Press release

NEURONAL STEM CELL IN ADULTS
New neurons for the olfactory bulb

For the first time, researchers showed how a neural precursor gradually acquires functional characteristics to become a genuine neurone. This study was led by the team of Pierre-Marie Lledo, Head of the "Olfactory perception and memory" (CNRS URA 2182) unit of the Institut Pasteur, in collaboration with the team of Arturo Alvarez-Buylla of the University of California in San Francisco, and will be published as a preview on the site of Nature Neuroscience (http://www.nature.com/neuro/). This could contribute to creating new therapeutic strategies.

We have recently found that stem cells are able to produce new neurones in adults. A cell proliferation zone at the heart of the brain permanently generates immature neurones. These young cells migrate over long distances (several centimetres in humans), at high speeds (100 µm/hour), thanks to a so-called "chain'" cell migration process, before reaching their target tissue.

Although important progress has been made on the means of production of immature neurones, maturation stages, the mode of integration and the functional consequences of the arrival of newly formed neurones remain unexplored. Researchers from Institut Pasteur and the University of California have used mice to monitor the evolution of neurones born in the sub-ventricular zone next to cerebral ventricles, and migrating towards the olfactory bulb where young cells are gradually differentiated into neurones. Roughly two weeks are required for a new cell to reach the olfactory bulb and integrate the existing circuit. Researchers have proved that the cerebral capacity for the production of new neurones depends on unique mechanisms in the adult brain, entirely different from embryonic processes. Researchers have also shown that newly formed neurones are not only able to integrate an existing network, but can also, and above all, add new properties to the neuronal network accepting them.

"This research adds to our knowledge of the central nervous system's regenerating mechanisms and functions. In therapeutic terms, this could lead to new strategies based on the transplant or transfer of the newly formed neurones from their original zone in the brain. Obviously, many questions remain unanswered. How does a newly generated neurone cell migrate and find its target? How does it choose its future development?", said Pierre-Marie Lledo.

Researchers are currently attempting to answer all these questions.

Source:

"Becoming a new neuron in the adult olfactory bulb". Nature Neuroscience. May 2003.

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