The Brain: How The Brain Rewires Itself

Where do you feel that? Ramachandran asked. On his left cheek, Victor answered--and the back of his missing hand. Ramachandran stroked another spot on the cheek. Where do you feel that? On his absent thumb, Victor replied. Ramachandran touched the skin between Victor's nose and mouth. His missing index finger was being brushed, Victor said. A spot just below Victor's left nostril caused the boy to feel a tingling on his left pinkie. And when Victor felt an itch in his phantom hand, scratching his lower face relieved the itch. In people who have lost a limb, Ramachandran concluded, the brain reorganizes: the strip of cortex that processes input from the face takes over the area that originally received input from a now missing hand. That's why touching Victor's face caused brain to "feel" his missing hand.

Similarly, because the regions of cortex that handle sensations from the feet abut those that process sensations from the surface of the genitals, some people who have lost a leg report feeling phantom sensations during sex. Ramachandran's was the first report of a living being knowingly experiencing the results of his brain rewiring.

THINKING ABOUT THINKING

AS SCIENTISTS PROBE the limits of neuroplasticity, they are finding that mind sculpting can occur even without input from the outside world. The brain can change as a result of the thoughts we think, as with Pascual-Leone's virtual piano players. This has important implications for health: something as seemingly insubstantial as a thought can affect the very stuff of the brain, altering neuronal connections in a way that can treat mental illness or, perhaps, lead to a greater capacity for empathy and compassion. It may even dial up the supposedly immovable happiness set point.

In a series of experiments, for instance, Jeffrey Schwartz and colleagues at the University of California, Los Angeles, found that cognitive behavior therapy (CBT) can quiet activity in the circuit that underlies obsessive-compulsive disorder (OCD), just as drugs do. Schwartz had become intrigued with the therapeutic potential of mindfulness meditation, the Buddhist practice of observing one's inner experiences as if they were happening to someone else.

When OCD patients were plagued by an obsessive thought, Schwartz instructed them to think, "My brain is generating another obsessive thought. Don't I know it is just some garbage thrown up by a faulty circuit?" After 10 weeks of mindfulness-based therapy, 12 out of 18 patients improved significantly. Before-and-after brain scans showed that activity in the orbital frontal cortex, the core of the OCD circuit, had fallen dramatically and in exactly the way that drugs effective against OCD affect the brain. Schwartz called it "self-directed neuroplasticity," concluding that "the mind can change the brain."