Kog.Neuro. (Subject) / Memory under Stress (Lesson)

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• What is the response of the body/ response pathway under stress? -two different pathways; one slow, one fast pathway -stressful events reactivate the rapid autonomic nervous system (ANS) and the slower Hypothalamus-pituitary-adrenal axis (HPA) -stress hormones can directly or indirectly affect the brain
• What is the slow pathway? Hypothalamus-pituitary-adrenal axis -hypothalamus releases corticotropin releasing hormone (CRH) into the pituitary gland  -then, pituitary releases adrenocorticotropic hormone (ACTH), which acts on the adrenal gland -the adrenal gland then releases cortisol into the system -cortisol acitvates brain, body cells and the endocrine glands
• What is the fast pathway (stress reactivation)? the autonomic nervous system -brain sends message through spinal cord -sympathetic system of spinal cord is activated to stimulate the adrenal gland -adrenal medulla releases epinephrine into the system -this reactivates body cells, brain, endocrine glands
• Does stress improve or impair? remembering words, stress before encoding! 1. Domes et al, 2. Kirschbaum et al -inconclusive findings Domes et al found that stress before encoding impairs the memory of words, while Kirschbaum et al found that stress before encoding improves learning of words
• Glucocorticoid in mice, avoidance learning! Rozendaal et al glucocorticoid injection after inhibitory avoidance learning ->> boost avoidance learning/memory!  
• Cold pressor stress after learning emotional and neutral slides Cahill et al -->> significant difference for emotional content! -stress after learning improves emotional content learning!
• cold pressor stress before retention test Buchanan et al stress before retention test impairs retrieval of word with emotional content
• Does the timing of stress play a role in memorizing? Yes! Timing matters! Stress effects on memory are time-dependent! -stress before encoding > mixed findings -stress after encoding > positive!  -stress before retrieval > negative!
• How stress can affect our memory what does the model by Roozendaal & mcGaugh say about how our memory is altered? -memory is simultaneously altered by glucocorticoid and noradrenergic activity in the basolateral amygdala
• What predictions do Roozendaal and McGaugh make, based on their model on how our memory is altered? -stress effects disappear after noradrenergic or clucocorticoid blockade -stress (hormone) effects disappear when the basolateral amygdala is damaged?
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• Interactive effects of glucocorticoids and noradrenaline in trained rats: recognition task! Roozendaal et al. -after learning, the glucocorticoid is injected -> positive effect on task! -after beta-adrenergic blockade -> effect disappears! ->> but only, if beta blocker is injected into the basolateral amygdala! -habituation to glucocorticoid makes its effect disappear -the effect returns, when noradrenaline is injected! -->> stress effects require simultaneous glucocorticoid and noradrenergic activity in the basolateral amygdala
• Stress and the engagement of multiple memory systems in rats rats were trained in a specific spatial location > spatial learning -when no stress they sticked to the spatial strategy -when under stress, they shifted from spatial partially to S-R strategy (whatever that is...) ->> stress promoted shift in memory system
• Stress and the engagement of multiple memory systems in HUMANS Schwabe! -learning task - participants were stressed: where is the win-card?  -also shift vom spatial learning to S-R learning -performance is not affected! ->> imaging data: hippocampal acitivity is reduced during classification learning when stressed >also striatal activity changes, also amygdala activity changes
• Does this research topic, stress effects on memory, have clinical relevance? -several clinical impairments, which are characterized by deviant memory processes or/and dysfunctional stress responses! -eg PTSD, depression, drug addiction
• Pilot study with participants prone to develop PTSD after accident, treatment:propranolol 2002 -41 participants, within 6h propranolol, for 10 days -60% in propranolol group showed PTSD symptoms, but 87% in control group!

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