Nerves Do Regenerate

Neurons, once thought to be irreparable, can grow anew—even in the brain

- Diana Kwon

BILLIONS OF NERVE CELLS send signals coursing through our bodies, serving as conduits through which the brain performs its essential functions. For millennia physicians thought damage to nerves was irreversible. In ancient Greece, founders of modern medicine such as Hippocrates and Galen refused to operate on damaged nerves for fear of causing pain, convulsions or even death.

The dogma stood relatively still until the past two centuries, during which surgeons and scientists found evidence that neurons in the body and brain can repair themselves and regenerate after injury and that new nerve cells can grow throughout the lifespan. In recent decades this knowledge has inspired promising treatments for nerve injuries and has led researchers to investigate interventions for neurodegenerative disease.

In humans and other vertebrates, the nervous system is split into two parts: the central nervous system, composed of the spinal cord and brain, and the peripheral nervous system, which connects the brain to the rest of the body.

Attempts to suture together the ends of damaged neurons in the peripheral nervous system date back to the seventh century. It was only in the late 1800s, however, that scientists began to understand how, exactly, nerves regenerate. Through his experiments on frogs, British physiologist Augustus Waller described in detail what happens to a peripheral nerve after injury. Then, in the 1900s, the influential Spanish neuroanatomist Santiago Ramón y Cajal provided insight into how nerve regeneration occurs at the cellular level. Still, there remained fierce debate about whether stitching nerves together would harm more than help.