The first glimmer of hope for CNS regeneration came in 1981, when Samuel David and Albert Aguayo of McGill University in Montreal showed that damaged CNS nerve cells could regrow if they were provided with a bridge made of tissue from the PNS. Normally, something in the CNS was preventing growth, but that something was absent in the PNS. The experiments "told us for the first time that neurons in the CNS have the capacity to grow," says David.

Experiments by Andrew Blight, now vice-president for research and development at Acorda, told Cohen he didn’t have to reconnect all the axons. When Blight took a careful look at damaged spinal cords, he found that animals that retained less than<10% of their axons intact could still walk. Meanwhile, Wise Young at New York University Medical Center had coordinated a study showing that high doses of methylprednisolone , a corticosteroid thought to act as an anti-oxidant, had beneficial effects if given within 8 hours of injury. The effect was modest, but it proved that SCI was a tractable problem. Young helped Cohen form Acorda in 1995.