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 helped to explain the delay in symptom improvement experienced by patients. Evidence has also emerged that environmental enrichment and exercise can also stimulate neurogenesis and produce antidepressant-like effects. Yet the exact contributions of increased adult neurogenesis remained elusive.
To identify them, the researchers used genetic engineering to create mice lacking a gene that normally kills off 50-80 percent of newborn neurons in the adult hippocampus. These mice with a relative surplus of adult-born neurons were champs at learning to discriminate between a chamber where they had previously received a foot shock and a similar-looking chamber that was safe. By contrast, mice in which adult hippocampal neurogenesis was blocked performed poorly at this fear discrimination learning task, often freezing in safe chambers.
Yet, the mice with genetically enhanced adult neurogenesis did not show improved anti-anxiety or antidepressant-like behaviors, such as increased exploration in anxiety-producing situations. Such behaviors emerged in these mice only after four weeks of wheel running exercise, suggesting that neurogenesis might need to be accompanied by some kind of environmental enhancement to produce such effects.
Hen and Sahay said they are now using neuronal growth factors in combination with enhanced neurogenesis to explore possible mechanisms underlying such anti-anxiety and antidepressant effects. They are also weighing emerging evidence that neurogenesis in the bottom part of the hippocampus influences mood and anxiety-related behaviors, while neurogenesis in the top part of the mouse brain structure may have more to do with thinking and memory.
Increasing adult hippocampal neurogenesis is sufficient to improve pattern separation. Sahay A, Scobie KN, Hill AS, O'Carroll CM, Kheirbek MA, Burghardt NS, Fenton AA, Dranovsky A, Hen R. Nature. Epub 2011 Apr 3.
The mission of the NIMH is to transform the understanding and treatment of mental illnesses through basic and clinical research, paving the way for prevention, recovery and cure. For more information, visit the NIMH website, www.nimh.nih.gov.
About the National Institutes of Health (NIH): NIH, the nation's medical research agency includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov.
Jules Asher | EurekAlert!
A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
On the way to developing a new active ingredient against chronic infections
18.08.2017 | Deutsches Zentrum für Infektionsforschung
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
18.08.2017 | Life Sciences
18.08.2017 | Physics and Astronomy
18.08.2017 | Materials Sciences