Molecular Mechanism for Overcoming Fear Identified

Researchers working with mice have found that L-type voltage-gated calcium channels (LVGCCs), a type of electrical switch found in brain cells, are required to overcome fear but play no role in becoming fearful or expressing fear. Their findings were published in the October 15, 2002, issue of the Journal of Neuroscience.

Both the acquisition and extinction of conditional fear are forms of active learning. The acquisition of conditional fear requires a unique pairing of an initially neutral conditional stimulus with an aversive unconditional stimulus. In this study, the conditional stimulus was a tone and the unconditional stimulus was a mild foot shock.

In examining this process, researchers from the University of California, Los Angeles (USA; www.ucla.edu), injected mice with the LVGCC inhibitors nifedipine and nimodipine to test whether LVGCC activity is required for the acquisition, expression, and/or extinction of conditional fear. The results showed that blocking LVGCC activity had no effect on the acquisition or expression of fear, but effectively prevented extinction.

"Brain plasticity, or the ability of the central nervous system to modify cellular connections, has long been recognized as a key component to learning and memory,” explained senior author Dr. Mark Barad, assistant professor of psychiatry at the David Geffen School of Medicine at UCLA. "The discovery of a distinct molecular process in overcoming fear bodes well for development of new drugs that can make psychotherapy, or talk therapy, easier and more effective in treating anxiety disorders. More broadly, the findings also suggest that distinct molecular processes may be involved in the expression and treatment of other psychiatric disorders.”



Related Links:
University of California, Los Angeles