During threatening situations, many interacting parallel pathways that involve neuronal, chemical, and hormonal activity are activated. The autonomic nervous system creates internal visceral movements, while the voluntary motor pathways orient us and begin activating for external movements to freeze, flee, or fight. This illustrates how emotion of fear and movement are involved in the "flight-or-fight response."
When activated, whether by fear or an arousal, causes a flood of activity toward the motor cortex to initiate and guide a movement response. At the same time, messages from our aroused limbic system are transmitted to the cortex to evaluate that incoming sensory stimulus or data. Once a decisions is made, guidance is sent from the cortex back to our amygdala.
For example, when our brain responds to some sound like a shutter banging in the wind we prepare to handle possible intruders, until the frontal cortex intercedes and takes into account the wind as opposed to the likelihood of an intruder. The amygdala cools down and then the brakes are applied to stop us from a tactical move over just letting the realization the wind is up get us taking inappropriate actions.
The amygdala activates the anterior cingulate and the hypothalamus, which then switches on the autonomic nervous system, the motor system, and the endocrine system, which causes our bodies organs to adjust to the demands of a situation. This triggers an increase in heart rate due to stronger heart-muscle contractions, constriction of blood vessels (seen in the neck, etc., as waring signs or nonverbal tells) and increase blood pressure, an opening of the airways of the lungs, decreased movement of our digestive organs, and increased blood flow to the skeletal muscles. Meanwhile, chemical neurotransmitters are sending out message to the entire body and activates hormones that will significantly influence the nervous-system reactions and organ systems of the body.
Physiological reactions to the flight-or-fight response that the person feels as fear. A primitive, hard-wired emotional response that prepares us for the strenuous motor efforts required for running or fighting. This is clear evidence of the intimate link between our emotions and our movement.
FEAR is a universal emotion that includes everything from the decision to flee or fight to the insidious increase and effect of stress. The freeze part is NOT an indication of indecision in the face of fear, it stems from our ancestral skill used to respond to predators. The fear stimulus primes our body with adrenaline and triggers the fastest physical reaction possible.
When triggered the brain activates the autonomic system and stress hormones. The amygdala receives instant input from the thalamus and acts to start up the internal readiness and reaction system. This bypasses the cortex and any consideration of the context and such - it just acts/responds. This fear stimulus and programmed response are indelibly etched into the amygdala, and its job is to alert us to dangerous, novel, and interesting situations and to direct its response.
Because the physical and mental response to fear was critical to our survival as primitive humans the process remains a very powerful and long-lasting one. Unfortunately, this adaptive response is not always appropriate in today's world.
The Cascade of Reactions: heart rate soars, blood pressures increases, and the senses become heightened as the body prepares to take action.
In a training and practice, with hopefully experience(s), the objective is to bypass, initially, the direct link to trigger the freeze, flight or fight response of our ancient ancestors so that the frontal cortex can create enhanced responses to the amygdala so that pathway becomes a new one so that the initial triggered reaction can evolve to something more appropriate for these trying and interesting modern social times. The idea is to create a training and practice program that reprograms the amygdala and limbic system so that the upper brain, the logic circuits, don't interfere with the speed the lower lizard system needs to achieve success in survival, dealing with conflict and violence. This process removes the thinking part necessary for training and practice so you "JUST RESPOND/ACT."
You train your cortex to re-evaluate situations and the encode that in the amygdala so it inhibits the standard flight or fight response into a more robust appropriate and effective response.
We cannot operate without movement and emotions, they are tied together but we can program and encode actions and resposed more appropriate to the emotions, such as fear and anger, so they don't rule us but we rule and utilize them as they are meant to be in triggering movement, actions necessary to get the job done.
As a trining process we must become self-aware and must understand that which would trigger fear and/or anger so that we take actions, movement, appropriate to any given situation which will keep us in the square of self-defense for self-protection.
Extracted from a source on the brain: Ratey, John J. “A User’s Guide to the Brain: Perception, Attention and the Four Theaters of the Brain.” Pantheon. January 1, 2001.