Scientists find way to end anxiety attacks

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Scientists find way to end anxiety attacks

November 7, 2002

LONDON - Scientists have pinpointed an area of the brain involved in

overcoming fear, which may help to improve treatment for people

suffering from post-traumatic stress disorder and anxiety attacks.

When they stimulated that region of the brain in laboratory rats which

had been conditioned to associate a sound with a small electrical shock,

the rats' fear levels diminished.

'We've found an area of the brain that is activated, or turned on, when

fear is reduced,' said Associate Professor Quirk of the Ponce

School of Medicine in Puerto Rico.

'Consistent with that, if we stimulate that area electrically, we can

reduce fear.'

Fear is a reaction to danger and a survival instinct in animals and

humans.

Scientists had suspected that there was a system in the brain that

reduced the level of fear, but without completely erasing the memory of

it.

But until now, they did not know where it was.

'We think we have found it, because in this part of the prefrontal

cortex it is the first time an area has been activated, or turned on,

when fear is reduced,' he added in an interview.

Dr Quirk and colleague Mohammed Milad think the job of the prefrontal

cortex, which they found by studying recordings of nerve cells in the

brains of rats, is to inhibit the fear response.

They suspect the prefrontal cortex reduces fear by inhibiting the

amygdala, a hub of fear memory deep in the brain.

The rats in the study were taught to associate a sound with an

electrical shock, and froze when they heard it. All animals and humans

learn fear associations.

But when the rats heard the tone without the shock several times they

learnt not to be afraid - a process called extinction.

However, the original fear association was not erased - because it is

important for survival - but overtaken by the new memory.

'Our data suggest that the rats that were shown the tone-fear stimulus

again and again with stimulation of this area had very low fear,' said

Dr Quirk, whose research is reported in the science journal Nature.

People with post-traumatic stress disorder appear to have weak activity

in the prefrontal cortex of the brain, the scientists said.

They believe a painless experimental technique called transcranial

magnetic stimulation might help them control fear.

'Now that we have identified the area it should be straightforward to

strengthen the connections in this area so they have stronger safety

memory,' Dr Quirk said. --Reuters