Anxiety: ‘Fight, Flight or Freeze’
The Physiology behind anxiety symptoms
‘Fight, Flight or Freeze’
This is the response to feelings of threat. In evolutionary terms the response is to enable us to escape from our predators as fast as possible.
The thalamus is the part of the brain which registers threat. When it does so it sends signals to both the amygdala and the cortex. If the amygdala senses threat it makes a split second decision to activate fight or flight before the cortex can override it. In order to escape efficiently the sympathetic nervous system and adrenal-cortical systems are activated.
These systems cause the body to tense up and become very alert to increase efficiency of escape. The heart rate increases, breathing rate increases, pupils dilate, blood is diverted from the skin to the muscles, you may sweat to keep cool hence ‘a cold sweat.’ Meanwhile non- essential systems such as digestion, immune and reproductive systems are shut down. This explains the feeling of nausea associated with anxiety and an increased vulnerability to infection and issues with fertility associated with chronic stress.
The blood supply within the brain also alters. There is a shift from the cortex to the limbic system. The cortex is the part of the brain associated with higher level thinking where language is produced, where there is a clear sense of past and future, and thinking is sophisticated and nuanced. However, it is also the slowest part of the brain.
In times of stress the blood is diverted to the limbic system which is the home of emotions including rage and fear. This part of brain has a visual memory; however the language stored here is limited to yells, screams and expletives. This part of the brain processes information more quickly; hence time appears to slow down. Limbic thinking is very threat based. There is no time for nuanced thought in times of peril and thinking becomes very black and white. It is focused in the present and has no sense of past or future. This is illustrated by the experience of ‘flashbacks’ when traumatic experiences recalled from the limbic system appear to be happening in the now.