(This question is in relation to this question here)How does fear paralysis occur? What is the mechanism that makes this happen in brain?
How does fear paralysis occur?
fear
Taken from hereThe Fear Paralysis Reflex begins to function very early after  conception and should normally be integrated before birth.  It can be  seen in the womb as movement of the head, neck and body in response to  threat.  It is sometimes classified as a withdrawal reflex rather than  a primitive reflex. If this reflex is retained after birth, it can be  characterised by withdrawal, reticence at being involved in anything  new, fear of different circumstances, and is often described as the  scaredy cat child who bears the brunt of teasing by normally  adventurous children.This behaviour appears to be  due to the reflexs involvement with the parasympathetic nervous  system. Most of us are familiar with the fight or flight adrenalin  rush of the sympathetic nervous system, however the FPR taps into the  opposing system urging the body to eat and stay.  The  parasympathetic nervous system is intimately involved with the vagus  nerve.  This nerve comes directly from the brain to aid the organs.   It bypasses the spinal cord, so in the case of spinal injury we are  still able to digest our food.  The vagus nerve may be mechanically  trapped in the skull, chest, abdomen or neck.  Release of this nerve  entrapment corrects one physical factor that contributes to the  retention of the FPR.