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

It turns out this theory is not just wrong, it is spectacularlywrong. Two new books, Train Your Mind, Change Your Brain (BallantineBooks, $24.95) by science journalist Sharon Begley and The Brain ThatChanges Itself (Viking, $24.95) by psychiatrist Norman Doidge, offermasterfully guided tours through the burgeoning field ofneuroplasticity research. Each has its own style and emphasis; both areexcellent.

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

Those permanently paralyzed stroke patients? Quite a few are nowrecovering far more function than conventional physical therapy allows,thanks to new rehabilitation programs that capitalize onneuroplasticity. Other breakthroughs include treatments for learningdisorders like dyslexia, mental training programs that can halt andeven reverse senility, and promising treatments for post-traumaticstress, ­obsessive-compulsive disorder, depression, and other notoriousills of the human mind. Some of the new techniques are so low-tech thatthey could have been employed by physicians of antiquity, if only theyhad known about them.

In fact, great breakthroughs in applied neuroplasticity wereapparently made long ago by practitioners of Tibetan Buddhism. Thescientific investigation of Buddhist meditation, one of the mostfascinating areas of neuroplasticity research today, is the focus andpolestar of Begley’s book. In elegant and lucid prose, she recounts thestory of a remarkable collaboration forged just a few years ago betweenWestern neuroscientists and senior Tibetan Buddhist monks. Theirspiritual 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 majorworld religion may rouse suspicion among hard-nosed skeptics, but anopen mind here will be rewarded. The research does not concernmetaphysical claims regarding reincarnation and karma; rather, itinvolves measurable, replicable effects of Buddhist meditationpractices on the mind and brain. This rigorous mental training drivesneuroplasticity in ways that awe many of the scientists studying it.Brain scans reveal that the neural activity of highly trained monks isoff the charts, relative to meditation novices, in circuits thatinvolve maternal love (caudate), empathy (right insula), and feelingsof joy and happiness (left prefrontal cortex). Even when these monksare not meditating, their brains bear the imprints of their psychicworkouts. The latter two structures, for instance, are anatomicallyenlarged. Based on results like these, Begley holds out hope that ouremotional lives and personalities, far from being carved in stone byour genes and early experiences, will prove as sculptable throughmental 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 oneof neuroscience’s hottest areas. A practicing psychiatrist, Doidgechronicles not only the science and theory of neuroplasticity, but alsohis conversations with diverse patients—dealing with all manner ofemotional and neurological afflictions—who are directly benefiting fromthe science. He speaks with researchers, too, about their moments ofinspiration and insight. Along with eminently clear accounts of therelevant concepts and experiments, he gives well-turned descriptions ofpersonalities and in-the-moment reactions. This wider sampling and moreintimate depiction makes for an appealing read.

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