[escepticos] un poco de neurociencia...

["planetario de pamplona" <planetario@...>]

Un poco de comidita para el lunes:
http://www.sciencedaily.com/releases/2001/03/010327080532.htm

NYU Neuroscientist Examines How Brain Responds To Fears That Are Imagined
And Anticipated, But Never Experienced

Although people learn about potentially dangerous events through hard
experience (a given dog is dangerous because it once bit you), often we
learn about such events through communication (a given dog is dangerous
because you heard it bit somebody else.) In understanding the neural systems
of fear learning, most researchers have focused on the former type of
learning, which is called fear conditioning. However, little is known about
the neural system underlying fear-learning through communication, in the
absence of aversive experience.
Using fear conditioning, the neural systems of fear learning and expression
have been eloquently mapped with both human and animal research. This
research has indicated that a brain structure called the amygdala is
critical to the expression of a conditioned fear response. But is the
amygdala involved when you encounter a fear-invoking event that you have
merely heard about?

NYU neuroscientist Elizabeth A. Phelps addressed this question by examining
activity in the human amygdala with a task called "instructed fear." Using
fMRI, Phelps found that the amygdala is indeed activated in response to
verbally communicated "threat" stimuli. Furthermore, in this and follow-up
studies, Phelps and her colleagues found that this amygdala activity is
related to the physical indications of a fear response.

During "instructed fear," subjects do not actually receive an aversive
stimulus, but rather they are told an aversive event might occur in
conjunction with a neutral stimulus. In this case, subjects were presented a
series of three images on a computer screen: a yellow square, a blue square,
and the word "rest." Subjects were told they might receive a shock,
delivered by an electrode on their wrist, when one color was presented (the
threat condition) and that they would not receive a shock when the other
color was presented (the safe condition). Although all subjects indicated
that they believed they would receive a shock, none of the subjects actually
received a shock during the study.

Taken as a whole, Phelps' findings extend the amygdala's involvement in the
expression of fear to situations where the aversive consequences are
imagined and anticipated but never experienced. In other words, fears that
exist only in our minds activate some of the same neural systems as fears
that are learned through experience.


This research was conducted in collaboration with Michael Davis, Christian
Grillon, John C. Gore, Christopher Gatenby and Kevin J. O'Connor. These
studies were conducted at the Yale School of Medicine's Department of
Radiology.

Elizabeth A Phelps is an associate professor of psychology and neural
science at NYU. She received her Ph.D. from Princeton University.





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Note: This story has been adapted from a news release issued by New York
University for journalists and other members of the public. If you wish to
quote from any part of this story, please credit New York University as the
original source. You may also wish to include the following link in any
citation:

http://www.sciencedaily.com/releases/2001/03/010327080532.htm