Proximity Affects Stressor's Impact
> 8/31/2007 1:21:36 PM

Coming face to face with a bear would make anyone afraid, and scientists at the Wellcome Trust Centre for Neuroimaging in London have explained that our distance from such a threat is a main factor in the amount of fear we feel. They created a Pac Man-like computer game in which subjects negotiated a maze with a predator in pursuit. Subjects who were caught before reaching the end of the maze received a small electric shock. FMRIs of the subjects’ brains showed that when the predator was farther away, the ventromedial prefrontal cortex, an area of the brain associated with forming strategy, was more active. The periaqueductal gray area, an area associated with the primitive fight-or-flight reaction and with release of the body’s natural painkiller, opioid analgesia, became more active as the predator closed in. This differentiation between close or immediate threats and distant threats has an adaptive purpose, as Dr. Dean Mobbs, the study’s lead author, explained in a press release:

The most efficient survival strategy will depend on the level of threat we perceive. This makes sense as sometimes being merely wary of a threat is enough, but at other times we need to react quickly. The closer a threat gets, the more impulsive your response will be – in effect, the less free will you will have.

For those who have experienced a traumatic event, physical distance can mean the difference between minor and lasting effects. Researchers at Cornell and NYU have shown that people who were close to the World Trade Center on 9/11 are , six years later, still feeling the emotional effects of what they saw. Brain scans of witnesses who were within two miles of the attacks revealed heightened activity in the amygdala, the area of the brain responsible for emotional response and memory, compared with those who were two hundred miles away. Remembering details about the attacks caused a greater increase in amygdala activity in those who were two miles away than in those who were five miles away.

There is no doubt that people who have experienced a traumatic or threatening event from close range are at risk for anxiety and panic disorders. Even witnesses of 9/11 who have not been diagnosed with post-traumatic stress disorder could develop psychological disorders later in life because of hyperactivity in the amygdala. The scientists at Wellcome Trust point to abnormalities in the way the brain distinguishes between immediate and distant threats as one possible cause of excessive panic and anxiety. For someone whose periaqueductal gray area or amygdala is overactive, even ordinary situations can feel threatening. With this new information, it may be possible to create treatments that counteract these overwhelming reactions and help make these normal responses more appropriate for context.


Fascinating. And I can't help wondering if there is any kind of link with personalities who suffere addiction/alcoholism.
Posted by: A Bohemian Road Nurse... 9/1/2007 4:08:46 AM

Unfortunately, I don't use spell-check (aargh..)
Posted by: A Bohemian Road Nurse... 9/1/2007 4:27:47 AM

Really good article. But anyone who can use "periaqueductal" in a sentence should know the difference between "affect" and "effect."
Posted by: Kathy 9/2/2007 9:07:28 AM

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