Selasa, 06 Maret 2012

Stress and Memory



Cortisol is another hormone released by the adrenal glands during stress.  Cortisol is more of a long-term stress hormone, as it is not immediately released during stress (like epinephrine/adrenaline), but if the stress is severe enough or long-lasting, it will be.  Cortisol seems to prevent encoding of new memories as well as memory retrieval.  In every day life, this can have big effects on exams for college students… the more stressed they are, the more difficult it will be to form and retrieve the information they have studied.  In other situations, this might be a good thing. 

It is thought that this might also be driven by the fact that glucose (which provides energy) is diverted to muscles and away from the brain and the hippocampus (which encodes memories).  In fact, the hippocampus may have some degradation due to chronic stress and the diversion of resources, like glucose.

On the other hand, stress mediated by norepinephrine/noradrenaline can act through the amygdala,  with direct projections to the hippocampus to enhance specific memory encoding.  This comes into play with flashbulb memories (such as where you were when you heard about an event- like when JFK was shot or 9/11) and also in post-traumatic stress disorder (PTSD) when a person may re-experience a stressful event or be “haunted” by the memories of it.

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