Brain & Behavior Research Foundation Scientific Council Member and three-time NARSAD Grantee, Rene Hen, Ph.D. of Columbia University Medical Center (CUMC) led a team of researchers that may have found a way to reduce anxiety in post-traumatic stress disorder (PTSD) and panic disorder, without negatively affecting learning. The research team utilized a cutting edge new technology called optogenetics, invented by fellow Scientific Council Member, Karl Deisseroth, M.D., Ph.D. of Stanford University with the support of a 2005 NARSAD Young Investigator Grant. This technique allows scientists to insert light-sensitive proteins into the brains of mice, selectively activate specific neurons and then observe the corresponding behavior. Results of the study were published in a recent online edition of the journal Neuron.
With the use of optogenetics, the researchers found for the first time selective activation of the dentate gyrus, a portion of the hippocampus, can reduce anxiety without affecting learning. The dentate gyrus has been known to play a key role in learning and some evidence suggested it could also contribute to anxiety. "But until now no one has been able to figure out how the hippocampus could be involved in both processes," said senior author Rene Hen, PhD, professor of neuroscience and pharmacology (in psychiatry) at CUMC.
The researchers discovered that elevating cell activity in the dorsal dentate gyrus increased the animals' desire to explore their environment but also disrupted their ability to learn. Elevating activity in the ventral dentate gyrus lowered their anxiety, with no effect on learning. "It turns out that different parts of the dentate gyrus have somewhat different functions, with the dorsal portion largely dedicated to learning and the ventral portion dedicated to anxiety," said lead author Mazen A. Kheirbek, PhD, a NARSAD Young Investigator Grantee and postdoctoral fellow in neuroscience at CUMC.
"The therapeutic implication is that it may be possible to relieve anxiety in people with anxiety disorders by targeting the ventral dentate gyrus, perhaps with medications or deep-brain stimulation, without affecting learning," said Dr. Hen, professor of neuroscience and pharmacology.