UCLA scientists have identified a neurochemical mechanism in
mice that is involved in helping them overcome fear.
The researchers conducted a study on mice, by conditioning them
to fear an audio tone. Each time the mice heard the tone, it was
accompanied by a shock.
However, when the researchers played the tone without the shock,
the mice initially reacted with fear, but after repeated tones
without shock, the mice eventually became unafraid of the tone.
This gradual reduction in fear is an important psychiatric
concept called extinction.
Researchers then treated the mice with chemicals that inhibited
a neurological mechanism in their brains, and found that they
continued to react to the tone ““ without the shock ““
and did not lose their fear.
Then the researchers concluded that this mechanism, called the
L-type voltage gated calcium channel, was an important part of
extinction.
Further research indicated that while inhibiting the mechanism
would prevent extinction, it would not prevent the learning of
fears, suggesting that there are different mechanisms for learning
fear and for extinguishing fear.
The work was conducted under neuroscientist Dr. Mark Barad, the
UCLA Neuropsychiatric Institute’s Tennenbaum Family Center
faculty scholar and assistant professor in-residence of
psychiatry.
Most of the experiments were designed and conducted by Chris
Cain, a fourth-year Ph.D. student in the Interdepartmental Program
in Neuroscience.
For Cain, who joined the Barad lab because he “was
interested in looking at the extinction of fear,” this study
is the culmination of more than a year and a half of work.
“We’ve identified a new target for drugs for
treating people with phobias,” Cain said.
Both Barad and Cain hope this research will soon provide relief
for some of the millions of Americans suffering from phobias and
anxiety disorders.
“This research should go rapidly to the clinic,”
Barad said.
The next step is figuring out how to manipulate LVGCCs to
increase extinction and determining what areas of the brain are
being effected by these manipulating drugs.
It is their hope they will be able to work with drug companies
to develop drugs that will target LVGCCs to increase the rate of
extinction.
Barad’s lab is financially supported by the National
Institute of Health, the National Alliance for Research on
Schizophrenia and Depression, and the Tennenbaum Family
Interdisciplinary Center, which named Barad their first faculty
scholar last July.