BBC: The brain's miracle superpowers of self-improvement
For many years, the consensus was that the human brain couldn’t generate new cells once it reached adulthood. Once you were grown, you entered a state of neural decline. This was a view perhaps most famously expressed by the so-called founder of modern neuroscience Santiago Ramon y Cajal. After an early interest in plasticity, he became sceptical, writing in 1928, “In adult centres the nerve paths are something fixed, ended, immutable. Everything may die, nothing may be regenerated. It is for the science of the future to change, if possible, this harsh decree.” Cajal’s gloomy prognosis was to rumble through the 20th Century.
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Although it took several decades, Merzenich and Bach-y-Rita were to help prove that Cajal and the scientific consensus were wrong. The adult brain was plastic. It could rewire itself, sometimes radically. This came as a surprise to experts like Robertson, now a Director of Trinity College Dublin’s Institute of Neuroscience. “I can look back on giving lectures at Edinburgh University to students where I gave wrong information, based on the dogma which said that, once dead, a brain cell cannot regenerate and plasticity happens in early childhood but not later,” he says.
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Scott says something similar about speech and language therapy. “There were dark days say, 50 years ago, where if you’d had a stroke you didn’t get that kind of treatment other than to stop you choking because they’d decided it doesn’t work. But now it’s becoming absolutely clear that it does, and that it’s a phenomenally good thing. But none of it comes for free.”
My experience is that the adult brain is more than plastic enough to learn a new language, and that the biggest obstacles will usually be the lack of opportunities to use the language day-in and day-out during decades of life, school and work. Indeed, as both sfuqua and I have personally witnessed, adult language learning can be startlingly rapid, given no more than a few thousand pages of comprehensible input.
But at the same time, adults don't get everything for free. There are educated adults who've spoken French as their primary language for decades, starting in their 20s, who still make gender errors. Accents are also notoriously rough for adults, and the people who completely eliminate their accents often do intense amounts of focused work. The adult brain isn't infinitely malleable. But it doesn't need to be—adults can learn a language well enough to use it in pretty sophisticated ways.
(And even in situations where we know the adult brain is notoriously inflexible, there are interesting bits of research that pop up from time to time that probably deserve a bit more medical study.)
