In order for any experience, traumatic or not, to become part of memory, it must be "sensed".
It must be experienced by the individual. First step in experiencing is "sensation".
The five senses of the body have the capacity to transform forms of energy from the external world (e.g., light, sound, pressure) into patterned activity of sensory neurons.
First "stop" of this sensory input from the outside environment (e.g, light, sound, taste, touch, smell) and inside body (e.g., glucose levels, temperature) is the lower, more "regulatory" parts of the brain - brainstem and midbrain.
As the sensory input comes into the brain stem and midbrain, it is matched against a previously stored patterns of activation and if unknown, or if associated with previous threat, an initial alarm response begins.
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Missed it could be up to 7cms long to where it connects to... think it was 7...
thats this 0|---------------------------------------------|0 long,
Wonder what they would look like layed out in length.
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