Brain and behavior disorders are increasingly considered to be caused by
altered functioning in the circuitry of the brain. Now known to be a vast
and sophisticated network, the circuitry of the brain has proven elusive
for scientists attempting to understand its language and correct its
dysfunction. A great step forward was made in 2005 when Karl Deisseroth,
M.D., Ph.D., of Stanford University used his NARSAD Young Investigator
Grant to invent optogenetics. Optogenetics is a new technology that uses
light to make neurons fire one at a time, giving researchers extraordinary
control over specific brain circuits in living animals. Thanks to
optogenetics, neuroscientists can go beyond observing correlations between
the activity of neurons and an animals behavior; by turning particular
neurons on or off at will, they can prove that those neurons actually
govern the behavior.
A recent special issue of Biological Psychiatry was dedicated to
understanding the impact of optogenetics on psychiatry. Now in use at over
1,000 laboratories, this method is enabling the identification of the
mechanisms that give rise to depression, anxiety, post-traumatic stress
disorder and other brain and behavior disorders. Thomas R. Insel, M.D.,
Director of the National Institute of Mental Health, wrote in a commentary
in the publication: Understanding the circuitry underlying mental
disorders is a daunting task but one that becomes more attainable
with each new discovery about the complex circuits involved in behavior.
Optogenetics has revolutionized systems neuroscience by providing precise
control over circuitry in awake, behaving animals. This is the exciting
part of optogeneticsthe control over defined events within defined cell
types at defined times and the ability to observe the resulting behavior
in animalsthat offers a new level of precision necessary to ident
ifying the biology of brain and behavior disorders.
Dr. Deisseroth looks forward in his introductory comments in the special
issue, stating that, Optogenetic tools provide experimental leverage
leading to insights into neural circuit function and dysfunction that are
impossible to establish by other means this approach must be integrated
well with existing sophisticated psychiatric disease-model research
methods spanning behavior, psychology, imaging, electrophysiology,
pharmacology, and genetics. Additional technologies also need to
be developed further for this approach to reach its full potential.
–NARSAD

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