IN SOME WAYS, the nervous system is like a thunderstorm, the controlled chaos of gathering electrical activity occasionally rendered visible in a bolt of lightning. The delicate skin of every neuron is studded with proteinaceous pumps that siphon positively charged ions—potassium, sodium, calcium—out of the cell and into its watery surroundings

This is the paradox of pain, the one the scales fail to fully capture: it is profoundly intimate. In the language of philosophy, our experience of pain is incorrigible, something that cannot be accessed from beyond the bounds of our own bodies: no one can fully know another's pain; we can only believe it.

The brain is not just a passive observer in the experience of pain. It shapes pain, amplifies it, echoes it. Brains exposed to prolonged periods of pain become more sensitive to it, the neurons that receive the signals of pain firing more readily, recruiting their neighbors to sense pain, too: pain begetting pain, a relentless cycle of suffering.

In some cultures, the mind is a private space, while in others, it is open to outside influences--loved ones, elders, and the divine--in important ways that shape how inner voices are received or even heard.

In patients with functional weakness, these imaging studies show that the structures that suppress unpleasant memories of traumatic experiences are overactive. Perhaps the neurons of the motor cortex are suppressed, too, collateral damage from a haunted brain struggling to quiet itself. In patients with functional tremors--not the circumscribed

A confabulation is not a falsification; unlike a fabulist, a confabulator has no intent to deceive, but he also has no insight that the stories he tells are entirely of his own invention. Rather, a confabulation is a story that is true for the person who tells it, even if the facts have no grounding in the real world: a new memory in the place of

… another part of me, standing at the neurologist's side, felt brilliantly alive—as if I were witnessing something miraculous, an alchemical transformation from a series of minute observations about someone's body to an essential truth, equal parts deduction and ritual. In my three years of medical school, I had already started to learn that there