects - suppression of immune system, high blood pressure, reduced fertility
Evolutionary reason for stress
fight or flight helps us survive, reactive/reflexive brain may be more advantageous in immediate danger.
Chronic stress - early stress lead to negative outcome, including antisocial behaviour, aggression and social isolation. Might prepare an organism for similar adversities later in life. Tough life bro, your aggression or social mistrust prevents you from being hurt and robbed when hsits are scarce
Describe the chicken and egg relationship between hippocampus size and PTSD
Some people found smaller hippocampus in twin brothers of veteran who has not been exposed to stress - so disposition to develop PTSD
but also other people said the reverse….
What phisiologicla change is associated with PTSD?
FMRI says - increased amygdala and insula activity to threat and reduced ventromedial prefrontal inhibitory activity to threat
What is the link between stress and psychiatric disorders?
Depression - similar brain areas implicated in chronic stress and depression, depression considered a stress related disorder
Schizophrenia and bipolar disorder - triggers increased severity of symptoms
Alzheimer’s - women with serious stressors in middle age more likely to develop memory impairments
Effect of stress on emotional memory
Glucocorticoid - noradrenergic response in basolateral nucleus of the amygdala - enhancing retentino of emotional stimuli
stress hormones - greater memory consolidation in animal and human studies
Link between stress, emotional memory and PTSD
Trauma - release of stress hormones - overconsolidation of trauma memories - PTSD symptoms (intrusive memories)
Evidence for reprograming bad memories
Condition a fear response for spider, give some people propanolol - reduced startle response
The implication of reprograming bad memories?
Memories can be relearned without fear response
Other considerations - tool for evil - reduced ompensation, less compassion?
How does this impact someone’s identity
What are the benefits of meditation?
Non-reactive purposeful monitoring of the moment-to-moment content of experience.
Improve anxiety, distress, stress and quality of life
Mya work by increasing cognitive flexibiliyt, tolerance for uncomfortable physicla stress/anxiety sensation. Could reduce escalation of physical symptoms and hyperarousal and reduce perception of threat
How does early life stress affect hte brain?
Early life stress - epigenetic hcanges - lasting biological changes that impair decision making and health
More negative behaviour and life circumstances
