Lead researcher Justin Feinstein said: “Because she is missing her amygdala, she is also missing the ability to detect and avoid danger in the world.

“It is quite remarkable that she is still alive.”

Adam Perkins, a postdoctoral researcher at the Institute of Psychiatry, King’s College London who specialises in researching the causal basis of anxiety and fear looked at the research.

He said the study was interesting because it suggested the amygdala is the neural seat of fear - and specifically responsible for generating feelings of fear, rather than emotions in general.

The researchers hope that by studying the woman they can understand how the brain processes fear.

This could be useful in treating patients suffering from PTSD - such as soldiers who have been serving in conflict areas.

Mr Feinstein added: “Their lives are marred by fear and they are often-times unable to even leave their home due to the ever-present feeling of danger.”

By studying the woman, researchers hope to create treatments that selectively target the brain areas that can sometimes allow fear to take over.