If old dogs haven’t been able to learn new tricks, maybe that’s because no one has known how to teach them properly. Until quite recently orthodox neuroscience held that only the brains of young children are resilient, malleable, and morphable—in a word, plastic.This neuroplasticity, as it is called, seems to fade steadily as the brain congeals into its fixed adult configuration. Infants can sustain massive brain damage, up to the loss of an entire cerebral hemisphere,and still develop into nearly normal adults; any adult who loses half the brain, by contrast, is a goner. Adults can’t learn to speak new languages without an accent, can’t take up piano in their fifties then go on to play Carnegie Hall, and often suffer strokes that lead to permanent paralysis or cognitive deficiencies. The mature brain, scientists concluded, can only decline.

It turns out this theory is not just wrong, it is spectacularly wrong. Two new books, Train Your Mind, Change Your Brain (Ballantine Books, $24.95) by science journalist Sharon Begley and The Brain That Changes Itself (Viking, $24.95) by psychiatrist Norman Doidge, offer masterfully guided tours through the burgeoning field of neuroplasticity research. Each has its own style and emphasis; both are excellent.

Both authors present more or less the same historical background,recounting landmark experiments by a small constellation of neuroscientists who doggedly championed the idea of adult neuroplasticity through its wilderness years, from the 1960s throughmid-1990s. Both also describe how mainstream neuroscience, to its chagrin as well as its delight, is finally warming to the idea that much of the neural dynamism in the childhood brain remains active all through life (it just needs a little help to manifest fully). Finally,both authors conclude that adult neuroplasticity is a vastly undertapped resource, one with which Western medicine and psychology are just now coming to grips. An important emerging research agenda is to figure out ways to direct and maximize this brain repair and reorganization.

Those permanently paralyzed stroke patients? Quite a few are now recovering far more function than conventional physical therapy allows,thanks to new rehabilitation programs that capitalize on neuroplasticity. Other breakthroughs include treatments for learning disorders like dyslexia, mental training programs that can halt and even reverse senility, and promising treatments for post-traumatic stress, ­obsessive-compulsive disorder, depression, and other notorious ills of the human mind. Some of the new techniques are so low-tech that they could have been employed by physicians of antiquity, if only they had known about them.

In fact, great breakthroughs in applied neuroplasticity were apparently made long ago by practitioners of Tibetan Buddhism. The scientific investigation of Buddhist meditation, one of the most fascinating areas of neuroplasticity research today, is the focus and polestar of Begley’s book. In elegant and lucid prose, she recounts the story of a remarkable collaboration forged just a few years ago between Western neuroscientists and senior Tibetan Buddhist monks. Their spiritual leader, the Dalai Lama, who brokered much of the discourse,comes across as remarkably astute and friendly to science.

This unusual syncretic exercise between the academy and a major world religion may rouse suspicion among hard-nosed skeptics, but an open mind here will be rewarded. The research does not concern metaphysical claims regarding reincarnation and karma; rather, it involves measurable, replicable effects of Buddhist meditation practices on the mind and brain. This rigorous mental training drives neuroplasticity in ways that awe many of the scientists studying it.Brain scans reveal that the neural activity of highly trained monks is off the charts, relative to meditation novices, in circuits that involve maternal love (caudate), empathy (right insula), and feelings of joy and happiness (left prefrontal cortex). Even when these monks are not meditating, their brains bear the imprints of their psychic workouts. The latter two structures, for instance, are anatomically enlarged. Based on results like these, Begley holds out hope that our emotional lives and personalities, far from being carved in stone by our genes and early experiences, will prove as sculptable through mental training as our bodies are through physical training.

Doidge’s book covers more territory at the expense of tighter focus.This is not a bad thing, since the end result is a solid survey of one of neuroscience’s hottest areas. A practicing psychiatrist, Doidge chronicles not only the science and theory of neuroplasticity, but also his conversations with diverse patients—dealing with all manner of emotional and neurological afflictions—who are directly benefiting from the science. He speaks with researchers, too, about their moments of inspiration and insight. Along with eminently clear accounts of the relevant concepts and experiments, he gives well-turned descriptions of personalities and in-the-moment reactions. This wider sampling and more intimate depiction makes for an appealing read.

If either book can be faulted, it would be for the occasional whiff of overstatement. At times each author seems to say that our brains’ potential for transformation is essentially infinite, rather than merely astonishing and paradigm busting. But these excesses of enthusiasm are understandable, given the present-day backdrop. Science,like any other human endeavor, is susceptible to trends and pendulous swings of groupthink. The current vogue is for “neurogenetic determinism,” the view that your genes and subconscious are the true,essential shapers of who you are and how you think and behave; the conscious mind is little more than a self-important figurehead along for the ride. Begley and Doidge wade against this current with a strong message of hope: By recognizing neuroplasticity as a real and powerful force, we can tilt our theories of mind back into a realm where choice and free will are meaningful concepts, and where radical improvement to the human condition is possible using the right, scientifically proven techniques. The wonderful thing is, the hope they offer is not of the blind variety. There are solid, empirical reasons to think they may be right.