Neurological Roots Of 'Stressing Out'

[© 1998, Reuters Health eLine]

NEW YORK, (Reuters) -- Stressful events set up a chain of neurochemical
changes in the brain that intensify emotions while undermining
concentration and intellectual performance, according to one expert. She
believes 'stressing out' is a survival tool that may have served humans
well at one point in their evolutionary history, but is much less useful

"These neurochemical changes may explain why the stress of an initial
error can cause an athlete to lose concentration and thus lose a
competition," said Dr. Amy Amsten, a neurobiologist at Yale University
School of Medicine in New Haven,Connecticut. Her report is published in
the June 12th issue of the journal Science.

Amsten is interested in the neurological mechanisms that cause us to
react with heightened emotion to a traumatic event, suffer subsequent
(short-term) declines in mental acuity, but still grant us a persistent,
vivid memory of the incident itself.

She explains that as the 'trigger' event occurs, substances called
catecholamines(primarily dopamine, norepinephrine, and epinephrine)
activate the amygdala, an area deep inside the brain believed to play a
role in associating stimuli with emotions. These are the same 'fight or
flight' chemicals that switch off nonessential body functions
(digestion, for example) under panic conditions.

As the amygdala spikes the emotions, it also activates the hippocampus,
a nearby area of the brain concerned with long-term memory. This
combination of responses has its roots in the survival instinct, since,
as Amsten explains,"long-lasting memories of aversive stimuli would be
enhanced in order (that we)avoid such stimuli in the future."

However, the catecholamines that enhance amygdala function also suppress
the function of the prefrontal cortex, an area at the front of the brain
concerned with concentration, inhibition, and rational thought. Under
these conditions, the function of the prefrontal cortex is impaired,
affecting the individual's ability to focus on complex socializing or
intellectual tasks and behaviors. Amsten says this explains
why "humans exposed to loud noise stress are less able to sustain
attention or to inhibit inappropriate responses."

She believes the 'stressing out' response may have come in handy during
humanity's more primitive beginnings, when survival meant speedy
reaction times and an avoidance of similar situations in the future.

"However, in modern human society these brain actions may often be
maladaptive," Amsten writes, since "we need prefrontal cortex regulation
to act appropriately" at the workplace and in the home.

She believes the response may also help to explain why prefrontal cortex
problems feature in psychiatric diseases worsened by stress, such as
depression and schizophrenia.

"And finally, this understanding may allow us to be more compassionate
with our own failings in response to life's stressors," Amsten

SOURCE: Science 1998:280:1711-1712.