'Second Thoughts' Are Real

is specifically designed to let
you pull back from doing something you were just about to do.

University of Pennsylvania researcher Martha Farah, PhD, says the findings
have major implications. Farah was not involved in the study.

"It is very important to identify the circuits that enable 'free won't'
because of the many psychiatric disorders for which self-control problems
figure prominently -- from attention deficit disorder to substance dependence
and various personality disorders," Farah says in a news release.

In their study, Brass and Haggard hooked up 15 healthy young adults to
functional MRI machines that did real-time scans of their brain activity. The
participants were asked to decide to push a button at times of their own
choosing. Some of the time the participants were asked to decide at the last
minute not to push the button.

Brain scans taken when the participants actually pushed the button were
different from those taken when the subjects restrained themselves from pushing
the button.

This self-control came at a cost. The subjects reported feeling frustrated
when they did not push the button as they had intended to do. That fit with
their brain scans; a part of the brain linked to feelings of frustration (the
anterior ventral insula) lit up along with the dFMC "free-won't" brain
region.

Interestingly, some of the study participants were less likely to refrain
from pushing the button than others. These subjects had relatively weak dFMC
activity, while those with better self-control had stronger dFMC activity.

"This could be a factor in why some individuals are impulsive, while
others are reluctant to act," Haggard says.

Brass and Haggard report their findings in the Aug. 22 issue of the
Journal of Neuroscience.

(When do
you lose your self-control ? Eating? Driving?
Shopping on the Net? Talk aboutB your control issues on WebMD's Health Cafe
message board.)

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By Daniel DeNoon
Reviewed by Louise Chang
B)2005-2006 WebMD, Inc. All rights reserved