Can an adult brain really rewire itself?

Yes, an adult brain can rewire itself, but within limits. Neuroplasticity is the brain's ability to reorganize and rewire its neural connections, enabling it to adapt and function in ways that differ from its prior state. For most of the twentieth century scientists believed the opposite: up until the 1970s, neuroscientists believed that the brain's structure and function was essentially fixed throughout adulthood. Research since then showed that many aspects of the brain exhibit plasticity through adulthood, although the developing brain is more plastic than the adult brain.

The evidence is concrete. Eleanor Maguire documented changes in hippocampal structure in London taxi drivers, associated with learning the layout of the city, and found a redistribution of grey matter compared to controls. In people recovering from stroke, regions of the brain that remained healthy could sometimes take over, at least in part, functions that had been destroyed. Michael Merzenich's monkeys, whose hand maps stayed nearly normal after a nerve was cut and rejoined, convinced him that the view that we are born with a hardwired system had to be wrong.

But the story has a catch. Plasticity is not always a gift: phantom limb sensation occurs in 60–80% of amputees, and phantom limb pain was found to be the perceptual correlate of cortical reorganization, a phenomenon sometimes called maladaptive plasticity. And some cognitive abilities may never fully recover after injury or disease, according to those who stress that plasticity is constrained.