Psychologists call this an amygdala hijack, a point at which the most unevolved part of our brains — the amygdala — overrules every other civilised impulse and quite simply, goes nuts.

In the mid 1990’s, I was introduced to the concept of an "amygdala hijack." The amygdalae are two small almond-shaped structures in the brain that among other things, monitor environmental and social threats and allow us to respond reflexively when perceived levels get too high. They figuratively hijack our volitional choice by redirecting behavioral control to more primitive responses such as fight, flight and freeze.

[The amygdala] is the brain's center for emotional memory, for emotional reactivity, and which has the ability to scan everything that's happening to us moment to moment to see if it perceives a threat. [If it does,] it mobilizes the entire brain instantly in an amygdala hijack, the signs of which are three: One, you have a very intense emotional reaction two, it's very sudden and three, when the dust settles, you realize that it was very inappropriate.