GARDEN CITY, N.Y. - Now that surgeons have operated on Stacey Gayle's brain, her favorite musician no longer makes her ill. Four years after being diagnosed with epilepsy, Gayle recently underwent brain surgery at Long Island Jewish Medical Center to cure a rare condition known as musicogenic epilepsy.Gayle, a 25-year-old customer service employee at a bank in Alberta, Canada, was suffering as many as 10 grand mal seizures a day, despite being treated with medications designed to control them. The condition became so bad she eventually had to quit her job and leave the church choir where she sang.Eighteen months …