What is the neurological mechanism responsible for losing one's temper? I'd imagine that losing one's temper is quite normal, I can not think of anyone who has not experienced it.  For me, it is rare, but does happen, I find that there can be 3 broad stages occur (note: this is not a self help question, but just an example), a generalized example would be:


"The calm before the storm" - I actually feel calm just after the object of frustration occurs and before the next stage - this step is usually very short.
"The storm" - it feels like the anger/rage comes from within and erupts, for me, it is in shouting, for some it is violence, for others, it is both.  The length of this stage varies.
"Sunshine again" - not all sunshine and lollipops, but calmer with rationality kicking in.


My question is what neurological triggers initiate each step?
I have addressed your three points in three parts.


The calm before the storm.

I would dispute the calm before the storm. I would suggest this would depend on the trigger. Sometimes people can experience a feeling of shock at what they are processing, before they become angry.


The storm.

The sympathetic nervous system is the part of the autonomic nervous system that is responsible for our fight and flight response.
What causes people to get angry?

You might have many things to feel threatened about — from financial
crises and peer pressure to drug addiction and war — and some people
respond in a negative way. Still, most people don't walk around
feeling mad all the time. When someone explodes with anger, there's
usually a triggering event — such as a disagreement at work or being
stuck in traffic — that brings a mix of simmering emotions to the
boiling point.

What happens when we get angry?

When we get angry, the heart rate, arterial tension and
testosterone production increases, cortisol (the stress hormone)
decreases, and the left hemisphere of the brain becomes more
stimulated.

Increased heart rate and arterial tension primes the body for fight or flight.
Testosterone is linked with aggression.

Cortisol is released in response to stress, sparing available glucose
for the brain, generating new energy from stored reserves, and
diverting energy from low-priority activities (such as the immune
system) in order to survive immediate threats or prepare for the
exertion of rising to a new day.

The left side of the brain is responsible for;

Dopamine [II] is the neurotransmitter that is not only responsible for
modulating a lot of our physical movement, but also sex, aggression,
motivational drive, and, counter-intuitively, long-term planning and
restraint or impulse control. In nearly all right-handed and most
left-handed humans who are left-brain dominant, dopamine rules the
left side of the brain.



Calm after the storm

The parasympathetic nervous system is the part of the autonomic nervous system  responsible for the more restful activities and will restore the autonomic nervous system's  balance.

The body takes about 20 minutes to return to normal after a full
fight/flight response. ..//...
...//...  Angry people will not completely comprehend any explanations,
solutions, or problem solving options until their body returns to
normal again.  [III]

What happens when we get angry? Hormonal, cardiovascular and asymmetrical brain responses
Neus Herrero, Marien Gadea, Gabriel Rodríguez-Alarcón, Raúl Espert, Alicia Salvador.    Hormones and Behavior, 2010; 57 (3): 276 DOI: 10.1016/j.yhbeh.2009.12.008
How dopamine may influence gender differences in psychiatric disorders [II]
Published on May 17, 2011 by Emily Deans, M.D. in Evolutionary Psychiatry
Controlling Angry People  [III}
What would you do if you came face-to-face with an angry person?
Published on January 5, 2011
Jack Schafer, Ph.D.
Let Their Words Do the Talking