Introduction
This page is the first part of a study of the article
Stress effects on memory: An update and integration by
Lars Schwabe, Marian Joëls, Benno Roozendaal, Oliver T. Wolf and Melly S. Oitzl
The stress response
A stressor is, in one way, something that causes a change in the body and the stress response is what tries to bring the body back to its normal state.
The regulation of the body environment is called “Homeostasis”.
In a stress response, this is done by the release of hormones, neurotransmitters and peptides by the 2 stress systems :
The SAM axis that mainly releases catecholamines like adrenaline and noradrenaline causing increased heart rate and blood flow to skeletal muscles.
Catecholamines
Hormones produced in the adrenal gland released in response to stress.
Adrenaline
A.K.A. Epinephrine
A hormone and neurotransmitter produced by the adrenal glands. It is involved in the fight or flight response. It is synthesised from noradrenaline.
Noradrenaline
A.K.A. Norepinephrine
A hormone and neurotransmitter produced by the adrenal glands. It is involved in the fight or flight response and the neurotransmission in the sympathetic nervous system. It is synthesised from dopamine.
Skeletal muscle
Muscles connected to the bones that cause voluntary movement.
The HPA axis that releases glucocorticoids from the adrenal cortex.
Adrenal cortex
The outer largest part of the adrenal gland that produces hormones such as cortisol, androgens and aldosterone.
These hormones regulate different functions such as metabolism and blood pressure, puberty and sexual behaviours, blood salt content.
These two systems work in different ways but combined, they cause many changes to the body.
More about the neurobiology of stress
The effects of stress on memory
Stress has different effects on all stages of memory.
It can cause both positive and negative effects at any of these stages.
When the stress appears before the learning, the memory may be improved if the stress is related to it, if it has any emotional value and what kind of emotion or depending on the time between the stress and learning events.
If the stress is after the learning, the effects become slightly predictable.
When it appears during the consolidation process, the stress molecules usually enhance memory. Especially for emotional memories.
However, when it comes before, during or after memory retrieval, it usually impairs memory. Again, this effect is stronger on emotional memories.
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