We
all get anxious from time to time, but what happens in the brain when this
dreaded feeling looms? New research helps to answer this question.
In a study of monkeys, Ilya Monosov,
Ph.D., of the Departments of Neuroscience and Biomedical Engineering at
Washington University in St. Louis, MO, discovered specific cells in the brain
that are activated in response to anxiety.
The researcher recently published
his findings in the journal Nature Communications.
In simple terms, anxiety is defined as
feelings of worry, nervousness, or fear about an event or situation that could
yield an unpleasant outcome, such as a job interview or an exam.
While these feelings may quickly
subside for some people, others may develop anxiety disorders, wherein anxiety
persists or worsens over time.
According to the Anxiety and Depression
Association of America, anxiety disorders affect around 40 million adults in the United States.
Dr. Monosov believes that his new study
may open the door to new treatments for anxiety disorders, after identifying a
group of brain cells that play a role in anxious feelings.
Uncertainty triggers specific brain
activity
Dr. Monosov came to his findings by
studying the brains of rhesus monkeys, which have many brain structures similar
to those of humans.
He focused on the anterior cingulate
cortex (ACC) of the brain, a region in the prefrontal cortex that
previous studies have shown plays a role in behaviors
associated with uncertainty - a key driver of anxiety.
For his study, Dr. Monosov trained two
monkeys to associate three different geometric patterns with three different
outcomes. One pattern was associated with receiving an irritating puff of air
in the face (representing a certain outcome), one pattern was associated with a
50-50 likelihood of getting a puff of air in the face (representing an
uncertain outcome), while the third pattern was associated with no outcome.
As the monkeys were shown each
geometric pattern, Dr. Monosov used MRI to measure neuronal
activity in the ACC of their brains.
The
researcher identified brain cells in the ACC that were activated in response to
the geometric design associated with an uncertain outcome. However, when the
monkeys were shown patterns associated with a certain outcome or no outcome,
these brain cells showed no activity.
"We found a population of neurons
that activated specifically when monkeys thought something bad or annoying -
like a puff of air to the face - might be coming, but not when they knew for
certain it was," explains Dr. Monosov.
Findings may fuel new treatments
In another experiment, Dr. Monosov
trained the monkeys to recognize two geometric patterns associated with the
certainty or possibility of receiving a sip of juice, representing a positive
outcome.
The
results were similar to those seen in the first experiment: when the monkeys
were presented with an uncertain outcome, a specific group of brain cells in
the ACC were activated. These cells were not activated when the monkeys were
presented with the certain outcome.
According to Dr. Monosov, these
findings not only help to explain the brain mechanisms that underlie anxiety,
but they may also pave the way for new treatments for anxiety and other
behavioral disorders.
"Now that we know which cells are active
when an animal is faced with the uncertainty of a bad experience, we can try to
disrupt the activity of these cells. It opens up avenues of research, which may
one day lead to new ways to treat disorders such as anxiety and depression."
Ilya Monosov, Ph.D.
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