We don’t want to believe that we’re ever too old to learn.

We would much prefer to think that the amazing machine called the brain is infinitely fertile and receptive throughout our lives, and that we could master whatever new skills interest us, regardless of age.

Some of us intend to take up the violin one day, for example, and dream about the unlimited musical potential that lies within us. Or maybe we plan to learn to speak at least one other language fluently before we’re done — perhaps even begin to think in that new tongue and grow closer to understanding a foreign culture.

We debunk the old saw that “You can’t teach an old dog new tricks” as silly and self-defeating. Just because our parents didn’t lead us to the piano when we were four, let’s say, or we weren’t exposed to a foreign language until high school, doesn’t mean that we can’t pick up these skills later in life. Bright and curious adults don’t have to be slaves to their uninspired childhoods. Given the time and the inclination, who knows what greatness we could awaken inside ourselves?

While those possibilities exist, you might want to hold off on promising your friends tickets to your much-belated Carnegie Hall debut. For along comes evidence to suggest that the full extent our adult brainpower is determined early in life by the influence of parents and teachers. The parts of our brains that we’re not trained as children to use are quickly lost to us forever.

According to an article in Technology Review, published by the Massachusetts Institute of Technology, the cortex of the brain operates at adult speed by the age of two. By four, a child’s brain is more than twice as active as an adult’s, madly gobbling up glucose as it tries to sustain trillions of connections between neurons. The connections represent potential pathways for message-carrying electrical impulses. Those that are strengthened by external stimulation are opened forever. Those that aren’t exercised early on can never mature.

At 10, the frantic brain activity begins to slow down until it settles back to adult levels at 16. By then, say the researchers, the computers in our heads are already pre-wired. Whether they are wired to accomodate our burgeoning musical yearnings later in life, for instance, really depends on whether we took music lessons as very young children.

So the broadest possible education is the key, after all. The more stimulation we get as children — a little of everything in those formative first years — the better our brains will function as adults. Deprive little Johnny of his finger paints and crayons, in other words, and big Johnny has little chance of becoming the next Picasso, no matter how much he tries.

And there you have it: science as the great burster of adult creative bubbles, the crusher of our latent dreams and ambitions. None of us wants to admit that we suffer from premanently blocked brain pathways. We hate to think that we’ll never realize our full potential because our parents preferred bowling to Beethoven and never took us to museums.

The evidence is there, however. At 40, your chances of becoming another Kenny G. on the sax are pretty slim if you never played any instrument as a kid. But while not all adults are pre-wired for greatness, this latest research holds a valuable lesson for parents of young children. Nourishing their early lives with a stimulating feast for the mind is at least one new trick that no adult is too old to learn.