Anxiety, fear and safety

Regardless of whether you are more logical or intuitive, whenever we encounter a problem, most of us identify the cause of the problem and then concentrate our efforts on finding a solution. In the case of anxiety disorders, this approach has lead neuroscientists to concentrate their research on the brain's fear circuits, as most anxieties are triggered by our fears.

However, in a ground-breaking example of lateral thinking, neuroscientists Eric Kandel and Michael Rogan decided to instead investigate the brain's "safety circuits". These exist deep within the brain and are responsible for the good feelings associated with safety and security. The results have been surprising and are providing a different perspective on anxiety disorders.

In the past the neurobiology of happiness has been generally ignored by physicians. Understandable really as very few physicians will have had patients who complained of feeling happy. But in Dr Rogan's words "the missing part of our picture of anxiety is the good feelings associated with being safe and secure."

Perhaps another reason why there is very little research into happiness is because it is harder to study. For example, how do you know when you have made a mouse feel safe and secure?

Michael Rogan managed to do just that! He trained mice to recognise that they were safe from danger (mild electrical shocks) when they heard a particular sound. He then recorded what happened in the mice's brains before and after they heard the safety sound.

As expected, in accordance with previous theories, information about the safety sound travelled through the brain's fear circuits and reduced the amount of activity in the brain's fear centre, the amygdala.

But Rogan and Kandel also found that the safety signal travelled through other, previously unknown circuits that lead to the brain's caudoputamen, a region known to be involved in motivation and reward. This region became more active when the mice felt safe and secure.

It therefore seems that just as the brain is alert to and capable of responding to fear and danger, it also has circuits that respond to safety and that create a sense of wellbeing.
In the same way as an understanding of these neural circuits may eventually help alleviate the symptoms of anxiety, the researchers believe that it creates hope for other types of treatment that can act on our sense of safety and security. It may for example lead to a better understanding of addiction since the circuit operates in the same part of the brain known to be involved with that. Just as there is a feeling of invulnerability that comes with alcohol and other drugs, so it may be that drugs of abuse artificially activate some aspect of this safety mechanism.

The next step, Dr Rogan says, is to verify that the same safety circuits are present in people. He is now planning a brain imaging study that will look for activity in the caudoputamen of people. However, whereas the lab mice were taught to feel safe from a mild electric shock, they may have to think of something a little more subtle for their human volunteers!

Published January 2010

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