Home' Trinidad and Tobago Guardian : July 10th 2017 Contents A22 body & soul
guardian.co.tt Monday, July 10, 2017
Why do some people prefer stable, predicta-
ble lives while others prefer frequent changes?
Why do some people make rational decisions and
others, impulsive and reckless ones? UCLA be-
havioural neuroscientists have identified changes
in two brain regions that may hold answers to
The research---reported by Alicia Izquierdo, UCLA
associate professor of psychology and a member of
UCLA's Brain Research Institute, and her psychology
graduate student, Alexandra Stolyarova---is published
in the open-access online science journal eLife.
The new experiments, which involved studying the
orbitofrontal cortex and basolateral amygdala brain
regions, assessed the ability of rats to work for rewards
under both stable and variable conditions.
Rats earned sugar pellets after choosing between
two images displayed side by side. The animals made
their selections by using their noses to touch a screen
the size of an iPad.
When a rat touched one image, it received a sugar
pellet at a predictable time---generally ten seconds later.
When the rat touched the other image, it received a
sugar pellet at a time that varied. This was the riskier
option as the rats might have to wait as little as five
seconds or as long as 15 seconds. The rats did this for
a month at a time, as long as 45 minutes each day.
The researchers discovered that the rats learned the
task and were able to detect the fluctuations in wait
times. When the rats experienced more variation in
those wait times for their reward, the amount of the
brain protein gephyrin in the basolateral amygdala
region doubled, Izquierdo and Stolyarova reported.
In some of the trials, the researchers made one op-
tion better than the other, with a shorter wait time.
All rats were able to learn the pattern and make the
better choice. They showed some evidence of learning
on the first day and did better the second day and on
subsequent days. In a group of rats without a function-
al basolateral amygdala, the rats learned more slowly
about the changes, but caught up about two days later.
Rats without a functional orbitofrontal cortex, how-
ever, did not learn at all, and instead treated each ex-
perience as a "reset" button, the researchers report.
It is as if these rats did not have a record of the full
range of possible outcomes. The important role for
the orbitofrontal cortex surprised Izquierdo, who said
there was more evidence that the basolateral amygdala
would be important in conditions of uncertainty, and
not as much for the orbitofrontal cortex.
Stolyarova and Izquierdo are the first scientists to
link gephyrin levels to the experience of reward. They
report that when the rats experienced risk, the brain
protein GluN1 also increased significantly in the ba-
"I think the experience of uncertainty is making these
changes occur in these brain regions," Izquierdo said.
All rats chose the risky option more often. The ex-
ception was the rats without a functional basolateral
amygdala; those animals stayed risk-averse throughout
The orbitofrontal cortex and basolateral amygdala
share anatomical connections, and both regions are in-
volved in decision-making, earlier research has shown.
The new research indicates this is especially so during
changing or uncertain circumstances.
Changes in these brain regions and brain proteins
may help to explain a person's preference for uncertain
outcomes, Izquierdo said. Humans have individual dif-
ferences in orbitofrontal cortex and basolateral amyg-
dala function and in the expression of these proteins,
For example, variations in the gephyrin gene have
been linked to autism, and a feature of the disorder is
a strong preference for order and certainty.
In the future, Izquierdo said, precision medicine may
be able to target any brain region to treat any disorder,
including behavioural addictions such as gambling.
People with obsessive-compulsive disorder also
have a strong preference for order and certainty. Fu-
ture research may answer whether the same brain
changes occur in this disorder as well. (University of
Changes in brain regions
may explain why some
prefer order and certainty
A UCLA study has identified changes in brain regions that may hold a key to why
some people prefer order and organisation and others do not.
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