What Are The Effects Of Trauma On Memory?
New memories are stored in the region of the brain known as the hippocampus. However, not all memories that enter the hippocampus are stored by the brain permanently.
Only some are transferred to the cerebral cortex for long-term storage; the rest fade away. The more important the memory, and, in particular, the more intense the emotions connected to the memory are, the more likely it is to be permanently stored. This process in called memory consolidation.
When an event occurs that is very threatening or damaging to us, the stress of this causes stress hormones ADRENALIN and CORTISOL to be released into the brain.
The effect of these stress hormones is to strengthen the memory of this threatening or damaging event.
The stress hormones released into the brain (in particular, the amygdala) also ensure the memory of the negative event becomes strongly associated with the emotions (such as fear and terror) that it originally evoked.
So, for example, if we are viciously attacked and maimed by a savage and demented Rottweiler, cortisol and adrenaline will be released into our brain to ensure that the memory is indelibly stored. These same stress hormones will also ensure that the emotions we felt at the time of the attack, such as fear and terror, also become strongly associated with the memory of our unfortunate encounter with the less than friendly canine miscreant.
This way of storing such memories evolved for the survival value it confers on our genes.
Also, when extremely traumatic events occur, the hippocampus can become so excessively flooded by stress hormones such as cortisol and adrenaline that it incurs damage.
This damage can then alter the way that the traumatic event is stored. Because of this the memory may become:
– ‘foggy’ / ‘blurry’
– inaccessible to conscious awareness
Furthermore, the memory of the extremely traumatic event may become highly invasive – especially when the person in possession of the memory is reminded of the traumatic event (even tangentially) – and constantly break through into consciousness wholly unbidden, re-triggering the release of excessive amounts of stress hormones into the brain ; this can lead to:
David Hosier BSc Hons; MSc; PGDE(FAHE).