Adult mice engineered to have more newborn neurons in their brain memory hub excelled at accurately discriminating between similar experiences an ability that declines with normal aging and in some anxiety disorders. Boosting such neurogenesis in the adult hippocampus also produced antidepressant-like effects when combined with exercise, in the study funded by the National Institutes of Health.
Researchers, for the first time, pinpointed the effects of enhanced adult neurogenesis by creating mice lacking a gene required for programmed cell death of newborn neurons in the adult hippocampus.
"These mice with more young neurons were better at recognizing patterns tasks that become more challenging as we age," explained Rene Hen Ph.D., of Columbia University in New York City. "A deficit in this ability can also contribute to anxiety, as over-generalization sometimes leads to mistaking ambiguous cues as threatening. Our study demonstrates that the stimulation of adult neurogenesis is sufficient to improve such pattern recognition behavior, but, while necessary, not sufficient to lift depression-like behavior."
Hen and Amar Sahay, Ph.D., grantees of the NIH's National Institute of Mental Health (NIMH), and colleagues, report on their discovery online April 3, 2011, in the journal Nature.
"By helping to disentangle effects of enhanced neurogenesis on cognition from those on mood, this study brings us closer to understanding how it might be harnessed in the service of better treatments for disorders like depression, post traumatic stress syndrome and panic disorder, as well as for cognitive decline," said NIMH Director Thomas R. Insel, M.D.
In earlier studies, Hen and colleagues had shown that birth of new neurons in the hippocampus was necessary for the therapeutic effects of current antidepressant medications. Since it takes weeks for these cells to grow and become integrated into brain circuits, this he
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NIH/National Institute of Mental Health