Despite a long-held scientific belief that much of the wiring of the brain is fixed by the time of adolescence, a new study shows that changes in sensory experience can cause massive rewiring of the brain, even as one ages. In addition, the study found that this rewiring involves fibers that supply the primary input to the cerebral cortex, the part of the brain that is responsible for sensory perception, motor control and cognition. These findings promise to open new avenues of research on brain remodeling and aging.