Fear is one of the most ingrained reactions in living beings. Its purpose is to protect them from external threats. It plays such an important role that it is present in both the most basic and the most complex forms of life. It can take very simple forms, for example the automatic retraction of a snail’s antenna, or very articulated, as in humans, where fear triggers mechanisms that start from the brain in response to a stimulus and involve the whole organism.
The fear response begins in a region called the amygdala. The amygdales are two small almond-shaped structures located deep in the brain. From here, whenever we are faced with a stimulus that is interpreted as a threat, a complex chain reaction starts: stress hormones are released, a part of the nervous system (the sympathetic nervous system) involved in those functions is activated. defined as “fight or flight”. The brain enters a state of alert, the pupils dilate. The breath quickens. It also increases heart rate, pressure, and blood flow. More glucose is sent to the muscles, while non-vital organs, such as the gastrointestinal system, are put into a state of reduced activity.
The focus is all on the danger that is being experienced at that moment, while everything else is set aside. The whole body prepares to face it. At the same time, a threat assessment starts. Other areas of the brain (in particular the hippocampus and the prefrontal cortex) help interpret the perceived threat. The “thinking” part of the brain tells the “emotional” part if you are faced with a false alarm (and then the response goes off) or in front of a real danger (and then the response continues to be fed). It is this complex system that has allowed man to survive countless dangers throughout his history. And it is the same mechanism that is activated in the face of dangers that threaten our survival such as disease.