Chicago runner Lynn Rogers knows the brain and nervous system in detail. After all, she earned her Ph.D. in biomedical engineering. Every day in her research, she uses non-invasive brain stimulation to understand the connections between mind and muscle. But even with a brain-science background, she struggled to find information about her prognosis when, last year, she received a rare diagnosis: chronic inflammatory demyelinating polyneuropathy, or CIDP. The disease causes her body to attack her own nerve cells, destroying their protective coatings and short-circuiting their signals. After three weeks of paralysis and three months as an inpatient at the same...