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It was a humble beginning to a career in neuroscience that led to the University of Ottawa and Harvard University, and the discovery, announced Thursday, of a new way to coax damaged nerves to repair themselves.
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Until about the age of two, the neurons in the human brain are still growing, stretching out long arms known as axons to form connections and build networks and circuits. After that, experience and learning shape those connections largely through pruning, said Dr. Smith, now 32 and running her own lab at Carleton University. Superfluous connections are trimmed; those used more frequently are strengthened in a variety of ways that don't involve the growth of axons.
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Now, she and colleagues at Harvard have a found a molecule that appears to put the brakes on neuron growth in adult mice.

It is called SOCS3. When the scientists blocked it in adult mice with crushed optic nerves, the damaged neurons began to sprout.