In order to understand exactly how obsessive thoughts appear, let’s start by considering the reaction to an alarm signal, which is “built-in” in the human brain by default. This reaction is sometimes also called a stress reaction, a “hit – run” reaction or, which better reflects its essence, “hit, run or freeze”. It sets the body up for a whole series of actions, and all of them bring results when you are really in danger. This includes the release of adrenaline, increased heart rate, changes in the rhythm of breathing, increased alertness associated with the expectation of a threat, tunnel vision and many other changes in perception. It feels like an attack of fear or horror. The center of the response to the alarm signal is the amygdala, consisting of two structures located in the temporal lobe of the brain, each the size of a walnut. The amygdala can only be in two states-active or passive: it either triggers a reaction to an alarm signal, or it does not. The reaction to an alarm signal is not expressed in words – you can imagine it as the ringing of a bell warning of danger. There are no partial reactions and other nuances here.
Since the goal is to warn you, the amygdala is activated at the slightest hint of a possible threat. Her task is to protect you, not to take care of your comfort, so she would rather give a thousand false signals and cause as many bouts of fear when there is no problem, than miss at least one real danger. Initially, it was supposed to provide primitive survival. The occurrence of an alarm signal in the absence of a real danger is called a false alarm. If the signal is not sent under threat conditions, an exception error is reported. Your amygdala generates a great many false positives, because it does not accept the risk of an exception error.
In situations of real danger, for example, when a car rushes along the highway or a boulder falls on you, quick reaction, muscle strength and increased blood circulation, which are part of your threat response system, will serve a good service. An immediate change in the respiratory rate is necessary for fast running in an emergency situation. Even sweating helps to cool your body, which warms up from running. Your amygdala is designed to save lives, so it reacts very quickly, trying to protect you from any possible threat.
The trigger can be a car approaching at high speed or a sudden shout from a friend behind you. The fear reaction manifests itself extremely quickly.