Santiago Ramón y Cajal

paths,” once laid, could not be widened or narrowed, much less rerouted. They stood with Santiago Ramón y Cajal, the eminent Spanish physician, neuroanatomist, and Nobel laureate, who in 1913 declared, with a tone that left little room for debate, “In the adult [brain] centres, the nerve paths are something fixed, ended, immutable. Everything may die, nothing may be regenerated.”8 In his younger days, Ramón y Cajal had himself expressed doubts about the orthodox view—he had suggested, in 1894, that the